Great forum we have for exchanging information. The guy who makes my driveshafts says the rule is the same angle at each end, so 2deg up and 2 deg down is on the money.
I have heard the one about if you have the alignment perfect the needles in the yokes brinnel the surface but I can't for the life of me see a living moving driveshaft ever having perfect alignment except once in a while.
I think I've got an answer (hand in air)! What happened can be explained within the context of drive train / suspension development. Until 1949, Ford used torque tube drives which only had a universal joint at the transmission output. Throughout the suspension travel, the drive shaft was always on the same axis as the pinion as they shared a common axis and the shaft moved with the rear end housing. The single joint made parallelism between the crank/trans centerline and pinion centerline a non-issue. The engine could be level and the ball socket / u-joint in the torque tube handled the angular changes at the trans. Parallelism between pinion and crank / trans centerline became important when the open drive shaft with a joint at each end replaced the torque tube. Sound right?
Well.....the reason your carb face is on a angle is so the carb will sit level and not affect your float level. Most old flatheads....they weren't that critical.....weren't that sensitive.......and also....the driveline was more flat. Designers of autos are a sneaky bunch. They usually do things for a reason....might not be the one that you usually suspect.
Got to remember....automotive systems are sensitive systems. There's oil levels to worry about.......flows......most offroad folks use EFI systems on their offroad buggies because carbs can't handle the extreme angles they transverse....also rollovers can cause serious fires where fuel will pour out of a carb..... where EFI's won't
Pinion angles are another one.......while torque is being generated by your engine.......the torque going to your rear causes your rearend to wrapup in your springs or suspension........if it weren't for that pinion angle....you'd notice a slight shudder from your driveshaft geometry being slightly out......also stress on your u joints, and you also got to worry about the oiling of those front pinion bearings that are singing happily at the enormously high rpms before turning that really big ring gear, etc, etc.....things can really get complicated for some of these engineers.
I must have skipped class when you guys were learning about drive shift angles. Going back and I do mean way back, I was taught not to use yokes and universals as drive shaft extensions. To keep vibrations out of the car, if your setting the engine in "flat", use 2-3 degrees of downward pinion angle. Over the years the rear end gears kept getting taller,pull the corner faster, more R's in the motor and the cost of the motors just kept climbing! 3/8's tacky track 6,52's and a 8700 rev limiter chip. To day that might get you in the middle of the pack! Any way I carried that setup over to the bucket, only because I didn't know any better! You know what? works fine. same universals as the day the drive shaft was installed!
Here's a question for you. I am going to run a Jag rearend. If you look from the top down on the chassis the pinion is slightly to the right of the pumkin. Do you offset the engine to get the drive shaft lined up straight which means that one axle will hang out the side more. I assume that you don't do that and that there is a particular angle for the pinion as seen from the top.
When you set up a rearend that has a centered pinion you put angle in to the vertical plane...
If your setting up a rearend that has an offset pinion such as a 9inch ford or a jag like yours you work from center of the housing. The driveline angle can work from left to right also, or a combination of both... But you have to have the housing centered if not its gonna look funny...
Boy I would hate to drive around town with them wheelie bars hanging off the back, (A real COP getter) way out there.. Better to set your chassis up so they are not a needed thing...
i can see all the offset in your rearend, especially at the wheelie bar mounts.. i myself, would never set a rearend in a car like that.. yea it works but not my preference..
jmr122848; How? If your punkin is offset to center the pinion, to center the car between the wheels the pumpkin is offset. Or am I delusional?
To center the housing of the pinion centerline you would end up with one axle sticking out past the frame more then the opposite side. You would then need to either shorten the long side or lengthen the short side. That would also cause you to adjust (as in replace) one of the axles. With C-clip style axles you pretty much have to buy a new custom length from someone like Moser. C-clip axles are usually not able to be shortened. If you have a Ford 9" then soom axles can be cut and resplined but I don't like that option. You are better off getting new axles from Strange or Moser. There are a number of problems with resplining hardened axles.
When I built my Vega i used a '57 Ford 9" with two short axles. just had to shorten the one side of the housing a beat the hell out of the floor pan with a BFH.
That is a good way to do it if you can end up with the correct width and it is a drop out 3rd member style rearend. The C-clip S-10s are the ones that trap you in to new axles when you narrow them. Problem is even the famed 9" is getting scarce in the wrecking yards. That's the main reason Ray Currie had to start manufacturing new 3rd member carriers, cases and housings. They bought up most all of them in a 3-4 state area.
I'm glad I asked this question as its something that isn't obvious. The reason I asked it was that I measured the arms on my jag rearend as I was pulling it out of the suspension cage. I realised that both arms were the same length and I did not want to shorten a complete side of the IRS.
another option instead of a 9inch is the tried and true 8.8 ford explorer rearend.. its offset (1 5/8 off center) if i remember correct... and you can do the trick youngster was talking about as to cutting down the long side 1 5/8 inch and getting a short side replacement axle.... the 8.8 out of ford explorers are limited slip, 3.73 or 4.11 gear and good possibility its disk brake and a very good rearend at pretty reasonable price with the disk brake setup..
ive also cut down gm 10 and 12 bolt rearends and put 9inch housing ends on and got axles with the GM spline but ford bearing ends from moser...
when i cut down an 8.8 like this i had to use a boring mill to get the cut straight and square.... i watched a guy do it on his garage floor with a sawzall and a grinder and a T-square, guess it worked for him, he drove the car for a while then sold it. i think it was more luck than anything though ..
Why not just make a cover (rear) for the offset third member, so now it looks to be centered??? and also trick at the same time.. a bolt on rear cover plate, Alum... How do they say it? fake it till you make it.. after all, they are mostly for LOOKS anyway, it seems ..
I see those fake rear end covers all over the place, you know and I know, but the common person knows nothing about what they are lookin at, as far as these cars go... plenty of then fake teets out there
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