How much to shorten driveshaft for OD?

[Dennis in NY]

Does anyone here know the EXACT amount that one should shorten a driveshaft (from a '49 without OD) for use in a '49 that now has OD? Someone told me "about 4 inches". I was hoping for something less vague....

Anyone have any experience with this?

Thanks as always.

[hudsonkid]

I don't know if it is an option, but I doubt an OD driveshaft would be that hard to find...

I think spending the $$$ to shorten one, it would be cheaper to just buy an OD one...

[46HudsonPU]

Does anyone here know the EXACT amount that one should shorten a driveshaft (from a '49 without OD) for use in a '49 that now has OD? Someone told me "about 4 inches". I was hoping for something less vague....

Anyone have any experience with this?

Thanks as always.Dennis,
I'm getting ready to do this myself, for the first time, 3-speed to 3-speed w/OD. I have a thread, which as some advise from some knowledgeable people -
http://www.classiccar.com/forums/showthread.php?t=5648

According to "Uncle Josh", the difference in length is more like 8 1/4" between the two transmissions, so your 4" figure doesn't sound right. If you have both transmissions there (new/old), you might want to measure them to see.

Also, the advise given to me is that the figures may work for preliminary estmates, but nothing beats your own measurements.

Did a Google search on "Measure for a Driveshaft" and came up with this -
http://www.corvettemania.com/useful/How%20to%20Measure%20for%20a%20Driveshaft(Dennys). pdf

This site page has a LOT of good techical info - downloadable via .pdf, mostly on suspension info & work -
http://www.corvettemania.com/useful/

[jsrail]

Did a Google search on "Measure for a Driveshaft" and came up with this -
http://www.corvettemania.com/useful/How%20to%20Measure%20for%20a%20Driveshaft(Dennys). pdf

This site page has a LOT of good techical info - downloadable via .pdf, mostly on suspension info & work -
http://www.corvettemania.com/useful/
Thanks for the info Rick, good site that I have bookmarked so I can refer to it when I get to the driveline stage.

I've been lacking on the forums, but, did you settle on a rear end to sit behind your LS1?

Jay

[46HudsonPU]

Thanks for the info Rick, good site that I have bookmarked so I can refer to it when I get to the driveline stage.

I've been lacking on the forums, but, did you settle on a rear end to sit behind your LS1?

JayHi Jay, and you're welcome. I was thinking about putting it into a separate post, as there is a lot of good info in that area - I even bookmarked it myself...:rolleyes:

I try to check my email & the Forum on a daily basis - am almost up to the magic '1000 posts' (actually, I would be past that point by now, but have been deleting some of my older & 'less notable' posts - mainly on obsolete & expired ebay threads).

Haven't settled yet, but am thinking of a GM (Blazer/Jimmy/S10) rearend, mainly since I've already got my 5.3L & 4L60E. The rearend is available in two widths (54 1/2"=2WD version, and 59"=4WD verson). The heavier duty version of the axle is 8.5", with 3.08, 3.42, 3.73, 4.10 etc., gears. I am leaning more toward the 3.42 or 3.73 for the economy, but not to the extreme of the 3.08.

[Jon B]

If you have it shortened be SURE to have it CHECKED and DOUBLE CHECKED for balance when done. I had one shortened years ago, got an immediate vibration. The guy re-checked and pronounced it okay. Still vibrated. Took it to a driveshaft place a couple years later, they checked, pronounced it good, it still vibrated. Third driveshaft place: "This thing is WAY out of balance!". And THEY fixed it! So beware.

[46HudsonPU]

If you have it shortened be SURE to have it CHECKED and DOUBLE CHECKED for balance when done. I had one shortened years ago, got an immediate vibration. The guy re-checked and pronounced it okay. Still vibrated. Took it to a driveshaft place a couple years later, they checked, pronounced it good, it still vibrated. Third driveshaft place: "This thing is WAY out of balance!". And THEY fixed it! So beware.Jon, as always - sound advice!
Since we are 'somewhat' local to each other (VA/MD), can you PM or email me with the 'third' shop that you took your driveshaft to? (and possibly the TWO others - to avoid! :eek: )

[Hudson308]

I added overdrive to my '49, and had to shorten the (front) driveshaft EXACTLY 8-1/8".

[Dennis in NY]

Thanks for all the great info everyone..... Hudson308, I am going with 8.25". Thanks.

[Hudson308]

Okay, Dennis; Just remember that the front driveshaft doesn't have a yoke that slides in and out of the transmission like a modern (rear drive) vehicle... it bolts into the front u-joint yoke on the rear of the transmission. You may be able to make up that 1/8" in the center carrier mounting hole slop, but 8-1/8" will put you dead on. That's the length difference between an O/D and non-O/D single-lever ('48-51) Hudson 3-speed transmission, as measured from the front of the bellhousing to the u-joint yoke.