pcsguy953

need some info on using pre 87wheels on a post 87 944s. Spacers? what size? the wheels I would like to use are 16x7 and 16x8 momo. Any guidance would be appreiciated.

keith

can't do it.
only the other way around.

Dan in Pasadena

Interesting and annoying. So, for examplem if I wanted to replace my '87 phonedials with pre '87 Fuchs, I couldn't do it? No way, no how?

keith

well, if the Fuchs were extremely narrow...

the earlier stuff has LESS posiyive offset, meaning essentially, they stick out farther.

Mount them on a late offset car and it's fender-rub city!

You can do it the other way around because you can always space a wheel out. But you can't space a wheel in!

Your only recourse (if you HAD to have it) would be to change all the late late offset suspension components with early offset components - but you'd need a donor car or a buddy who wants the opposite swap to make it easier. Its still a hassle, as it would include A-arms, spindles, hubs, rotors, tie rods, trailing arms, stub axles, and possibly half shafts (not sure on that last one...). Plus a 4 wheel alignment, yada, yada.

I know this because I am committed to swapping from my old offset to new offset, at least on the front...

Danno

If you really want Fuchs, you can get aftermarket 3-piece ones here:



http://www.lindseyracing.com/wheels.htm

http://www.hrewheels.com/Car/340Series/index.htm

Tabor

On some early offset wheels they are made so that you can machine part of the wheel off and "convert" them to the late offset. But some wheels do not have enough material in the correct places to do this. Also, it is hard to find a machinist willing to take on the task.

CA944

Yep....I learned the hard way. DON'T EVEN TRY IT!!!! I wasted a brand new set of tires that way. I figured......big deal, it rubs a little WRONG. Rubs a LOT!!!!

ast2000

I went with early rims on my 87 944 and had to go to 50 series tires so they wouldn't rub. I don't really care for the small tire look but I've had it on the track and they don't rub. (Phone dials have winter Blizzaks on them) Is there an issue with changing the geometry of the suspension or only tire/fender intercourse?

Danno

Whenever you change the offset away from stock settings, you change the load balance between the inner and outer bearings. On straight line driving, using the early-offset wheels on the later cars will put extra load on the outer-bearings and less on the inner-bearings.

However, under cornering, the loads will be more even because in stock trim, the inner bearing is loaded more than the outer one under cornering.

The wider track also increases your cornering power as well. Although not as much as getting wider rims and tires using the correct offset.

pcsguy953

Thanks for the info. I am planning to use the early offsets for autox only 225/50 F, 245/50 R. My main concern was the fenderwells. The geometry now is a concern as well. I only do 4 or 5 events a year now. The 944s gets reclassed next year so I was planing on possibly doing more. Again thanks

ast2000

Thanks Danno for the specific information. I assume the same must hold true for wheel spacers.

Danno

Yeah, with or without wheel spacers, the load is based upon the effective offset. Which is the offset minus the thickness of the spacers. Putting late-offset wheels 52.3mm) on a pre-'87 car with 29mm spacers effectively gives you 23.3mm offset. This is the same as stock on pre'87 cars and the loads will be identical as well. Once the lug-nuts are tightened, the entire wheel/spacer/hub assembly becomes one solid unit (the only load on studs is in tension, there is no bending or vertical cantilever loads).

Then the resultant lateral twisting load on the bearings is the integral of the torque around the moment of the bearings across the contact patch. That is, imagine pushing up on the tire's contact patch from the inside edge all the way towards the outside edge. Each point along the way, you tilt the wheel outward or inward. The point pushing up directly between the bearings has zero tilt inward or outwards. Sum up all the torques from each point across the contact patch (integrate) and you'll have the net torque.

In essence, as long as the inside and outside sidewalls are in the same location as stock, you're OK. Or if you increase the tires' width, add the same amount to the inside as outside.

That said, I'm still a little leery of early 23.3mm offset wheels on a late-offset '87+ car...