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Th-350 DIY question

921 views 5 replies 6 participants last post by  lt1bbody 
#1 ·
I recently rebuilt my third th-350 tranny using B&M's kit... my question is that after i rebuilt this one i have no first gear in drive. it starts out in second and goes to third no problems. If i put it in manual first the tranny seems to be siezed and if you give if some gas it vary slowly creeps foward and sounds horrible like a tranny that is slipping really badly. The cars stops rolling like applying the brakes when you let off the gas. The tranny was rebuilt for "Rv/towing" use in a daily driver in an older 3.8l buick. Could this be a problem with clearances in the clutch packs, also the pump went on extreamly hard had to draw it into the case using the bolts.

Any ideas/places to start looking... i assume this is an internal problem and not a valve body problem.

Thanks, James
 
#4 ·
350

You said that you had to draw the pump in with the bolts, could you turn the input shaft after the bolts were tight? Did you check the end play? If you could not turn the shaft then some of the clutch plates in the forward clutch did not line up right and you should disassemble to see if anything is damaged.

The other thing that could be wrong is with the governor, if it is stuck partially open the valve body with think you are already moving and put the trans into 2nd gear. Remove the gov and see if the valve inside is moving freely and all the way up and down.

Reviewing your original post, I would assume that you have an internal problem.

Good luck,
Rick
 
#5 ·
I wonder if you installed 3 frictions in the 2nd gear clutch pack? it is the top clutch before you install the pump.

IF the tranny was a 2 friction clutch pack set-up and you installed 3 frictions & steels with out cutting down the apply piston on the back side of the pump .... when you bolted the pump in , it bound up the 2nd gear clutch pack.

So........ when you put the tranny in "D" the tranny acts like it is 2nd gear, when it shifts to third gear the roller clutch "over runs" so the tranny acts fine.

When you put the tranny in "R" , you now have a bound up 2nd gear clutch pack , the direct clutch pack applied ( should be in R) and the low/reverse clutch applied (should be in R).... it will bind up the tranny since the 2nd gear clutch pack should not be applied.

All of this is a wild guess since I am not there.
 
#6 ·
When I rebuilt my first th350 I had a problem with my pump going on. One of the thrust bearing (one with 3 prongs) were not lining up. The input shaft wouldn't turn. I tried putting on 5 or 6 times and couldn't get it to work. I figured out that it goes on real easy when you actually put the tranny facing bellhousing up. You may have had this same problem.
 
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