Turbo 350 to 700R4 question.

[Jiggity76]

I'm sure it's been covered and I apologize it it's been covered but got a question about my tranny.

Using the drivetrain out of my 91 Suburban 4X4, has the overdrive trans, guessing it's the 700R4 but not sure. My original truck is a 87 High Sierra 4X4. Both trucks have the 5.7 and same transfer cases I think. Working on the 87 today, I'm having issues with getting the driveshaft on the front axle. Seems to be a little short and was wondering if I have to get some sort of transmission adapter/spacer or maybe one for the transfer case. Rear driveshaft went together with no problems but the front is short like I said. I assume the overdrive tranny is a little longer than the turbo 350? Should the front driveshaft work with the new tranny or like I said, do I need a new adapter or spacer or something?

 

[Honky Kong jr]

The 87 should of had a 700r4 in it as well. And the drive shafts would also be the same.

 

[Jiggity76]

Ok, I know that it didn't have overdrive and the pan is different so maybe someone converted it to a turbo 350 before I got it. The drive shaft out of the 87 is longer than the one out of the 91 Suburban. I thought I could just use the drive shaft out of the Suburban since I'm using the motor, tranny, and transfer case from it but it seems to be a little short. But your saying that both the turbo 350 and 700R4 use the same front and rear drive shafts then.

 

[Honky Kong jr]

Ok, I know that it didn't have overdrive and the pan is different so maybe someone converted it to a turbo 350 before I got it. The drive shaft out of the 87 is longer than the one out of the 91 Suburban. I thought I could just use the drive shaft out of the Suburban since I'm using the motor, tranny, and transfer case from it but it seems to be a little short. But your saying that both the turbo 350 and 700R4 use the same front and rear drive shafts then.

Does the drive shaft from the truck fit? If the burban one is to short and the truck one is a bit longer? Not sure a 208 ever came on a th350 but the tail ends are the same so they fit.

 

[Jiggity76]

Before we tore the 87 apart, the drive shafts worked fine with the turbo 350. Using the same drive shafts, it looks a little short when using the drive train and 700R4 from the Burb. I think that I will try again next week and mount the drive shaft to the front diff first, then the other end to the transfer case. Shouldn't the tube adjust out little on the front shaft since it has to move with the front axle? I might clean out or replace the front yoke too to avoid stripping or breaking bolts.

 

[Honky Kong jr]

Before we tore the 87 apart, the drive shafts worked fine with the turbo 350. Using the same drive shafts, it looks a little short when using the drive train and 700R4 from the Burb. I think that I will try again next week and mount the drive shaft to the front diff first, then the other end to the transfer case. Shouldn't the tube adjust out little on the front shaft since it has to move with the front axle? I might clean out or replace the front yoke too to avoid stripping or breaking bolts.

Yes there is a slip joint in the front shaft.

 

[Jiggity76]

Thanks so much for your help! I will update next week and let ya all know what happened.

 

[Honky Kong jr]

Thanks so much for your help! I will update next week and let ya all know what happened.

Your shaft might just be seized not allowing it to move.

 

[Jiggity76]

How do you fix that?

 

[Honky Kong jr]

How do you fix that?

Take apart and clean and lube it up. There is a sheet metal nut on the diff part of the shaft. Remove that and it should come apart be sure you mark it so you put it back together the same way or it will shake but I'm thinking they have a double spline so it will only go together one way but mark it just for good measure.

 

[Honky Kong jr]

How do you fix that?

You must be registered for see images attach

 

[Jiggity76]

I bet that's it! You are AWESOME! Thanks so much. I knew that the front shaft moves in and out with axle travel but for some reason my is frozen, can't move it either way. I bet if I do take it apart it should bolt right in. I won't be able to work on it until the 2nd week of July for work reasons but I will update everyone. Once I get it apart, does it have to go back to the same spot for the nut to bolt in? I'm sure I'll figure it out once I get it apart.

 

[Honky Kong jr]

I bet that's it! You are AWESOME! Thanks so much. I knew that the front shaft moves in and out with axle travel but for some reason my is frozen, can't move it either way. I bet if I do take it apart it should bolt right in. I won't be able to work on it until the 2nd week of July for work reasons but I will update everyone. Once I get it apart, does it have to go back to the same spot for the nut to bolt in? I'm sure I'll figure it out once I get it apart.

It's a balance phasing thing. Mark it before and if it does have double spline your covered either way.

 

[Jiggity76]

Ok, thanks again!

 

[HotRodPC]

And what was this truck tore apart for? If you tore it down to do a lift kit, good possibility you driveshaft is now to short if you lifted 6in or more. 2.5 and 4 inch you should still be OK but 6in and above the front driveshaft probably needs extended.

On this truck with the Th350, is there a spacer block between the transmission and the Tcase adapter? If was originally a 700r4 truck and someone converted it to Th350, if done right, it should have about a 1in spacer.