Rear drive shaft length

[Br0nc0xrapt0r]

Hello all, I twisted a rear drive shaft coming off the Tcase to the first drive and sourced a replacement from a parts dealer. I put it in and it went well but there was only about a half inch in between the flanges with the shaft fully compressed. I know there is not an insane amount of travel going on but what should the compressed length of the driveshaft? It's a bone stock 1971 M35A2. Last think I want to do is hit a big bump and break off a yoke or twist another shaft. I also need to know this so I can repair the other shaft. Thanks.

 

[gringeltaube]

Stock length, compressed = 45-1/2" (center to center of U-joint bearing caps).



G.

 

[Br0nc0xrapt0r]

Stock length, compressed = 45-1/2" (center to center of U-joint bearing caps).G.

Much appreciated thank you.

 

[Jeepsinker]

Assuming you don't have a shorter wheel base model, like an M275. The shaft you got probably wouldn't go in at all if that was the case though. They are considerably shorter.

 

[Br0nc0xrapt0r]

Assuming you don't have a shorter wheel base model, like an M275. The shaft you got probably wouldn't go in at all if that was the case though. They are considerably shorter.

So what you're saying is, if its a complete take out shaft from another truck, its going to fit or it is not. There isn't much room to **** this up.

 

[Jeepsinker]

Pretty much. I have seen some odd length ones from time to time.

 

[Jeepsinker]

For what it's worth to you, I was rolling around under my truck today, and installed, the shaft only has about 15/16" or so of room to compress.

 

[gringeltaube]

I know it sounds strange but it really doesn't need more than that. In normal service that slip-joint does see some extension, but barely any compression.
From level position (empty truck) to all the way up against the bump stops, the fwd rear-axle only shifts forward (= closer to the T-case) approx. 2mm, which is almost nothing. And fully loaded it is even less!
Even considering that the dogbones could extend a bit due to having rubber bushings, I would say, all combined, 1/2" is about the max. possible compression.



G.

 

[Br0nc0xrapt0r]

Well that makes me feel a lot better. It took me quite a while to get a new shaft to my door and I don't want to do that again. Hopefully I can get my old one in the lathe soon and get it doctored up.

 

[rustystud]

I know it sounds strange but it really doesn't need more than that. In normal service that slip-joint does see some extension, but barely any compression.
From level position (empty truck) to all the way up against the bump stops, the fwd rear-axle only shifts forward (= closer to the T-case) approx. 2mm, which is almost nothing. And fully loaded it is even less!
Even considering that the dogbones could extend a bit due to having rubber bushings, I would say, all combined, 1/2" is about the max. possible compression.



G.

That's one of the wonders of our rear axle suspension system. On a regular truck that slip must be able to move almost 4" .