Zap Racing

I have an 89 IROC--350/700r4 manual shift. Just started this yesteday--when I let off the gas, in any gear, it does not slow down the car like normal. It's like it goes into neutral. It still shifts like it always has,--no slipping-- even at WOT, but when U let off, it's as if U pushed in the clutch (if it was a manual).

Possible causes--fixes? Minor or major?

Although It is not due, (only about 5000/6000 since last one) would a fluid/filter change do anything?

I tried to do a search for this, but could not figure out what word or phrase what to search for.

18inchboyds

my dad has a tq converter like that in his car b4 , it was a turbo 400 in a 77 ta but his did that . did yours just start doing this or did you just install the trans ?

Zap Racing

Just started doing that. It's been in the car for several years.

Knyghtmare

That wouldnt have anything to do with the Lock up would it?

bobdole369

I'm still a novice - still tearing down my first 700r4, but from what I understand about how the 700r4 works - that it uses the overrunning clutch (or is it the forward sprag?) to obtain the "engine braking" effect. Also from what I understand that those particular parts are high wear items that take a lot of abuse, particularly if manually shifted. I would surmise that it's rebuild time and it doesn't seem like something a fluid/filter change would resolve.

You mention "manual shift", does that mean you have one of those shift kits that reprograms the transmission valve body so that when the gear selector is in 1, it stays in first, and when it is in 2 it shifts to second and stays there, etc?

Angelis83LT

that might be something worth a note if it is a full manual Valvebody or if it is a shift kit that is installed doing the manual shift setup.

Zap Racing

Sorry-- should have included better info to start with.

I have the paperwork for the tranny being built 3 times before I bought the car--the second time was about a month before I bought it.

The best I can tell, YES it is a manual valve body. When U put it in first it's in first. If U put it in third it's in third--no mater what engine rpm speed/mph. The first rebuild receipt says "install customer supplied valve body" ( I am assuming that is when the manual valve body was first installed--no receipt for the VB by itself)

It does have the plunger (I installed myself about a year ago) that enables U to shift third to fourth at WOT.

It does NOT have a lock-up torque converter anymore. It could be one of two different TC's--not sure which is in there, but i have receipts for 3 different TC's--the first being from '98 (i doubt it's that one) a receipt for an ATI 708220.

The second TC receipt is from '99/2000 for a part # B-29H (description is) "298mm 30 sp 2000 stall GM"
The second rebuild receipt includes a "shielded vette planetary" and a "vette servo".

The paperwork for the third and final rebuild is from 3/28/2003 (a month before I bought the car--17,000 miles on it since I bought it.) It does not say anything about parts used or TC being replaced.

One other thng I can add, is that I talked to a very good long time friend who is the tranny instructor at UTI @ Houston campus. He said:
First of all it is not the front pump or main line
pressure problem. It could possibly be a torque converter concern but if
you drop the pan that will tell you what condition the transmission is
in. If the pan is clean or has a little amount of material then you know
it is nothing serious. If it has an excessive amount of material then it
is time to go through it. You have to start somewhere.

I guess I will drop the pan and see if there's any unusual crap other than the "normal" amount of friction material in it, but from what I have been told, for a 700 to have almost any amount inthe pan is not good, compared to the amount of material U can get away with in a 350tranny.

So, if any of this helps diagnose it or at leas give enough info to take a guess from some of U people that speak "autotransmissionese", I sure would appreciate any help.

mystikkal_69

iTrader: (2)

more than likely as mentioned it will be an overrun clutch/seal issue. could be a sprag, but not likely. best to open it up and do a thorough inspection/cleaning.

Pro Built Automatics

It is in the overrun clutch assembly area. The sprag going away is the most common, the overrun clutch hub breaking is next, then the clutches, etc. The transmission will have to come out on this, to fix this.

Zap Racing

Yeah, I probably knew that in the back of my mind, but not knowing about the inner workings of a 700, thought I would check it out anyway, to see if there was a possibility there might be quick fix.

So somebody educate me here on a couple things.

1. Torque convertor--I know that for the most part the rule of thumb is that U never reuse a lockup TC, but non -lockup can usually be flushed out and reused. Is that correct or not? good idea or not a good idea? Deal or No Deal? LOL

2. Since it still seems to be shifting like normal (even at WOT) what would happen if I kept driving it like this. (Not that I'm going to) Is this something that would spread the trash in the fluid, thru the rest of the tranny and cause damage?

3. The overun clutch assembly--is this a multi clutch pack similar to the foward drive clutch packs? Since it is a manual shift tranny, can these be beefed up like other clutchpacks or other parts in the tranny?

4. The shop where it needs to go is about 20/25 miles away. Can I drive it to the shop or should I have it towed? If there is the possibility that it will self destruct on the way to the shop, even though it'll be a 100.00 tow bill, I can/will have it taken there on the hook.

ThankU everybody for all the advise and info. I wish I knew more bout automatics--but like most, I think I am a little gun shy of the unknown.