wheelbase side to side question

I have a question for frame builders on wheelbase being a different length on one side or the other for road crown. I know on big trucks Kenworths and such I'm told one side is 3/8ths inch longer .
Anyone know about this on our builds?
Really appreciate any comments, Thanks Gerry

 

Having been a heavy truck mechanic since 1975 and a Kenworth and Peterbilt mechanic starting in 1988,I believe your information is wrong,longer wheelbase on one side or the other would make the truck pull to the right or left and drag the rubber off the tires. as far as road crown,Paccar ( KW and Pete) has an allowable spec for frame height,usually 1" or less side to side

 

Sounds like the original steel body 1935 Willys panel I bought years ago on an aftermarket frame. Wheelbase was 1 1/8" shorter on the passenger side - the damn thing would not drive in a straight line and kept on driving towards the ditch. Now it has a proper frame....

 

A shop I know lengthened a frame on a kenworth even and the first trip wore the tires out. He was ready to sue and the shop called KW and was told one side had to be just a little longer, after repair second trip tires were good. I also worked in trucking and built two large wreckers and when I lengthened mine I did it exactly even and I didn't have a problem after. So who knows ????

 

Different wheelbases on two sides of a vehicle shouldn't affect tracking, unless it's due to a solid rear axle being askew in the frame. Several Renaults of the '60s and '70s had a difference of up to almost 3" between the left and right wheelbases, due to transverse rear torsion bars being placed one behind the other. No problem.

 

A 3" difference in wheel base would make the car go around in circles.

 

Uh, not necessarily. Funny cars have their front wheels offset 2'' (to increase rollout) and they tend to go straight. They're independent of course. I saw a joker with a mud racer who tried it with a straight axle. That car wanted to turn circles.

 

I read somewhere that Ford had a factory tolerence on side to side wheelbase differences of 1/4 inch on the 40s models.

 

Repeat after me.....Stagger.....

 

Unless there is something I don't know, this sounds wrong to me. When we built my Son's T bucket we were in a rush to get it done for Turkey Run, and somehow when we triangulated the suspension we got the wheelbase off by 9/16 of an inch on one side. It wouldn't handle worth a damn, so we went back to square one and trued up everything so the wb was identical side to side...........problem solved, car goes right down the road now.

Don

 

My TAFC had 1 3/8" stager.

 

Fixed it for ya.

 

If you skew the wheel base with solid axles, and all other things are equal it will pull to the shorter side naturally. Making it go straight will eat tires.

If you staggared the front on an independent front suspension it will really fuck up the ackerman. It will probably drive straight but turning will be rough especially with the big side in.

Circle track probably.
Drag cars, maybe so the car is actually straight while the torque is trying to twist it in half.

 

Like Mike Britton said, it is called stagger. Most pro built drag cars, and all pro class cars (funny cars, dragsters, pro stock, pro mod) have about 2 inches of stagger built into the chassis. In other words the front axle is not square to the chassis. This allows the driver a "running start at the starting line". It may not seem like much but a lot of races are won or lost by thousandths of a second. The rear axle on the other hand really needs to be perfectly square to the frame rails. As long as all the wheels are pointed straight, the car will track straight. If the rear axle is not mounted perpendicular to the chassis, under accleration it will push the rear of the car one way and the front the other way. Not a good thing but very common.

 

Here's a pretty good explanation of why they staggar the fronts on the drag cars.

http://wediditforlove.com/techtalk3.html

Decreass Red lights, increases roll out distance, 0.0xx more acceleration time before the clock starts.

I don't see how this pertains to road manners of a street car, can be compared to a semi dealing with road crown, or a solid front axle.

 

as to road crown if a problem cured thru caster...........

 

I would say that given the length of a big truck 3/8" would be within spec. In the 60's a car was generally within spec at 1/4" + or - . Not saying it was right, just in spec.

 

hey guys I'm only 5 years late but what the hell...I was doing some googleing for info on my Renault 16 and found this thread, and I just had to respond...
my 1978 Renault 16 has a longer wheelbase on one side (only by about 3") than the other. it's because the rear suspension uses torsion bars inside housings that are about 3" wide and the housings have to be on the same level. Renault discovered that their first idea of unequal length trailing arms affected the handling, so they tried leaving the parallel torsion bars alongside each other, one in front of the other, and equal length arms -voila - perfect handling!
Renault sold a couple of million of 16s so there was obviously no problem - the 16 is noted for a very smooth ride and excellent handling - the only thing that looks a bit off is that during 'spirited' cornering, the inside rear wheel can lift off the ground - a bit....mainly downhill...left or right wheel....
the 16 has a huge load area (45 square feet with the seats out, takes about 1 minute to do that) and as the load increases the torsion bars get stiffer - I've had 6 people in the back and still had suspension movement - amazing little cars - 100mph from 1.6 litres !
had a race with my 16 against a V8 Monaro on a dirt racetrack one day - he blew past me on the straights, I went inside or outside of him on every corner - he beat me in a drag race to the finish line, but we swapped the lead 12 times in 4 laps!!!
cheers from Down Under!
BP

 

Stagger --- tire on one side taller than the other side ,,,,,, set back --- wheelbase shorter on one side than the other side ............. !

 

When I repaired accident damaged cars for a living it was not that uncommon for there to be a slight variation in side to side wheelbases when measured with a trammel bar (Centre to centre on front and rear axles). Then again the bodies were not always uniform and identical in both lengths and diagonals. 1/8" would be nothing to worry about IMHO however 1" would have me looking for hidden or obvious damage.