A bit more info from a guy that builds high angle drivelines. Jesse says that greater than 8° is the angle at which an added joint is a consideration. At 8° he suggests that a steel shaft is a crap shoot as far as vibration is concerned, he says that an aluminum shaft is his recommendation. His theory is that at high angles the rotating driveshaft will speed up and down 2 times per revolution. The heavier steel shaft pronounces the vibration noticeably more than the lighter aluminum.

Disclaimer: After watching the spectacular video of the Shaw suspension. I am feeling confident that my setup: Equal output and input angles and u-joint operating angles of 8° is going to handle the 400hp from my Y-Block. I will report.

Has anyone out there, running an early Bird, figure out a design to reduce the operating angles???



.150 Stroked Y-Block:327.25 ci @ >1hp per ci
 

DryLakesRacer,

What kind of u-joints do you use?



.150 Stroked Y-Block:327.25 ci @ >1hp per ci
 

From the engineering drawings of the early Birds, I come up with 6-7 degrees operating angle at the pinion which is angled upward, furthermore the output shaft is angled down which puts the two angles outside of the 1 degree of margin between them.

I'm settling in to the fact that 8 degrees at both joints is going to work.





.150 Stroked Y-Block:327.25 ci @ >1hp per ci
 

"Overthinking things" is part of the process of making it right. 

the dana book claims  as long as the face angle on trans output  is within 15 degrees of face angle  input of the diff you will be ok the trans can be higher as long as the diff flanges are parallel to the trans flanges.,meaning the pinion can be off centre to the trans, the limit there is as long asujoint  crosses don't rub. ther is a magnetic degree tool works well,  they are made of plastic with magnet glued to hold them in place. the 15dgs is the max, and should be with the truck on the ground . and the spring bushings on the anchor end tight (no slop)

The perch pad was a good question, I did use blocks to adjust the axle ride height.

Larry Shaw Modified Rear Suspension 4-link POV - Bing video

I'm feeling lots better after watching the video, thanks! The pinion operation angle is all over the place and at full throttle.

I think the early Birds were designed with the u-joints at high angles, I wish I had paid attention before taking it apart.

I am hoping to hear how Vic Correnti has his Bird set up. He gets the front wheels off the ground. I can't imagine a way, without serious modifications, to reduce the angle to within the textbook specs.

I do like to play outside of the box, and I do tend to overthink things before crossing the line. Thanks again...





.150 Stroked Y-Block:327.25 ci @ >1hp per ci
 

Open You Tube and go to “Larry Shaw Modified Suspension” and move the time to 1.55 and watch the movement using a 9” Ford rear..... I believe your all over thinking this. A u-joint can perform over a 22* movement, that’s 11 up and 11 down. Not that we would ever do or abuse them in such a manner.

We use leaf springs in our 1/2 mile dirt car with a slider and a shackle and in 7 years never had a problem with just normal greasing..

56 Vic, B'Ville 200 MPH Club Member, So Cal.

Sorry, I meant the spring perches lower the ride height about 2". The perches are taller, but being located under the axle housing, they actually lower the ride height. 

Is your new 9" from a 57 T-bird? The 55-57 T-bird spring perches are taller than non-Bird axle housings, thereby dropping the rear ride height approximately 2". If you do not have the original spring perches, it could put your driveline angle outside acceptable limits. 

Thanks Jeff,

The joints are within the, optimal, no more than1 degree difference. The transmission output shaft cannot be lowered or angled down anymore without cutting the x-member. The pinion can be raised (another .5" comfortably) toward the height of the output shaft thereby reducing the angle of the driveshaft and operating angles. But, if I have the calcs correct: The driveshaft is 31.5” long, using a right angle calculator, this equals rise of around 5” in the length of the driveshaft, to get too 3 degrees the rise must be around 1.5” meaning the pinion would have to move up towards the height of the output shaft approx. 3.5" I don't think that is achievable.

One thought: If the rear axle was mounted upside down the pinion would be close. Is that possible?



.150 Stroked Y-Block:327.25 ci @ >1hp per ci