Wasn't sure where to post this tried a search no luck. I know this topic has been covered before but it seems I ran across some contradictory info. Once I read that this was set from the factory and has something to do with the ecm. I also read somewhere that its all in the TV cable adjustment. Can somebody please tell me how to get this thing to shift from 3-4 under WOT conditions.

 

Can't do it without a shift kit. It's in the way the valvebody is set up. You can play with the TV cable all you want but it's not gonna help.

 

I don't have a shift kit in my 88 Formula and it will do WOT 3rd to 4th upshift.

 

I know someone knows the answer to this. Its such a common problem. What do I need to do?

 

A search of the transmition/drivetrain board found this which should be of some help. As it says, a shift kit will not change this wot shift problem. B&M sells a kit that makes it go from about 1/2 or less throttle to 2/3 or less for OD to be availible. I personally don't think that part would be worth the hassle of an install let alone the price. GM also has a part, PN mentioned in the linked post, that gives you full throttle OD shifts. I believe it was OE on police f-bodies. It isn't expensive, but from what I understand there are no type of instructions and where and how that thing gets installed seems to be some what debated on this board.

You do have to ask yourself why the general didn't do this from the factory? Without a built tranny, I would imagine wot od shifts, and wot od cruising could be pretty stressfull on a 700-r4. Maybe a tranny cooler would be warranted with this mod.

This anoys me also, but I have decided that a T-56 will be the best solution for me

 

It's not really that hard on the tranny since you are going so fast when it upshifts to 4th, at least it doesn't feel too hard for the tranny. Mine shifts to 4th between 100 and 115. Next time I get the urge to fly, I'll note the exact speed it upshifts at.
I don't drive the car that hard the much since it's my beater and the tranny is kinda worn so I don't want to kill it.

 

Od has the least number of clutches of the foreward gears. If you could shift into 4th at wot your trans wouldnt last long without beefed up cluthpacks.

 

Yeah agreed... A lot of worn trannies might not even withstand one or two WOT 3-4 shifts. I would be extremely hesitant to do it on a stock 700-R4....theyre notoriously weak and WOT 3-4 is verrryyy hard on the trans. There isnt enough line pressure in applying overdrive so at WOT I imagine there is heavy clutch slip so eventually the clutches will be worn bald and the car won't engage into Overdrive anymore....or it will try and slip out of gear.

 

Does heavy clutch slip smell like burnt clutch in a manual or like your brakes when you brake hard a bunch of times?

 

You probably won't smell it since it's sealed inside the tranny. You would notice the fluid being dark & stinky, though.

 

As far as I know my Trans is stock. Shifts pretty strong though may have had a shift kit put in at some point but I have to go on the assumption that its stock for now. Given that, am I understanding not only were they designed not to give the 3-4 WOT shift but I should also avoid modifying it to do so until I replace the tranny with something stronger? I almost wouldn't mind the fact that it didn't shift into fourth under wot but when I can't even punch it or hold full throttle in fourth gear just kills my high speed freeway blitzes and races. In the 1/4 I will just keep it in drive. Any other comments on this subject I woudl still like to hear.

 

The GM part number in that thread above is what you want if you want WOT 3-4 upshifts, as I understand it is from the B4C cop car (and maybe some other 350TPI cars). I specified that part number to my tranny rebuilder and had it put in my 86 IROC's tranny when I had it rebuilt and it does the trick nicely. I've only rarely ever used it though... Don't know about any extra wear it might cause though, no ill signs after a couple years. On my 87Z's tranny which I had rebuilt first I didn't get that part put in, I trusted the tranny guy who said it would make the shift with the beefier parts he put in and alas it will not hit 3-4 at WOT...

 

I recommend the b-body fix kit. This is the GM kit mentioned in the other posts. It includes pan gasket, valve body gaskets, slightly larger boost valve and a new 3-4 upshift sleeve, valve & spring. Shuffle, shuffle, search, look. . .

Ahh, here's the number: GM #8673948

I put this kit in my '92 and it does prevent a WOT 4-3 downshift. I've never tried a WOT 3-4 upshift but it is supposed to allow that also.

The '92 used to 4-3 downshift at 2/3 to 3/4 throttle or more. Hated it. Now once over 75-80 mph it will hold 4th (OD) at WOT.

The 3-4 upshft valve sleeve is the only one with a half moon shape on the end. Goes into the valve body.

RBob.

 

Thanks guys. That is a standard GM part that I can get at the dealership? Anyone remember what they paid for it?

 

Dealership may have it in stock, otherwise will order it. IIRC about $20 US.

RBob.

 

You probably can get it from www.gmpartsdirect.com I order'd mine from there... then I burnt out the clutches... laf I got a probuilt 700 SS now.

 

GM Service Bulletin #91-7-4L60.08

Tuliped exhaust valves on Caprice Police cars with 350/700R4. Came out in Jan 1991. Gives part numbers and procedures for replacing the valve responsible for the part throttle 4-3 downshift.

Part number listed above is correct.

Enjoy.....

I suspect that GM did NOT put this in cars meant for public consumption simply because you could go A LOT faster than ya really needed to........ (that, and they knew the brakes weren't up to the task of dragging you down from those kind of speeds....)

 

I stumbled across a site today where a guy shows how to accomplish WOT 3 to 4 shift with nothing more than 2 bolts and some epoxy. I suppose the pictures alone would be helpful with the GM part install also (no instructions included).

Is his method worth doing to your car?? You be the judge:

http://w1.601.telia.com/~u60113744/t...tranny_wot.htm