FrontEngineDragsters.Org Forum

Technical => Roo Man's Room => Topic started by: sawdawg on November 18, 2018, 05:01:49 PM

Title: wheel backspacing
Post by: sawdawg on November 18, 2018, 05:01:49 PM
If I measure from the wheel mounting surface to the roll cage sheet metal I get 8 inches
I borrowed come wheels from my neighbor and the tire bulge was 1 inch (That is the tire bulges out one inch from the edge of the rim)
If I use a wheel with a backspace of 5 inches I get two inches of clearance between the edge of the tire and the body
Is two inches the right amount or should I try for less?

8-1-5=2
Title: Re: wheel backspacing
Post by: rooman on November 19, 2018, 05:02:43 AM
I like to run mine as tight as possible. My frames are generally narrow at the lower rail than at the shoulder hoop --more like a Woody than a Long- so any air space is magnified by that factor. I generally shoot for 1/2"  at the closest point. If you look at photos of cars from back in the late 60's/early 70's they are generally in that range and some of them have the scuff marks on the side of the body from when they got sideways to prove it.

Roo
Title: Re: wheel backspacing
Post by: wideopen231 on November 19, 2018, 06:50:32 AM
Ever have any rubbing issue with 1/2" space. Asking because I have spacers on mine to get 1" and no problem removing them if 1/2" will work,heck cheapest weight reduction I have gotten.LOL
Title: Re: wheel backspacing
Post by: THE FRENCHTOWN FLYER on November 19, 2018, 06:59:19 AM
As rooman alluded to, the biggest hindrance to running them tight to the body/frame is from turning. My cars have the paint worn off from getting crossed up, where the tread is pulled inward against the bodywork. At five or six psi in the tires it doesn't take a lot of lateral G's to move the tires an additional inch inward.
Title: Re: wheel backspacing
Post by: Roger on November 19, 2018, 08:43:00 AM
Here's what the rub looks like on my altered with a 1/2" static clearance. Only way to get the tire to touch the frame is to turn a corner at speed, like turning off onto a return road. This is with 7 psi in the tire. Like the Flyer said, it don't take much lateral movement for the chassis to contact the sidewall.
Title: Re: wheel backspacing
Post by: 225digger on November 19, 2018, 09:26:54 AM
watch your back spacing and wheel diameter, some wheels with deep back spacing you cant use drag brakes

running a shallow wheel will mean a shorter axle, which means less weight {if no one mentioned it}

some guys dont like them but many use a spacer if its alittle to close for comfort.
Title: Re: wheel backspacing
Post by: wideopen231 on November 19, 2018, 10:51:32 AM
yea shorter axle and shorter housing all mean less weight and the reason I have spacers. Some call it greedy I call it getting all I can.
Title: Re: wheel backspacing
Post by: sawdawg on November 19, 2018, 03:42:26 PM
Does the one inch tire bulge seem like the right amount ?
Title: Re: wheel backspacing
Post by: rooman on November 20, 2018, 04:32:42 AM
Does the one inch tire bulge seem like the right amount ?

That really depends on wheel vs tire width, tire size and construction etc but is usually pretty close.

Roo
Title: Re: wheel backspacing
Post by: gregm784 on November 21, 2018, 11:08:00 AM
I too like about 1/2" - 1".  Mine have only kissed a couple times (when it shakes super hard).