rkg8554

iTrader: (10)

I just installed my new trans into my 87 Iroc and am wondering if it is operating correctly. I have a 350 bored to a 355 with approx. 300 rwhp connected to the 700r4 and a 9 bolt with 370 gears. The trans is built with a shift kit for firm shifts, the valve body is an auto/ manual with constant pressure mods and a 2300 to 2500 stall with lock up. My question is when I am just leaving a stop the car wants to chirp the back tires shifting from 1st to 2nd. This is driving like I would if a cop was next to me, not getting on it at all. Now when I want to get on it, it is awesome barks in 2nd and 3rd. When just cruising 1st to 2nd wants to chirp and 2nd to 3rd, and 3rd to 4th shift the way I would expect. My lock up for 4th is working as it should.
Thank you for any comments.

paulo57509

I did a forum search for "constant pressure valve body" and found some comments.

Based on what I have read, I believe your transmission is operating correctly.....for now.

Ron U.S.M.C.

What causes the bark/chirp in and auto is a very crisp shift with street tires. In your case there is so much pressure there is no slip. With a higher rear end gear ratio and that stall its even more pronounced.
If you run a sticky tire it should not do that as much but it is harder on the 9 Bolt. Kind of like a few small "hooks".

Night rider327

iTrader: (13)

With the "constant pressure valve body" mod yes that is normal. Sticky tires will be less likely to chirp, and a higher stall torque converter will tame that low speed chirp some too

sofakingdom

iTrader: (1)

Adding a 2nd (larger) cushion spring to the band servo, around the one that's already there, will soften the 1-2 shift at low throttle input, somewhat.

IMO the "constant pressure" idea is a very poor plan for the street. Sounds like you have the B&M shift kit, well and widely known to do exactly what your car is doing, and to cause short transmission life as well. Might be OK for racing but bad for street. I'd suggest undoing that and using the TransGo on one of the light or medium settings instead.

rkg8554

iTrader: (10)

When I ordered the trans I told them it is mostly for the street with some track. They warranty the trans for 3 yrs and unlimited mileage. Undoing it as you say and putting in a Transgo is that something I can do. I am mech inclined, infact I just got done rebuilding this car from a roller, but trans experience is minimal. Can this be done on the car? Is this something I need to do now or can I do it over the winter.

Pro Built Automatics

If install my modified TransGo Street/Strip setup, it will give you all you want at WOT and nice smooth shifts at part throttle. I have never understood the logic to constant pressure valve bodies. I am surprised though at that they are offering a 3 year warranty on this as these destroy the front pumps within a few months of driving. This can be done from the bottom. Call me with any questions, best in the afternoon or evenings if you are interested in doing this.

rkg8554

iTrader: (10)

I sent you a pm. Should I not drive the car, I only put maybe 100 miles a week if that on it. I don't want to destroy this trans, I have put enough $ into this car.

vortec350s10

My first 700r4 from TCI had very harsh 1-2 shifts at very light throttle. Got annoying after a while. When I tore it apart I noticed the output shaft had a hairline crack running lengthwise between the lube holes. Can't say for sure if always was cracked or if it happened when I had it. This was with under 400 fwhp. I don't understand the point of a constant pressure setup either. The only benefit I can think of is if you dont connect the TV cable you won't have too low of line pressure and wear it out quickly.