driveshaft length question

-
S

spudsterier

Well-Known Member
Joined
Feb 23, 2009
Messages
153
Reaction score
1
Location
mendota, il
I was wondering if anyone would happen to know what length driveshaft i would need for my car.

68 plymouth valiant. 2 door
727 transmission
8 3/4 rear end.

The trans is actually out of a mid 70`s 1-ton ambulance van. But i do believe ihas the long tail shaft.

I dont have a slip yoke so i cant measure the length that i need, but im trying to find out the size needed to figure out how hard it will be for me to find a driveshaft.
If its going to be difficult to locate or i have to have a custom one made, then im just going to sell this car. This is basically going to be my deciding factor.

Any help would be appreciated.
Thanks
 
Whoa, the driveshaft cut and weld is only about $40...dont sell for this chump change! A 904 compared to a 727 is 4 inch shorter (actually 4.01 but...) but your golden with a 8 3/4 because its longer than 90% of the rear ends under these cars so your driveshaft can come from a 727/8.25 or even a 727/7.25 (where that combo is a mystery, maybe taxi or police?
And then cut it down. 3/4 to 1 inch out of the slip yoke up front to the loaded rear end.


found this on another forum...
"But, a couple book listings show that a 1970 Dart (340) auto. with 8.75" rear and the 3.25" dia. shaft indicate a length of 47.99" or with a 3.00" dia. shaft the length shows at 44.99". The only difference I can see between the two is that the longer (shaft) would be with the 904 and the shorter with the 727. BUT, a 340 with a 904? No way. Remember that ALL automatics within the same family (ie.727) were the same length, whether used in a Dart or a Charger. Only the 833's came shorter in the A-body."

your 68 has a 108" wheelbase but I dont know if the driveshaft length changes or they just put the tires more forward of the engine....
 
Check this out, fantastic! from a pdf, find model, then year, then combo on the same line...good luck.

IMG-20121207-00645.jpg
 
Thanks for the reply.
When i got this car it was completely gutted so i dont even have the original drive shaft to go off of.
I just need to try and find one at a local junk yard or on ebay that will work.
 
pishta said:
Check this out, fantastic! from a pdf, find model, then year, then combo on the same line...good luck.

IMG-20121207-00645.jpg
Click to expand...

That would be awesome but i cant really read it.
Maybe i will have to try to get a better look at it when my cumputer is back up and running
 
sorry its small Check line 21...68 Barracuda/Valiant V8 (Barracuda) 727 + 8.75 = 48.88 driveshaft length, darn good reference, located here in a wonky pdf that I printed and put together for easier decoding: [ame]http://users.eastlink.ca/~imackinnon/driveshaft.pdf[/ame]

There are a few typos ie. 340/393.....


here is direct link to mine, maybe you can see it better downloaded and magnified
https://lh5.googleusercontent.com/-...AAFKw/08mTVYHLI6Q/s800/IMG-20121207-00645.jpg
 
First you need a slip yoke. There are different styles and different lengths so you need to start there. Avoid '65 slip yokes as they had a grease lubricated spline, and a vent hole in the cap under the u joint. Every car and combo is slightly different, depending on ride height, differential, pinion angle etc. Slide the slip yoke in until it bottoms, then out 1". Place it so that the u joint bores are horizontal, and the same on the differential yoke. With the car resting at ride height on the suspension, measure u joint center to center, this is your length. I would suggest trying to find a complete shaft and slip yoke from a wrecking yard - try bigger cars (C bodies) or trucks with single piece driveshafts, and one longer than you need. Avoid Dakotas - the slip yokes look the same but the splines in them are cut different and are not interchangeable with 727's. Measure as described above, and take the shaft to a machine shop that is experienced in cutting shafts (4X4 shops, machine shops that specialize in high performance etc) and have it shortened to that length. If it is done properly and true you will find that you are probably ok without balancing it. I have had several done by people who know what they are doing, and never had a balance issue. The whole thing should not set you back more than $100 - $150. When you get your shaft ensure that the rear u joint is the same size as your rear end yoke, if not a conversion joint will set you straight.

My 2 cents
 
EZ to read/manipulate excel spreadsheet available, how do you post a spreadsheet file?
 
I don't know about that list...

A Duster which is a 108" WB with a 727 and 8.75 uses a driveshaft in the 44.85-45" range. Actually the book says 44.99.

Valiant is the same wheelbase
 
Thanks for all the info guys. I just might end up keeping this car after all. But i will still have to soo.
 
You must log in or register to reply here.
-

Back
Top