Grant MacPherson Posted November 25, 2021 Share Posted November 25, 2021 I need the drive shaft length and yoke length for turbo 400/ 454 combination. Just pulled mine and don't think it's right, only 1" spline engaged. Drive shaft measures 53 3/4 center joint to center joint and a 5" yoke. thanks Quote Link to comment Share on other sites More sharing options...
Scott S. Posted November 26, 2021 Share Posted November 26, 2021 What is the overall length of your transmission ? They can vary from 29' to 34"to 38". It sounds like you got a driveshaft for a shorter tail shaft version. So you'd want to go with the next longer shaft. I believe the factory spec was 56"... center to center. The 5" yoke is the typical one for most 454's. Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted November 28, 2021 Author Share Posted November 28, 2021 quick measurement looks like 29". Yes a 56" would put where it should be. From your info it doesn't seem that the drive shaft I have would work for any application. I have a yoke from a 480LE (not sure) but it is the same size and splined to the end so at least there would be 3" of spline contact. Thanks Quote Link to comment Share on other sites More sharing options...
Scott S. Posted November 29, 2021 Share Posted November 29, 2021 How original is your Monte ? After 50 plus years, parts may have been changed, ie. 12 bolt in for the old 10 bolt. TH350 replaced with the TH400. etc..... Just as an example, when I did the 10 bolt to 12 bolt swap, just about every bit of information I checked said I'd have to change the rear U joint. But thanks to a couple of guys on here who mentioned I might have a Buick 10 bolt, (yes the factory did that...) I didn't have to change the U joint. Everything pretty much bolted together. So, unless one can document the car, someone may have slipped something in that was handy at the time..... Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted November 29, 2021 Author Share Posted November 29, 2021 Hi Scott Rear end is original 12 bolt that I just changed the 2.56 open to 3.42 posi, that is when I noticed the yoke looked to far out of the tail shaft. The trany is a 1970 turbo 400 short tail shaft ( also how it came as per build sheet). Nothing looks changed with motor (stock L5 454) or trany mounts. I guessing your right about things being changed over the last 51 years and somewhere along the way somebody grabbed the wrong driveshaft. Are you sure on the 56" measurement? It looks like that would put in the right range just want to be sure as I go hunting. Thanks for your help Grant Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted November 29, 2021 Share Posted November 29, 2021 Could, and I stress could be that somewhere along the line someone changed out the yolk at the transmission from the one with the weight to one without. There is a difference in length. Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted November 29, 2021 Author Share Posted November 29, 2021 Was the weighted one used with the turbo 400? I had a 71 new way back when, big block 402, turbo 400 and I am quite sure it did not have the weight? Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted November 29, 2021 Share Posted November 29, 2021 My 71 402 aka Barn Find had the weight. Idk about others but it did. Quote Link to comment Share on other sites More sharing options...
Scott S. Posted November 30, 2021 Share Posted November 30, 2021 Hey Grant, 56" is a original factory length, from what I've been able to find. As for the weighted driveshaft, Montelishi came with the 350/th350 combination, and has the transmission end weight. (built into the yoke.) Due to the size of the tail end of the TH 400 (diameter of metal around the output shaft), I don't know if there's enough clearance for the weighted yoke. I found this issue when I switched to a 200r4. So I would guess that you can't use one. Just a shot in the dark here, but I'm wondering if someone didn't pull the original driveshaft, and when they tried to put it back in, couldn't make it fit, so they had it trimmed a couple inches ??? The differential will swing forward if you raise the car by the frame, and maybe (?) the previous owner solved his problem by cutting instead of raising the housing...... Like I said, just a shot in the dark. Quote Link to comment Share on other sites More sharing options...
Scott S. Posted November 30, 2021 Share Posted November 30, 2021 21 hours ago, MC1of80 said: My 71 402 aka Barn Find had the weight. Idk about others but it did. Hi Thomas, just curious, did your "barn find" have a th350 or th400 ?? Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted December 1, 2021 Share Posted December 1, 2021 402, th400, 12bolt originally. Numbers matching.. Quote Link to comment Share on other sites More sharing options...
Dtret Posted December 1, 2021 Share Posted December 1, 2021 71 SS original drivetrain 1 Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted December 1, 2021 Author Share Posted December 1, 2021 Dennis, what is the drive shaft lenght in the pictures? Maybe my problem isn't the drive shaft but the yoke? Thanks Grant Quote Link to comment Share on other sites More sharing options...
Dtret Posted December 1, 2021 Share Posted December 1, 2021 Ok I’m one person laying under a car so here’s what I got. Between 55 1/4 and 55 1/2. I measured from the outside of the u-joint holes. If the front yoke was off, it would be the absolute longest measurement you can get. If you want center to center of u-joints subtract 1 1/2 inches. I’m not taking the driveshaft out of the car so don’t ask what the yoke length is. lol 😂🤪😁 Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted December 1, 2021 Author Share Posted December 1, 2021 thanks Dennis, mine overall measurement is 55 1/8 ? Maybe I just need to find a yoke that has the balance ring?? Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted December 1, 2021 Author Share Posted December 1, 2021 Does anyone have a 400 yoke with the balancer off the car that can be measured? Quote Link to comment Share on other sites More sharing options...
Dtret Posted December 1, 2021 Share Posted December 1, 2021 45 minutes ago, Grant MacPherson said: thanks Dennis, mine overall measurement is 55 1/8 ? Maybe I just need to find a yoke that has the balance ring?? I just did it with a tape measure so it’s not perfectly accurate. Lol. Quote Link to comment Share on other sites More sharing options...
Dtret Posted December 1, 2021 Share Posted December 1, 2021 30 minutes ago, Grant MacPherson said: Does anyone have a 400 yoke with the balancer off the car that can be measured? I knew you were going to ask for that measurement. Lol. Quote Link to comment Share on other sites More sharing options...
Dtret Posted December 1, 2021 Share Posted December 1, 2021 If you need me to, I will pull my driveshaft but I’m hoping someone can answer this before I have to. Knowing my luck I will break something else. Someone?? Anyone?? Lol. Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted December 1, 2021 Share Posted December 1, 2021 I believe I still have a 400 yolk with the balancer/weight on it. Won't be able to get measurements until Saturday though. 😞 Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted December 2, 2021 Author Share Posted December 2, 2021 no rush, thanks, we are still looking at 5 months of [censored]ty weather here. Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted December 5, 2021 Share Posted December 5, 2021 Sorry late, but as promised... 1- 400 compared to a 350 yolk 2- the 350 has splines to the end, 400 does not. 3- better look at where the 400 splines start 4- how deep inside before the splines start 5&6- overall length. Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted December 5, 2021 Author Share Posted December 5, 2021 Thanks for the info, here is a picture of my 400 yoke. The blue line is where the seal lip rides, 2 " of no spline so I only have 1 " of spline contact. Even with the 8" yoke in your picture my drive shaft is still short. What I need is a drive shaft that is 55" center to center which makes no sense at all . I spoke with a wrecker yesterday and he said it should be 56". Clear as mud!!!!!!!!! Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted December 6, 2021 Author Share Posted December 6, 2021 Thomas the 8" one you have would give me 2" of spline contack, maybe that is enough? It looks like it would leave about an inch of free play which is ok. what does your drive shaft measure? And do you want to sell the yoke? Grant Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted December 6, 2021 Share Posted December 6, 2021 Grant, does yours look like the one I have in pics 3&4? How far in before the splines start? I believe the correct length for a big block driveshaft, just the shaft, not the yolk is 54 1/2". Willie may be able to shed some light on the length. Sounds like, even with the yolk I have, your driveshaft will be too short. Quote Link to comment Share on other sites More sharing options...
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