QA1 Conversion Trouble

tfowler9 · Aug 9, 2024

Looking for some help! I have a 1971 Mustang Coupe with the 351 Cleveland, AC and AOD Trans. I decided to upgrade to the QA1 coil overs. I purchased the 500 lb, single adjusting kit (recommended by QA1). My intention was never to lower the front end. Wanted to retain the original height but benefit from the better suspension. The current suspension was installed in the mid '80s. In order to get the required height (29" from floor to center of fender) I needed to adjust the spring fairly high. I have about 3-4 inches of thread showing on the bottom of the shock. I have the shock adjusted at 10 clicks. When I take it for a ride, I am getting a lot of banging when I hit any bumps. Like the spring i bottoming out. Very frustrating. Any suggestions on what is causing this and how to fix?
This is a great forum that I read everyday. Lots of very talented people will to help their '71 - '73 family.
Tom from Utah

mjlan · Aug 9, 2024

I don't have any experience with the QA1 system but if your springs are going solid (coils contacting each other) then you may need to increase the spring rate to reduce how much the suspension moves.

giantpune · Aug 9, 2024

What's the measurement from the center of the wheel to the fender arch? That's how ford specifies the spec in the manuals. There are different specs depending on what suspension your car came with. The competition suspension sets a bit lower than the base model.

It could be that QA1 designed their kit based off the competition suspension, not the 6-banger granny numbers.

On my car, I did the full QA1 swap on the front end. Its setting at 12.75" from the center of the wheel to the wheel arch which is right where the shop manual says it should be for competition suspension. This is about where my coilover is adjusted to, plus or minus a few clicks.

Mine have clicks to adjust dampening and rebound (the red and black knobs in the picture below). When you install the kit, you turn them both down to zero to the shock can be manipulated by hand. Then you're supposed to put a few clicks back onto both of those knobs. If you don't, then its like you're driving around on 50yr old worn out shocks and bouncing like crazy and bottoming out.

tfowler9 · Aug 10, 2024

Thanks for the response. Yours looks great. I'll take a picture and send on. I am in a Car show today with my other Mustang. A 2014 Shelby GT 500. SO won't get to it today.

I can say that the measurement that QA1 says to use is from the floor to the fender arch. I think the center of the wheel to the arch would be 1/2 that. So for my car it would 14 1/2. My spring is compassed much more then yours, just seeing the amount of threads you have exposed from the bottom to the start of the Spring. Mine is double that, which I think is the problem. I only have the one adjustment (click). I did turn it all the way to the left to start, then added clicks. Currently at 10 clicks.
Tom

rcadd1ct · Aug 10, 2024

Also check to see if the spring is rubbing on the coil spring cover with the bump stop attached.

Bentworker · Aug 10, 2024

tfowler9 said:
Looking for some help! I have a 1971 Mustang Coupe with the 351 Cleveland, AC and AOD Trans. I decided to upgrade to the QA1 coil overs. I purchased the 500 lb, single adjusting kit (recommended by QA1). My intention was never to lower the front end. Wanted to retain the original height but benefit from the better suspension. The current suspension was installed in the mid '80s. In order to get the required height (29" from floor to center of fender) I needed to adjust the spring fairly high. I have about 3-4 inches of thread showing on the bottom of the shock. I have the shock adjusted at 10 clicks. When I take it for a ride, I am getting a lot of banging when I hit any bumps. Like the spring i bottoming out. Very frustrating. Any suggestions on what is causing this and how to fix?
This is a great forum that I read everyday. Lots of very talented people will to help their '71 - '73 family.
Tom from Utah

Post up some pics of your install. Someone might identify an issue visually.

giantpune · Aug 10, 2024

tfowler9 said:
Thanks for the response. Yours looks great. I'll take a picture and send on. I am in a Car show today with my other Mustang. A 2014 Shelby GT 500. SO won't get to it today.

I can say that the measurement that QA1 says to use is from the floor to the fender arch. I think the center of the wheel to the arch would be 1/2 that. So for my car it would 14 1/2. My spring is compassed much more then yours, just seeing the amount of threads you have exposed from the bottom to the start of the Spring. Mine is double that, which I think is the problem. I only have the one adjustment (click). I did turn it all the way to the left to start, then added clicks. Currently at 10 clicks.
Tom

The problem with measuring from the arch to the ground is that different size tires and wheels throw your number off. If you measure to the center of the wheel, then that takes the size of the tires and wheels out of the equation. That way you are only measuring the suspension.

tfowler9 · Aug 24, 2024

rcadd1ct said:
Also check to see if the spring is rubbing on the coil spring cover with the bump stop attached.

I lowered the height from 29" to 27 1/2" floor to arch and it did help with the noise...but not all of it. And now th back sits at 29" and the front 27 1/2". Going back to my original suspension.

rcadd1ct · Aug 25, 2024

tfowler9 said:
I lowered the height from 29" to 27 1/2" floor to arch and it did help with the noise...but not all of it. And now th back sits at 29" and the front 27 1/2". Going back to my original suspension.

Put it on ramps and see if the sway bar is touching the strut rod.

Did you torque the lower control arm at the frame?

Mine popped until I torqued it. Normal tight feel was not enough

tfowler9 · Aug 25, 2024

Thanks for your response. I did retorque the lower control arm. I will check the sway bar but I would have thought I would have noticed that when I was installing the coil overs.
Its frustrating. I also have a 1968 Shelby GT 350 convertible. The ride is so much better than the 1971. Tom

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