Driveshaft / U Joint Clearance...

[PeteVS]

I'm putting a '48 rear into a '32. I had the torque tube shortened and now, I just got back the '34 driveshaft back from being shortened (using a 6-10 spline coupler.) Before I finalize the rear end, should I just assemble it and mate it up to a transmission with the universal and all the ball joint stuff and use an aluminum foil ball to make sure there's clearance? How much clearance should there be? Thanks!

 

[DICK SPADARO]

The internal torque tube ball and the torque tube cup and torque tube cap already have the correct spacing when assembled, you should check the interior ball cap to insure that it is not scored or has a wear groove from lack of lubrication. The most important issue is to make sure that your driveshaft has not been cut to long or to short before assembling the torque tube as a unit.

You should do a trial assembly of the drive shaft by correctly positioning the rear axle at the correct wheel base and ride height, installing the drive shaft with a bolt for a temporary pin and inserting the drive shaft into the ujoint, by holding the torque tube at the side of the drive shaft and butting it to the flange of the banjo you can then check the index of the drive shaft to the torque ball cup wear mark and determine that the drive shaft is not cut to long to bottom out on the ujoint or cut to short to misalign the speedometer gear. Its is just an easy check before assembly that can eliminate some potential problems.

 

[JWL]

The only "clearance" issues are the end of driveshaft to the attachment bolt which connects the u-joint to the transmission output shaft. This distance, unlike other cars, does not change during operation of your Ford except to the extent the face angle might bring the tip of shaft closer to the bolt head. Probably 1/4" clearance is completely adequate.

 

[PeteVS]

Thanks guys! Today, I'm gonna assemble the driveshaft into the torque tube and then attach them to the transmission. If I slide the driveshaft all the way in until it contacts the universal bolt head, I can measure from the torque tube flange to the cross hole in the driveshaft and compare that measurement to that of the pinion in the banjo.

 

[Kurt in NJ]

The end of the driveshaft should be about flush with the bell on the torque tube --, when the bearing, washer, and speedo gear can be installed, the snap ring fits in it's groove and there is still a slight amount of clearance (you can moove the speedo gear some) there should be no problems with the shaft bottoming out in the u-joint.

 

[rotorwrench]

The old timers always told me to shorten the drive shaft to fit the dimension you want for best fit of the rear axle in the frame then record the exact amount you shortened it. At that point you shorten the torque tube the exact same amount. Dick's method of checking is the best for a final fit check and Kurt in NJ is very close on how the shaft length should be with the torque tube installed on the rear axle. If it sticks out too far it will bind with the u-joint, not enough and it won't have the intended full spline mate with the u-joint.

Kerby

 

[PeteVS]

Got some help from my brother today. Checked clearance between front of driveshaft and U joint bolt. Works out to be 1/4"! Perfect. So, with the two of us, we got everything torqued up, painted and in the back shed before I remembered to take a picture. It's no longer a one man job to horse it around! Next will be backing plates and radius rods. Thanks guys!!
In the photo, that's the original '32 rear directly behind the shortened '48 and an A behind that (with the wheels.)

 

[DICK SPADARO]

1 /4" from the bolt is too far inserted in the u-joint. Customers were at the shop this weekend measuring a number of driveshaft torque tube combinations and it was established that an accurate index for a drive shaft was about 1/8" below the level of the torque tube cup face. The driveshaft does not stick out the interior end the spline section of the u-joint. So before you bolt everything up put a straight edge accross the torque collar and check that the drive shaft is somewhere around 1/8" below that level and you should be good to go..