phaledax

well anyway it's 2:00am and my 700R4 transmission just went out. or I have gears P,R,N,1,2 it's automatic and I lost the other gears except 1 and 2. making the new top speed at 20MPH at 2000-2500RPM's, this is a 87 Z28 I-ROC, daily driver. now my questions: what should I do step by step? what does a rebuild normaly cost? Should I buy a new one? if so should I buy rebuilt, remanufactured, or brand new. I have a little mechanical ability and my dad has alot more, with a good amount of tools but no hoist. would it be better to buy hoist and do it my self? I could use some help and idea's thankyou for your time.
P.S. obviously never dealt with a trany before.

ede

easiest thing would be to let someone else do it. i'd be very selective about who i let rebuild it from reading some of the stories on here. swapping out the trans wouldn't be hard to do and you could buy a rebuilt unit, again from someone you'd trust to stand behind it. cheapest thing would be to swap in a used trans but that's a big gamble you'd be doing it again in the future. you can buy a th350 fairly cheap and swap in with the b&m adapter kit.

Randy82WS7

yes ask around and find out some ppl that have had a trans rebuuilt and that are happy with the rebuild and find out from them who rebuilt it and so forth

but also note how they drive and how long ago it was rebuilt,


good luck

ringo234

Mine did the exact same thing about a year ago. I drove into a Trans shop (real slowly) near my home and they swap in a rebuilt by the next day for $950 installed at the door.

my3rdgen

I rebuilt mine with my dad's help. I have been an industrial maintenance mechanic/electrician/technician for over 13 years, and have worked on cars for over 20, but never had I done a transmission before. My dad was an Allison auto trans mechanic back when I was younger, and he helped me rebuild it.

It was a very interesting project and I was glad we did it because I am now familiar with the inside of the 700R4, I saved money on labor and I was able to spend that savings on upgrade parts (cost me $1200 total).

If your dad has ever rebuilt an auto trans and is willing to help you, and has the tools needed. Go for it. There are certain "selective" parts though that may need to be ordered when you do the rebuild. When you install the rebuild kit the tolerances change and GM has several parts in there that are called "selective" parts. This means that after you install the new parts you have to check the tolerances to make sure they are correct. If they are out of spec, you have to change the "selective" part to get the tolerance correct. This means ordering the part at the GM dealer.

I had top order a new plate for my forward clutch when I rebuilt mine. It was $12.00.

91Z28TTOP

Dude, if you have patience, some know-how and your not afraid to try something new, then order a full kit, a spring compressor for the clutch packs and a lip seal tool, and have at it. Also they sell books and videos on how to rebuild a 700R4. I have done three of them and sold two of them. I never saw or heard from the other people that bought one. I like the way mine shifts, the only aftermarket parts that went into mine was a corvette servo and .500 boost valve. I think I paid about $20 for both the servo and boost valve. I bought the complete rebuild kit off E-bay for about $80.00 and the spring compressor off line for $35. If you don't have the time to do the job then find a reputable transmission shop and have it swapped out. If you take it to just anyone they might swap a so-so trans and put your old converter back in and the trans will go down hill in a short time. There is alot of stuff inside but a clean work area and enough space to lay everything in order as it comes out will make assembly a breeze. Also if you rebuild it you'll need a feeler gauge to check the clutch packs for spacing tolerances that was mentioned above.

Hey "my3rdgen" I too have a 2800 stall converter and like the way it shifts. My tach is no working right now and I was wondering what are your RPM's at around 55 to 60 MPH?

phaledax

at 60 MPH and on level ground is 2000-2200 RPM I think, and thats before It broke. thanks for all your advice it has help alot, and I will talk with my dad and look into thoes options. see if we can do it our selves.

my3rdgen

I will have to let you know. lol!! The car is in the shop having the body restored. I just got the new motor fired back up over the summer (had issues the first go-round), been taking me almost 3 years so far to get this thing finished. Not much time has been available to dedicate to it. But it should be road worthy and pretty much complete by spring.

EDIT: I didn't think about it but I did drive the car with the new rear (3:73's) and with the tranny before we rebuilt it, at 65 I was at around 2800-3000rpm with the TC locked up.

It shouldnt matter what your stall speed is for cruising rpm's unless you do not have the lockup feature. Mine has it so the cruising rpms would be the same even with the higher stall speed.

GOTMYZ

iTrader: (1)

i would expect about 1900 in top end parts.

That is what my estimate for mine is.

my3rdgen

I did mine for around $1200. That included 5 gear front and rear planets. I bought my input shaft with the drum already pressed on it, a beast shell with the torington bearing vs. the cheap plastic stocker, and a stator support from Art Carr. They were pricey but he guaranteed the parts and they are put through a special hardening proccess.

The biggest expence were the planets, and the parts from Art Carr. All those parts combined were around $600-700.

Basically it is now a 4L65.

91Z28TTOP

EDIT: I didn't think about it but I did drive the car with the new rear (3:73's) and with the tranny before we rebuilt it, at 65 I was at around 2800-3000rpm with the TC locked up.

The rear end is still stock ratio what ever that is. I have tried cleaning all the road grime off the axle tubes and see what the code or ratio is as the book indicates but no dice. Is 3:73's stock? Another thing I notice when driving it and shes cruzin around 50 or so the pedal is barely depressed and goes pretty far when I smack it to the floor. The only problem right now is the rear tires are almost slicks and the azz end will fish tail and even when it shifts from 1st to 2nd it breaks loose. All the internals except the servo and boost valve are stock normal parts. The pump is a 13 vane.

my3rdgen

No 3:73's are not stock, well on my car anyway. I wouldn't be suprized if your Z has 2:73's.

My TA originally had 2:73's and would cruize 65 at around 2200rpm.

The only way to tell is to open the cover on the rear end and count the teeth.

Divide the ring gear teeth by the pinion gear teeth.

eg. 41/11=3:73 (well.... =3:7272727272727272727etc.)