tranny problem, really freaked out

[wheelhaus]

Originally Posted by sweetfrs

I would think it would put more stress

Understanding how the transmission actually works internally will help you understand why more power doesn't equate to synchro wear. Other parts of the tranny can wear faster and/or fail from additional power/torque, such as gear teeth, bearings, and cause other problems like shaft deflection, etc. Higher RPM causes more wear because there's a larger delta between each gear, so the synchros need to do more work to engage a gear.

Synchronizers are like little clutches between each gear. They create friction when you try to select a gear, and it won't allow the gear to engage until the speeds of the chosen gear and the input shaft are matched. The only wear they see is when these speeds are different.

Upshifting can be timed so there's almost no difference in speed when you click into the next higher gear, because the input shaft naturally slows down from oil friction when you clutch in and are in neutral (between gears). This is why you can time your shifts to be buttery smooth, catch the engine at just the perfect RPM as it falls, and not lurch at all. Do this well enough and a passenger can't even tell you've changed gear beyond the sound of lower engine RPM.

Downshifting can put more strain on the synchro because the synchro is being used to force the input shaft up to a higher speed. This is why rev-matching is important, it speeds the engine up to a higher RPM so the clutch engagement is done at match-speed. Double clutching bypasses the synchro function entirely and revs the input shaft along with the engine via rev match while in neutral. Do this smooth enough and a passenger can't even tell you've changed gear beyond the sound of higher engine RPM.

Engine power/torque numbers are irrelevant to synchro wear because it's function is during shifts, not power delivery. Hard shifting however is relevant, as is fluid choice and component tolerances from the part manufacturer.

Make sure you can tell the difference from a true grind and an occasional notchy shift. Many of the complaints I see IMHO are related more to the fact that first, second, and third use triple cone synchros which are much more durable, but don't feel as smooth with that nice single bump of resistance. At low rpm you can feel a few extra bumps as it engages, which can be misinterpreted as a grind.

[sweetfrs]

Originally Posted by wheelhaus

Understanding how the transmission actually works internally will help you understand why more power doesn't equate to synchro wear. Other parts of the tranny can wear faster and/or fail from additional power/torque, such as gear teeth, bearings, and cause other problems like shaft deflection, etc. Higher RPM causes more wear because there's a larger delta between each gear, so the synchros need to do more work to engage a gear.

Synchronizers are like little clutches between each gear. They create friction when you try to select a gear, and it won't allow the gear to engage until the speeds of the chosen gear and the input shaft are matched. The only wear they see is when these speeds are different.

Upshifting can be timed so there's almost no difference in speed when you click into the next higher gear, because the input shaft naturally slows down from oil friction when you clutch in and are in neutral (between gears). This is why you can time your shifts to be buttery smooth, catch the engine at just the perfect RPM as it falls, and not lurch at all. Do this well enough and a passenger can't even tell you've changed gear beyond the sound of lower engine RPM.

Downshifting can put more strain on the synchro because the synchro is being used to force the input shaft up to a higher speed. This is why rev-matching is important, it speeds the engine up to a higher RPM so the clutch engagement is done at match-speed. Double clutching bypasses the synchro function entirely and revs the input shaft along with the engine via rev match while in neutral. Do this smooth enough and a passenger can't even tell you've changed gear beyond the sound of higher engine RPM.

Engine power/torque numbers are irrelevant to synchro wear because it's function is during shifts, not power delivery. Hard shifting however is relevant, as is fluid choice and component tolerances from the part manufacturer.

Make sure you can tell the difference from a true grind and an occasional notchy shift. Many of the complaints I see IMHO are related more to the fact that first, second, and third use triple cone synchros which are much more durable, but don't feel as smooth with that nice single bump of resistance. At low rpm you can feel a few extra bumps as it engages, which can be misinterpreted as a grind.

Yea i know what you mean by that notchy feel but it definetly grinds only when downshifting from 5th-4th in higher rpms

[steve99]

Originally Posted by sweetfrs

So I took the short shifter out all that is left is the whiteline shifter bushing do I really need to take it out?

YES !

You : But its only a bushing.

Service Manager : Yes a non standard bushing that according to our Engineering staff it constructed of a less flexible material than the standard bushing which was designed with a specific amount of flex, the aftermarket bushing due to its construction has contributed to increased shock loads on the transmission and contributed to the resulting problems with your transmission.

You : errr well I reckon xxxxxxxxxx

[sweetfrs]

Originally Posted by steve99

YES !

You : But its only a bushing.

Service Manager : Yes a non standard bushing that according to our Engineering staff it constructed of a less flexible material than the standard bushing which was designed with a specific amount of flex, the aftermarket bushing due to its construction has contributed to increased shock loads on the transmission and contributed to the resulting problems with your transmission.

You : errr well I reckon xxxxxxxxxx

i don't think they should have a problem with that

[steve99]

Originally Posted by sweetfrs

i don't think they should have a problem with that

It should not matter but better to be safe than sorry

[Cridland]

I dont experience any grinding but when down shifting into second sometimes it is literally impossible (I dont want to force it in) any thoughts?

[Turkish]

Originally Posted by Cridland

I dont experience any grinding but when down shifting into second sometimes it is literally impossible (I dont want to force it in) any thoughts?

What are the conditions when it won't go into second?

[Cridland]

Going 45-50km downshifting from third to second, rev matching with clutch in and I cant get it into second until I come to a dead stop

[Turkish]

Originally Posted by Cridland

Going 45-50km downshifting from third to second, rev matching with clutch in and I cant get it into second until I come to a dead stop

Sounds like a warranty issue to me, I'd make sure your transmission is back to stock if you have made any mods to it and take it to the dealer to diagnose.

[Cridland]

Originally Posted by Turkish

Sounds like a warranty issue to me, I'd make sure your transmission is back to stock if you have made any mods to it and take it to the dealer to diagnose.

It's only happened once or twice, think I should wait? And all I have is a trd quick shift kit. I installed it though does that make a difference?

[Turkish]

Originally Posted by Cridland

It's only happened once or twice, think I should wait? And all I have is a trd quick shift kit. I installed it though does that make a difference?

It could, even if it isn't related to the issue, they may finger point to deny warranty.

[Cridland]

Originally Posted by Turkish

It could, even if it isn't related to the issue, they may finger point to deny warranty.

Thanks a ton for the help!

[sweetfrs]

I'm going to take out the bushings and then take it in. already took the short shifter out, stock shifter sucks compared to my kart boy lol

[PoWn3d_0704]

Mine just went in today. Just got a call abnout 10 minutes ago.... Issue in tranny.

I guess someone is out driving it now and I'll hear a call back.

I left my Perrin Shifter Bushing in, and I dont have the stock tune on the car, but the guys seem nice enough.