• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

Measuring for new driveshaft

machelis

Well-Known Member
Local time
10:52 AM
Joined
Dec 27, 2017
Messages
105
Reaction score
33
Location
Montreal
Howdy,

So I need a new driveshaft and I've read around about pushing the yoke in all the way and pulling out an inch. I can't bottom mine. I noticed some folks have a yoke seal that's about flush with the end of the tailshaft, but mine protrudes about an inch and starts to squish before I hit anything. Am I going to need to pull the seal to measure then replace? Or is there a distance from end of tailshaft to flat surface of yoke that works? Before I started I notice that the yoke already stuck out from the seal about 2 inches which could explain my death wobble at about 70mph.

Also, is there more than one model of yoke seal for a bb 727?

Thanks.
 
Thanks Fran. Is that tool for long dust cover specifically? Or works with all seals?
 
I just had one made for me as I didn't have one. The guys at A-1 driveshaft in Baltimore made it. They told me to push the trans yoke all the way in and measure from the CL of the axle yoke to the CL of the trans yoke.
Did that and brought them the trans yoke couple days it was done.
Is yours shaking because it threw a weight?
 
I can't get the yoke in all the way. That's the issue. I did find a dent in the shaft just now. Plus the PO told me he tossed it in just because it was all he had. No idea what it's from or if it was even straight. Now that O have a 451, I need a little strength :D
 
I would go to Denny's Driveshafts website, they will have a measuring diagram on your application to use and or explain how to properly measure for you new driveshaft. They do very good work and reasonable prices.
 
If I understand your question, you measure from the end of the tailshaft to the bottom of the U-joint sadel. The seal doesn't matter.
 
That tool is to pull the bushing without removing the tailshaft the installation tool is the smaller piece . Had a driveshaft that was to short, rattled at 3200 rpm and up. Picture 2 this is my car with weight on rear end. The trans shaft sticks out 1"or 1 1/8" from tailshaft with no seal. If you change bushing it needs to be in the right position for lubrication.
tb1.jpg
DS7.JPG
wdud.jpg
 
There are different yokes for a 727 with different length snouts that slide into the trans. You need to use the one that will go on the new driveshaft. The large dust cover usually compresses enough to get that measurement, if not, consider replacing the dust boot/seal.
 
I didn't realize that boot was just a secondary dust cover. I'll tap the yoke in farther and go from there. If the trans shaft sticks out 1" from the tailshaft I shouldn't be far off from as far as it can go. I'll get back under the car after work today. I have another trans in need of a yoke seal, so maybe I'll invest in that tool.

Thanks folks.
 
Don't need a special tool, if don't want to. Careful use of a screw driver or chisel can remove the old one. the correct size deep socket can install, carefully tapping it in. But a good special tool is nice.
 
I bought that exact tool setup on eBay 6 months ago. I eliminated some driveline vibrations that were plaguing my car. Installed new Neapco 727 yoke, output shaft bushing and u-joint. The tool was a little pricey for probably the only time I'd need it. I will say though it made the whole ordeal faster and easier than if I made do without.
 
I just bought a new Strange Engineering driveshaft for my charger from Doctor Diff
The instructions on the Doctor Diff site are to measure from the Center line of the rear pinion yoke to the transmission housing
and then to measure from the transmission housing to see how far the shaft stands out from the Transmission
The end result fit wonderfully (even with my over thinking it)

From the Doctor Diff website:

Please provide the following dimensions. Vehicle's full weight must be resting on it's suspension while measuring.
A. Measure from the center of the rear U-joint to the end of the transmission tail-housing (A dimension, Figure 1)
B. Measure from the end of the transmission tail-housing to the end of the output shaft (B dimension, Figure 1)


driveshaft-measure.jpg
 
I was going to go with a local shop I've never tried or order from bears performance just over in ontario. I like finding good local stuff.
 
Auto Transport Service
Back
Top