Ok guys, I'm having large problems with my GSR trans in my car. In higher rpm's (8200 or so) the trans won't shift into gear, doesn't grind, just hits a wall. I've tried changing gear oil twice, first was syncromax, 2nd is GM syncromesh. Is this a problem of syncro's, or more a problem of gear lube?

 

where is your clutch freeplay?

 

Does your shift linkage have a lot of play?

 

I'm not sure what you mean by clutch freeplay? Shift linkage has bushings, so it doesn't have a large amount of play.

 

clutch freeplay is how much clutch movement you have before the slave cylinder actually moves.

the root cause might have been a clutch issue but now there is probably tranny damage.

i bet if you open the tranny you will find excessive wear on the syncs and gears.

 

flush the fluid in the clutch system and re-bleed. Get some motul DOT 5.1 (non synthetic) from Iron Pony it has a bit higher boiling point and im sure the turbo manifold has to be somewhere close to the slave cylinder. Try that first.

 

x2. Verify the system is in good working order. For clean shifts the clutch must be able to fully disengage for that split second.

 

I'm having this same problem with my transmission. I've noticed that the problem doesn't seem to exist when i'm on the street with normal tires. Only when i've had my slicks on at the track.

problem is i've got to let out of the throttle enough to drop rpms so that it will engauge, and by this time i've got to try & build boost again when i get into the next gear, which is killing my times.

I've check my slave cylinders motion & it's fine, i've even bled all the fluid anyways. I've also tried synchromesh as well as just some 10-30 oil in my trans, neither as resolved the problem.

As i stated, the synchro's are working perfectly when i'm beating the crap out of teh car on the street.

 

up for answers

this only seems to occure when shifting between 8500 & 9500 rpm's

 

I would be willing to bet its your clutch. I had the exact same problem a while ago. At first I thought it was my tranny fluid overheating. I did the same thing as you and tried all kinds of tranny fluids. After replacing the clutch and slave cylinder and bleeding it all its good to go now and shifts smoother than ever even at high rpms.

 

I guess my suggestion is also a question, with increased torque at the higher end of the RPM’s could the gear shafts be separating thus not allowing the gears to engage.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EddieCRX &raquo;</TD></TR><TR><TD CLASS="quote">I guess my suggestion is also a question, with increased torque at the higher end of the RPM’s could the gear shafts be separating thus not allowing the gears to engage.</TD></TR></TABLE>

It is rather common to have shifting issues especially at higher RPM....basically the OEM synchros have a few missing teeth from the factory. The missing teeth can be viewed as an opportunity for engagement. An old trick is to remove additional teeth from the synchros to provide more opportunities. This allows easier shifting at higher RPM.

To add opportunities for engagement follow these guidelines: Synchro had 3 teeth missing, remove 3 more (as equally spaced as possible). If the OEM synch had 4 teeth missing, remove 4 more for a total of 8. Do this for the 1-4 synchros. This will greatly improve the High RPM Shifting and not affect the low speed shifting.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by integratuner77 &raquo;</TD></TR><TR><TD CLASS="quote">I would be willing to bet its your clutch. I had the exact same problem a while ago. At first I thought it was my tranny fluid overheating. I did the same thing as you and tried all kinds of tranny fluids. After replacing the clutch and slave cylinder and bleeding it all its good to go now and shifts smoother than ever even at high rpms.</TD></TR></TABLE>

It's an ACT 6 puck with unsprung disk & extream pressure plate. With only 3000 miles on it, it works flawlessly. I highly doubt it's the clutch failing, but thanks for your input.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hypothetical &raquo;</TD></TR><TR><TD CLASS="quote">

It is rather common to have shifting issues especially at higher RPM....basically the OEM synchros have a few missing teeth from the factory. The missing teeth can be viewed as an opportunity for engagement. An old trick is to remove additional teeth from the synchros to provide more opportunities. This allows easier shifting at higher RPM.

To add opportunities for engagement follow these guidelines: Synchro had 3 teeth missing, remove 3 more (as equally spaced as possible). If the OEM synch had 4 teeth missing, remove 4 more for a total of 8. Do this for the 1-4 synchros. This will greatly improve the High RPM Shifting and not affect the low speed shifting.

</TD></TR></TABLE>

I understand the theroy behind this but i'm suprized i've never heard of this meathod until now. I'd have to hear a lot more stories of success before i'd chance destroying my synchro's.

Once again, thanks for your input. I'm thinking it has to be something a little more simple than this. People rev GSR tranny's to redline every day. How come i'm having issues with slick on & not street tires?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Running925 &raquo;</TD></TR><TR><TD CLASS="quote">Once again, thanks for your input. I'm thinking it has to be something a little more simple than this. People rev GSR tranny's to redline every day. How come i'm having issues with slick on & not street tires?</TD></TR></TABLE>

Your problem could come down to Motor Mounts/Traction. On the street the tire will free wheel much easier than on a set of slick on a sticky track. Could be the extra traction is creating the extra twist in your engine tranny and therefore misaligning parts of your linkage or binding your cables if it is a cable shift unit.

BTW, I agree that it is something simple for you most likely...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hypothetical &raquo;</TD></TR><TR><TD CLASS="quote">

Your problem could come down to Motor Mounts/Traction. On the street the tire will free wheel much easier than on a set of slick on a sticky track. Could be the extra traction is creating the extra twist in your engine tranny and therefore misaligning parts of your linkage or binding your cables if it is a cable shift unit.

BTW, I agree that it is something simple for you most likely... </TD></TR></TABLE>

Shift linkage is metal bars with good bushings.
Mounts are HAsport's with 3k on them total. It's pretty solid.

Keep goin tho.. maybe we'll stumble accross the problem!!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Running925 &raquo;</TD></TR><TR><TD CLASS="quote">Keep goin tho.. maybe we'll stumble accross the problem!! </TD></TR></TABLE>

I've done what I can in this internet garage. Good Luck with it...

 

i changed drained my clutch fluid & replaced it with a synthetic blend that is supposed to be tolorable up to 500 degrees f.

drove it a bit last night & this morning to work, seems better but wont' knwo if the problem is gone till i can take it back to the track with the slicks on it.

 

keep us posted

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by integratuner77 &raquo;</TD></TR><TR><TD CLASS="quote">I would be willing to bet its your clutch. I had the exact same problem a while ago. </TD></TR></TABLE>

I have seen the same thing... At the last IDRC event I went to I was having the same problem.... I had an ACT 6 puck clutch also.

There was a problem with the pressure plate not disengaging completely. It was not "flat". You could see some discoloration caused by heat over an area of about 1/4" wide and 2" long.

This put a slight amount of drag between the motor and input shaft not allowing the synchros to do their job. Just think about what the synchro has to do… It has to “synchronize” the gear you are selecting and the shaft it rides on before the slider can “lock” the gear into place. So going from 1st to 2nd gear the synchro has to slow down the input shaft to match 2nd gears’ ratio. If the clutch is dragging, the clutch is fighting the syncho. The clutch will win to

I switched out the clutch with an Action unit and the problem was gone.


To the O.P. :

I would check the travel of your slave cylinder. If it is too short, then your problem is in the hydraulic system. If not then the only way you will find out is to drop the tranny and inspect the clutch for uneven wear.... if that’s not it, then you will have to tear the tranny apart

I also wouldn't do any high rpm shifting until you get it fixed, as it will just cause more damage.



Modified by TrueNorthStar at 2:16 PM 5/30/2008

 

ive seen a warped crankshaft cause the problem, a buddy and i changed every drive line piece in the car 3 times before we tried a different crankshaft, by then the eagle crank had already destroyed the block.

probably not your problem but if you do reach the end of your rope trying there is a last ditch idea

 

So I have some what of a similar problem, my GSR won't down shift into 2nd from 3rd i have to come to a complete stop so the pressure plate will disengage Im running a tilton carbon clutch anyone have this kinda prob?

 

up

 

I've found that the bearings in my transmission that hold the shafts in place have failed and that was the cause of my shifting problem.

I'll be replacing the bearings asap & hope to report back with good news.

 

I had the same problem you're having when I used the same clutch you have now.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by V-SPEC 1 &raquo;</TD></TR><TR><TD CLASS="quote">I had the same problem you're having when I used the same clutch you have now.</TD></TR></TABLE>

how would an act2600 cause this?