Minimum Lift Question

I can say this:

My brother and I both have 2003 Rubis, both with 4.5" RE lifts. He has

You cannot put 33x12.50 on the factory wheels, they will rub because those wheels have too much backspacing. 3" of suspension lift is the bare minimum with a 1" body lift a good idea for a little more clearance to insure the 33" tires won't rub.

Jerry

Fred Garv> I have a 2004 Rubicon that I want to put 33" MTRs on. I would like to know

Just out of curiosity, can the stock rims take the 33x10.5's or the super traction 33x9.5's and not rub?

Mike

Jerry Bransford wrote:

Yep, 33x10.50 tires are not a problem for factory wheels, the problem is with the added width of the 33x12.50 tire.

Jerry

Mike Roma> Just out of curiosity, can the stock rims take the 33x10.5's or the

POINT OF ORDER Don't you really mean an inch LESS of backspacing. The stock rims have 5", wouldn't you need only 4" to avoid rubbing.

For your 16" wheels, the best MTR size for minimal lift (~2") is

Steve

Fred Garv> I have a 2004 Rubicon that I want to put 33" MTRs on. I would like to know

I am running wheel spacers on my cj5, work great, make sure they are torqued right,

I priced out spacers for my CJ, $200.00 a pair US, so $400.00 US, or about $480.00 Canadian plus shipping and taxes, I just bought a set of 5 new rims, ( ProComp Rock Crawlers ) for my daughter for $430.00 Candain including shipping and taxes. So I agree, definately don't bother with spacers.

Some countries are a bit strict on use of spacers due to additional stress on the bearings. For example, in New Zealand, spacers are illegal. Also if you change your track width by more than 25 mm (roughly 1 inch), you have to have your rig "certified" by a low volume vehicle certifier. Its an expensive and time consuming exercise. BTW, this includes changing backspace on your rims in New Zealand (what a bummer for me). On top of that, the tyre has to stay within the outer edge of the fender flare!!!

TW

I've never understood the issue with spacers. I used to have a 1 ton dually truck that used big ol' honken spacers on the front wheels so that you could run the same rims front and back, and it came that way from the factory.

If I have a rim with 5" of back spacing and add a 1" spacer I have the equavalent to a rim with 4" of back spacing. I don't see the how it matters if there is a spacer in there or not, back spacing is back spacing. Of course I am asuming that we are talking about properly installed quality parts. All bets are off if we are talking about junk installed by an idiot.

Dean

It depends on the bearings I believe.

Something like a CJ has cone bearings and adding a spacer stresses the crap out of them.

I have read that the sealed hub unit used on the Cherokee, YJ and TJ uses flat bearings so the spacer has way less 'bad' effect.

The cone acts like a lever for stress.

I could be off base here but don't think so.

Mike

Dean wrote:

I can understand how decreasing the backspacing would put additional stress on the bearings. Where I am confused is how does the bearing "know" that the additional stress is coming from a spacer vs. a wheel with less backspacing?

Everybody says spacers are bad, OK, but why? Assuming we ignore any increased bearing load what makes spacers evil. I know my state doesn't accept them either. But, they didn't blink an eye at my truck, and like I said before it came from the factory with big spacers.

Dean

The attachment point is farther away from the center of the bearing set. This puts the stress directly on the outer bearing. With a normal attachment point, the tire is gradually moved out farther by the rim shape.

The end is the same so yes having a modified backspace will cause faster wear on the bearing no matter what, it is just less of a load than the spacer gives.

Think about a teeter totter. You can put a smaller load on the end to over balance it or a much larger load up close to the pivot point to balance it the same or a massive load right on top of the pivot.

Once you get out past the center balance or pivot point for the bearing set, the down angle radically increases stress. When the direct hit is straight down on the bearing, it should last longer.

I think that makes sense.....

Mike

Dean wrote:

Mike Romain did pass the time by typing:

It does.

Think of it as two different forces at the hub bearing a) shear b) torque

Example: Take a toothpick and hold it about mid-point like a bearing would hold the axle. _______ )

_______)

Now press with your fingernail right next to your fingers. _______ )

_______)^ Takes a lot of effort to shear that toothpick because all the force is shear. _______ )

_______) ^

Now move your fingernail out toward the unsupported end and do the same thing. The shear force in both examples is the same but second example adds torsion force. The torque force plus the shear force is what will snap the toothpick.

The math is out there for folks that want to know.

Anyhoo, bearings are designed to resist gobs of shear, not torque and that's why spacers are bad ju-ju.

Merry Christmas!