dcvice1967 Posted September 29, 2013 Share Posted September 29, 2013 I bought a used 72 350 and TH350 trans to bulid for my son's 71 Monte. We just has the TH350 built, new stall, shift kit, the whole 9 yards. We just finished pulling the old one out. The bad news is it looks like the tail shaft on the rebuilt TH350 is 3" longer that the one that came out of the Monte. I assumed the TH350's all had the same tail shaft. That's what I get for assuming... I did notice the yoke on the from of the drive shaft had what looked like a 3" wide spacer. I assumed this was for balancing. Is it possible I could just get another yoke for the front of the drive shaft and not have to cut it? Has anyone seen this before? I am not sure exactly what car/truck the rebuilt trans came out of. Any help would be greatly appreciated. David Quote Link to comment Share on other sites More sharing options...
zmanabba Posted September 29, 2013 Share Posted September 29, 2013 Unfortunately you have two choices at this point. 1. Is to shorten the drive shaft. I am not sure the balancing weight would buy you enough and you would have to rebalance the shaft anyway once it's removed. 2. Swap tail shafts and output shafts. This involves complete disassembly of both transmissions and assembly of the one used. FWIW I would do number 2 because I am anal that way but once the meds kick in I should be ok lol. Sorry but this will cost you more money no matter what the choice. One other thing you might check is if you have to relocate the cross member no more money involved but something more that will need to be done. Good luck, David Quote Link to comment Share on other sites More sharing options...
Toppless72 Posted September 29, 2013 Share Posted September 29, 2013 There are 3 lengths of the THM350. Over all lengths are: 27 11/16 inches 30 11/16 inches 33 27/32 inches The first gen M/C uses the 27 11/16" case and tail assembly. At this point the cheapest way out would be shorten the drive shaft. However, I'm not sure of the impact of using the 9" tail shaft would be or what other modifications are necessary. Maybe some of the other members that have been down this road will comment. Quote Link to comment Share on other sites More sharing options...
footballubet Posted September 29, 2013 Share Posted September 29, 2013 I'm not sure if there is enough room for the long tailshaft to fit in the underneath tunnel. I would suggest swapping the tailshaft and output shaft. I don't think there is an easy way out of this. I know that isn't the answer you were looking for though. Quote Link to comment Share on other sites More sharing options...
dcvice1967 Posted September 29, 2013 Author Share Posted September 29, 2013 Thanks for the help. I guess its a good thing I noticed this before putting the rebuilt trans into the car. I will contact the shop that did the trans and see what the estimate would be. My luck the old short shaft is worn and I will need a new one, just to add the mix. I don't know of anyone nearby that can cut the shaft and balance it. I guess I will have to look for that as well before making a decision. David Quote Link to comment Share on other sites More sharing options...
dcvice1967 Posted October 5, 2013 Author Share Posted October 5, 2013 Did some checking and found info on only 1 drive line shop in the area. Issue is they have a reputation of taking cut and balance jobs and turning them into complete new drive shaft jobs. Talked to the guy who built the trans. He is an old car guy from long ago. He offered to completely tear down the freshly rebuilt trans swap out the longer output shaft for the correct one and rebuild it again with the correct tail housing for less than $300. This is less that the quote to cut and balance the drive shaft. If all goes well with the trans after install, I will definitely send him some business. David Quote Link to comment Share on other sites More sharing options...
zmanabba Posted October 5, 2013 Share Posted October 5, 2013 That is a good deal. In the end I feel you will be happy you went this way. Even if the driveshaft shop would have been cheaper you would have had a steeper driveshaft angle (not sure how much). My personal feeling is there is a reason that GM went with the short shaft in the mid-size and smaller cars and long shaft in the larger vehicles. You know if GM could have went with one transmission length and saved money, they would do it. David Quote Link to comment Share on other sites More sharing options...
72-CLASSIC_RIDE Posted October 13, 2013 Share Posted October 13, 2013 Have you considered the possibility of selling/swapping it for the one needed? Considering the cost of modification and after calculating benefits of either/or, may lessen the cost impact. Just a thought. Doug Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.