drive shaft / rear end angle question

alright so i am at the stage of getting the rear end in place on my 31 A bone! running a 40 sumthing ford rear end with an open driveline conversion gonna run a th350*******...
what is the angle you should get your rear end set in at or should i do other things before like get the motor and******* in? because i am sick of moving the frame by lifting it up if it rolled it would be much easier haha

thanks guys
tom

 

The most important thing is that the angle of the face of your output yoke on the******* is the same or very close to the angle of your fange on your rearend. They should be as close to parallel as possible.

 

not this...

 

The angle between the engine and the driveshaft should be the same as the angle between the driveshaft and the rear end. The rear end will normally come out pointing down a few degrees. you need to set the engine first or have means to adjust the rear end angle.It takes a lot of fiddling because changing the rear angle changes the front angle some too!

 

...so you at least need to locate the motor/tranny in place to get your angles, you can always pull it out after. Just my .02.

 

alright so off to the garage i go to start on this faze! so the best advice is to get everything in then worry about the rear end angle.... right?

 

They do not need to be parallel. They need to be at the same angle and as small an angle as possible. 35 yrs as a profesional engineer.

 

alright so pretty much keep the rear end and******* at the smallest degree and the same degree

 

Here's a good link on this subject.
driveline angle and phasing

 

It's pretty simple.

Mount your engine and rear at the SAME ANGLE. Mount the engine so that the carbs are level, then measure the angle at the crank or the bellhousing flange or the yoke or any other surface that runs parallel or perpendicilar to the crank. Mount your rear at the same angle, as measured at the yoke. The rear yoke will look like it's pointing up in the air and the******* yoke will be pointing down.

Your ideal driveshaft should run close to that same angle, but it wont, especially if you've stepped or lowered the rear. To be safe, run your numbers through the driveline calculation program on www2.dana.com/expert (click on the "Torsional*****ysis" link).

This is PROFESSIONAL ADVISE for an OVER-THE-ROAD vehicle, not something the guy at the carwash once heard his uncle say. Racecars will be set up differently.

Here's a link to a TECH post I made last January


Ed

 

[ QUOTE ]
They do not need to be parallel. They need to be at the same angle and as small an angle as possible. 35 yrs as a profesional engineer.

[/ QUOTE ]

Now I may not be a professional engineer, but if they are at the same angle, isn't that in fact parallel?

 

The response that they be parallel does make the angles the same as I suggested. It is a possible case where the angles are the same. If on end has an angle between parts of 3 degrees up and the other end oalso was an angle of three degrees up then they both have the same angle but are not parallel. This is the relationship that all the cars I have seen are set up. Both solutions are correct, but the way I suggested is the way Detriot did it. If anti-squat geometry is built into the rear suspension, the rear end will turn down as the suspension is loaded. This will increase the angle at both the rear and the trans. If one angle is positive and one negative they will not be the same anymore. If both angles are in the same direction, then they will not change as much as the suspension works.

 

I doubt the A in question is running parallel leaf springs...

but for those who are, it is generally recommended that you rotate the rear downward such that there is about 1 or 2 degrees difference between the rear yoke and*******. This is especailly true for torquey engines and heavy cars. What this does is to compensate for the axle wrapping up during acceleration. I have set up about a dozen cars like this, and it works great!

 

If drive shafts ran CV joints like front wheel drive axles do, all this shtuff would be earelephant.

The drive shaft and pinion should be parallel but not in direct line with each other when the car is running at whatever attitude it runs at most of the time.
If it's a drag car then that is under extreme forces of acceleration and the axle wrap-up has to be compensated for in the initial set up so the parallel situation will be in effect at that "normal situation" of acceleration.
If it's a highway cruiser that compensation won't work in fact it will make it shudder.

Of course, 80's Camaro style Torque arms throw this stuff out of the design books, and don't even get into proper phasing of the '58-'64 Chevy out of phase two piece drive shafts...