700r4 shifting and shaking problem

[itsnotanova]

First off this 700 is in a 88 S10 2wd blazer.
Blazer history in last 3000mi=rebuilt motor,rebuilt supension and brakes, axle replaced, rebuilt tbi, all sensors on motor are new except knock and temp, new O2 and brake pedal sensor, new u-joints, new tires, new shocks, new exhaust.

The problem=When I bought this truck it shaked a little bit and got horrible gas milage. With 225000 miles on it, I just assumed it was from being worn out. Well after the crankshaft broke in half I replaced all the stuff in the above paragraph. I also replaced the transmission with one I took out of a 89 cop car that I've been holding onto for 4years. That transmission had only about 1000mi on it after it's rebuild. After almost everything being rebuilt or replaced it still shakes and bad MPG. At 65mph it runs at 4000rpm and when cold 1&2 shift at 5000rpm. The only thing left is balancing the drive shaft and replacing the torque converter.

Bad speed sensor, TCC,wiring to transmission,converter?

 

[megaladon6]

i don't know that it would cause shaking, but the first thing to check on any 700 or 200r4 is the TV cable adjustment. check the fluid for level, color, and smell too.
what does your speedometer read? if the trans has the wrong speedo gears, relative to the rear ratio, it will throw off the computer.

 

[itsnotanova]

The axle ratio in the S10 is the same as the one in the caprice the transmission came out of and the tv was adjusted after everything was put in by the shop that was also doing the alignment. The transmission fluid and filter was changed at the 500mi and still seems good. I've been told a sticking TCC valve will cause the 1,2 shifting problem.

 

[megaladon6]

honestly i don't know transmission well enough, but the easiest way to check would probably be to just unplug the electrical connector on the case. this way the TCC won't engage.

 

[itsnotanova]

I don't think it's going into lookup because I've heard that if you hit the brakes on the highway, you should be able to feel it kick in and out. I've been meaning to get under and unplug the conector to see what happens

 

[megaladon6]

usually you see about a 200rpm when the TCC cycles.

 

[1986montecarlols]

any

transmission with that many miles on it is going to have some form of wear out. I would think its on its way out.

 

[JESSE]

trans problem

your right about the sticking tv valve causing the trans to shift at high rpm's, unfortunely the only way to check it is to pull the pan..once the pan is off you will see the valve is stuck in the rear most position... the only way to fix it is to pull the valve body and remove the valve and clean it with emory cloth.. now if your a daring soul this is the time to install a shift kit..the b/m kits have easy to use directions to follow....having said that if it is shifting at high rpms when it's cold and then shifting normal after warming up is something that happens after installing a street strip shift kit. my trans has been doing that for about four years now with no problems...usually if a tv valve sticks it stays stuck...now at 65mph at 4000 rpms tells me that it's not shifting to 4th gear that could be a stuck tv valve,a linkage problem or possibly a stuck shift valve and or a half a dozen other things...but you've got start some where so imo you should do as megaladon6 suggested and disconnect the tcc and road test it to see if that helps with the balance problem if it still shakes look at your flywheel for cracks ,loose or missing bolts,check all the bolts in your cross member all the bolts on the transmission and engine mounts also check the exaust to make sure there not toching the frame anywhere an take into consideration the load and twist under power...now by the time you check all that stuff the trans has cooled down you might as well pull that pan an see what's going on with that valve, since your all ready on jack stands all fixes are simple once you find them...i don't know if this is the kind of advice you wanted but there is a good chance you can fix it your self if you want to give it a try 8) with all trans problems there is a chance that the trans will have to be pulled so knowing this lets see if you can fix it..once you pull the pan look in the bottom and see whats there. if you see metal and shinny bronze things and the fluid stinks ,go to plan b and let me know what you find.....jesse

 

[JESSE]

trans problem

i've been giving your balance problem some though and can tell you how to look for your problem. by the way what engine are you using? the broken crankshaft scares me into thinking that the prolbem maybe in the balance of the motor ...flywheel or balancer sliping... to check if it's the motor or something else just disconnect the torque converter bolts and slide the converter to the rear and crank the motor an see if it vibrates..let me know what you find...jesse

 

[itsnotanova]

The motor is a 4.3 and the rebuilt transmission worked fine when it was in the cop car 4 years ago. I did reuse the flywheel and torque converter from the previous combination and I think thats where my vibration problem is coming from. I think this because if you rev motor in park or neutral, it has a vibration. Can a bad converter cause all or most of these problems?