I recently purchased a 1993 Z28 because it was a good value and I wanted a project car. I purchased it from a dealership that told me that the overdrive doesnt work.

When we drove it home and before we changed the transmission fluid it would not shift to a higher gear until you reached about 5000 rpm. So when your going 65 its about 2700rpm.

Then we changed the fluid and it would shift through all the gears perfect when my dad drove it. Then we pulled over and I drove it I must have hit the gas a bit too much right away and then it went back to the ways where it would have to rev til 5000 to shift again. We then stopped, put it in reverse, and went back and forth though the gears and then it was again perfect it shifted like it was sopposed to.

Then today, I drove it all around took my mom out for a ride, took my great grandpa who was a mechanic who has put in 100s of transmissions out for a ride and he thought it shifted well.

Then I drove to my friends home to show it to him where it was still fine and it shifted perfectly.

We then turned around and stopped and i touched the gas a little bit more because a car was coming and then it went back to the rev til 5000 then shift.

Please Help me
Any advice would be nice.

 

in 93 they had the old style trans. with tb cable or kickdown cable they will do that if this cable sticks
it is what controlles the shift timming

 

How can I tell if mine is the old style or not? We have a hunch that it looks like its from another car and when we look at it there are alot of electrical things going to it.


Also this does not have a muffler and exhaust

I was looking at the Magnaflows for it are they a good product or what else would be a good exhaust for it.

 

How should I go about fixing this then.


We drove it today and it shifted good then when my dad stomped on it and we stopped then it wouldnt shift again.
He seems bent on rebuilding the tranny. Does it really need it?

Or should we do it anyways because it will need to be done sooner or later anyway.

 

I am assuming you have the 700R4/4L60, and not the 4L60E, if this is the case, then the throttle valve (TV) can get stuck (somewhat common) and then it frees it self up till you do what makes it stick again. At a minimum the Trans-Go Junior Shift kit will solve this, but if you want firmer WOT shifts then install the Trans-Go Performance Shift kit. This kit has the self-cleaning TV valve as does the Junior. If I can be of help let me know?

 

So a shift kit would help this?

Could i clean it out by opening the pan taking off the filter and cleaning out the valve?

Also when we open it we see Wires running to it does this mean it is a 4L60E?

If it is could you please tell me how i could fix my problem with that transmission?


I dont want a shift kit because i have hurd that they shift too harshly and snap too much.

 

Sure, a Trans-Go is a perfect solution if you want to burn the transmission up. The TV valve is probably the culprit. The problem is, when the TV valve sticks, it's usually because something is coming apart in the transmission and shedding metal.
When you changed the fluid was there any metal in the pan? Did the old fluid look metallic? Did it look brown, or black? Did it smell burnt? All these are signs of a transmission on its way out. The 3-4 clutches have to hold for 3rd and 4th, but so does the 2-4 band. These are 2 of the most common failure areas of a 700 transmission...Yes, you have a 700 (4L60) Your transmission is still governor shifted. '94 brought in the 4L60E, which is electronically controlled.
The condition of your fluid is something that will point you in the direction of your problem.
The next time this occurs, lift the hood. With the car running, snap your TV cable a few times (This is the cable running to your transmission). See if this helps the problem. If your pan/fluid looked good, it could just be a small piece of debris in the valve. This would be a best case scenario. During a normal rebuild, I always install a small return spring in my TV valves. It's actually a reproduction of an old Ford FMX conical governor sping. Most of our rebuild kits include them, but you should be able to find a shop that can drop the valvebody and install one for you.
For my last piece of advice...Stay away from the Trans-Go shift kits. TG is a widely used "Buzz Word" for some reason. I can assure you that TG kits tear transmissions up. I've been building automatic transmissions for racing for almost 15 years. I've never taken one apart that had a TG kit in it that didn't have a burnt 2-4 band and 3-4 frictions. You'll see many many posts on here about repeated transmission problems, and everyone bad mouthing the 700/4L60E transmissions. My 700 has right around 200 12 second passes on it. If you need further proof of these transmissions durability (WITHOUT A TG KIT) look up Dirk (AKA RACINLT1). Ask him how many low 11 second nitrous passes he's got on his 4L60E I built him over 2 years ago.

Frank

 

When I changed the fluid it was coffee-black and it just smelled completly burnt. I also found one piece of metal when i changed it.

Do you think that it needs to rebuilt or would attempting to Fix the TV fix the problem.


Also do you reccomend getting the tranny rebuilt or just getting a new one from B&M or GM?

Thanks for all your help

One more question what kind of cat back exhaust system do ya reccomend. I want one thats a fair price and not too loud.
I was thinking Magnaflow.
Thanks again.

 

It all depends on if there are any reputable shops in your area. I'd advise against big chain shops. GM just rebuilds SERTA units with all the same design flaws back in them.
Where are you located?
Yes, if the fluid was that bad, you're probably due for a rebuild. Trying to fix the TV will probaly just be a waste of time and money.

Frank

 

I'm from North Dakota And as far as shops our farm mechanic has a friend that was the transmission guy at the big Chevy dealership in Fargo for 17 years and now has his own shop and he will rebuilt it.

My dad is getting a wild hair that he and I should rebuilt it but i dont think thats a very good idea.

 

The trans go shift kit is the way to go! i love when stuff breaks...An excuse to put a faster part in its place!

 

700 transmissions aren't a very good "beginner" transmission.

 

So your saying we should take it out and bring it to a professesional to rebuild it.

 

i have to disagree about the trans-go. I've installed both trans-go and B&M shift kits in many different transmissions, and never had any problems. My truck has 700r4 with 130,000 hard miles, and no problems. 94Z has 98000 no problems yet!

 

What Rebuilding kit do you reccomend?