700R will not shift to 4th
Thread Starter
Instructor
Joined: Dec 2005
Posts: 188
Likes: 0
From: Riverside CA
700R will not shift to 4th
Hi All,
I am running a S.C. TPI with lots of mods.
I did not have any 700R4 trans problems untill I installed the 383 engine.
Once I did, I noticed that the trans would not shift up like it use to.
Its like the vacuum line was not hooked up. This causes the trans to delay shifting untill upper R's. It would like go into nutral when you let off the gas, and I would not go into 4th untill I drove the car 20 min.
After the 20 min. it was fine: IE short shifs at low R's as usual.All gears worked fine at that point.
Engine is cammed up but still make 10 lbs vac minimum at cruze and light excell. It goes up to 15-18 vac. on decell.
Its been behaving like this for about 1500 miles.
Most reciently, I whent to the drags. After about 10 runs, it would not go into 4th at all.
Any Input for me?
Is there a vac. line going to a diaphram on the trans?
Could the S.C. boost pressure break a diaphram?
From the top, the vac. line does not apear to be broken /disconected by sucking on it.
I will be going under the car soon to varafy vac. line conection and condition.
Can enything else cause this? Mechanical issues?
Thanks,
Chad
I am running a S.C. TPI with lots of mods.
I did not have any 700R4 trans problems untill I installed the 383 engine.
Once I did, I noticed that the trans would not shift up like it use to.
Its like the vacuum line was not hooked up. This causes the trans to delay shifting untill upper R's. It would like go into nutral when you let off the gas, and I would not go into 4th untill I drove the car 20 min.
After the 20 min. it was fine: IE short shifs at low R's as usual.All gears worked fine at that point.
Engine is cammed up but still make 10 lbs vac minimum at cruze and light excell. It goes up to 15-18 vac. on decell.
Its been behaving like this for about 1500 miles.
Most reciently, I whent to the drags. After about 10 runs, it would not go into 4th at all.
Any Input for me?
Is there a vac. line going to a diaphram on the trans?
Could the S.C. boost pressure break a diaphram?
From the top, the vac. line does not apear to be broken /disconected by sucking on it.
I will be going under the car soon to varafy vac. line conection and condition.
Can enything else cause this? Mechanical issues?
Thanks,
Chad
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
There are no vacuum connection that go to a 700r4. Anytime that shift timing, or shift quality is a problem, the tv system is the first thing to check. If it is anything other than spot on, it could give problems.
Focus your attention here. A pressure guage is needed for a full diagnosis.
Focus your attention here. A pressure guage is needed for a full diagnosis.
