View Full Version : Shifting Problems @ High RPM - Done Drill Mod + New Parts, Bad MC?


OD4gen
06-07-2008, 10:44 PM
So earlier this year i got a new clutch and slave. A couple months ago my master went bad, so i replaced it. However, i got it from the place i got my clutch (KY Clutch). It was $65 and i was short on cash (they have good prices on their clutches too, which are pretty good), otherwise i would have got a GM replacement.

Now when i replaced the MC i did the drill mod, and i have bled the system multiple times since. Pedal feels fine. When i try to shift at high rpms it won't let me go into the next gear immediately, i have to wait a second.

Do you all think it's just a POS master? It looked identical to the GM master that was in my car, but maybe it just sucks on the inside. Think it's that or something else maybe? I've bled it multiple times, but maybe that is still a possibility?

Thanks for any input.

wrencher
06-09-2008, 12:40 AM
Hard call but have seen numerous problems cause this condition.
A poor hydraulic system, air or alot of freeplay in the pedal can cause problems.
A stock style pressure plate can be on the weak side. At high RPM depressing the pedal can make the pressure plate 'hang up' for a milli-second from centrifical force of the motors rotation. That can cause high RPM shift trouble as well.

When did the problem start? how does the pedal react/feel under those conditions (hi RPM shift?)

1966goat
06-09-2008, 12:50 AM
Hard call but have seen numerous problems cause this condition.
A poor hydraulic system, air or alot of freeplay in the pedal can cause problems.
A stock style pressure plate can be on the weak side. At high RPM depressing the pedal can make the pressure plate 'hang up' for a milli-second from centrifical force of the motors rotation. That can cause high RPM shift trouble as well.

When did the problem start? how does the pedal react/feel under those conditions (hi RPM shift?)

I agree it could be one or a combination of problems

vetteboyc5
06-09-2008, 01:01 PM
is your pedal getting Hard? Im having issues with this and Im curious to see what your problem is...

OD4gen
06-10-2008, 01:45 PM
The pedal always seems fine. I'll go double check how it feels at high rpms. I was paying attention more to the shifting problem but didn't notice any weird pedal feel.

I got a new clutch and slave and everything was fine until my MC started going bad (sticking pedal, then no pedal). I changed that and bled it decently. Then bled it better a little later. And even one or 2 more times since. I didn't really hammer on it much after my new MC install. Only recently have i been trying to shift at high rpm and have been noticing the problem more.

Someone did say something about my clutch's pressure plate. It's a KY Clutch. I'll ask him about it. He said he had to get an adjustable MC due to the pressure plate. He couldn't operate the clutch until he got an adjustable, but mine has been fine. It seemed fine with the stock MC. I'm pretty sure it went out due to the mileage (100k miles).

sacabuche
06-11-2008, 12:44 AM
did you ever change the pilot bearing, it may be worn and cause the input shaft to still rotate

BlackScreaminMachine
06-11-2008, 06:49 AM
Well I have the same problem....

went from a stock LS6 clutch to a Tex oz700. It hangs like yours.

I did a new pilot bearings, GM slave and had it power bleed, a stock MC and now a RAM adj. master, and their flywheel.

At this point since everything has been changed, I am going to put a shim in and do the drill mod. At the same time adj the MC down a little and see if it helps.

LS1C5Vette
06-11-2008, 07:50 AM
did you ever change the pilot bearing, it may be worn and cause the input shaft to still rotate

+1, also what clutch do you have and how many miles are on it/did you put at least 500 miles on it before beating on it?

OD4gen
06-11-2008, 02:17 PM
Yea the i have a new pilot bearing. I have a "Stage 2" Kentucky Clutch. I talked to some F-Body people around here and some of them have them and say they are pretty good. Better than OEM but not real high performance. I only have exhaust and lid so it should be fine. Yea i put at least 500 miles on the clutch, if not 1000+ before hammering on it. I don't get on it a lot as is, especially if i have a new part, because i can't afford for it to mess up.