QA1 LCA has no bumper

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Needswork

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I bought an unfinished 67 Dart project car from a guy that had purchased but not yet installed QA1 upper and lower control arms. I was looking at the lower control arms tonight and there is no provision for a rubber bumper. That seems strange. Without one I would expect a nasty "bang" when hitting a pothole or something.

I noticed on the "Full Suspension upgrade of 67 Dart" post by Craig67 that his pics showed the LCA with a rubber cap-like bumper. But, the QA1 Website still shows it with no bumper.

Has anyone running the QA1 LCA without a bumper noticed any issues?

I suppose I could try and fabricate one just to be safe. But perhaps it's not really a problem.
 
I would call QA1, My LCA's came with them....

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Thanks for the detailed pic.
I contacted their Tech Line today. The guy mentioned that adding the bumper was a "running change" that occurred about a year or so ago.
I asked if they provided a retrofit kit so someone could add the bumper. The answer was no. They'll sell you the rubber bumper itself, P/N 9047-1116.

Maybe I'll consider fabricating a bumper stop. Maybe not. I suspect it's not a big problem as I searched and didn't see anyone complaining about metal to metal contact. Perhaps the LCA doesn't travel enough to actually hit the frame rail. Something else might get in the way before that point.
 
Well that's below average! I'm thinking it's a good idea to have them, at least in this area. California roads leave a lot to be desired!
 
I have a set that doesn't have any bumpers, bought over a year ago.

I also ran a set of CAP made tubular LCA's, basically identical to the QA1 tubular LCA's except CAP made them with super crappy welds (Qa1 bought CAP out for their designs). I ran the CAP tubular LCA's for like 60k miles on my Challenger and never had any contact issues. I did have a crappy, CAP auto weld fail on one of those LCA's though. But no marks to indicate the tubular LCA ever hit the frame, and that car was lowered a good 2". I briefly had a set of drop spindles on it, when I took them off I put the car right back where it was without them.

One of the things about the tubular LCA design is that they're not as tall in profile height as the original LCA's. In fact, at the location of the original bump stop the Qa1 LCA's are about an inch shorter in profile height. That means a full additional inch of travel at that location, which means almost double that amount of travel at the wheel. Meaning, you're a lot less likely to bottom out the tubular LCA's than you are a stock set of LCA's.

This is something I've considered, my plan for dealing with it when I mounted the Qa1 LCA's on my Duster was to check to see where the interference would occur and then drill and tap a hole in the frame to mount a bumpstop there. There's a reinforced provision on the frame for the original bump stops to hit, so I figured adding a poly bump stop like the ones I run on my stock LCA's would be pretty easy as a "just in case" feature. It may be overkill though, I know that on 72BBSwinger's car he was actually getting some tire rub at the top of his wheelhouses up front (top of the wheels contacting the bottom of the inner fender). That was with stock LCA's if I remember right. So, with the additional clearance the QA1 LCA's offer translating into additional suspension travel the thing that stops the suspension might not be the LCA hitting the frame anyway, it could be the top of the tire hitting the bottom of the inner fender. And on a car that isn't lowered it probably wouldn't be an issue at all unless you were running tiny little torsion bars.

This is what I run on my stock LCA's, would be simple enough to just drill and tap a hole in the frame to screw them into for insurance if you're worried about it. They make thicker ones as well.

https://www.summitracing.com/parts/ens-9-9132g
ens-9-9132g_ml.jpg
 
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One of the things about the tubular LCA design is that they're not as tall in profile height as the original LCA's. In fact, at the location of the original bump stop the Qa1 LCA's are about an inch shorter in profile height. That means a full additional inch of travel at that location, which means almost double that amount of travel at the wheel. Meaning, you're a lot less likely to bottom out the tubular LCA's than you are a stock set of LCA's.
View attachment 1715069016

Good point. I compared the QA1 with a stock LCA and there is definitely more room for travel before hitting the frame.

As you suggest, I'll likely add a bumper to the frame itself for a little bit of "insurance". Thanks!
 
No problem!

Actually, looking at the ones with the bumpers installed I'm glad I got a set before they started doing that. Honestly the increase in travel is why I bought them to begin with, they really don't add a whole lot besides that. Their new design would add some strength as well, although with good welds I really don't think that would be needed. I did gusset the set I've got based on what I learned about the design from the failed CAP set, but it was totally overkill. All that design really needed was good welds and I know Qa1 took care of that.
 
Is it worth pointing out that a wheel drops into a pothole bringing the upper arms bump stop into play? I suppose a stabilizer bar could bring the lower bump stop into play on the opposite side.
 
Is it worth pointing out that a wheel drops into a pothole bringing the upper arms bump stop into play? I suppose a stabilizer bar could bring the lower bump stop into play on the opposite side.

I'm not sure what point you're trying to make. The UCA bump stop limits suspension extension and the LCA bump stop limits compression. Pot holes can cause extension, but they also cause compression when the wheel hits the opposite edge of the hole and has to bounce back up onto the road surface. And every road surface variation isn't a hole, there are plenty of bumps too. Not to mention that hard braking causes suspension compression, as well as hard cornering. A nice downhill corner taken at speed can bottom the outside wheel's suspension. In my experience I've found the lower bump stops actually get used much more frequently than the uppers.

Some of the tubular UCA's out there don't address the fact that they don't line up with the upper bump stop either, which is a problem too.

And if you substantially lower a car and install really large torsion bars you have to use taller upper bump stops to keep the adjusting bolts from coming off the torsion bar adjusting arms at full extension because of the narrower range of adjustment the larger bars have. It makes sense though, when you lower the car you're changing the center point on the range of suspension travel. The large bar reduces the need for suspension travel on the compression side, which is used to lower the car, and the taller upper bump stop limits the extension to match the compression distance so the new ride height is still in the middle of the range of travel (which is now smaller).
 
I'm not sure what point you're trying to make. The UCA bump stop limits suspension extension and the LCA bump stop limits compression. Pot holes can cause extension, but they also cause compression when the wheel hits the opposite edge of the hole and has to bounce back up onto the road surface. And every road surface variation isn't a hole, there are plenty of bumps too. Not to mention that hard braking causes suspension compression, as well as hard cornering. A nice downhill corner taken at speed can bottom the outside wheel's suspension. In my experience I've found the lower bump stops actually get used much more frequently than the uppers.

Some of the tubular UCA's out there don't address the fact that they don't line up with the upper bump stop either, which is a problem too.

And if you substantially lower a car and install really large torsion bars you have to use taller upper bump stops to keep the adjusting bolts from coming off the torsion bar adjusting arms at full extension because of the narrower range of adjustment the larger bars have. It makes sense though, when you lower the car you're changing the center point on the range of suspension travel. The large bar reduces the need for suspension travel on the compression side, which is used to lower the car, and the taller upper bump stop limits the extension to match the compression distance so the new ride height is still in the middle of the range of travel (which is now smaller).

Do you have a part number suggestion for the taller upper bump stop?
 
Do you have a part number suggestion for the taller upper bump stop?

Yup, this is what I use

https://m.summitracing.com/parts/ens-9-9136g

Works pretty well, good height too. I actually run an 1/8" spacer under mine, but, I sit pretty low and run 1.12" bars. I still have almost 6" of travel at the wheel from bumpstop to bumpstop, it's just the travel is recentered around a lower ride height.
 
Yup, this is what I use

https://m.summitracing.com/parts/ens-9-9136g

Works pretty well, good height too. I actually run an 1/8" spacer under mine, but, I sit pretty low and run 1.12" bars. I still have almost 6" of travel at the wheel from bumpstop to bumpstop, it's just the travel is recentered around a lower ride height.
Thanks! I just ordered 1.12 bars. I went back and forth on 1.06 vs 1.12 and decided to just go for it. I'll be running them with the Hotchkis adjustable shocks. I'm shooting for a ride height similar to Peter Bergman.
 
I was flipping through a Mopar Action just this morning and they were reviewing these arms and mentioned the lack of bump stop. It was stated that adding them was supposed to be a running change.

It was also stated that they had much more travel which would reduce the necessity of the bumper. Tack a bracket on there and roll it.
 
I was flipping through a Mopar Action just this morning and they were reviewing these arms and mentioned the lack of bump stop. It was stated that adding them was supposed to be a running change.

It was also stated that they had much more travel which would reduce the necessity of the bumper. Tack a bracket on there and roll it.

The arms have bump stops now, so if you buy a new set you get ones like MomsDuster posted above.

Which is kind of a waste really. Because adding a fully functional bump stop requires drilling a single hole per side. I just added the bumpstop I was running on my stock LCA to the stop on the frame. Like this...

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The other thing is, you need a bump stop unless your tires are super short. When I installed the QA1 LCA's on my car I measured the hub to inner fender. And, even with the bump stop installed I came up with 13". So, with a 26" tall tire the tire would hit the flat spot on the top of the inner fender on full compression. I actually bought the QA1's to increase the suspension travel a bit to gain back some of what I gave up lowering the car. I didn't really add much because of that clearance, you'd have to raise the inner fenders to really take advantage of that.

Here's a picture of my new set up on the car now. The whole write up is in my build thread linked in my signature.

IMG_4572.JPG
 
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