And now, a not so stupid question., Wheel spacers/offset effect on bearings Options

[Dr. Roger]

So now I expect the new rear 11" hollow spoke turbo twisties to come in tomorrow.
Then I will figure the spacer width required.
Then I worry about what I thought I heard about crazy bearing wear rates if I go too spaced out. (IMG:http://www.914world.com/bbs2/html/emoticons/smoke.gif)
I think I want to use my Sheridan flares but.........
If I use them I will need to space the wheels a substantial amount.
I'm guessing >3"...

Aren't all the guys using Sheridan flares either spacing out their fat rubber or using huge positive offset wheels?

I'm looking for feedback from people who've actually seen or done this before.

Thanks!
Roger

[byndbad914]

I have the sheridan std kit with old school 15x8-1/2" right now that barely tuck inside the fenders due to the "deep dish" wheels. I have 4" b/space which sets the wheel and tire out a bit.

I don't think the backspacing really matters until you go passed the 1/2 way point ... if you use a deep dish wheel or a backspace with spacers, the issue is where the centerline of the load is in relation to the centerline of the bearing's reaction - standard kind of Force *distance (moment reaction) stuff. Now use a 6" b/s on an 8" wheel, and you move the reaction location out another 2" (increasing the d in F*d).

Deep dish wheels were also known as "bearing killers" back in the 70s because the tire centerline is so far away from the bearing centerline (this old timer mechanic told me I was crazy when I was 16 and put deep dish Cragars on my 70 Mustang because of all the wheel bearings he replaced on those 'crazy vans' with those wheels) (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

So, wider wheels that offset the centerline outward from the bearing centerline will always induce additional loading to the bearing surface due to the addition of moment to the equation. In the end, run the tire width and backspacing you think looks good and keep an eye on the bearings. I would personally try to keep the b/s no more than the 1/2 way point (4" on 8" wheel for example) as additional adds more moment. Less leaves the moment at the 1/2 way point no matter what.

If you race a lot, you should knock the car down annually and inspect everything anyway, so just replace the bearings (cheap really). If you don't race it a lot, or not at all, those bearings will last quite a while... probably 50K.

That is my guess, no real science or testing to it other that what seems to make sense. Then again 525HP in a 914 makes complete sense to me as well (IMG:http://www.914world.com/bbs2/html/emoticons/cool_shades.gif)