Evening all, I bought a 95 Z71 last night. I have a 90 Identical to this without the stepside. I have a real weak reverse until the shudder goes away under moderate acceleration (roughly 1500 rpm) All forward gears shift firmly lots of go. When I put her in R she hesitates for a few seconds, engages (Idle drops) bring Rpm to roughly 1500 and she will roll back then shudder and then it hits real hard. Once in reverse I can peel the rubber right off the rims (stays engaged) Go back to drive and then back to reverse I find myself with the same problem. I havent had a 700 apart in years. Our shop is not equiped to rebuild and my boss hates the smell of tranny fluid, lol. I am thinking reverse boost valve sticking but would like some feedback. I do have engine brake in 1st but does not seem as strong as my 90. I did hook up the wynns trans flush machine today and dumped a bottle of lucas in it but it made no difference.

Also on this truck, Wrong topic but hey I'll ask. Blows smoke, not just on start up but all the time. Oil rings? Gonna fire in a set of valve seals just because. The truck sat for 2 years before I got it, so the valve seals are probably all dried up, is it possible the oil blow by is all seals or are the rings siezed / shot?


My 90.. Only when cold I have a real noticable flare on 2-3 shift moderate to heavy acel, has a mild shift improver kit from transgo in it. Why only when cold???? Started this after the move from Northern Ontario to Alberta. The trip up here was great no slips/flare-ups pulling a small trailer with our camping gear on it. The only problem we had was the damn headder bolts fell out til I double nutted em.

Thanks in advance. Rick.

Mileage on these units?

The 1995 truck has a 4L60E trans... sound like the clutch packs are worn out for reverse.

1990 2-3 shift flare is too much clearance , worn out clutch pack or both usually... mileage on trans?

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Save the earth , choke a tree .... save a squirrel

95, truck has 291 on it not sure if trans was re-built or not (no history on it) However once engaged it holds real good, if it was worn or steel on steel I would have no hold at all?? right?

90 Built last year by a GM tranny tech, good friend of mine, never seen or heard of any of his trannys bugging out so soon.

Tks, Rick

1. nope.. You have a pressure leakage or clutch pack problem. Since the vehicle moves / drives fine in forward gears , i suspect a problem only in reverse. Hard seals or clutch pack

2. it is a mechanical item. I;ve built trans for decades. Most have gone a very long time, others .... not so much.

3..I am curious; If you have a good bud that is a GM trans tech, why are you here asking trans questions?

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Save the earth , choke a tree .... save a squirrel

He is 40 hours away with a 3 hour time difference. lol, would have been 1 am or so last night when I started looking for answers on the net. I like to try to figure things out by reading other forums before I call someone, sometimes the answer is right there and a guy doesnt feel like a fool when he calls. I will call him today, however you think the pack has gone south eh? I like the dried seals theory due to the truck sitting, either way guess I'm building or lookin for a used one.

Thanks Rick.

Yeah, after I read this I looked at a map of Canada, the distance is about, the equivalent of Virginia to Texas, maybe further.

lol, you get my point, I did talk to him today and he said the same thing you said. Then laughed at me and said " well you could just drive it here and I rebuild it for you.. Bring coffee" 40 hours driving each way is not my idea of saving some cash on a rebuild, so regretfully I declined the offer. Guess I'll go shoping later.

Thanks for all your input, Maybe someday I can return the favour.

Rick.