anonymousagain

[Spacers= slid on longer wheel lugs ; Adapters= bolted on stock wheel lugs with new lugs for wheels]

Have always heard that wheel spacers/adapters are bad for bearings, due to overloading them. Consensus is to get more offset in the wheel instead.

* Both '85-'86 MY (I think that's right) have the factory spacers which tells me Porsche was fine with the addt'l load.

* Know a few 930 widebody owner's with 2.5" adapters in the rear and never any issues (although IMHO that seems too wide for stock lugs to hold).

* Old Landcruiser guys usually follow a 1.5" max rule of thumb. TLC's get worked hard and no premature bearing failure that I've heard, simply due to 1.5" adapters.

* Have been told that too much wheel offset is bad for wheel bearings as well.

SO, is it that an increase in wheel offset <say 3"> is essentially the same as using a 3" adapter? There is a limit to "how far out there you want to space the wheel"?

This would mean that everytime someone says to get more offset rather than use an adapter, they are 'kind of' incorrect ...although it would be more appropriate with the correct offset. The weight of the wheel is X-mm from the hub, whether by spacer or by offset (assuming lug strength/length is not exceeded).

Always followed the 1.5" guideline, but keep hearing negatives about it and how it'll wear the bearings faster, even that I should consider removing them from SATA ==> would like to know if anyone has some facts to support "spacing=bad" or is this just a misconception that should be "too much spacing=bad".
.

heinrich

never have heard this

mark kibort

have you seen our rear wheel bearings???? i wouldnt give it a moment of thought.
I was hit hard in the rear wheel in 2002 by the out of control typeR mustang in SpeedGT. that bearing finally went bad 4 years later . that impact would have CRUSHED at 911 or most any other cars rear suspension. it actually bent my lower control arm, but not enough for me to correct by a little more camber setting.
with my spacers, i would be worried about studs coming out of a block of aluminum. kind of scarry. i should have put the longer studs in the rear when i had the darn thing apart for replacement.

mk

PorKen

Late 911s use the same (massive) rear bearing - 999 053 050 00

dr bob

My amateur opinion:

The issue is the loading angle on the bearing assembly. With that in mind, there is no difference to the bearing between an offset wheel or a wheel with a spacer. The rear bearing is a pair of ball bearings that take angular loading quite well. In my opinion, darn near anything you can stuff in the stock wheelwells will be fine as far as the bearing is concerned. Most folks buy a wider wheel to hold a wider tire, then use spacers to fine-tune the position of the wheel and tire to avoid rubbing. Many later cars came with rear spacers from the factory as options, so there's a tacit factory blessing for their use.

Moving the wheel center out from the body will increase loading on potentially really old bushings, so make sure you renew those rear rubber bits before you go too crazy with wheel spacers. It may be tough or impossible to maintain proper rear camber with a combination of tired bushings and more offset, especially in a car that has sagged on tired springs. Remember also that you are lengthening the lever that connects the tire to the suspension, functionally softening the springs, anti-roll and shocks as you move them further out on the moment arm.

svp928

It's not really the spacers that cause a problem, its moving the centerline of the contact patch outward that creates problems. Most spacers for our cars are used to accomodate wider wheels inside the existing fenderwells, so the wheel contact centerline doesn't move much. Now, if you cut away your fenders and put huge spacers or major positive offset in the wheel, so they stick out from the side of the car like a jacked up 4x4, then you have moved the contact centerline way outside the from stock. This produces a different load on the bearings than they were designed for, and can lead to failure. So far, I haven't seen any 928's in that state...

Jim bailey - 928 International

As usual Dr Bob is correct that what matters is the centerline of the tire relative to the bearing and that if you mount wider tires but they are wider inside as well as outside the centerline stays much the same. Where people have wheel bearing issues as well as scrub radius issues is when they move the whole rim tire way out (think big wheel toys) then the loading on the bearings especially front wheel bearings gets very high... In Australia the safety laws severly restrict mounting wide tires on road cars (perhaps in response to the roadwarrior movies)

Art_Z

928 4x4

anonymousagain

Wow, wouldn't you notice decreased torque spec on the lugs if they studs began pulling out of the aluminum? It would seem the aluminum is sufficiently hard to combat the studs pulling out, 6061 billet is rather strong.

Longer studs is an option, provided the studs are rated for that stress, but studs are not real strong with shear if out too far/long ... would seem that 2 shorter lugs with the adapter would be stronger than a single big 'ol 4" stud??

Thanks dr bob and svp928 - seems the leverage is the real concern, regardless of how it got farther out there. [Good point for new components if anticipating overly out-there spacing dr bob]

FWIW, I was considering the addt'l load from Louie's wider fender flares. He's definitely got a wader patch out there AND waayyy more HP for quicker twist of the bearings, yet it doesn't appear to be an issue. Seems the size of the bearings for a 928 are a benefit and piece of mind, but also that it's more of a myth thinking offset is better on bearings than spacers.

Appreciate that one Jim!!

Jim bailey - 928 International

Mark Anderson on the race car has BROKEN the front aluminum hub ! but that is racing ! big slicks and huge loads but his bearings have been fine ...and no one puts more stress on a 928 than he does ....NO ONE , like on the high banking at Fontana GPS at 171 MPH !! into a CORNER

mark kibort

but the parts around it fold like napkins!

mk

mark kibort

good point. i feel a little better about it now.

MK

mark kibort

i dont know, i think a good wack to the rim by someones bumper can eceed the forces of a 170mph on the banking, or hitting a birm at 80mph.
but your right, mark has found the limit of some of the components of our suspensions. i remember that broken hub. we thought it was warped rotors. then we noticed it was badly broken at the hub. one of the risks of visiting Mark at the races with your street 928, is that if mark needs a part on it, he will take it off your car! either his dad or some other 928 owner at the track, donated a hub while we were there if i remember correctly!

MK

svp928

Art LOL! There is a BMW 635 4x4 around here, I laugh every time i see it....
So I guess I didn't beat Dr. Bob to the punch, he did a better job splainin it than I did....but you get the jist. If the wheel stays in tthe stock fender, you ok..

tommytomaso

Id say you all hit it on the nose...our cars arnt going to see an impact on bearing wear...unlike the 4x4s that i use to run with..they would add spacers (for looks if you ask me) to get the tire out wider, that and the fact they were running larger tires would kill bearing faster then $hit......not that all the mud and rock crawling did anything.

BUt i would say if the wheel isnt put on correctly it will fail twice as fast as one with out spacers.....not that anyone would put the wheels on wrong.

...i do miss my old INT SCOUT II..and my 76' Plymouth Trailduster...damm them rust buckets were fun. <--burn out in the MUD