The Stovebolt Site Forums The Parking Lot Big Bolts Thoughts and concerns on axle shortening

Ok, so I was reading over Grigg's tech tip on P30 axle swaps for the millionth time today and I got thinking (which can be dangerous some times! )

The conventional wisdom is when narrowing the P30 axle to fit under our big bolts, to make it just narrow enough to put the tires under the fenders for both aesthetics and turning radius' sake. BUT, here's another concern that's been hitherto ignored or overlooked: In all modern duallie trucks, the front tires are set to track even with the inside dual when driving straight. This makes for better handling in rain, or even more so, in that strange white stuff called snow that we have in the north. Shortening the axle "just enough" to fit inside the front fenders may lead to tighter turning radius, but at the expense of handling in poor weather conditions.....

Am I overthinking this or is this a real concern that needs to be addressed?

Are you sure this is actually the case? I've not done any recent research but it appears to me that the track width of the front of some dual wheel trucks would not fit that pattern.

Thanks,
I did think about that, but I was not concerned... should I be?
I'll have to go measure mine with both the front and rear axle swap, I know the track widths don't match perfectly, but I forget how far off.

Any other thoughts on the matter?

Grigg

The reason I'm thinking about handling, is, at least with snow, the front wheels are going to cut a track, then the back wheels come along and cut two different tracks, filling in the first track..... It just struck me as non-desirable.....

Maybe it doesn't matter......

I think you may be overthinking this. I'd suggest wandering around a couple of car lots that sell dually trucks with a tape measure. Look for dually pickups and box trucks and even school busses.

One reason I say this is look at the tracks trucks make while making any kind of turn. You often have as many tracks as tires but yet it does not create an unsafe condition.

My narrowed P-30 front axle measures 59.5" center to center of tread (on 22.5" wheels/tires).

The rear P-30 axle measures 57" center to center of the inside dual wheels.

That's only a difference of 1.25" per side away from perfectly tracking in each others foot prints.

However, I narrowed that axle more than I should have (first installed in it the 1 ton) If I remember right it was about 1.625" to narrow per side than stock.
When I do it again I'll probably make it a little wider than stock, so the difference in front track to rear track width per side might be 3.25", or 6.5" total. That would make the center of the front tires track close to the outside edge of the tread on the inner rear duals. Or in other words only half way overlapping tread, and half way not.

Confusing enough?

I'm still not worried about it.

Grigg

Chevrolet had two different widths of rearends for thier ton trucks. A narrow one for the standard cab and chassis setup and a wide one for the dually (wide fendered pickup bed) setup, at least for the 73 and up years. The front track widths did not change. I think that it really doesn't matter that much if Cheverolet did it from the factory. Just my thoughts.

The GM 14-bolt came in two widths, if I remember right: 63 and 68 inches WMS to WMS.

GM also used Dana 70 HD and possibly Dana 80 rears under some trucks, and I just don't know what the variety of widths might be with those.

The 73' + years duallys had what is referred to as an RV axle. This was a surprise to all the bodybuilders back then because it required a utility body with of 93.5" v 88.5 for a standard one ton C &C. So it really does matter which one you measure to get your info from. I'm with Old Sub on this one..too much ado about nothing.