Pinion yoke angle

[rlhinit]

I recently installed a open end drive shaft conversion kit from HRM ( hot rod motorworks ) on my '37 Ford.

Using this conversion lowered the wish bone rods apprx. 3" from the original position on the torque tube.

Now I discovered that the angle of the pinion causes the drive shaft to bind. Plus the buggy spring suspension is slightly twisted at the shackle mounting.

What is the proper pinion angle ? How can I correct this problem ?

Could I raise the adapter to the inside of the frame rails v/s the manufactures instructed location ? Or , heat and bend the wish bone rods ?

Has anybody else had this problem in the past - and if so what did you do ?

Thanks - Rayzor

 

[V8 Bob]

I recently installed a open end drive shaft conversion kit from HRM ( hot rod motorworks ) on my '37 Ford.

Using this conversion lowered the wish bone rods apprx. 3" from the original position on the torque tube.

Now I discovered that the angle of the pinion causes the drive shaft to bind. Plus the buggy spring suspension is slightly twisted at the shackle mounting.

What is the proper pinion angle ? How can I correct this problem ?

Could I raise the adapter to the inside of the frame rails v/s the manufactures instructed location ? Or , heat and bend the wish bone rods ?

Has anybody else had this problem in the past - and if so what did you do ?

Thanks - Rayzor

Two simple rules to adhere to for single cardon joints:
1-Keep the U-joint working angle (angle through the joint) between 1 and 3 degrees, and
2-keep both U-joint angles the same, or at least within 1 degree of each other.

 

[JSeery]

Not sure I follow what you have, but did you convert to an open banjo rear axle and keep the original radius rods? If so, you can't just split the radius rods and connect them to the frame rails for several reasons. This will work on a front I-beam axle because the axle can twist as one wheel moves up and down. A rear axle will not twist and something is going to break sooner or later. A second issue is the radius rods will not hold the rear axle from twisting. In the original setup the torque tube provided this function, the radius rods are just triangular bracing to keep the rear axle square. They can be used as the lower portion of the axle bracing, but an upper portion is required. So, the forward ends radius rods have to be near the center line of the car and be able to pivot with the rear axle and secondly there has to be proper bracing for the rear axle. I will try an post so photos of what has worked for others. There is also a uni-ball approach, but I don't have any photos.

 

[supereal]

The better choice is to use parallel springs with the open driveshaft, or buy your u-joints by the case.

 

[JSeery]

I have used parallel springs, but there is nothing wrong with the cross springs if they are set up correctly. Without some type of ladder bar system you are going to get more rotation with parallel springs than with a cross spring, which should be near zero when set up.

 

[PeteVS]

In addition to keeping the U joint angles the same (post #2 above,) you have to have the ends of the driveshaft parallel. A single U joint working thru an angle will tend to speed up and then slow down the driven shaft if the driving shaft is rotating at a constant speed. Having the two U joints "in phase" allows the speed up / slow down of the second U joint cancel out the speed up / slow down of the first. Fords torque tube drive gets away with this action by keeping the drive shaft pretty much dead straight when the car is driven at a "design load." If over loaded or under loaded, the angle is rather small and the effects are not too bad.

ADDITIONAL: The only way for an open driveshaft to work properly is to have the transmission main shaft and the pinion PARALLEL. Both universals must work thru the same angle AND be properly in time with one another. That said, I don't think that using a buggy spring with Ford type radius rods, no matter what the attachment point is, will work properly. Use either a single U joint with a normally straight through angle, or use a double U joint set up with with an arrangement that will keep the pinion angle parallel to the transmission main shaft. If using the latter, and you want to keep the banjo rear, you might want to consider coming up with a four bar linkage rather than traditional radius rods.

 

[rlhinit]

JSeery, thanks for your info . However, I did not split the radius rods - the conversion that I'm using supplies a plate thats mounted to the bottom of the frame with a Hiem joint centered in the middle that the radius rods connect to and pivots. Plus, I purchased an optional bar that connects to the top of the stock rear end housing and runs parallel to the drive shaft and gets welded to the top of the passenger side radius rod. Using a Hiems at both ends of the rod.

With this rod installed it should stop the rear end from pivoting forward and causing the drive shaft from binding . If I adjust this rod in the present position - I feel it would put a strenuous load on the rod. (?)

My problem is - with this bracket mounted in this position - it brings the radius rods 3" lower than the original torque tube position. Thus causing all my problems.

Rayzor

 

[PeteVS]

My problem is - with this bracket mounted in this position - it brings the radius rods 3" lower than the original torque tube position. Thus causing all my problems.

Have you considered bending or "Zee-ing" the radius rods to allow them to align better?

 

[JSeery]

JSeery, thanks for your info . However, I did not split the radius rods - the conversion that I'm using supplies a plate thats mounted to the bottom of the frame with a Hiem joint centered in the middle that the radius rods connect to and pivots. Plus, I purchased an optional bar that connects to the top of the stock rear end housing and runs parallel to the drive shaft and gets welded to the top of the passenger side radius rod. Using a Hiems at both ends of the rod.

With this rod installed it should stop the rear end from pivoting forward and causing the drive shaft from binding . If I adjust this rod in the present position - I feel it would put a strenuous load on the rod. (?)

My problem is - with this bracket mounted in this position - it brings the radius rods 3" lower than the original torque tube position. Thus causing all my problems.

Rayzor

Sounds like you have the correct setup for sure. If my calculations are correct then that should be about a 3 degree change from the original position. That is not that bad, but on the edge of what you would want. Any idea what the angle of the transmission u-joint is? As I'm sure you know they need to be close to each other in the angle they make with the driveshaft. Have you talked to HRM about this issue? I have not dealt with them, but have heard good things. As far as changing the pinion angle, the way radius rod angles are commonly changed is to make a "pie" cut near the axle and re-weld the rods at the new angle. In your case you would make a cut near the axle from the bottom side of the radius rods. The cut does not go all the way through the rod, just far enough allow the rod to bend to the new angle. It will not take much to make an angle change over the distance of the driveshaft. However, I would still check with HRM first to be sure something else is not going on. The U-joints have to be in phase, is there anyway a driveshaft was shortened and the ends re-welded out of phase?

 

[Kahuna]

email sent

 

[rlhinit]

Called HRM today - they suggested that I heat and bend the castings on the radius rods.
However , I think your suggestion of cutting them ( slightly) would work as well - perhaps better.

I'll give ita try .

Thanks Rayzor

 

[rlhinit]

P.S.- the drive shaft u-joints are in the right phase.