What do y'all think about poly bushing or nylon bushings?
LCA Bushings and Other Bushings
- Thread starter Old Tired Rebel
- Start date
-
fastbackmopar
Mopar Fanatic
If you use a greasable lower control arm pins with the poly bushings they won't squeek. If your just going for a stock style rebuild the factory style rubber bushings are fine. For tight handling the polys are the way to go, just make sure the polys or nylons work with your pins. Some only work with the greasable style pins.
younggun2.0
Well-Known Member
i dont like the poly lower control arm bushings. they are not a press fit and are not positively located into the lower control arm. the rubber can style presses in and is fixed in the control arm. just food for thought.
I read that before - that the poly does not locate the LCA ...
This image shows the opposite - the poly has a lip that seats it completely in the shell -
I did have to get new pins, and these are just suspension pieces that have slots to tighten the pin nuts on - but the setup works great - it's not greasable but has never squeaked in the 5 years it has been on the car. I prefer them to the rubber pieces for my street car.
This image shows the opposite - the poly has a lip that seats it completely in the shell -
I did have to get new pins, and these are just suspension pieces that have slots to tighten the pin nuts on - but the setup works great - it's not greasable but has never squeaked in the 5 years it has been on the car. I prefer them to the rubber pieces for my street car.
younggun2.0
Well-Known Member
I read that before - that the poly does not locate the LCA ...
This image shows the opposite - the poly has a lip that seats it completely in the shell -
I did have to get new pins, and these are just suspension pieces that have slots to tighten the pin nuts on - but the setup works great - it's not greasable but has never squeaked in the 5 years it has been on the car. I prefer them to the rubber pieces for my street car.
but the bushing just slides on the pin by hand. it is not pressed on with an inner and outter sleeve on the bushing. the bushing simply sits in place. that is what i was referring to. I like the idea of the pin being a press fit into the control arm. not knocking them. just expressing my opinion.
Poly has some issues when used for LCA bushings. One is location - that can be addressed by the front bushings on the strut (where they attach to the K). Some photos and drawings on my website. Best is to dry fit, then cut the poly strut bushings to the right size. Slight differences in the struts and lengths on later As which I don't recall off the top of my head.
Other issues with poly is yes the squeak (althought th polygraphites werent as bad the one time I used them) and permanent deformation or wear under extreme situations (had that myself on a different set). Nylon requires some extra effort on installation. That's what I'm using now with greasable 'pins'.
With nylon you will feel the road a bit more! I've got leather wrap on the steering wheel and on a rumbly or rough pave like the NJ Turnpike your hands will be getting a constant vibration. This is with 70 series Firehawk Indy 500s - an M&S rated tire. But I'm still happy with the decision - but I would not recommend it except for the most serious sports car experience. For serious autocross or vintage racing - do it, but know the price.
Other issues with poly is yes the squeak (althought th polygraphites werent as bad the one time I used them) and permanent deformation or wear under extreme situations (had that myself on a different set). Nylon requires some extra effort on installation. That's what I'm using now with greasable 'pins'.
With nylon you will feel the road a bit more! I've got leather wrap on the steering wheel and on a rumbly or rough pave like the NJ Turnpike your hands will be getting a constant vibration. This is with 70 series Firehawk Indy 500s - an M&S rated tire. But I'm still happy with the decision - but I would not recommend it except for the most serious sports car experience. For serious autocross or vintage racing - do it, but know the price.
How hard was it to install the nylon bushings?
1970Duster
Well-Known Member
- Joined
- May 30, 2010
- Messages
- 6,644
- Reaction score
- 219
Hmm better shocks should take that away. Try bilstein when you change shocks again.
You are correct there is nothing holding that lower from moving to the rear. The poly bushings are not press fit as the standard. The only thing holding the control arm front would be the strut.And that is only the outside of the arm.
I had a poly kit (red) on my Duster. First time I foot braked it I saw red pieces flying out the side. The strut bushings were destroyed.
Maybe if you would shim the torsion bars to hold the control arms front. But would that clip hold it???. I just put the standard bushings back in mine.
They have to be tightened correctly so the bushings can travel the same distance of twist in both directions or they will rip off of the sleeves and you will have the same problem as a poly bushed car. This is done with putting the control arms in the center of travel before tightening the front control arm nut. using the upper and lower bump stops as a locator. make the distance the same upper and lower. Then tighten the nut. The bushings are designed to travel a certain distance before tearing. You want them to travel the same distance in each direction, This goes for every pressed bushings even the uppers. This process does make a difference.
I had a poly kit (red) on my Duster. First time I foot braked it I saw red pieces flying out the side. The strut bushings were destroyed.
Maybe if you would shim the torsion bars to hold the control arms front. But would that clip hold it???. I just put the standard bushings back in mine.
They have to be tightened correctly so the bushings can travel the same distance of twist in both directions or they will rip off of the sleeves and you will have the same problem as a poly bushed car. This is done with putting the control arms in the center of travel before tightening the front control arm nut. using the upper and lower bump stops as a locator. make the distance the same upper and lower. Then tighten the nut. The bushings are designed to travel a certain distance before tearing. You want them to travel the same distance in each direction, This goes for every pressed bushings even the uppers. This process does make a difference.
Even with a shop press to help in disassembly and assembly there is the joy of very carefully cutting the old shells out of the LCA. I used a sharp cold chisel. I had a new set of rubber bushings with steel outer sleeves - which are needed as well. I don't think anyone sells the steel sleeves seperately.
The new nylon bushing gets pressed into a steel shell, the shell into the LCA.
If you use Firm Feel's pivot pins with grease fitting, the inner steel sleeve for the the nylon bushing is not needed. I think the same is true for the polyurethane bushings - but I've not taken measurements of the different brands of lower control arm polyurethane bushings to know for sure.
edit: I also scored the outside of the steel sleeve before pressing into the LCA. Probably not neccessary, but the nylon on the inside will not compress they way poly will. So, by scoring it, the steel has a place to go.
The factory rubber was used as isolators. A lot of hard parts like bronze bushings and/or heim joints would transmit through the steering linkage and chassis. Steering wheel vibrates along with seat and everything else.
Shock absorbers do only that, absorb shock. They cannot isolate the steering linkage.
To replace all the worn out parts with OEM type can make a 30 year old car drive just as it did when new.
A lot of performance minded aftermarket parts turn it into something different. The choise is yours.
Shock absorbers do only that, absorb shock. They cannot isolate the steering linkage.
To replace all the worn out parts with OEM type can make a 30 year old car drive just as it did when new.
A lot of performance minded aftermarket parts turn it into something different. The choise is yours.
refering to me?
The SPAX shocks are adjustable, and I will be experimenting more with the settings for highway. I did not change the shock settings since switching from the poly LCA bushings to the nylon. In fact this last drive on the NJT I had wanted to soften them up because of the late winter storm that was going to make conditions wet, slick and potentially slushy. But I didn't have a chance. I did keep the air pressure in the tires down at 36 front, 34 rear which is about 10 psi under max load pressures. I find these pressures are pretty good for the road conditions around here.
That's right. Nylon has about zero damping. Poly has some damping and rubber has the most damping (and rubber durameters and thickness can and are selected by the OEMs pretty carefully, aftermarket who knows!).
The reason for using nylon is that with very sticky tires (ie r compound) in competition on good pavement, it helps with camber.
For those looking for more performance in this area, the place I recommend most people to start is with the sway bar bushings. Switching them effects the transmission of vibration very little, but makes the bar more effective and with less delay. Even so, if the end link bushings are changed to poly without using much thicker steel washers then often the washers will get punched through by the steel sleeve. Also sometimes the poly bushings will compress and not bounce back, so the end links need to be checked for tightness now and then.
I will say that some shocks have a poor high frequency control that will transmit to the entire vehicle. Usually, with single and most double adjustable shocks, the adjustments mostly effect the low frequency response. Hopefully this year I'll get to experiment a bit with the shock settings on the course as well as off. Right now it seems like a little less damping may be better.
That's basically what Doug Dutra does (over on the slant six forum). He makes a spacer.
The real problem comes when the aftermarket strut bushings are installed, and then the poly control arm bushings just compound it. Many of the aftermarket strut bushings had the wrong thickness. So Joe Mopar installs these and lower control arm never gets pulled all the way forward to where it belongs.
I was at firm feel and see the bushings he offered and it got me to thinking about making my Dart handling better. I am not looking for a new car feel I want my joe dirt looking car to surprise a lot of people. The information here is very helpful
Ironracer
Gearhead
Brother, my Duster and I are experiencing this now, due to previous owners...
It’s an easy fix. A set of adjustable strut rods like the ones QA1 sells will let you set the length of the strut rod so there’s no binding on the LCA within its range of travel. They work great with poly or Delrin LCA bushings.
Poly strut rod bushings aren’t really a good idea anyway. Even if they were the right thickness (most aren’t), the stiffer material is only a benefit in one plane of motion, whereas the strut rods have to move in two. So, on braking or acceleration the stiffer bushing material is good, it keeps the LCA from flexing back and forth like they did with the big, soft rubber strut rod bushings. But, when the LCA moves up and down the stiffer material of the poly strut rod bushings resists that movement, which adds binding to the suspension travel. Which isn’t what you want. The adjustable strut rods with the heim as a pivot solve both of those issues. They let the LCA move freely up and down, but don’t allow it to move forward and back.
With a set of properly tuned adjustable strut rods, paired with poly or Delrin LCS bushings, you can pretty much eliminate all the binding and drag in the LCA movement. That allows the suspension to react faster, and inputs to be more precise for better handling.
Ironracer
Gearhead
The Duster looks like a gasser after I get on it. The toe changes, along with the camber. When the suspension unloads and raises, it stays up. And I can see about a half inch of rearward movement at the pivot. Thinking of going Delrin. It's just a street car though... I just hate the thought of putting rubber in it. Today's rubber is crappy compared to back in the day. And I wouldn't mind a performance gain. The front end was done by the previous owner about 10 years ago. But those poly bushings are deteriorated, and binding, hanging up..I'm ready to order the parts as soon as I make up my mind. I just don't know if the upgrade would be noticeable..
Last edited:
I have Delrin bushings in my Duster, which is a street car despite being set up pretty aggressively for handling. I haven’t had any issues with running them on the street, they work great.
Now, as far as a noticeable improvement, it depends. When I installed the Delrin bushings I was replacing poly bushings. But they were installed with greaseable pivot pins, used with adjustable strut rods, and after 10k+ miles looked brand new after I wiped the grease off. I honestly didn’t notice a difference between the poly and Delrin bushings.
If your poly bushings weren’t installed or cared for properly you’ll see an improvement no matter what as long as you do the installation correctly. Both the poly and Delrin LCA bushings should be used with adjustable strut rods. The poly LCA bushings need greaseable pins. The Delrin LCA bushings are supposed to be self lubricating, so greaseable pins shouldn’t be necessary. Mine are installed with greaseable pins anyway though. Partly because I already had them, partly because they fit the Delrin bushings best of all the pins I had, and partly just as insurance in case I needed to grease them later.
If you intend to keep the factory strut rods, you should use rubber bushings at the LCA and the strut rod. A company called “Proforged” actually makes decent OE style LCA bushings. I can’t say how they hold up, but unlike the garbage Moog is putting out now they’re actually the right size and look decent. The strut rod bushings are an issue though. If you have the later, 73+ style strut rods the two piece bushings are not currently available and haven’t been for like a year. Moog has had massive issues supplying them, and at the moment no one else does. If you have the 67-72 style that uses the single piece strut rod bushing those are available.
There is a difference going from all OE rubber bushings and non-adjustable strut rods to either poly or Delrin bushings with adjustable strut rods. The handling and response is better and more accurate. The handling feels more precise, you don’t feel the slop and give that the OE stuff has. But keep in mind that’s not what you get changing a single bushing, that’s the result after changing everything. And keeping all the parts working together, ie, using the adjustable strut rods with the poly or Delrin bushings, tuning the length of the strut rods so there’s no binding, using modern alignment specs to match the level of performance of the tires being used, etc.
Ironracer
Gearhead
It looks like Delrin bushings and his pins for the lca's would be about the easiest way to get that going. So you're saying the qa1 adjustable strut rods is the direction you'd head? As far as manufacturers of adjustable struts?
Last edited:
The strut rod plus the t-bar keeps the arm from moving back and forth
I prefer the QA1’s for adjustable strut rods, yes. Because they have a double adjuster, setting the length of the strut rod is as easy as loosening the lock nuts and turning the barrel of the strut rod. With the other styles, the connection at the LCA uses a bolt. So, you have to loosen the bolt, then set the length, then tighten the bolt again. But loosening and tightening that rear bolt can change the length a little. And since you have to cycle the suspension through it’s range of travel each time to change the length of the strut rod it can get a little cumbersome. The QA1 strut rods make it very easy to tune the length of the strut rod so there’s no binding in the motion of the LCA in its travel.
The torsion bar does not- not really anyway. The torsion bars are not bottomed out in the LCA hex socket and against the retainer clip in the torsion bar anchor at the same time. Typically there’s a good 1/4” gap (or more) at the clip if the bar is fully seated in the LCA hex. The bars can actually shift back and forth slightly as they’re loaded and unloaded, so the torsion bar does not positively locate the LCA in such a way that it can’t move backward the distance between the length of the bar and the length between the end of the socket and the retainer clip. Even that relatively small amount of movement would result in significant changes in your caster angle.
As far as the strut rods go, yes, that’s literally why they exist as a component in the suspension. But you will never convince OMM that anything other than the rubber in the OE style LCA bushings is what holds the LCA on. You can cite logic, physics, the specific material properties of the different materials used, or appeal to the 10’s of thousands of miles you’ve used poly and Delrin LCA bushings without your LCA’s falling off, it simply doesn’t matter.
Ironracer
Gearhead
Thanks! I have a set of the moog strut rod bushings, but I won't need them with the QA1's, I'm assuming? Do they use a bushing? Or just bolt (?) To the k member? Much appreciate the time you have been taking to explain this to me! I know a few guys that run poly but they're not using the adjustable struts. So this is a new territory to me. And I don't just wanna toss cash at the car in the wrong direction. I want it to make a difference. Plus, there many different suppliers out there ..... so your knowledge and experience are priceless to me, as you have been there, done that! Lol... I installed the offset upper control arm bushings in the front of my upper control arms I used a piece of pipe and a homemade kit to press them out the piece of pipe didn't fit on there right on the driver side I had to grind a little bit of the control arm out of the way but it fits perfect on the passenger side I'm wondering if I have slightly bent or tweeked upper arm? Is there a way to check them for " square" I have looked and looked but caint find anything... I've seen some $200 tubular arms but I'm scared to death of putting some kind of Chinese junk on there
I’ll show mine (what I made up) tomorrow. Should be interesting. In fact I might as well do it now, kinda late but..
-
