Transmission Swap Too! :(

[Oldscarnut]

After discovering the band adjustment bolt on my supposed TH350C, now really a TH250C, and with the obstinate Torque Convertor that refuses to seat all the way, and attempting to install it now 3 times with no success, I have decided to seek a TH350 to finish this! It then occurred to me that the driveline will be a slightly different spline size too. Am I correct?

Will a TH350 be the same as a TH350C when it comes to the shaft or am I looking for a TH350 only driveshaft too? The seller has one to go with the transmission, out of a GBody, so I am getting it just to be safe, but in my plan was never a transmission swap. Everyone told me the 250C will last about an hour, so what would be the point of installing it just to blow it up? I think my Dad is telling me something, making sure I don't waste time, energy and money on the damn project from HELL! This is change #57 in the simple engine swap, and I blew my budget 5 months ago! Money Pit is starting to be my wife's name for it...Damn I wish I had some help! Short of a grenade...

 

[pagrunt]

A TH350C is the one with a lock up converter, TH350 is the regular non-lock up one. Your driveshaft will work as the TH350/TH250/TH200/TH200 4R are all the same lenth bellhousing to tailshaft.

 

[Ribbedroof]

If you can't get the convertor seated in a TH250, how different do you think a TH350 will be?

Have you verified that the correct convertor is being used? "C"s and "regular" THxx0 use different convertors.

The TH 250C is fine for "normal" driving, I have owned several which served me well

To answer your question, the TH250, TH250C,TH350, and TH350C all use the same shift lever, and driveshaft. Just put a TH350 in my wagon that replaced the TH250C that was in it, that replaced the original TH350C. No changes to any peripherals were required for any of these swaps.

 

[olds307 and 403]

Good call and yes, a direct swap. I smoked my TH250C in one day behind my mild 403. It did have 400,000 km behind an Olds 307 then Olds 350. The 403 was just too much. I would buy the Jegs 2300 stall converter for the regular TH350. Only $100 and has good reviews.

 

[fleming442]

Splines are the same; Th400 is the break point.

C'mon, Chuck! You got this!

 

[Oldscarnut]

A TH350C is the one with a lock up converter, TH350 is the regular non-lock up one. Your driveshaft will work as the TH350/TH250/TH200/TH200 4R are all the same lenth bellhousing to tailshaft.

Thanks. I figured the difference was WB length mostly, short vs long tail being the difference between a mid-size and G Body

 

[Oldscarnut]

If you can't get the convertor seated in a TH250, how different do you think a TH350 will be?

Have you verified that the correct convertor is being used? "C"s and "regular" THxx0 use different convertors.

The TH 250C is fine for "normal" driving, I have owned several which served me well

To answer your question, the TH250, TH250C,TH350, and TH350C all use the same shift lever, and driveshaft. Just put a TH350 in my wagon that replaced the TH250C that was in it, that replaced the original TH350C. No changes to any peripherals were required for any of these swaps.

I am unsure why this TC won't seat. I figure it was somehow damaged in removing it. It just WON'T get the 2 clicks and seat all the way. Someone else can figure it out if they want it. I changed the filter only tool, nothing apart but the pan off. The TC is what came off and was working fine. I have had no troubles with TH 400 or TH 350 getting the TC on and seated, I have done it dozens of times! So it is not the loose nut working on it. That is why I think it will be different!

 

[Oldscarnut]

Splines are the same; Th400 is the break point.

C'mon, Chuck! You got this!

I had it once but I don't know where I lost it! I restored a 67 Cutlass, a 67 442, a 70 Vista Cruiser, a 76 Cutlass Supreme and a 74 Delta 88. GBody seems to be the odd one out....just saying.

 

[Oldscarnut]

Good call and yes, a direct swap. I smoked my TH250C in one day behind my mild 403. It did have 400,000 km behind an Olds 307 then Olds 350. The 403 was just too much. I would buy the Jegs 2300 stall converter for the regular TH350. Only $100 and has good reviews.

I may not have the torque of a 403, but mine will be above 365 hp. I would rather rest assured it is beefy enough so it doesn't strand me the first time I get challenged by some zoomie. I don't plan to race it, but there will be times I need to get the gunk out! My wife even asked me why I need horsepower. Before I am done I will be getting both wheels spinning instead of one and the TH 350 can handle my high rear end too! "Don't need it honey, got to, got to , got have it!

 

[Oldscarnut]

A TH350C is the one with a lock up converter, TH350 is the regular non-lock up one. Your driveshaft will work as the TH350/TH250/TH200/TH200 4R are all the same lenth bellhousing to tailshaft.

I was not concerned about the length but the spline size on the front end. I did get my answer a few messages after yours so I have the answer, but thanks. I would love to report 2 steps forward and no steps back sometime in this project...I am making a lot of stupid choices