69 Barracuda front RMS suspension issue

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67dodgedartconv

67dodgedartconv

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The shop that has my Barracuda says the outer tie rod is hitting the inside of the rim as shown in the picture. Wheels are 17 x 8 inch torque thrust ll's with 5.48 inch backspace with p235 tires either 45 or 40 series. Car is a new build that just had alignment done and is not on the road yet. Has anyone else had this problem with an a body or barracuda with this set up? I don't know if it needs less backspace or a narrower rim or something else. Shop is supposed to call RMS but wanted to hear from others experiences as well.

IMG_20231005_110703.jpg
 
just bend it. or clearance the wheel with a hammer.

kidding, kidding. you probably, might, maybe get away with less backspace. try putting on a 1/4" spacer and see if that helps. a narrower rim may also be a solution.

a lot of 17" rims foul the outer tierod, and that's the reason most people step up to 18's when going for larger rubber up front.
 
Here's what I used with my RMS setup with the 11" wilwood disk brake package.


Front Wheels: Torq Thrust Model AR105M 7765B 17 X 7 0 Offset , 4" backspace.

Rear wheels: Torq Thrust Model AR105M8966B 18 X 9 34 Offset, 6.34 Backspace

Hers's what RMS recommends.


Wheel and Tire Information



1696526057512.png
 
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67dodgedartconv said:
The shop that has my Barracuda says the outer tie rod is hitting the inside of the rim as shown in the picture. Wheels are 17 x 8 inch torque thrust ll's with 5.48 inch backspace with p235 tires either 45 or 40 series. Car is a new build that just had alignment done and is not on the road yet. Has anyone else had this problem with an a body or barracuda with this set up? I don't know if it needs less backspace or a narrower rim or something else. Shop is supposed to call RMS but wanted to hear from others experiences as well.

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Yikes!!!

That’s not something that should be happening at that amount of backspace with a 17” rim. Do you have any more pictures? Is there a steering stop somewhere?

What brakes do you have on the car? There are a few options, and they can affect the track width which can change the backspacing needed.
junkyardhero said:
just bend it. or clearance the wheel with a hammer.

kidding, kidding. you probably, might, maybe get away with less backspace. try putting on a 1/4" spacer and see if that helps. a narrower rim may also be a solution.

a lot of 17" rims foul the outer tierod, and that's the reason most people step up to 18's when going for larger rubber up front.
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The factory torsion bar set ups generally get into issues with 17” rims and the outer tie rod end at around 5.7” of backspace, so, more than what the OP has. Which is weird anyway, considering that it’s got a rack and pinion with that RMS suspension.

Honestly I haven’t heard of this issue with the RMS suspensions, it seems weird that it would be more limiting than the factory steering even with a 17” wheel. Although I know most of the RMS cars with wide front tires are running 18’s. It seems strange though that RMS says it should work, Bill’s pretty well versed in what fits and won’t at this point.
 
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72bluNblu said:
Yikes!!!

That’s not something that should be happening at that amount of backspace with. 17” rim. Do you have any more pictures? Is there a steering stop somewhere?

What brakes do you have on the car? There are a few options, and they can affect the track width which can change the backspacing needed.


The factory torsion bar set ups generally into issues with 17” rims and the outer tie rod end at around 5.7” of backspace, so, more than what the OP has. Which is weird anyway, considering that it’s got a rack and pinion with that RMS suspension.

Honestly I haven’t heard of this issue with the RMS suspensions, it seems weird that it would be more limiting than the factory steering even with a 17” wheel. Although I know most of the RMS cars with wide front tires are running 18’s. It seems strange though that RMS says it should work, Bill’s pretty well versed in what fits and won’t at this point.
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oh you're right, thanks for pointing that out. i'd just considered/assumed that the tierod would be vaugely in the same place.

i'll bet you're right on a steering stop. maybe the rack isn't centered? or installed incorrectly? or has the wrong tierods?
 
junkyardhero said:
oh you're right, thanks for pointing that out. i'd just considered/assumed that the tierod would be vaugely in the same place.

i'll bet you're right on a steering stop. maybe the rack isn't centered? or installed incorrectly? or has the wrong tierods?
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Actually a bunch of stuff changes since the RMS rack is a front steer set up vs the rear steer of the factory set up.

But yeah, I'm curious to see a bit more of what's going on there. I'm better versed in the factory style steering. But I know @abodyjoe was running 17x8" Mustang Bullitts with a 5.72" backspace on his Dart with RMS suspension, this was his car

dart-carlisle-fixed-jpg.jpg
 
better pictures would be nice. like stated i ran 17x8 with 5.72 back space with no issue. you confident the shop knows what they are doing? best bet is to call bill at RMS and maybe send him good pictures.
 
abodyjoe said:
better pictures would be nice. like stated i ran 17x8 with 5.72 back space with no issue. you confident the shop knows what they are doing? best bet is to call bill at RMS and maybe send him good pictures.
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Which brakes were you running on your RMS set up? Just to help rule some of the other contributing factors out
 
72bluNblu said:
Actually a bunch of stuff changes since the RMS rack is a front steer set up vs the rear steer of the factory set up.
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oof, again i'm way off the mark. i'm going for a full strike out here. i think i may have cooked my brain at the yard earlier. time for a beer and a cool down.
 
My Dart has 1/2" spacers on the fronts for the 17" Ford Bullets. Probably from a 90's Mustang, bought it that way.
 
CRUZE 418 said:
My Dart has 1/2" spacers on the fronts for the 17" Ford Bullets. Probably from a 90's Mustang, bought it that way.
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1/2"? Yikes. I mean, there are a few different backspaces and widths for those wheels and the copycat versions of them so I may be wrong, but I wouldn't think 1/2" spacers would be necessary. 1/8" or even 1/4" I could understand, but even with all the versions of the 17's I can think of I don't think any would need a 1/2" spacer. The most popular size for those is a 17x8" with a 5.72" backspace, and most folks get them clear of the tie rods with an 1/8" spacer.
 
I didn't measure the gap, they are still close, 5.72 seems about right. It has longer studs, they do require a couple of follow up re-torque after removal to settle down. Haven't had any issues otherwise.
The 245x45x17's do make it jumpy on the road, always have to be driving it.
 
CRUZE 418 said:
I didn't measure the gap, they are still close, 5.72 seems about right. It has longer studs, they do require a couple of follow up re-torque after removal to settle down. Haven't had any issues otherwise.
The 245x45x17's do make it jumpy on the road, always have to be driving it.
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Jumpy sounds like nowhere near enough positive caster to me.
 
abodyjoe said:
better pictures would be nice. like stated i ran 17x8 with 5.72 back space with no issue. you confident the shop knows what they are doing? best bet is to call bill at RMS and maybe send him good pictures.
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Only picture I have at the moment. The shop is good, they have successfully installed several RMS systems. They will talk to Bill, as they have in the past on other builds. Will post what happens.
 
Difficult to get a good front end alignment these days, but will work on the positive caster.
Thank you!
 
My brother has struggled with his ControlFreaks front suspension because the rack gives way too much steering angle. He talked to the manufacturer about getting a rack with shorter steering stops or something and they couldn't (wouldn't?) help him so he is going to add his own external steering stops.

Best guess is that everything is fine when the wheel and tire are narrow enough, but add a wider wheel and/or more backspacing and it becomes an issue. My brother is running a pretty deep custom BS wheel because the suspension seems to be much wider than factory and he couldn't get the tire under the fender without doing something like that.

I would bet that is the issue here, the RMS rack allows for too much steering angle for the wheel the OP is running. Maybe a custom steering stop would work here?

The one outlier is Joe and his Mustang rims. Maybe RMS changed the rack since then?
 
CRUZE 418 said:
Difficult to get a good front end alignment these days, but will work on the positive caster.
Thank you!
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I wouldn’t think it would be hard at all to get plenty of positive caster with that RMS suspension, and camber bolts should be well within the capabilities of even a basic alignment tech. I bet you have a factory spec alignment on suspension that has no business using the factory specs.

I wouldn’t be surprised if some shops wouldn’t touch it just because it’s aftermarket though.

But yeah, 245’s on an RMS suspension shouldn’t be “jumpy”.
DionR said:
My brother has struggled with his ControlFreaks front suspension because the rack gives way too much steering angle. He talked to the manufacturer about getting a rack with shorter steering stops or something and they couldn't (wouldn't?) help him so he is going to add his own external steering stops.

Best guess is that everything is fine when the wheel and tire are narrow enough, but add a wider wheel and/or more backspacing and it becomes an issue. My brother is running a pretty deep custom BS wheel because the suspension seems to be much wider than factory and he couldn't get the tire under the fender without doing something like that.

I would bet that is the issue here, the RMS rack allows for too much steering angle for the wheel the OP is running. Maybe a custom steering stop would work here?

The one outlier is Joe and his Mustang rims. Maybe RMS changed the rack since then?
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That’s interesting. Even with “too much” steering angle you’d think the tires would contact the frame first. Since they don’t that would mean the rack reduces the clearance to the rims compared to the stock steering.

I could be mistaken, but I thought RMS used a modified rack. I know one of the original beefs with the RMS was reduced steering angle. I don’t recall hearing about wheel clearance issues at the OP’s amount of backspace though. Maybe an unmodified rack got through? Or maybe RMS had to change suppliers or something, it’s tough to do aftermarket stuff like that and always have to be babysitting suppliers and production quality on stuff you’re using and not making. Like it might not be an issue at all for the original intended application, but it creates issues with the custom use.
 
72bluNblu said:
That’s interesting. Even with “too much” steering angle you’d think the tires would contact the frame first. Since they don’t that would mean the rack reduces the clearance to the rims compared to the stock steering.
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I'm drawing a blank on what was interfering on my brother's car. Might be wheel to frame, not sure.

Since it is a front steer, I wonder of the steering arms are longer to help with Ackerman, thereby putting the rack further forward and resulting in the issue. Don't know, just spit balling.
 
72bluNblu said:
wouldn’t think it would be hard at all to get plenty of positive caster with that RMS suspension, and camber bolts should be well within the capabilities of even a basic alignment tech. I bet you have a factory spec alignment on suspension that has no business using the factory specs.
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yup plenty of adjustment. problem is finding an alignment shop that knows what they are doing is a lot of areas.
 
DionR said:
I'm drawing a blank on what was interfering on my brother's car. Might be wheel to frame, not sure.

Since it is a front steer, I wonder of the steering arms are longer to help with Ackerman, thereby putting the rack further forward and resulting in the issue. Don't know, just spit balling.
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So on a factory car the steering arm actually puts the ball joint outside the rim. So the pivot point isn’t inside the rim so the wheel to tie rod end relationship doesn’t change. Even with 18” rims and deep backspace that’s mostly true, you can see that on my car with its 18x9’s and ~6.1” backspace

IMG_5336.jpeg


The angle of the tie rod can change and that changes the wheel clearance to the tie rod end, but turning the wheel doesn’t put the rim any closer to the tie rod because of the location of the pivot.

With the RMS you can see the steering arm and rack pivot point is well within the rim, so, turning the wheel changes the clearance between the rack and the wheel. Which limits the backspace if the steering angle is enough to cause interference.

The fix is either less steering angle or less backspace. The fact that it worked on Joe’s car leads me to believe something about the rack has changed.

abodyjoe said:
yup plenty of adjustment. problem is finding an alignment shop that knows what they are doing is a lot of areas.
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Yeah I didn’t really think it was an issue with the RMS. It’s getting harder to find alignment shops that want to deal with aftermarket parts or custom alignments. It still surprises me because it’s not like camber bolts are hard to deal with. But I suppose it shouldn’t, since I bought my own alignment gear because it was such a PITA to get it done right.

Do you recall what you were running for caster?
 
Oh, and I don't have RMS suspension on my Dart. It's got PST uppers, reinforced stock lowers with delrin bushings, stock swaybar, '73 spindles, Bilstine gas shocks and I pulled the 1" torsion bars for stock ones. Never have been able to get the bullfrog out of the front. Just gave up and drive with the radio and road noise on. It's all good, sometimes I just don't win! Will look into that caster.
 
72bluNblu said:
Yeah I didn’t really think it was an issue with the RMS. It’s getting harder to find alignment shops that want to deal with aftermarket parts or custom alignments. It still surprises me because it’s not like camber bolts are hard to deal with. But I suppose it shouldn’t, since I bought my own alignment gear because it was such a PITA to get it done right.

Do you recall what you were running for caster?
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its not even just custom parts, even with a stock suspension shops want to put it on the rack and turn things till the light turns green for the original specs. luckily i have a few shops in my area that will put an alignment where i want it but many places do not..

had casrer at 4.5 or 5. i'm sure i could have gotten more but there was no need.
 
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