I've got a 91 Formula, currently running some used SLP progressive rate springs I picked up off eBay.

In April I installed a DTS prepared for a 3rd gen Ford 9" rear, with a BMT adjustable torque arm.

Since then I've had a problem where very small speed bumps and dips in the road cause the top of the torque arm mount to botom out against the bottom of the body.

I'm thinking I need some heavier weight springs to keep this from bottoming out likr this. However, I am not interested in trying to lower the car, with the dual cats exhaust and SLP Tri-Y headers it's plenty low enough already.

So, what do all the experts here suggest I use for rear springs?

How are your shocks?

Kat

Less than a year old. However , I was under the impression that the shocks only dampen the rebounding/oscillation - not the amount of travel. Am I wrong on that subject?

To a point. If you have a shock that is weak on the compression side it will cause the suspension to compress to quickly.

Over the winter my DS loop used to hit the DS on a certian bump. Now that it is 90° out, it doesn't all I can think of is that the rear shocks have more pressure in them because of the heat.

Needless to say when I get a few free minuites I'll install the Koni red's I have sitting here. lol

Kat

I may have to try shocks, those these are only 16 months old. Springs are ??old (have no idea, got them from an eBay vendor I've had good luck with in the past).

Anyone else have any ideas?

Surely someone else has installed a Ford 9" before.....

did you replace the torque arm mount?

Is this in the rear at the top of the torque arm?

Is it hitting the top of the trans tunnel behind the parking brake cable bracket?

It's the top of the torque arm mount on the DTS Ford 9" that's hitting at the top and barely behind the trans tunnel.

My global west setup does the same thing...I call it "self clearancing". A couple of good whacks when the rear hits the bump stops, and it's all good.

To aid in the clearancing, stick a "large person" in the pass. seat, and hit those bumps a couple of times. Or, break out the BFH and tweak the tunnel. BTW, with my global west setup, I'm running really weak springs (S-67) in the rear per their recommendation. I think they're only 125 lbs/in. For comparison, with the stock torque arm, the ones I ran from them where around 190 lbs/in. All I know is the rear sticks, and even though it's a little soft, it works. Also, the car is lowered. I would pitch the adjustable rate springs.

What kind of shocks are you running now? I had nothing but trouble with the koni reds...a couple trips to the track and they started leaking. I'm running koni yellows and have had no problems.

What shocks am I running? OK, get ready to laugh....

I'm actually running a set of Gabriel Hi-Jacker air shocks. I've got an on-board compressor ang gauge so I can adjust the pressure from the driver's seat while going down the road. I installed them when I had to pull a small trailer on a 1000 road trip (each way) but decided to leave them on so I could drop the pressure when I need a good launch.

So, go ahead and flame me for that one, but I still think it was a good decision. Of course, I've been wrong before, too!

Since you already have them, I would stick the koni reds on there just to see if there's a difference (which there probably will be compared to the hi-jackers). I would set them on soft and see what happens before buying new springs. Just keep an eye on them, I busted 2 sets of rears from trips to the track (warrantied, no problem) before I ditched them.

Uh, I think you crossed up a message somewhere, I don't have any other shocks Koni reds or otherwise.

So now what would you suggest?

They were in kat's post...I just need to put the crack pipe down!!

I think shocks would probably be a good place to start to see if it stops bottoming out. I'm sure your SLP springs are stiffer than stock, which should be more than adequate. What kind of struts are you running up front? Might be time to upgrade all the way around. And it's a BMR torque arm, correct?

BTW, when mine hits the body the rear also hits the bump stops; it usually takes a big dip along with a passenger to make it happen.