Rapid Designs A90 Supra Differential Brace

[Strat-Supra]

Personally, I don't think you would actually feel a noticeable difference. At the end of the day, all of the braces on the market should perform the same. The only benefits mine brings to the table are easier fluid changes, wedgelock washers, and pretty colors lol.

I appreciate even considering changing over to mine however!

Thank you, still considering

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[razorlab]

We were thinking you were saying someone had already installed it

Yea I can see how my comment could have came across that way. I meant someone already got under there and looked, which was you.

 

[rwense]

Just a reminder, the group buy period will end tomorrow 2/27 at 11:59 PM EST!

 

[rowdy]

going to do a re-torque on the bolts. Initial week with the brace had no issues. I went out of town for a week and first day back i drove the car and noticed it having a clunk at low speed/rolling to near stop and it occurs when switching from drive to reverse (the chassis rocks/twists when switching between Drive and reverse) and vice versa so my thoughts are the brace bolts might have slightly settled while I was gone and loosened up causing the differential to move more. I’ll update after

This is all new territory for me so if anyone has thoughts if it is something else or advice when going back under. I would appreciate it.

 

[i3igpete]

Any chance you changed the diff fluid at the same time?

 

[tracer bullet]

On the bolt torque subject, I want to say that I do NOT know if I'm looking at the correct information here, and so this is a question only: What, for sure, is the bolt torque spec to be used here? The guide for the brace indicates 45 ft-lbs, but if I'm reading the Toyota doc here correctly it is intended to be 103 ft-lbs? That feels crazy high to me, and so I could have this wrong, but wanted to ask.

(I don't currently have access to the BMW system to cross check).

 

[rwense]

going to do a re-torque on the bolts. Initial week with the brace had no issues. I went out of town for a week and first day back i drove the car and noticed it having a clunk at low speed/rolling to near stop and it occurs when switching from drive to reverse (the chassis rocks/twists when switching between Drive and reverse) and vice versa so my thoughts are the brace bolts might have slightly settled while I was gone and loosened up causing the differential to move more. I’ll update after

This is all new territory for me so if anyone has thoughts if it is something else or advice when going back under. I would appreciate it.

Just remember, the brace rigidly mounts the diff so NVH is expected. Personally I have noticed a small clunk starting from a stop or applying load when under <5mph but its never been repeatable on command. More than likely its either slight movement of the diff or another drivetrain component.

I wouldn't be too concerned

Also, those wedgelock washers should prevent any movement of the bolt, but id still paint mark them just so you dont have to get under the car and check.

 

[rwense]

On the bolt torque subject, I want to say that I do NOT know if I'm looking at the correct information here, and so this is a question only: What, for sure, is the bolt torque spec to be used here? The guide for the brace indicates 45 ft-lbs, but if I'm reading the Toyota doc here correctly it is intended to be 103 ft-lbs? That feels crazy high to me, and so I could have this wrong, but wanted to ask.

(I don't currently have access to the BMW system to cross check).

That is correct, the spec is incredibly high. I consulted with numerous people about this as I did research on what spec I should specify for the install. No one, including myself, could figure out why such a value is needed since all these bolts are doing is sealing the aluminum cover to the diff housing which compresses a bit of sealant between the two. So there shouldn't need to be a high level of tension applied to maintain that seal.

When doing development I had my brace off and on a handful of times and I can tell you, re-torqueing those bolts was SCARY at 103 ftlbs

My specs are derived from NASA's document you can find HERE. For obvious reasons I trust their data in pullout strength and such.

EDIT: if you look into other specs for other diff braces, my torque specs should be in line with them

 

[i3igpete]

I also had the same thought about torque after reading the directions. In this case because it's a wedge lock going into an aluminum surface, I trust the wedge lock specs. Since this is a specialized part, over torque would probably destroy it.

 

[minn19]

going to do a re-torque on the bolts. Initial week with the brace had no issues. I went out of town for a week and first day back i drove the car and noticed it having a clunk at low speed/rolling to near stop and it occurs when switching from drive to reverse (the chassis rocks/twists when switching between Drive and reverse) and vice versa so my thoughts are the brace bolts might have slightly settled while I was gone and loosened up causing the differential to move more. I’ll update after

This is all new territory for me so if anyone has thoughts if it is something else or advice when going back under. I would appreciate it.

Bolts etc don’t settle by sitting. They loosen because of vibrations and heat cycles. Which, is why you should always recheck your wheel lugnut torque after a few drives when you’ve switched out a wheel set. Or when tracking etc.

I’d retorque them as he mentions you may have to do in the instructions (paint mark) and make sure you assembled the washers correctly etc.

 

[rowdy]

Any chance you changed the diff fluid at the same time?

the only thing i can think of was, since i am limited on tooling, i had used my jack to lift the rear of the car via the differential itself (correct lift point via direction of another thread) and did the install that way that maybe putting on the brace while it was preloaded might have caused the brace to not seat correctly once dropped. I’m might also try buying some ramps or something to slide under the wheels so i can drop it back down and the differential be in its natural state when re-torquing.

 

[i3igpete]

Oh, yeah that is probably compressing the bushings upwards. Not sure if it's the source of the clunk, though.

Doing it on stands would let it sag with ~50 lbs of preload down. But with the jack on there, the bushings have 1500 lbs of preload up.

The reason why I asked about fluid is that the clunk is likely the clutches locking or releasing near parking speeds. And depending on the fluid, it could make it louder or quieter.

 

[rowdy]

Oh, yeah that is probably compressing the bushings upwards. Not sure if it's the source of the clunk, though.

Doing it on stands would let it sag with ~50 lbs of preload down. But with the jack on there, the bushings have 1500 lbs of preload up.

The reason why I asked about fluid is that the clunk is likely the clutches locking or releasing near parking speeds. And depending on the fluid, it could make it louder or quieter.

That makes sense, but yeah i didn’t touch the fluid.

The slight clunk on low speed/near stop seems normal based on other responses so i rest easy with that knowledge.

I think what was scaring me the most though was how much noise and physical rock/jolt was coming from changing Drive to Reverse and vice versa.

 

[Rensuhlo]

that small clunk is fine. I've had it, others have had it. Take that worry and redirect it to figuring out what you're having for lunch today.

 

[Wilzzonn]

So glad I checked in on this, order placed!

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