Rear unstable under heavy braking

[underdonk]

2018 GT3 with PDK, Agate grey with Xpel Stealth film on entire car so it looks matte. Got it for a great price since it came with the 18 way seats, replaced them with the GT2 seats. Still own the car and drive/track it occasionally. Keeping it indefinitely. Manual transmission in the GT3 is great but went with the PDK as it is faster on the track and my boys have no interest in driving a manual.

Awesome. I bet it’s a joy to drive. My 718 had a PDK. Best transmission ever, don’t care if it isn’t manual because it was amazing.

I’ll for sure be back in a Porsche after I have some fun with my Supra. Trying to get my Supra to be quicker than my 718 around a track!

I'm curious of your opinions on the ZF8 in the Supra compared to the PDK for track work? I drove a Porsche 911 Turbo S on their track in Atlanta, GA that had a PDK, but it was tough to compare, as it was a short period of time and I didn't own the Supra at that point (this was 2 years ago).

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[OneTimeAccount]

I'm curious of your opinions on the ZF8 in the Supra compared to the PDK for track work? I drove a Porsche 911 Turbo S on their track in Atlanta, GA that had a PDK, but it was tough to compare, as it was a short period of time and I didn't own the Supra at that point (this was 2 years ago).

Can't compare on track yet. I'll be heading to the track with my Supra for the first time next week and will report back my findings on how the ZF8 compares to the PDK.

As for daily driving and some spirited driving, the ZF8 is still a great transmission and it's hard to believe it's a torque converter! I have found a very, very slight delay in upshifts near redline and at slower speeds, but not all the time. Otherwise it's really sharp. It doesn't interfere and you can rely on it, which is important.

The PDK felt more solid, with the shifts being instant, in any condition, and it did a great job at keeping the car smooth at lower speeds without any judder or jerkiness. Never a hiccup. And the mechanical sounds it made right behind you were awesome.

 

[underdonk]

Can't compare on track yet. I'll be heading to the track with my Supra for the first time next week and will report back my findings on how the ZF8 compares to the PDK.

As for daily driving and some spirited driving, the ZF8 is still a great transmission and it's hard to believe it's a torque converter! I have found a very, very slight delay in upshifts near redline and at slower speeds, but not all the time. Otherwise it's really sharp. It doesn't interfere and you can rely on it, which is important.

The PDK felt more solid, with the shifts being instant, in any condition, and it did a great job at keeping the car smooth at lower speeds without any judder or jerkiness. Never a hiccup. And the mechanical sounds it made right behind you were awesome.

Thanks for the perspective. I'd love to hear your opinions after a day at the track. You echoed what I tell people about the ZF8 as well - can't believe it's a torque-converter-based transmission. Seems like they got it right with this one, and probably the reason BMW is moving away from DCTs completely in future models (I read it on the Internet so it's obviously true).

Enjoy the day at the track! Hitting NCM this Sunday myself.

 

[jorligan]

Always surprised regarding the ZF but I think that it is a little sluggish as compared to the PDK and sometimes, it shifts unexpectedly on the track when you drive it in automatic mode. This is somewhat of an unfair comparison as the PDK is probably the best dual clutch on the market especially when trying to pick the correct gear to keep the engine in the power band.

 

[SavageGTR34]

Honestly their was an alignment issue on mine but had it done 2 days after I drove it 50 miles home. But one other thing I did was add the H&R lowering springs and the Cusco front tower brace (didn’t get the rear done before I went back on the road), the mid cross member (that thing is a flimsy piece of shit) and Cusco front and rear sway bars. I will be completely honest the new front a rear sways add an much better feel to the car. Steering feels more solid and controlled. Could mention more but 30min break almost over then heading to VA….but will say this next 2 upgrades are the axles and the damn brakes. Slowing that beast down from 158 was one hell of a choir. (Yes my 21 is tuned I got lucky, stage 2 bootmod with catless dp and AWE res touring exhaust, intake, charge pipe, inlet pipe, and a few others)

Also don’t take this wrong but granted it’s pretty even height across the whole car stock but once you brake heavy it’s hauling an tanker load for me….all of that fluid transfers to the front of the tank damn near lifting the rear so your brakes are working hard as hell slowing that beast down. Lastly….the stock pads suck beyond reason. Worked at Toyota for 10 years and honestly the crappiest and dustiest pads I’ve ever seen from them. Try improving your pads. Speed Industry has some good ones

 

[OneTimeAccount]

Honestly their was an alignment issue on mine but had it done 2 days after I drove it 50 miles home. But one other thing I did was add the H&R lowering springs and the Cusco front tower brace (didn’t get the rear done before I went back on the road), the mid cross member (that thing is a flimsy piece of shit) and Cusco front and rear sway bars. I will be completely honest the new front a rear sways add an much better feel to the car. Steering feels more solid and controlled. Could mention more but 30min break almost over then heading to VA….but will say this next 2 upgrades are the axles and the damn brakes. Slowing that beast down from 158 was one hell of a choir. (Yes my 21 is tuned I got lucky, stage 2 bootmod with catless dp and AWE res touring exhaust, intake, charge pipe, inlet pipe, and a few others)

Also don’t take this wrong but granted it’s pretty even height across the whole car stock but once you brake heavy it’s hauling an tanker load for me….all of that fluid transfers to the front of the tank damn near lifting the rear so your brakes are working hard as hell slowing that beast down. Lastly….the stock pads suck beyond reason. Worked at Toyota for 10 years and honestly the crappiest and dustiest pads I’ve ever seen from them. Try improving your pads. Speed Industry has some good ones

Great info, thanks. I plan on getting a feel for the car as close to stock as possible then upgrade things I feel I need to improve the handling and feel of the car.

Brake pads are next in my list for sure.

 

[jorligan]

Well, no Supra at MidOhio. The passenger control arm inner bushing was shot. You could move the arm and hear a clicking. 11000 miles on the car. 2 track events - total of around 400 track miles. All track events were on stock suspension.

 

[OneTimeAccount]

Well, no Supra at MidOhio. The passenger control arm inner bushing was shot. You could move the arm and hear a clicking. 11000 miles on the car. 2 track events - total of around 400 track miles. All track events were on stock suspension.

Wow, that’s no good. Any idea why it would have failed so early? Makes me want to move to SPL products ASAP.

When you say move it, you mean by hand? Was it easy to tell it was shot?

I’m sorry to hear that. What a bummer.

 

[jorligan]

No idea for the early failure. Move is car was on the lift and you could move the wheel by hand and see the lower control arm move and click. Going to SPL. Will be interesting to see the actual wear. Will post.

 

[kyippee]

No idea for the early failure. Move is car was on the lift and you could move the wheel by hand and see the lower control arm move and click. Going to SPL. Will be interesting to see the actual wear. Will post.

Would a Toyota dealership replace the control arm under warranty for this...? I wonder if it could be considered early failure, or if they would just say you're on your own for that own due to operator-induced wear

 

[jorligan]

Checked it today. The bolt was loose Retorqued and now OK. Checked all other suspension bolts and they were OK.

 

[OneTimeAccount]

Checked it today. The bolt was loose Retorqued and now OK. Checked all other suspension bolts and they were OK.

Awesome so you mean it wasn’t shot but just loose? I wonder how it even got loose.

Just finished a day on the track in the rain at Waterford Hills today. Was quite the experience with Pilot Super Sports in standing water…

 

[type-964]

Just finished a day on the track in the rain at Waterford Hills today. Was quite the experience with Pilot Super Sports in standing water…

Do tell. Would love to hear your overall impressions.

 

[gcmak]

Did not read through the posts, but after getting an alignment and returning to the track, the stability of the car over crests at high speeds as well as full hard braking from 120+ to 40mph, dramatically stabilized. My car from the factory was all over the place (although still within spec).

Hope an alignment solves the issue for you.

 

[jorligan]

Awesome so you mean it wasn’t shot but just loose? I wonder how it even got loose.

Just finished a day on the track in the rain at Waterford Hills today. Was quite the experience with Pilot Super Sports in standing water…

Don't know how it got loose, the rest are OK.

You must be local to me if you were at Waterford. I have driven it a couple of times when dry and the track seems to be pretty polished. Not high speed but pretty technical. Good times! I skipped the sessions at MidOhio when the track was wet, didn't feel to drive on ice. Ever been to Grattan, another technical track with a little more speed.

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