All - I just installed a fresh rebuilt 700R4 in my Trans Am.

I don't have the full specs on the rebuild, but it is a 1988 model FA. The pressures I have are all in spec with the GM guidelines that are shown in one of the posts on thirdgen here.

At 1000 rpm with TV connected I have:

74 psi in Park, Neutral, manual shifted 4th and 3rd.

118 psi in Reverse

But when in manual shifted 1st and 2nd the pressures are about 175 psi.

If there was a shift kit or some other performance upgrade on the trans would this account for the higher psi in 1st and 2nd?

With the TV cable fully pulled the readings were also in spec except for 1st and 2nd were high again.

As far as driving characteristics, overall it performs almost perfectly.

It holds a little longer in 1st than I would like, but it is a very crisp shift to 2nd no matter the throttle load. Under full acceleration it is a great shift to 2nd - it really launches, and 2-3-4 shifts are all very solid.

The 1-2 shift and 3-4 shift is just a tiny bit later under normal driving than I would like, but not annoying being a touch late and shifts firmly without any sliding.

Converter lock up and un-lock happens perfectly and I am pleased with that after getting the brake/vacuum switch adjusted in the brake pedal mount corrected.

The trans does the full 4-2 downshift 3-2 downshift and 2-1 downshifts and it doesn't downshift too quickly or hunt back and forth between gears and any time, under any different load, etc.

If it matters any, I installed a 2,000 stall torque and it is a bone stock crossfire 5.0 engine.

Basically it performs almost perfectly, but as stated, the 1st and 2nd line pressures are higher than the GM specs.

Again, is this 1st and 2nd pressure normal if there is a shift kit or other performance mods done in the rebuild?

Any input would be greatly appreciated - Thanks!

 

Can anyone weigh in on this one? I couldn't find the answer on a search.

 

http://www.lmgtfy.com/?q=transmission+pressure+table

May I suggest, the one from TCI Auto.

Yours look low to me but might be OK for a stock unit, especially behind a CrossFire motor, where it won't really be under much stress.

 

Sofa - thanks for that find. It is a good data point and I really appreciate your input.

Please don't take my further questions as anything other than trying to understand where I am at. I have a few more and am hopeful you can help.

Where I am confused is how my transmission would compare to the TCI Streetfighter.

According to the GM guidelines - for the FA model - My pressures are perfectly set except for the 1st and 2nd manual shifts.

My wonder is does a "shift kit" added to a mild build run higher pressures in just 1st and 2nd, but potentially not change the other gear pressures?

So now we have two data points - 1 = a stock FA model and 2 = a built Streetfighter. 1st and 2nd match closely to the Streetfighter, but the rest are dead nuts on the stock guidelines.

I would think that the Streetfighter build is probably more stout than the build I have - maybe in all areas, where as mine is beefed up in 1-2nd only.

So is it safe to make an assumption that the mods done on my trans impact the 1st and 2nd area - more comparable to the Streetfighter, but aren't as stout in other areas so the stock guidelines are more applicable?

I tried to attach the GM pressures guideline, but I already attached it in another thread and I can't figure out how to attach it here.

Here is the link:

https://www.thirdgen.org/forums/tran...-question.html

Thanks!

 

The Streetfighter is mostly stock, but with a few of the things that might make Grandma think her trans shifts "harsh" done to it, that are different from stock. Go drive a new car. Do you really want your car to shift like THAT?

Bottom line: You don't really want to build your trans to the stock GM pressure specs. It will shift too smooth, too early, and will wear out too soon. OTOH you probably don't want it jerking your eye-teeth out either; probably somewhere in between.

The pressures TCI gives are pretty much approppriate to what most of us here would consider a "good" street setup. I would consider the pressure they give to be the minimum acceptable for that use; the stock ones are altogether too low.

The purpose of a shift kit is mostly to raise the pressures under ANY conditions. When the pressure is higher, everything inside there happens later and quicker. So if you have a shift kit in it, then you should DEFINITELY be seeing higher pressures than stock.

 

The higher line pressure in 1st and 2nd is normal. The intermediate/reverse boost valve comes into play when the transmission is in "R" - "1st" - "2nd" shifter positions, that is why the higher line pressures in these positions. The shift kit won't change line pressures much without the addition of the larger boost valves. The modified TransGo Shift kit along with larger boost valves, and the Corvette servo will give you the best chance at good quality shifts along with longevity.