12:05 Garage- ’70 Duster build

[DionR]

I'll also ditch the poly bushings and go with heim joints.

I like the modern balljoint style connectors myself.

My plan on the '73 Hemi car is to use LCA's without the swaybar mounts and build a mount up higher so I can run links that don't need to be modified. But that's a project for after the car is running and driving.

 

[JBrian]

It feels very good with the exception of the body roll. The additional tire size is a noticeable difference in grip. They have definitely given me more confidence to carry more speed. I was 2 seconds behind a mult-time national female winner who was driving a C8. She had FTD. I know 2 seconds is a lot, but I'll call that good considering I'm driving grandma's car and she's in a modern supercar.

In October, after MoParty, I moved DOWN a size from Michelin Super Sport (300 Treadwear) 255/40-18x9, 285/35-18x9.5 to Falken RT660 245/40-18x9, 275/35-18x9.5 (200 Treadwear) tire designed as a very stretable autocross tire. The difference in grip was night and day. I was just fighting the car the entire time with the Michelins, sliding around almost every corner. I wore the front tires down to the wear bars in 2300 miles of street and autocross! The good news, I'm no longer fighting the car and dropped almost 4 seconds off my time with the Falkens compared to my other CAM-T coopetitors, and I can run higher tire pressure of 39/36PSI! I'm expecting to slice a few more seconds off my time next spring while I upgrade to sliders for my rear springs before I bend the offset shackles.

Tim, as usual moved from the Falkens RT660s I just upgraded too, and now runs a larger footprint Bridgestone RE71, which are still on the edge of streetable, but known as the best autocross tires for the past several years. That may likely change this year with new Hoosiers coming on the scene. I would guess the RE71s are worth about .50-.75 of a second on a similar autocross course. So, until I get within a second of Tim on the same course, I don't have any excuses but my driving ability. I've already chopped off 10 seconds from my quickest time last fall due to various upgrades and better driving. We'll see where we stack up next year.

For those those that haven't autocrossed, it's hell on these old cars. I even loosened ALL of my K-member bolts within 24 passes and have now added checking those bolts which are torqued to 150FTLBS after every event, typically 6 runs. Autocross is like turning into your driveway at 35MPH, actually borderline violent to ride in AND we can give rides with just a helmet required. In others words, it's a hoot! I can't wait till spring!

 

[DartManPlum340]

In October, after MoParty, I moved DOWN a size from Michelin Super Sport (300Treadwear) 255/40-18x9, 285/35-18x9.5 to Falken RT660 245/40-18x9, 275/35-18x9.5 (200 Treadwear) tire designed as a very stretable autocross tire. The difference in grip was night and day. I was just fighting the car the entire time with the Michelins, sliding around almost every corner. I wore the front tires down to the wear bars in 2300 miles of street and autocross! The good news, I'm no longer fighting the car and dropped almost 4 seconds off my time with the Falkens compared to my other CAM-T coopetitors, and I can run higher tire pressure of 39/36PSI! I'm expecting to slice a few more seconds off my time next spring while I upgrade to sliders for my rear springs before I bend the offset shackles.

Tim, as usual moved from the Falkens RT660s I just upgraded too, and now runs a larger footprint Bridgestone RE71, which are still on the edge of streetable, but known as the best autocross tires for the past several years. That may likely change this year with new Hoosiers coming on the scene. I would guess the RE71s are worth about .50-.75 of a second on a similar autocross course. So, until I get within a second of Tim on the same course, I don't have any excuses but my driving ability. I've already chopped off 10 seconds from my quickest time last fall due to various upgrades and better driving. We'll see where we stack up next year.

For those those that haven't autocrossed, it's hell on these old cars. I even loosened ALL of my K-member bolts within 24 passes and have now added checking those bolts which are torqued to 150FTLBS after every event, typically 6 runs. Autocross is like turning into your driveway at 35MPH, actually borderline violent to ride in AND we can give rides with just a helmet required. In others words, it's a hoot! I can't wait till spring!

View attachment 1716335564View attachment 1716335565View attachment 1716335566View attachment 1716335567

RIDES? How do I get one? I used to autocross Datsun Z cars back in the day. I'll stop by the Arena next spring/summer!

 

[JBrian]

RIDES? How do I get one? I used to autocross Datsun Z cars back in the day. I'll stop by the Arena next spring/summer!

Here is the STL SCCA schedule for 2025, all at Family Arena in ST Charles. I should be at all of them, just bring your helmet, shorts, tee-shirt and sneakers!

April 13th E1
May 2-4 SCCA National CAM/XS Challenge & E2 (This will be an *** kicking, but hey, someone has to be fodder )
June 8th E3
June 29th E4
July 20th E5
August 10th E6
Sept 14th E7 (Probably conflicts with MoParty)
Sept 28th E8
October 19th E9

 

[DartManPlum340]

Here is the STL SCCA schedule for 2025, all at Family Arena in ST Charles. I should be at all of them, just bring your helmet, shorts, tee-shirt and sneakers!

April 13th E1
May 2-4 SCCA National CAM/XS Challenge & E2 (This will be an *** kicking, but hey, someone has to be fodder )
June 8th E3
June 29th E4
July 20th E5
August 10th E6
Sept 14th E7 (Probably conflicts with MoParty)
Sept 28th E8
October 19th E9

Deal! I'll trade you a boat ride on the mighty Mississippi! Just bring your swim trunks, life vest and beer!

 

[racerjoe]

I like the modern balljoint style connectors myself.

View attachment 1716335570

My plan on the '73 Hemi car is to use LCA's without the swaybar mounts and build a mount up higher so I can run links that don't need to be modified. But that's a project for after the car is running and driving.

I've considered going this route as well. I would have to use the one with one side 90 to the other like this one. I would need to figure out that taper and simply drill my arms to match.

 

[mygasser]

you could get a second sway bar and make some aluminum blocks to clamp it under the existing one. cut the ends off where the end links bolt up for clearance. 2 clamps each side outboard of the k member and a pair in the middle. altering the position of the clamps alters the 'strength' of the sway bar/s. it was a common mod' for the ford anglia 105e (think harry potter, lol) when used for circuit racing in the 60's/70's.
neil.

 

[bjkadron]

It is bottoming out and it was before I even put this setup on the car. If you look close at the second picture, my inside rear is slightly off the ground. Ths only happens on high speed sharp turns. Denny supplies a 1" solid sway bar, the Hotchkis bar I used to run was 1.5" hollow. Using the Addco online sway bar stiffness calculator, there's a significant stiffness difference between the two. A member here, @bjkadron volunteered to help me do some mathing once I get him some weights for him. I'm going to make a splined end tubing type sway bar and I want to make sure I pick the right size tubing. Had he not volunteered, I would have just gone with the same size tubing the Hotchkis bar has, 1.5" x .188" wall. I may end up with that, but at least I'll have some math behind it instead of just guessing.

Yeah, I need to get to work getting all that math into a spreadsheet. I'm hoping to have some time to do that over the Holidays. I'm curious what we come up with. Should be a handy resource for me once I get it done too.

Yes, still have the 450lb springs. That's another thing that Benjamin will evaluate for me. I don't want to go too stiff on the spring if the bar can make up for it. After all, I still street drive this thing and I wouldn't want to make it so stiff that it becomes unpleasant. I'm going to scratch make everything for the sway bar and I'll detail it all here. I figured out a relatively "cheap" solution. The base of the design will be a larger diameter tube that spans across the current mounting points to add some rigidity. That tube will have bushings in the ends that can be swapped out to match the diameter of the actual sway bar tube. I also plant to have a few holes in the arms so I'll have some finite adjustability. I'll also ditch the poly bushings and go with heim joints. I'll have to see if those end up being too harsh for street driving. If they are, I can simply make up something with a bushing for one side and swap it out when needed.

My initial thoughts are that it is mostly your roll stiffness that is giving you trouble. I'm hoping to get to an event in person soon but at moparty and in pictures I don't really see issues with fore/aft weight transfer so I'm thinking that it is just the change is roll stiffness that your lower roll center, combined with the smaller swaybar threw off the roll couple front to rear. Increasing spring rates too much will just make the ride worse and could upset the car over bumps.

 

[72bluNblu]

Yes, still have the 450lb springs. That's another thing that Benjamin will evaluate for me. I don't want to go too stiff on the spring if the bar can make up for it. After all, I still street drive this thing and I wouldn't want to make it so stiff that it becomes unpleasant. I'm going to scratch make everything for the sway bar and I'll detail it all here. I figured out a relatively "cheap" solution. The base of the design will be a larger diameter tube that spans across the current mounting points to add some rigidity. That tube will have bushings in the ends that can be swapped out to match the diameter of the actual sway bar tube. I also plant to have a few holes in the arms so I'll have some finite adjustability. I'll also ditch the poly bushings and go with heim joints. I'll have to see if those end up being too harsh for street driving. If they are, I can simply make up something with a bushing for one side and swap it out when needed.

Totally, it's definitely a balance. But I know that even in my street driving I'm bottoming my suspension still with a 300 lb/in wheel rate and the Hellwig sway bars, and I've maintained about the same amount of travel as stock so I'm at a spot where I know I need increase my wheel rate some. The 1.18's with a 370 lb/in rate may be a bit high, I'll have see once I get them into the car. But I don't think a 350 lb/in rate is going to be too much.

@AndyF built a splined sway bar for the Red Brick that went through the k-frame. Maybe he will share some wisdom on that.

View attachment 1716335568

Yep, that's basically the same design as the Kit Cars used. It used a tube with bushings at the ends and a splined shaft sway bar running through the bushings. These are pictures from the spring car catalog, and some of the ones used on the kit cars. I split up the catalog page so it would be large enough to read here, check out those torsion bar diameter and wheel rates on the second page. 1.38" and 654 lb/in !

Yeah, I need to get to work getting all that math into a spreadsheet. I'm hoping to have some time to do that over the Holidays. I'm curious what we come up with. Should be a handy resource for me once I get it done too.

My initial thoughts are that it is mostly your roll stiffness that is giving you trouble. I'm hoping to get to an event in person soon but at moparty and in pictures I don't really see issues with fore/aft weight transfer so I'm thinking that it is just the change is roll stiffness that your lower roll center, combined with the smaller swaybar threw off the roll couple front to rear. Increasing spring rates too much will just make the ride worse and could upset the car over bumps.

Yep, definitely a balance. You have to evaluate the suspension travel and how often the bottoming out is happening. If it's just during cornering while autoX'ing then the larger sway bar would be the way to go and should take care of it. But if the bottoming is also happening through bumps then you may need to increase the wheel rate. Obviously too high of a wheel rate will upset the car over bumps, but, so does bottoming the suspension. You want the lowest wheel rate that allows you to use your entire suspension travel without bottoming out the suspension frequently.

For me at 300 lb/in and in the neighborhood of ~5.5" of suspension travel I still probably bottom the suspension a little too much, even just on the street and that's leaving a pretty wide margin for tire grip in the corners, I'd obviously push harder on an autoX course. I'm beginning to come around to the idea that 350 lb/in is a lot closer to where the car needs to be for just the wheel rate off the springs.

 

[HemiDenny]

if you wanted to try a bigger hollow (chromoly) bar I could get my fab guy to bend one up and tigg tubing adapters for heims on the ends. That heim end set up is what has been on mine for 15 years. Just let me know the od and wall thickness.

pictured is 1" solid bar with tubing adapters / heim ends. this was done to accommodate the sway bar with my LCAs forward the extra 1".

 

[bjkadron]

Totally, it's definitely a balance. But I know that even in my street driving I'm bottoming my suspension still with a 300 lb/in wheel rate and the Hellwig sway bars, and I've maintained about the same amount of travel as stock so I'm at a spot where I know I need increase my wheel rate some. The 1.18's with a 370 lb/in rate may be a bit high, I'll have see once I get them into the car. But I don't think a 350 lb/in rate is going to be too much.



Yep, that's basically the same design as the Kit Cars used. It used a tube with bushings at the ends and a splined shaft sway bar running through the bushings. These are pictures from the spring car catalog, and some of the ones used on the kit cars. I split up the catalog page so it would be large enough to read here, check out those torsion bar diameter and wheel rates on the second page. 1.38" and 654 lb/in !

View attachment 1716335642

View attachment 1716335643

View attachment 1716335649
View attachment 1716335648


Yep, definitely a balance. You have to evaluate the suspension travel and how often the bottoming out is happening. If it's just during cornering while autoX'ing then the larger sway bar would be the way to go and should take care of it. But if the bottoming is also happening through bumps then you may need to increase the wheel rate. Obviously too high of a wheel rate will upset the car over bumps, but, so does bottoming the suspension. You want the lowest wheel rate that allows you to use your entire suspension travel without bottoming out the suspension frequently.

For me at 300 lb/in and in the neighborhood of ~5.5" of suspension travel I still probably bottom the suspension a little too much, even just on the street and that's leaving a pretty wide margin for tire grip in the corners, I'd obviously push harder on an autoX course. I'm beginning to come around to the idea that 350 lb/in is a lot closer to where the car needs to be for just the wheel rate off the springs.

Neat pictures of the Kit car stuff, I need to look in my books and see what other cool stuff they did.

I think for wheel rates it is also important to balance the frequency front and rear. if you don't the car is going to be moving at different speeds on each end as it hits bumps. I am starting with 1.09s (270ish WR) for mine, but I'm wondering if I'll have to bump that up as I progress. I'm also considering rising rate/progressive bump stop setup to ease the impact of bottoming as you approach the limits of travel. Maybe something like Chris Windsong did with his charger even though I don't agree with a lot of his stuff.

 

[72bluNblu]

Neat pictures of the Kit car stuff, I need to look in my books and see what other cool stuff they did.

I think for wheel rates it is also important to balance the frequency front and rear. if you don't the car is going to be moving at different speeds on each end as it hits bumps. I am starting with 1.09s (270ish WR) for mine, but I'm wondering if I'll have to bump that up as I progress. I'm also considering rising rate/progressive bump stop setup to ease the impact of bottoming as you approach the limits of travel. Maybe something like Chris Windsong did with his charger even though I don't agree with a lot of his stuff.

Here's one from one of the T/A or AAR cars, it was in a Mopar Action article. The sway bar tube runs right through the K and is braced. Also shows the notch in the frame where the factory cars have the frame stop for the LCA bump stop, not only is that gone but the notch allows even more suspension compression travel. On an A-body that notch would probably put the tire into the inner fender on full compression even with a stock LCA.

The kit car/circuit car stuff is pretty interesting, there's some really cool tricks in there but really at this point with the parts available today a lot of the stuff they did isn't relevant anymore, or isn't relevant to a street car. It's helpful to understand the suspension and the chassis some, and then there's just the wow factor of seeing a part number for a 1.64" diameter torsion bar with a 1,455 lb/in rate!

I ran a 270 lb/in wheel rate on my Challenger for the entire 70k+ street miles I put on it. It was a decent wheel rate for a street car, once I ditched the KYB's and added RCD Bilsteins the ride improved to the point that I was ready to up the torsion bar size again. With a set of 200 tread wear tires on an autoX course it would probably be a bit light. I think 300 lb/in is a better starting point, and honestly for a dedicated autoX car that's probably the light end of the range. For a car that still sees the street I don't know how high you'd want to go, I guess I'll find out when I fit my 1.18's (370 lb/in rate).

The problem with a good progressive bump stop is they're tall, they need room to work. And on these cars with only like 5" to 5.5" of travel you don't have a lot of travel to give up to bump stop, unless you want to be constantly using them. It's one thing on an off-road vehicle running high speeds with a long travel suspension set up, it's something else on a car that gets used on the street and has a fairly limited amount of suspension travel. Personally I'd rather tune the suspension with the wheel rate to use almost all of the available travel and limit bump stop use, rather than figure in the progressive rate of the bump stops in that last bit of travel. But that's my opinion, and there are definitely some different takes on how to set a car up. On that note...

Birdsong is junk science. He throws around a lot of technical terms that he's using incorrectly and reveals exactly NONE of his actual geometry data while making wild unsupported claims. The few things he gets right he explains incorrectly so I have to assume he stumbled into something that worked just by sheer luck. And he clearly skips past signifiant issues with his own set up. Good for youtube views I guess, but that's about it.

 

[JBrian]

My front suspension is comprised of 1.08" Swayaway torsion bars, SPC UCAs, boxed stock LCAs, Bilstein shocks, Hellwig 55917 swaybar which is 1.25" hollow with additional voodoo parts from Bergman Autocraft. My alignment specs are - 1.8 camber, - 6.1 caster, 1/32" total toe in. I'm very happy with the 1.08" torsion bars. I only bottom out on the occasional road irregularity that I can't avoid, it still rides very well, meaning not super stiff and steers well. I also run the Hellwig 6907 .75" rear swaybar on the middle setting. Frankly, I couldn't be happier with the way my car drives and handles in it's current setup. If I dialed in more camber, it would probably start to get jittery on the freeway even though it would certainly help corner steer-in in autocross. It's a pump gas friendly, bounce off the rev limiter @6700RPM that cruises at modern freeway speeds with A/C, P/S, Brembo/Viper front calipers on a 14.1" rotor, DRDIFF rear disc kit with Hydroboost, hoot to drive Muscle Car that I can autocross and win trophy's at car shows. It's exactly what I setout to build.

 

[bjkadron]

Here's one from one of the T/A or AAR cars, it was in a Mopar Action article. The sway bar tube runs right through the K and is braced. Also shows the notch in the frame where the factory cars have the frame stop for the LCA bump stop, not only is that gone but the notch allows even more suspension compression travel. On an A-body that notch would probably put the tire into the inner fender on full compression even with a stock LCA.
View attachment 1716335726

The kit car/circuit car stuff is pretty interesting, there's some really cool tricks in there but really at this point with the parts available today a lot of the stuff they did isn't relevant anymore, or isn't relevant to a street car. It's helpful to understand the suspension and the chassis some, and then there's just the wow factor of seeing a part number for a 1.64" diameter torsion bar with a 1,455 lb/in rate!

I ran a 270 lb/in wheel rate on my Challenger for the entire 70k+ street miles I put on it. It was a decent wheel rate for a street car, once I ditched the KYB's and added RCD Bilsteins the ride improved to the point that I was ready to up the torsion bar size again. With a set of 200 tread wear tires on an autoX course it would probably be a bit light. I think 300 lb/in is a better starting point, and honestly for a dedicated autoX car that's probably the light end of the range. For a car that still sees the street I don't know how high you'd want to go, I guess I'll find out when I fit my 1.18's (370 lb/in rate).

The problem with a good progressive bump stop is they're tall, they need room to work. And on these cars with only like 5" to 5.5" of travel you don't have a lot of travel to give up to bump stop, unless you want to be constantly using them. It's one thing on an off-road vehicle running high speeds with a long travel suspension set up, it's something else on a car that gets used on the street and has a fairly limited amount of suspension travel. Personally I'd rather tune the suspension with the wheel rate to use almost all of the available travel and limit bump stop use, rather than figure in the progressive rate of the bump stops in that last bit of travel. But that's my opinion, and there are definitely some different takes on how to set a car up. On that note...

Birdsong is junk science. He throws around a lot of technical terms that he's using incorrectly and reveals exactly NONE of his actual geometry data while making wild unsupported claims. The few things he gets right he explains incorrectly so I have to assume he stumbled into something that worked just by sheer luck. And he clearly skips past signifiant issues with his own set up. Good for youtube views I guess, but that's about it.

I agree the 270 is a bit on the low end but they are for sure better than the 109 lb bars that are currently in there. I got the TBs a long time ago and have a lot of other things higher on the spend money list than slightly changing the spring rate for now. now if I find someone who wants to trade or a smoking deal on some big bars that may change haha.

I also agree on your take of most of the stuff Birdsong does. I actually commented on one of his videos to explain some of the downsides of his "magical balljoint drop plates" which I feel are a downgrade in geometry. Probably will get lost in the comments though. oh well.

 

[racerjoe]

Totally, it's definitely a balance. But I know that even in my street driving I'm bottoming my suspension still with a 300 lb/in wheel rate and the Hellwig sway bars, and I've maintained about the same amount of travel as stock so I'm at a spot where I know I need increase my wheel rate some. The 1.18's with a 370 lb/in rate may be a bit high, I'll have see once I get them into the car. But I don't think a 350 lb/in rate is going to be too much.



Yep, that's basically the same design as the Kit Cars used. It used a tube with bushings at the ends and a splined shaft sway bar running through the bushings. These are pictures from the spring car catalog, and some of the ones used on the kit cars. I split up the catalog page so it would be large enough to read here, check out those torsion bar diameter and wheel rates on the second page. 1.38" and 654 lb/in !

View attachment 1716335642

View attachment 1716335643

View attachment 1716335649
View attachment 1716335648


Yep, definitely a balance. You have to evaluate the suspension travel and how often the bottoming out is happening. If it's just during cornering while autoX'ing then the larger sway bar would be the way to go and should take care of it. But if the bottoming is also happening through bumps then you may need to increase the wheel rate. Obviously too high of a wheel rate will upset the car over bumps, but, so does bottoming the suspension. You want the lowest wheel rate that allows you to use your entire suspension travel without bottoming out the suspension frequently.

For me at 300 lb/in and in the neighborhood of ~5.5" of suspension travel I still probably bottom the suspension a little too much, even just on the street and that's leaving a pretty wide margin for tire grip in the corners, I'd obviously push harder on an autoX course. I'm beginning to come around to the idea that 350 lb/in is a lot closer to where the car needs to be for just the wheel rate off the springs.

Some wild stuff right there. Also note the huge spacers to drop the K down. Along with the pointy end of the UCA bent down for what I assume would be a better ball joint angle with a really low ride height.


Good conversation here... I wonder what an increased spring rate will do to shock performance. I'm approaching the upper limit of the settings now. Part of my brain says the settings wouldn't need to be as high since the spring will be stiffer and won't need to be dampen the motion as much. While the other part of my brain says a stronger spring will need more aggressive dampening. I don't know the science of shocks enough to forecast what may happen.

 

[bjkadron]

Some wild stuff right there. Also note the huge spacers to drop the K down. Along with the pointy end of the UCA bent down for what I assume would be a better ball joint angle with a really low ride height.


Good conversation here... I wonder what an increased spring rate will do to shock performance. I'm approaching the upper limit of the settings now. Part of my brain says the settings wouldn't need to be as high since the spring will be stiffer and won't need to be dampen the motion as much. While the other part of my brain says a stronger spring will need more aggressive dampening. I don't know the science of shocks enough to forecast what may happen.

Yeah, they essentially did a body lift in relation to the suspension. I'm assuming for tire clearance?

In general for higher spring rates you have to have a stiffer shock to control the oscillation force. So if you have a higher spring rate and more force and you are already at the top of your adjustment range you would likely have to look at re-valving or changing shocks.

 

[72bluNblu]

I agree the 270 is a bit on the low end but they are for sure better than the 109 lb bars that are currently in there. I got the TBs a long time ago and have a lot of other things higher on the spend money list than slightly changing the spring rate for now. now if I find someone who wants to trade or a smoking deal on some big bars that may change haha.

I also agree on your take of most of the stuff Birdsong does. I actually commented on one of his videos to explain some of the downsides of his "magical balljoint drop plates" which I feel are a downgrade in geometry. Probably will get lost in the comments though. oh well.

Oh for sure, you can do a lot with a 270 lb/in wheel rate. And the whole spring rate vs sway bar rate balance is something that even the really knowledgeable/experienced racers still disagree on, you have folks with tons of race experience in each camp for big springs/tune with sway bars and big sway bars/tune with springs. There's an article in the June '81 Hot Rod magazine that's a shootout between Dick Gulstrand and Herb Adams, with Gulstrand believing in poly bushings, high spring rates and sway bars for tuning only, with Adams being in the rubber bushings, stock (ish) springs, stiff shocks and giant sway bars camp. It's a Camaro shoot out, and there were other non-matching modifications to the cars that are not insignificant, but after comparing cars with very different set ups the result was the cars put down almost identical lap times, with each matching the driver's preferences for handling feel.

With a 270 lb/in rate you’d be in the ballpark for sure, if you could come up with a sway bar large enough it would be fine as long as you maintain some suspension travel. But I think you’d need a splined sway bar set up to do that, the off the shelf bars may not quite be enough. Still, you’d be able to do a lot with that set up.

I really don’t see how the ball joint drop is any significant improvement in geometry like he claims, especially since some of the conditions that he claims happen with the stock suspension don’t actually happen (positive camber gain, for example, isn’t a thing at all even after a 1” ride height drop). He makes claims that are flat out false about the geometry of the stock system and then makes really dramatic, unsupported claims that don't necessarily match up with the geometry he's changing. Based on what I've seen for geometry changes with a drop spindle, I'd think that his ball joint drop is likely to induce MORE bump steer, not less. That effect may be offset by the effective height of the spindle being taller, but that's something you'd have to see in the numbers, which he doesn't give.

Yeah, they essentially did a body lift in relation to the suspension. I'm assuming for tire clearance?

In general for higher spring rates you have to have a stiffer shock to control the oscillation force. So if you have a higher spring rate and more force and you are already at the top of your adjustment range you would likely have to look at re-valving or changing shocks.

I’m not positive with a B body, but with an A body and an E body I know that the tire clearance to the inner fender at full compression is an issue with a lowered car. If you alter the suspension travel so you get more compression the inner fender quickly becomes a limiting factor. My Duster is lowered about 2" and with a 25.6" tire and QA1 LCA's and modified bump stops heights my tires will just kiss the inner fender at full compression. Lower would require raising the inner fenders.

Thing is, raising the body with relation to the K and suspension also raises the the CG. And he hasn’t raised the engine, so, the header to ground clearance is still an issue. I mean, on my car I’m sub 4” from header flange to ground at ride height. With a couple inches of compression travel that doesn’t leave the hard parts very far off the tarmac. He claims he has 1” of clearance at full compression, but in the one video you can literally see and hear the header clanking on the ground. Even if he’s got 1” a moderately bumpy road could easily ground him out. On a street car you have to pay attention to your ground clearance at full compression, especially if you're running lower wheel rates. It's not like we're driving F1 cars on the track, if you go through a dip and bottom your suspension AND hard parts it could be a bad day for you.

 

[mpgmike]

In a street car, you have to worry about speed bumps in the shopping mall parking lots. They are significantly higher than 1"! Then there is also the occasional debris that lands on the road you're traveling. Some of it can exceed 1"-4".

 

[72bluNblu]

In a street car, you have to worry about speed bumps in the shopping mall parking lots. They are significantly higher than 1"! Then there is also the occasional debris that lands on the road you're traveling. Some of it can exceed 1"-4".

Yeah I don't know what his static height actually is, even if he really had 1" of clearance at full suspension compression his static would be at least an inch lower than I am with my car. And he didn't have an inch at full compression in the video I watched.

Granted the header flanges are basically a single point, it's not like the entire chassis is at 4" but that's about as low as I can manage with my car and still clear speed bumps in the parking lot without a ton of maneuvering. I ran my Challenger lower for a bit, had the header flanges down a bit below 3.5" to the ground at ride height. It doesn't sound like a big difference but that was basically the difference between dragging on every single speed bump and driveway apron or clearing the vast majority of it. Maybe a show car or weekend only car could pull it off but as a daily it was just too much of a pain in the ***.

Even as an autoX only car a lot of the parking lots and venues you use aren't actually all that smooth, you need to have some suspension travel.

 

[HemiDenny]

With the appropriate sized bushings (delrim / poly) I would think it would be fairly easy to add whatever size splined bar you wanted to the HDK K-frame sway bar mounts. The tricky part would be the the outer arms clearing your extra wide tires....but do-able. If the legs went under the tie rods vs over, making relatively quick sway bar bar changes would be considerably easier.

 

[JBrian]

With the appropriate sized bushings (delrim / poly) I would think it would be fairly easy to add whatever size splined bar you wanted to the HDK K-frame sway bar mounts. The tricky part would be the the outer arms clearing your extra wide tires....but do-able. If the legs went under the tie rods vs over, making relatively quick sway bar bar changes would be considerably easier.

Hellwig 55917 swaybar made for wide tires. It just cleared my 255/40-18s

 

[72bluNblu]

Hellwig 55917 swaybar made for wide tires. It just cleared my 255/40-18sView attachment 1716336177

It’s a nice bar, but I think the issue is that they need more rate than that bar provides.

 

[HemiDenny]

For you track guys I would think you would show up with several splined crossbars. For us coffee getters rolling into Bob Evens.... we use only one.

 

[racerjoe]

Learned something new over the weekend. I always thought my sure grip was the cone style so I never bothered taking the diff apart to inspect. I don't even know why I thought it was the cone type. I've had it forever! Well after trying out a new street recently opened near the house with a 1 mile straight, I'm happy to say the road is smooth, even at high speed. I give the road work guys and A+, hahaha. After 3 rips I noticed an odd sound coming from the rear end. Considering I was planning on autocross on Sunday, I figured it would be a good idea to inspect further. Well, it turns out it is a clutch type diff, and they are slap worn out. I'm assuming the spider gears didn't care for the additional clearance so they self destructed. Honestly, the diff is literally the only component on the car I've never inspected or rebuilt. I can't complain, it's my own ignorance/neglect. Also got lucky catching it before debris destroyed the ring and pinion. Tough year breaking stuff. First the lifter in the small block and now this. Let's hope that's it for a while.

 

[DionR]

Learned something new over the weekend. I always thought my sure grip was the cone style so I never bothered taking the diff apart to inspect. I don't even know why I thought it was the cone type. I've had it forever! Well after trying out a new street recently opened near the house with a 1 mile straight, I'm happy to say the road is smooth, even at high speed. I give the road work guys and A+, hahaha. After 3 rips I noticed an odd sound coming from the rear end. Considering I was planning on autocross on Sunday, I figured it would be a good idea to inspect further. Well, it turns out it is a clutch type diff, and they are slap worn out. I'm assuming the spider gears didn't care for the additional clearance so they self destructed. Honestly, the diff is literally the only component on the car I've never inspected or rebuilt. I can't complain, it's my own ignorance/neglect. Also got lucky catching it before debris destroyed the ring and pinion. Tough year breaking stuff. First the lifter in the small block and now this. Let's hope that's it for a while.

View attachment 1716337391

View attachment 1716337392

View attachment 1716337393

Glad you caught it before it got worse.