radar502

Any way to pin point the real reason my 04 Z is hard to shift under load and at high RPM ,the fluid is clean has new GM master does have 80,000 miles . The clutch and slave might be the one that came with the 04 was hot has been running hard for a wile ( might have boiled the fluid )?? Shifts great not under load . Just throwing parts sounds like big money and lots of work to hope that fixes it .. Thanks..

SuperVetteC5

Mine is very low mileage and is the same way. Even upgraded to a RPM Level VI tranny, Level III diff, MGW Flat Stick and RPS Triple clutch. nothing changed much.

radar502

Wow lots or work and money to not see much change .. I was thinking if it was a mechanical clutch instead of the slave might be the problem but nothing you can do about that deal .. Was reading can do some tricks to the trans but you got new trans so I guess not.. With headers and 550 Hp running it hard gets realty hot so might be boiling the fluid or under load the trans in a bind or both .. Changing over to Torque RT 700 brake fluid it has a high wet boiling point and a little cheaper that the others . The 04 works great if not running hard and hot or in a bind ,thinking maybe just not made to be shifted at high RPM and in a bind ?? Back to the drawing board.. Thanks

Bill Curlee

My immediate thoughts would be that you do not have enough clutch disk air gap. I have the same issues if I don't properly adjust my TICK master cylinder properly.

Try This:

Get her HOT (to the point that it starts shifting hard) and jack up the rear of the car and put it on stands. Start the engine, put it in gear and fully depress the clutch.
See if the rear wheel are still being driven.
There is usually some wheel creep but,, you should be able to easily STOP the rotation by hand if everything is properly adjusted and working correctly.

If there is a lot of powered rotation, you either don't have enough master cylinder fluid volume (not enough piston movement) or you have a WARPED CLUTCH DISK.

I have a TICK master cylinder and I can adjust how much piston movement it provides. DO NOT do too much as you will over compress the pressure plate springs and kill it.

radar502

Thanks, Not too long back installed a new Gm. master I guess I should went with a Tick but was tying just to stop the peddle from not returning ( The dreaded peddle on the floor deal ) that was the only problem I had at the time.The new GM . master seamed to have fixed that . Along with the hard shifting the peddle just felt hard and funny after it cooled off a little and not trying to shift under load , shifted fine .. Got to be something to do with the heat ( Headers 525 Hp ) and running hard , I'm thinking a brake down in the slave ,might be a combo , old slave not enough pressure from the master and very hot fluid all adds up to poor shifting.. May have to go with the Tick seems like the fix for hard shifting .. I will jack it up an check to see if the wheels are under load with the clutch in .. Also going with some high temp fluid going to try some RT 700 it starts at 638 % and drops down to around wet temp 435% might help.. Thanks..

jonpauls

Great troubleshooting tips! I encountered a similar problem a while ago with difficulty shifting and missed shifts (only at high RPM). I have the Tick master so after a little adjustment for some more fluid the car was back to normal.