GM Slave Cylinder?

[Speed_kills_WS6]

The guy at Advanced Auto told me the slave cylinder they carry is the same as the GM slave. It's roughly $70. The cheapest I have found the GM slave is $125. Anyone replaced their's using the one from Advanced? Any problems? Or do you guys just recommend the one made by GM? I'm sick of being locked out in 4th at high rpm's. With the 4.10's in now, I have to shift right before the traps. (1/8th)

[Snikker]

Hey, I hope I've caught you before you've bought the thing. If you can afford it go with the genuine GM part. I've seen almost every one of the advance deals fail. It is absolutely NOT the same as a genuine GM part(I cant stand it when people mislead others). The hydraulic channels and fitting hole diameters are much smaller than on the GM slave, Which are smallish anyway. The only aftermarket branded part I've seen not fail in that hydraulic system is the adjustable master cylinder by mcleod. Not to sound like a burn or anything here, I just want to save you some MAJOR headaches later on down the road
(823 miles to be exact). Good luck on the slave change man. And I hope this helps.

It also could be your clutch is not up to spec for the kind of driving you're doing (yeah I know it sounds silly but is very important). So If you're dropping the trans anyway I would definitely take a good look at the clutch assembly and examine it for any signs of glazing or heat checking on the flywheel. Also what kind of clutch is it?? and the master cylinder is the stock GM one then that is your problem right there, unless you replace the master cylinder with the mcleod above you must perform what is known as the "drill mod" because you're hydraulic system is so constricted that it cannot release the clutch completely when the fluid is hot. Does it go into 4th at all or only when you drive it hard? if it's only when you drive it hard it may just be as simple as your clutch needs an upgrade. so as to be more efficient.

here's a slave at summit, great shipping with them actually, very fast.
This is for an ls1 which is what I have, I am assuming you have an ls1 6 speed, I think the part should be the same for both v8 and v6 cars but I could be wrong (I have the dealer service manual for the ls1 cars, all 4 books, and the part numbers are the same but the picture is a little different possibly just the angle though)



-Alex

[Speed_kills_WS6]

Good deal. I'm thinking of doing an LS7 clutch. Normal driving, everything works fine. Just high rpm shifts it occasionally shuts me outta 4th. The stock clutch is in it now. Works great, just the hydraulics play hell on me.

[Snikker]

Yeah, I'm of the belief system that the ls7 clutch is more than fine with just about anything you can dish out. The stock clutch should not be sticking you out of a gear like that unless it isn't disengaging properly. Is it taking slightly more effort than before to shift it into the other gears at mid to low rpm?? the reason I ask is because I had a similar experience with my stock clutch and as it turns out I just needed a new clutch, (don't wait like I did or it'll get real expensive, My pilot bearing exploded, literally, just as I pulled into the trans shop) and ruined my input shaft on my transmission. If you do end up changing your clutch, I know it's more expensive, but go ahead and change the corresponding bearings while your in there. I didn't and I suspect that it's coming back to bite me right now, because my 3 month old clutch is slipping when you punch the throttle at cruising speed (~75 mph).

You said you have 4.10's in it, I'm gonna go ahead and assume you meant final drive gear, and not it's ratio (ie: 4 " : " 10). If thats the case the stock clutch should be able to handle that fine assuming you aren't producing more than about 400 hp at the flywheel. But to me honestly it sounds like it's one of three things.....


1. You simply need to bleed air from your clutch systems hydraulics (I know, it's a pain in the ass, but it is free and could fix it) **you didn't say if you had done this so that's why I am suggesting it.

2. Your clutch is on it's way out (not a good thing to wait on **see above) my advice is do not buy a SPEC kit. Go ahead and get something nice that is rated for your vehicle. Be sure to replace the flywheel if there is any heat "checking" (aka "hotspots") as no amount of resurfacing will fix that and if necessary replace the slave cylinder and it's bearings (especially the pilot bearing, even if you don't think you need one, it's a $29.00 part that could save you $1000.00 in work later so replace it anyway) and get the clutch kit as a matched set if at all possible. I mean Flywheel, Pressure Plate, and Clutch Friction Disk. It will make your life much easier (I think the ls7 kit comes as a true matched set).

3. Your slave cylinder is on it's way out. I didn't say leaking intentionally, because not every hydraulics failure is accompanied by a leak, sometimes parts become so gunked up internally and fail to function normally. In which case you should change both the master cylinder and slave cylinder as a pair. (you probably know this but I'm gonna say it anyway) once the slave or master goes, the other is right on it's heels.


However...

(make that 4 things)

given that your problem is at high rpms it leads me to believe though that your slave is okay and that the throwout bearing (the one on the clutch facing end of the slave) is not turning freely like it should be. In this case you should be able to get away with just replacing the throwout bearing (AND the pilot bearing, TRUST ME) and that itself should fix it.

Just be sure to check ALL of those things before deeming it something you've done to the car (not saying you couldn't have but, it is HIGHLY unlikely). and this last thing will sound silly, change your fluid in the transmission. I can't tell you the number of times
(I honestly don't remember, but it was alot) that I have seen that fix the problem.


The last thing that I will say it could be is that one side of the sychronizer face has been ruined (the blocking ring is probably shot and may have destroyed the engagement teeth) and this may have been caused by a shifter fork pad being broken or maybe even a bent fork. but if it goes into third and moves forward under its own power I doubt that one because 3-4 are on the input shaft. my advice is get any broken or worn parts fixed OR replaced (sometimes you get lucky) and put a fluid in it that is approved for synchromesh gearboxes (NOT dexron atf, that stuff was what gave the t-56 that annoying sticky feel as well as eating away at the fork pads) like penzoil synchrmax or royal purple's transmission fluid.



My advice is to do which ever one is cheapest (most affordable, do not scrimp on parts though, that's where you want to spend your money on quality, and go to a reputable shop preferably one that specializes in manual transmissions they may be able to TELL you exactly whats wrong without even taking anything apart, plus advice is FREE) and will get you what you want in the end. just be sure to check ALL of the above areas and that should pretty much cover you bases.


Best of luck, and sorry for the super long reply.

-Alex

[Speed_kills_WS6]

Definitely not the transmission. Already blew 3-4 synchro up and went back with all forged internals. Shoulda did the clutch then along with the slave. Hindsight is always 20/20 though. Thanks for the info.

[Red99TA]

go to kyspeed.com (site sponsor in case you didn't know already), you should be able to get the ls7 clutch kit and slave for 625 shipped, I found a brand new 02 master on ebay from jennings chevy for 170.99 shipped, you won't regret it