Driveline Question

[DanStokes]

With all the cars I've built I've pretty much put back what was there, maybe built or refined. Or maybe I was too dumb to worry about this before. Anyhow:

On the S-10 the rear end measures 4* up and trans measures 5* down. I can raise the trans a little but if I'm going to keep the shift linkage out of the tunnel I can't go too much. I have wedges that I can put in the spring pack/lowering block area and tip it down however much the wedges will yield. These measurements were with weight on the rear axle, not hanging loose.

So as a practical matter, how much is OK? If I can get the rear to zero (which is what I expect) will that work OK with the trans at 4* to 5* down?

I need to sort this out before I build the trans cross member.

Thanks all

Dan

[Barry Donovan]

Not sure..but to follow a typical car is a good idea. trans striaght to shaft, but rear end, never align it to the yokes. Up or down,but never align them. I learned that the hard way. This has been asked.. damn net.

[squirrel]

they seem to work ok with the axle pointing down a degree or so relative to the trans.

Is the trans pan parallel to the bottom of the truck?

[DanStokes]

With the Benz manual trans there's no pan and it's hard to tell. But the engine sits at about the same angle as my buddy's 300SD so I'm guessing I'm close to OK. We put the angle finder on both one day. The engine sits about 4* down in the Benz and his has fresh motor mounts (a Benz issue in that chassis). Mine's close to that. The Benz, of course, has IRS so the rear is solidly mounted and the driveline uses those hockey puck thingies. Kinda apples and bananas.

Dan

[oletrux4evr]

I think you want an angle difference so the u-joints will wobble and sling grease to all of the needle bearings......don't know how much would be too much.....

[tardis454]

JTR sells driveshaft alignment kits for lowered trucks in 2°, 3° & 4° increments.

http://www.jagsthatrun.com/Pages/Parts_S10-DrvshftKit-Short.html

[Loren]

The angle the engine-trans is at, and the diff pinion is at, of-course need to start at the same (i.e. parallel) then in a drag car the pinion should be down a bit to compensate for how things are going to move at launch, but for a top-end car less so as it's seeing less torque when you're aiming to make a top speed number (in final drive) than the drag car would. Maybe a degree or two?

But before that, they should be kinda pointing at each other in the first place. Not directly-perfect in a street driver and the only reason for that is to give the little roller bearings in the u-joints some motion or they'll cut grooves but in a race car, so-what. One of the first things my auto shop teacher told us way back when is that every time you make power change a direction there is a loss, so why make it change directions if you don't have to?

As for how to really figure if all that stuff is really in line or not, why not build a driveline-version of the good ol' fashion front-end-toe-alignment trammel bar? Lay a long-enough 2x4 piece of wood under the car to make the distance of engine/trans/rear, screw a piece of cut plywood to it up at the front that reaches vertical to be marked at the front pulley center, then one further back marking level with the trans tailshaft c/l, then another where the pinion comes out of the diff, then lay the whole thing over on it's side to pull it out of under the car and have a confusion-free illustrated picture of your real driveline angles? To get the pinion angle plotted out on such a thing you'd have to run a line down from along the diff cover sealing surface and figure your ninety degrees in or actually use an angle finder to make comparative measurements of the pinion and something on the motor parallel with the crank and then transfer that to your plywood, but that's all simple enough.

(Didn't sound simple when I said it)

[Deaf Bob]

Looking straight down on your pick up... Draw a line thru your left wheels.. Another thru the right wheels..
Motor needs to be parrallell to those lines.. They can be off center.. But need to be parrallell.. Close to the center, the better, or rather to the pumpkin..
Now if you were to look at the side, the engine should be level.. To a few degrees..
The rear end should be the same,
I believe that the rear normally points down a couple degrees.. ( I'll have to crawl under some cars to confirm that) reason being is the pinion rises on acceleration so you are seeing the same degree over center on acceleration..
Like Loren says.. A race car doesn't really matter.. But something to consider is if you install the rear so the pinion is level, will the diesel have enough torque to make the pinion rise too much? Will you need a pinion snubber?

For our derby cars we go 10* up, because in the end it is pointing towards down..

[Deaf Bob]

http://www.iedls.com/asp/admin/getFile.asp?RID=10&TID=28&FN=PDF

Hope this shows as a link whenI post!
Explains it all.. I was partially right mostly wrong in my above post..

[DanStokes]

Evident either Terry or the owner before him put those wedges in to point the pinion up - no idea why but maybe with the SBC the trans pointed up so it all made sense. Anyhow, not the case now.

The trans is pretty well centered in the tunnel but it would be a good idea to check it for longitudinal (how's THAT for a big word!?) alignment. Measuring off the outside of the wheels is a great way to do that. I can wiggle it a bit to center it with no problem. I actually built the mounts by centering the trans in the tunnel but that probably isn't very scientific.

The engine is (FINALLY) pretty flat in the East/West orientation. I had to rework one of the mounts and drop the right side of the engine 2" instead of using a 2" spacer on the left side (I didn't like that).

THANKS for all the great suggestions!

Dan

[DanStokes]

Bob - That brochure from Inland Empire Driveshaft is PERFECT! According to them I'm just about right though the pinion is up just a tad. I can fix that. They want the diff and the trans to be parallel and at 3 or 4 degrees so I'm almost there! A little tweaking tomorrow and I'm home free - though I do have to figure out if the engine and trans are in line with the body.

Again, thanks ALL
Dan

[Deaf Bob]

Glad to help...
And y'all thought derby guys just slapped stuff together...