Hello All,
Buddy of mine is sticking a 2wd Chevy S10 diff under a '31 Model A. We were eyeing things up the other night with the centerline of the bare frame and got the whole thing all good and centered. But lo and behold, even though the pumpkin and the wheels are centered, the yoke is offset by one full inch.
So if he lines everything up off the pinion yoke, then one wheel is gonna stick out a full inch more than the other. It goes without saying that this is not exactly optimum.
The axle housings are exactly the same length as each other. I was expecting two different lengths as most manufacturers do to account for pinion offset. Unequal length axles to fix silly one inch offset due to ring and pinion spacing.
My questions...
1.) WTF?
2.) Is the stock S10 engine/trans set one inch off of center?
3.) Anybody know of factory shorter axles (not ratio, length) than can be boneyard found? This alleviates the cost of cutting and resplining one axle to center the pinion yoke to the frame/tranny/engine. I don't mind narrowing an axle housing, not exactly rocket surgery. It's them hardened axles I'm worried about. Any other cheap alternatives here?
4.) Is there a difference in pinion offset between 2wd and 4wd diffs? Perhaps he just thinks he's got a 2wd rear end but in fact has a 4wd and the one inch descrepancy takes into account a transfer case???
As altruistic as I can pretend to be, my motive behind these questions is twofold. Yeah I wanna see my buddy's ride come together. It's pretty badass. The other reason is if I can find a cheap way to make this work for him, I'm gonna stuff one of these under the tail end of a small British sporty sport car with a big American lump between the front fenders.
Thanks much
Be well y'all
The 4WD S-10 axles are @5" wider than the 2WD ones, roughly 59" wheel mounting surfaces to mounting surface vs. 54" or so on the 2WD.
Easy answer would be a wheel spacer on one side, maybe?
Many drivetrains are offset to the passenger side. The S10 rear is offset as you have found. This allowed the axles to be the same length, and to allow more room for the steering brakes, etc. It is very common to offset the engine/trans and align the rear input to them. FWIW, the 05 and 07 Challenge Fiat had a 2" engine off set. My Datsun is 1 3/8". Most Ford trucks are 2 3/8". Many Mopars are 1 to 1 1/2". Contrary to intuitive thought, the higher the HP the engine makes, the closer to the centerline the engine should be installed. A lower HP vehicles can use more offset. The balance and preloads are different between the HP outputs, and the vehicle usage. You will do yourself a favor by installing the engine offset to the passenger side. The steering clearance and master cylinder installations are much easier. The E&T must be straight and perpendicular to the rear. Side to side oddset should be low, but before you get hung up on the lateral offset, remember that the vertical difference changes when you hit a bump and it can vary by plus and minus 4 inches on many vehicles. Yoke alignments and pinion angles are more important trhan offset.
AFIAK, there's nothing wrong with the driveshaft being at a slight angle and those universals accommodating the offset in one more plane. The universals don't care what plane the offset is in, as long as it's not too much offset.
Right?
I do, however, understand that streetrod guys are into aesthetics. He might be hung up on that and not able to get past it...
Clem
Most U joint setups will accept around 5 degrees misalignment and still run smoothly, much more than that and it's possible to get vibrations as the U joints speed up and slow down. 10 degrees would be way too much. I'd shoot for around 2 or 3 degrees max in both planes (up/down and left/right).If it gets 5 or 6 degrees at maximum axle travel, that still shouldn't present a problem.
My Jensen Healey's pinion is offset toward the passenger side approx 1 1/2". No ill effects that I can see. IIRC, the 1st gen RX7 is offset as well and that's from the factory on both cars. The Abomination's 2nd gen RX7 diff has no pinion offset. I had to finagle quite a bit to get the driveshaft angle acceptable, I wound up tilting the diff nose up a bit and lowering the rear of the tranny. The driveshaft is so short that I ended up with around 4 degrees. No ill effects so far.
That's why I post on this board.
Extremely helpful, fellas. Many thanks.
(Although I'm not so fond of the new site format...oh well)
I knew some vehicles had laterally offset engine/tranny but never put much thought into it all. I especially like the idea of sneaking things to the passenger side to allow just a little more room for steering and brake master clearance. Already cutting it very close in this regard.
Wheels777, when you say low/high HP cars, where does a 300+HP SBF in a 2000lb TR4 measure up? One inch offset shouldn't make much of a difference, right?
Thanks again.
