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The mkiv Supra Owners Club

R154 Gearbox noise help


DANWB

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Hello I’m hoping someone could help.

I’ve recently (ish) converted my twin turbo from automatic to manual. As the getrag is so expensive I went for the R154 out of the mk3 supra. I also went for a racing flywheel and clutch (again not hugely expensive I got a package from America £400 – £500 all in clutch and flywheel) this is where I gratefully need someone’s help. I will try to explain to the best of my abilities and post a picture of the flywheel/clutch similar to the one I used, if needed I will happily try to record the noise though I couldn’t guarantee the quality.

 

Tick over, with the clutch pedal pressed it is lovely and quiet BUT with the clutch pedal released it’s an audible whirling/grinding sound like in a circular motion (continuous)

 

Pulling away there is a very audible screech/whine (not great pedal) not all the time but most

 

If I attempt to hold on the clutch it’s as if you can really feel and hear the gears grinding and vibrating through the car.

 

Last thing I can remember if I’m driving 20mph ish in 2nd gear as I slowly accelerate up to 30 mph the same audible sound and vibration happens up till say 33 mph + then it disappears (again if doing 40mph in 5th gear it sounds/vibrates)

 

I don’t know if its mind over matter but since putting a single shaft prop on its a little worst?

 

I’ve carried out 3 gear oil changes and put in a quieter fluid

 

After a trip to a gearbox specialist he says he recons it’s a broken tooth?

 

Again if anyone can help and if you agree with the specialist does anyone know where you can get strengthened internals?

Thanks again

help 154.png

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Thanks Chris for your reply, what I'm concerned is (while driving) that if the gearbox locks which I hope it doesn't could that then lock the rear wheels or just stop the drive? thanks again for your help.

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Pulling away there is a very audible screech/whine (not great pedal) not all the time but most

 

If I attempt to hold on the clutch it’s as if you can really feel and hear the gears grinding and vibrating through the car.

 

That sounds like clutch to me, I had a car with a paddle clutch that used to screech and vibrate when pulling away

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Can you remember if there were damper prings in the hub of the driven plate? No damper springs, or ones of an incompatible strength will cause terrible drive line noises.

 

But the fact in neutral it goes quiet with the clutch depressed suggests the gearbox has worn input or layshaft bearings.

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my apologies for being thick :-) do you mean in the clutch setup? if so no I don't believe there are any springs at all so its very aggressive. I personally thought it was a bearing but trans bloke said different hence why I thought id give you lot a shout :-) it is occasionally quite difficult to put it in to gear say 3rd to 2nd if that makes any difference? you certainly sound like you know your stuff so im very grateful for your help. I don't want to break down but if it does it can be recovered so that doesn't bother me to much, what im worried about though is that hopefully not but if the gear box locks up will the rear wheels then lock up or would the gearbox more than likely just explode and lose drive (again I wont hold you to it as nothing can be guaranteed but just trying to get a little peace of mind out of someone experienced) thanks again

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The gearbox is unlikely to lock up, and if it does the inertia is likely to just shear teeth off and it will free again. But who knows, caveat emptor....

 

 

Hard to say from a description, although you describe things well ;)

 

A driven plate with cerametallic linings (puck clutch) and no damper springs will create resonances and harmonics down the drive train.

 

It's you saying the noise is there in neutral, and goes when you depress the clutch. I suspect you have two problems :( One may be in the

nature of the type of clutch. The other an internal gearbox issue.

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Thank you Chris for your help it really is much appreciated. I've heard on many occasions that using a lightened flywheel takes the dampening away making stuff noisier but when I said that to the gearbox man he said no, hence why im confused. thanks again.

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