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JamieP's Black Beast (update 1132bhp & 840ftlb at hubs)


JamieP
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My TRD/majestic diff is not to happy, started leaking from both sides a few days back, the oil was dropping on the exhaust and making a serious stink, I got home from work today and i swapped it out for one of my spare diffs, gonna drop the diff to Lee tomorrow to check out, i need that diff back in asap if im to do any drag racing.

 

Same problem as I am having?

http://www.supraforums.com/forum/showthread.php?549325-Diff-side-gear-(stub)-keeps-backing-out-and-diff-leaking-oil

 

So this power is still made on Shell V-Power? That's VERY impressive. Huge congrats Jamie!

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Same problem as I am having?

http://www.supraforums.com/forum/showthread.php?549325-Diff-side-gear-(stub)-keeps-backing-out-and-diff-leaking-oil

 

So this power is still made on Shell V-Power? That's VERY impressive. Huge congrats Jamie!

 

Seems so, thanks for the link, interesting that everyone with the problem seems to have a TRD diff, has yours been ok since the last update?

 

Yeah still V-power, i think there might still be some left in it an all.

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Could be off the mark here, but would this be a possible solution:

 

https://www.facebook.com/photo.php?fbid=220187667998427&set=a.219118351438692.71037.100000215866054&type=1&theater

 

Made by Accelerated performance

 

 

Eliminates the Factory Crush Sleeve. Eliminates any chance of forcing the pinion out and stripping the ring due to slop. Something we used to commonly have happen
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Interesting, I have a TRD diff and have had the same problem for a long while, I have even had the seal replaced and it started it doing it again a short while later, I was thinking it might be a bent drive shaft but maybe not.

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Seems so, thanks for the link, interesting that everyone with the problem seems to have a TRD diff, has yours been ok since the last update?

 

Yeah still V-power, i think there might still be some left in it an all.

 

 

Nope, I'm still having the same problem. We modified the locking rings during the winter to get some more locking force to keep the stubs in, but one stub came out anyway a week ago. Been thinking of getting a carbonetics LSD to replace the TRD.

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Could be, Im gonna check in the morning to see if the stub axle has come out, i was just looking through the pics i took on my phone and it dont appear to have, i cant be arsed to get out of bed now and go look.

 

It looks like it should be more in. Take a wooden block and put it on the stub and bang the stub in with a hammer. It should go in about 3-4mm.

 

 

 

Darrett: I dont quite understand what the Acclererated performance crush sleeve eliminator does?

Edited by Krister (see edit history)
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Hmm, cant tell from that picture. The first one you posted you can see the lip on the stub. Take a look at my pics of SF.com

 

 

Just bang them in and avoid wheel hop. You can try to do the same as I did, pry the locking rings a little more wider and you will get a little better tension on them. It seemed to have helped a little with my problem as the problem is not constant as it was before.

Edited by Krister (see edit history)
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I will have a think about this, but I reckon wheel hop and suspension compression with full power applied is doing it. There's now far too much torque loading on too small a c/v joint set up for the power you are now running, and the traction you have, the shafts now loose plunge (the ability to extend and contract lengthwise because of the "plunge" in the 2 c/v joints) The balls lock up due to the torque they are transmitting. The shaft then effectively becomes a fixed length and as the suspension squats they cannot extend, so pull the stub shafts out. When the torque excess is removed (you lift off) the plunge is restored, and there's no incentive for the stub shafts to go back in without external assistance. Early Can-Am cars, and other stuff with pre c/v joint drive shafts used a sliding spline joint with Hardy-Spicer universal joints for angular change only (no plunge) on independent rear suspension shafts. Even the docile Triumph 2000 and 2500 sixties British road cars used a sliding joint to accommodate rear drive shaft length changes. These grabbed even with the modest power of a Triumph 2000 road car engine, and made coming off the throttle mid corner very interesting, as the shaft suddenly freed and the suspension went from near solid to working normally. Lotus saw this issue and went with Rotoflex couplings, but those broke up regularly....The bigger sliding joints developed on the Can-Am cars were designed to take huge power without sticking, but power and grip from aero development went up, and the big joints did the same, and seized under torque loading. They then went to complex joints with rollers in them to aid against stickage.This was the main reason for c/v joint and tripod joint development, plus complex speed variation vibration problems with Hardy-Spicer type joints at high angles. You lot have now reached and gone beyond the torque capacity of the rear drive shaft joints and they now longer both transmit the rotational torque AND absorb the longitudinal plunge. Trick grease will help, Neo make some I use in serious race car joints, but it's VERY expensive. The real fix is bigger joints, or, as I think I said earlier, bin the independent suspension and go live axle with a spool, but then the car is 100% drag only. Having bigger shafts and joints made is not trivial, and will probably need bespoke side shafts for the diff machining, and bespoke hub flanges. It may be better to use tripod joints. GKN Motorsport could advise. http://www.gknservice.com/global/motorsport/cv_shafts_joints.html

 

Am I right about this? Hmmm, after having typed it and read it back I have gone form 85 to 95% sure I am. It all makes perfect mechanical and logical sense. When the Yanks talk of the cars being "bullet proof" they talk nonsense, there may be a good overhead of residual power handling ability in many aspects of the engine and drive train, but there is a very definite limit. You have found one of them. Drive shaft failure is very dangerous for both driver and spectators. Back seat passengers come in the very high risk category :)

Edited by Chris Wilson (see edit history)
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Oh, and yes, why is it seemingly a problem with cars with TRD or other LSD's? Well, an LSD is designed to transfer torque to both driven wheels. Without one, or with a feeble one, just one wheel will go light with the torque reaction, lift and spin, so the shafts and joints have to transmit far less torque. Add an LSD and the traction increases hugely, but so do the torque loadings on the joints and they don't want to plunge AND transmit it. It all makes perfect sense ;)

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Sounds perfectly plausible to me Chris.

 

Bigger joints to drop the contact stress or somehow the sliding friction of balls needs to be dropped. Extended use would probably prove this with visual signs of damage to the balls or the male/female coupling.

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Not sealed, well, sealed with a removable boot with an air expansion gap. GKN do special joints with polished tracks and undersized balls, but probably NOT for a Supra. Motorsport tends to use a relatively small range of C/V joints.

 

I suppose a proper surgically clean wash out and grease change is by far the cheapest first option for a fix:

 

https://shop.fluidsinmotorsport.co.uk/product/hpcc_1_synthetic_grease_360ml_cartridge/

 

then move on to:

 

http://www.chriswilson.tv/Motorsport_Catalogue.pdf

 

Have you cheque books ready though.

Edited by Chris Wilson (see edit history)
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One final thought for this morning. Is your tyre hop CAUSED by the plunge seizure of the C/V joints under extreme torque? The suspension will be locked, then freed, then when grip returns, locked again.... Drag racing is such a kick in the teeth to vehicles, very cruel, and quite pointless ;)

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Not sealed, well, sealed with a removable boot with an air expansion gap. GKN do special joints with polished tracks and undersized balls, but probably NOT for a Supra. Motorsport tends to use a relatively small range of C/V joints.

 

I suppose a proper surgically clean wash out and grease change is by far the cheapest first option for a fix:

 

https://shop.fluidsinmotorsport.co.uk/product/hpcc_1_synthetic_grease_360ml_cartridge/

 

then move on to:

 

http://www.chriswilson.tv/Motorsport_Catalogue.pdf

 

Have you cheque books ready though.

 

Chris, how much are these CV Joints and what power will they take?? I can get shafts made that will not brealk for around £500 a pair.

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