MSS91Z28

iTrader: (3)

Hey guys,

I have a '98 Z28 m6, bone stock, 115k miles. On the 1-2 shift,only at WOT, it grinds going into gear. Keep in mind this is only at wide open throttle/ high rpm and only from 1st-2nd. Under normal driving conditions/cruising the car shifts fine from 1-2. I already bled the clutch fluid and replaced it which didnt fix the problem.. and I'm about to buy a new clutch master cylinder and slave cylinder, and replace the clutch with an ls7 unit.

I'm just curious as to if you guys think my problems will go away after the clutch and new cylinders? If my tranny was in need of a rebuild wouldn't I be seeing grinding at all rpms or am I mistaken? Any help is appreciated..I'm prepared to rebuild if neccessary but hope I don't have to just yet.

Thoughts?

MSS91Z28

iTrader: (3)

Bump..someone give me some input!

SPEC-01

iTrader: (2)

The fact that this affects one gear at a very specific time would ead me to believe that the cause is more likley within the trans. Do you notice any greater or lesser chance of grind by shifting faster or slower?

thesource

iTrader: (60)

The syncro could be at the very early stages of failure. It could also be the clutch not fully disengauging soon enough at high rpms as well. What fluid is in the transmission?

SPEC-01

iTrader: (2)

Sure...that is why I was asking about the speed of his shifts. If the clutch were dragging, or if it were slow to release, it could cause a bit of a catch/hitch that would be lessened if he shifted more slowly.... It is possible...but it would also normally affect other gears at high-RPM too.

MSS91Z28

iTrader: (3)

If I shift it slow enough it won't grind. Not sure what fluid is in the trans..but the clutch fluid is pennzoil dot 3 synthetic

MSS91Z28

iTrader: (3)

bump..

MSS91Z28

iTrader: (3)

up again! someone give me some more input. Before I go through the hassle of replacing the clutch, master and slave cylinders, I wanna know what I may be in for

CW00BlackTA

iTrader: (31)

Your 1-2 synchro is probably on its way out.

earlz28

iTrader: (1)

I'm thinking 1-2 synchro as well, especially with 115k miles

MSS91Z28

iTrader: (3)

Thanks for all the input..

Ok guys I took the car out again last night to try and toy with it a bit. I would pull 1st gear to 6000 rpms, then wait a half second to full second before shifting to 2nd, and it never grinded at all. It only grinds when I shift quickly from 1st to 2nd.

Any further thoughts? If it was a bad syncro wouldnt it grind regardless of how fast or slow I shift?

mannyman84

iTrader: (2)

It's your syncro man. Think about it as a break, if it's gonna try to slow down the gear to engage it there is not enough meat to stop a gear that is going so fast, when u are driving slow it doesn't take much effort to stop the gear and engage it. So therefore it wouldn't grind because it's actually stopping the gear fine. Just get the second gear rebuild and u are gonna be fine. That's the gear that usually goes out by slamming gears and takes a lot of stress when racing

MSS91Z28

iTrader: (3)

I hear you, but remember..if I wait about a second before shifting to 2nd gear..it wont grind. And this is with the rpms still up between 5500-6000, so first gear is still spinning plenty fast..


Thanks for the input though, its deffinitely food for thought. Anyone else?

mannyman84

iTrader: (2)

I doubt that your RPM's would stay up in that area for a whole second, that's what I suggest u do. Get a Second gear rebuild and u gonna be ok. I've had that problem before with a little sentra and all it was, was a syncro. And 1st might be spinning fast but 2nd won't at the time u try to shift slowly

MSS91Z28

iTrader: (3)

How much can I get a 2nd gear rebuild for? If they are rebuilding 2nd isnt it gonna cost almost as much as redoing the whole trans?

mannyman84

iTrader: (2)

Not sure how much it would be for a t56. I doubt it would be as much as the whole thing. Just negotiate

95maroz28

iTrader: (21)

mine does the same thing with 130k. i guess ill be doing a rebuild when the stock clutch goes out