SPC Upper Control Arms (2nd Gen) and Bump Stop Question

[68BarracudaTT]

I am mocking up my suspension and notice the upper control arm is very far away from the bump stop. I am using the following parts:

SPC upper control arm (2nd Gen)
QA1 Strut Rods
Boxed stock lower control arms
F-Body spindles
Sway away 1.24" torsion bar

Setting the QA1 Strut Rod to be free from binding between the bump stops doesn't seem like it will be possible as I can't get the arm to the bump stop. According to the instructions, they are installed in the correct orientation.

I am waiting on some parts I forgot to order, so I can't get the car on the ground to see what it looks like at ride height. Has anyone else installed these upper control arms? Are you using the upper bump stop, and if so, what one?

Thank you for any and all help.

 

[dano]

I have the QA1 struts and don't care too much for them.

Can you swing it up and hit the lower bump stop? Do the arms fully clear the mounting area? Some arms hit and require some clearancing on the chassis.

 

[RogerRamRod]

There are taller bump stops but I don't know if tall enough for your app. I don't know the number right now (at work).
ALSO I think those spindles are taller than A-Body spindles AND it looks like those upper arms have a very pronounced arch to them. Plus with a 1.24 Torsion Bar, I'm guessing you are going to lower your ride height a bit. You might need to get a log out of your woodpile to act as a stop.

 

[72bluNblu]

Have you talked to @BergmanAutoCraft at all?

It doesn't look like the factory bump stops are in a position to do anything for you at all, which means you're going to have to come up with a solution so that you have an upper bump stop that works to set the suspension location for full extension. That's going to be important for a couple different reasons.

You won't be able to properly adjust the strut rod without having set the range of travel. The strut rods and LCA's are attached at an angle to each other so their ends trace out separate arcs. You can adjust them not to bind over the normal range of travel, but you can't adjust them not to bind over an indefinite range because the arcs diverge.

You're going to have to figure out your ride height, then set your range of suspension travel. Factory cars have about 5.5" of travel between the bump stops. With 1.24" bars you probably won't need that much, and honestly you may not get that much out of the bars because your wheel rate will be so high. But what you'll need to do is determine the ride height, then set the bump stops so that you have about 2.5" of travel at the spindle in each direction.

I had to do something similar on my Duster with the 1.12" bars I run and the lowered ride height I use. I set the ride height where I wanted it, then determined the size of the bump stops to put the final ride height as close to the middle of the range of available travel as I could. The result was a much taller upper bump stop and a very short lower bump stop. The upper bump stop I actually sized to keep the torsion bar adjusting bolt in contact with the adjusting lever at full droop. Really large torsion bars don't twist much with the weight of the car, so the adjustment of height becomes very precise because the range of adjustment is so narrow. Where you might put half a dozen turns on the adjusters with an average size torsion bar to get the car to factory height with the large bars you can go from sitting on the lower bump stop to factory ride height in a turn or two.

This is an older picture of my front suspension from when I installed my Gen I SPC's and QA1 LCA's. You can see that the upper bump stop is raised substantially, and the lower is just a pad. I've actually gone to a taller upper bump stop since then, to keep the torsion bar adjusting bolt from losing tension on the adjusting lever at full droop. With the curve on that upper arm of the Gen II's you may have to move the upper bump stop entirely somewhere else.

 

[68BarracudaTT]

I have the QA1 struts and don't care too much for them.

Can you swing it up and hit the lower bump stop? Do the arms fully clear the mounting area? Some arms hit and require some clearancing on the chassis.

The lower bump stops are one of the things that are on order. The arms look to clear everything, I have already reworked the normal interference areas.

There are taller bump stops but I don't know if tall enough for your app. I don't know the number right now (at work).
ALSO I think those spindles are taller than A-Body spindles AND it looks like those upper arms have a very pronounced arch to them. Plus with a 1.24 Torsion Bar, I'm guessing you are going to lower your ride height a bit. You might need to get a log out of your woodpile to act as a stop.

I think I found the taller bump stops on Summit, energy suspension number 9.9136? From what I have read the difference in spindle height is not too big, something like 3/8". These uppers do have a substantial arch, and I thought I installed them backwards at first. They also have additional height built into the ball joint, another 1/2".

Have you talked to @BergmanAutoCraft at all?

It doesn't look like the factory bump stops are in a position to do anything for you at all, which means you're going to have to come up with a solution so that you have an upper bump stop that works to set the suspension location for full extension. That's going to be important for a couple different reasons.

You won't be able to properly adjust the strut rod without having set the range of travel. The strut rods and LCA's are attached at an angle to each other so their ends trace out separate arcs. You can adjust them not to bind over the normal range of travel, but you can't adjust them not to bind over an indefinite range because the arcs diverge.

You're going to have to figure out your ride height, then set your range of suspension travel. Factory cars have about 5.5" of travel between the bump stops. With 1.24" bars you probably won't need that much, and honestly you may not get that much out of the bars because your wheel rate will be so high. But what you'll need to do is determine the ride height, then set the bump stops so that you have about 2.5" of travel at the spindle in each direction.

I had to do something similar on my Duster with the 1.12" bars I run and the lowered ride height I use. I set the ride height where I wanted it, then determined the size of the bump stops to put the final ride height as close to the middle of the range of available travel as I could. The result was a much taller upper bump stop and a very short lower bump stop. The upper bump stop I actually sized to keep the torsion bar adjusting bolt in contact with the adjusting lever at full droop. Really large torsion bars don't twist much with the weight of the car, so the adjustment of height becomes very precise because the range of adjustment is so narrow. Where you might put half a dozen turns on the adjusters with an average size torsion bar to get the car to factory height with the large bars you can go from sitting on the lower bump stop to factory ride height in a turn or two.

This is an older picture of my front suspension from when I installed my Gen I SPC's and QA1 LCA's. You can see that the upper bump stop is raised substantially, and the lower is just a pad. I've actually gone to a taller upper bump stop since then, to keep the torsion bar adjusting bolt from losing tension on the adjusting lever at full droop. With the curve on that upper arm of the Gen II's you may have to move the upper bump stop entirely somewhere else.

View attachment 1715997903

I have not reached out to Bergman, but will send an email to see if they have a recommendation. Thanks for heads up on the usable range, I will take that into account to setup everything.

Thank you all again for the help and input. Its my first time with this style suspension, so plenty of learning as I go. When I found out what works I will post a picture.