‘Bouncy’ rear end after rear lower control arm monoball bearing install on a GT350R

[fpa1974]

I installed a set of FTBR monoball bearings in the rear lower control arms of my GT350R. The immediate result was a much ‘bouncier’ rear end. Suspension Is more or less stock (stock MR dampers and springs) with the FP toe link bearing and SPC camber arms. I am running the FP track alignment spec
at this point. I am questioning if those bearings are maybe too ‘tight’. I am noticing an improvement the more car is used but nowhere close to before the install. Will they ever break in to the point the car will feel similar to before? I really appreciate the feel of the rear end otherwise but I need to do something about this bounciness. Is this expected with this type of ’upgrade’? I am willing to redo it with a different brand if that will address the issue.
I would appreciate any advice on this. Thanks a lot!

 

[Scootsmcgreggor]

I noticed something similar when I did mine, along with RLCA bearings and bearing upper shock mount. It’s my belief that the stock shocks are under damped and when you take all the rubber out of the suspension it becomes apparent. Better shocks solved this for me.

 

[Stan Whitney]

I did not get any extra bounce when I made the same changes to my gt500 mag ride. (cortex arm bearings and fp toe link bearing). But I do have a DSC sport controller that has some added rebound dialed into the rear. Before the shocks and springs went in the rear suspension was very free moving.

 

[fpa1974]

The underdamped shocks hypothesis crossed my mind as well - especially since when switching to 'sportier' suspension modes things get better. Short of physically replacing the shocks, I guess the DSC controller could be something that might help. Speaking of which, has anyone run the Steeda one on a stock suspension?

The part that made me also think those bearings might be a 'tad' tight is when driving the car in cold weather last winter (30-40F) the bounciness was pretty extreme. As the ambient temps went up and I drove the car more, the feel has been improving. Do these things break in over time?

 

[blacksheep-1]

FWIW, Bruce at FTBR is a pretty legendary Mustang guy, what did he have to say about it?

 

[JAJ]

I installed a set of FTBR monoball bearings in the rear lower control arms of my GT350R. The immediate result was a much ‘bouncier’ rear end. Suspension Is more or less stock (stock MR dampers and springs) with the FP toe link bearing and SPC camber arms. I am running the FP track alignment spec
at this point. I am questioning if those bearings are maybe too ‘tight’. I am noticing an improvement the more car is used but nowhere close to before the install. Will they ever break in to the point the car will feel similar to before? I really appreciate the feel of the rear end otherwise but I need to do something about this bounciness. Is this expected with this type of ’upgrade’? I am willing to redo it with a different brand if that will address the issue.
I would appreciate any advice on this. Thanks a lot!

Have you checked to see if the rear ride height sensors are correctly installed and connected after the work was complete? If not, they might have put the VDM module into some kind of confused state and blocked the function of the magride shocks. I've never touched my rear sensors, so I'm guessing, but the problem sounds more like a disabled magride than a bushing issue. If you have Forscan you can check the height sensor operation by scanning the VDM for codes and by checking the height sensor voltages.

I'm sensitive to this because I had a similar problem on my BMW E92 M3 after I did some work on the suspension, and it turned out that I'd put the rear height sensor back in with the linkage at the wrong angle. On that car, the sensor only controlled the headlight angle but the lights were pointed steeply downward (couldn't drive it that way) because of the install error. And it was an easy mistake to make - I didn't figure it out until I compared a photo of the correct install with what I'd done and then it was obvious..

 

[thelostotter]

My GT felt bouncy for a few hundred miles when I put in BMR RLCA bearings. Those bearings are incredibly tight when new so once they broke in a bit the bouncy feeling was gone.

 

[fpa1974]

Regarding the question on VDM and height sensors. I hooked up Forscan and everything seems happy. No error codes, performed the ride height calibration with no problems. That is why I am honing in on the bushings to be honest.
FTBR told me they have not seen this before and to check the install. They also mentioned their bushings are very tight out of the box.

I might just swap them for Cortex ones or go back to my original LCAs which I kept. I am a bit torn. But what I am experiencing is more than I bargained for in the beginning.

 

[JAJ]

Regarding the question on VDM and height sensors. I hooked up Forscan and everything seems happy. No error codes, performed the ride height calibration with no problems. That is why I am honing in on the bushings to be honest.
FTBR told me they have not seen this before and to check the install. They also mentioned their bushings are very tight out of the box.

I might just swap them for Cortex ones or go back to my original LCAs which I kept. I am a bit torn. But what I am experiencing is more than I bargained for in the beginning.

How did you do the ride height calibration? The early GT350/GT350R's had different calibration processes. The GT350 calibration was at static ride height (car sitting on level ground) and the R was at full droop (car on a lift in the air). That may have changed in later model years.

The reason I'm bringing this up is that it really does sound like a magride problem. I installed an early DSC controller back in 2017 and it was uncalibrated and my car bounced around like crazy until I got the calibration file loaded. Your symptoms sounded familiar.

 

[fpa1974]

Both Forscan and the tool my indy shop uses with the same results. I calibrated initially like the early Rs (suspension full droop) and then later tried like the tool was instructing (after 2018 suspension at ride height).