Alloy Wheel Help

[Guest mcramsay]

ok i need some advice on alloy wheels. im getting a bit swamped with info on the net. My marlin sportster is baised on a BMW donor car. However i did things a bit differently and i am basically building a 1 off marlin and am running into a few build issues. most marlins are built using a 3 series e36 donor. however mine uses a 3 series for the front suspension and a e39 5 series for the rear suspension. this is where things are getting confusing.

 

the front 3 series hubs will accept a wheel with a 5x120 PCD 72.6 Centrebore and off set of ET35-ET40.

 

the 5 Series rear suspension for some reason is different from everyother BMW made in that it will take a wheel of 5x120 PCD, centrebore of 74.1 and offset of ET10-ET20.

 

so basically i can fit a 5 series wheel to the front suspension with spigot rings, to take up the centrebore difference. But i cannot fit a 3 series wheel to the rear suspension.

 

i bought some 5 series alloys, and they fit on the front fine, but on the rear, they stick out past the arches. by around 30mm. the tyres on the wheels were 225/55r/16. thinking i might get lucky the smallest tyre i could get put on the wheel was a 205, however this still does not bring the rubber under the arch enough.

 

so really i need to find a wheel with a better suited offset to bring the whole wheel closer to the body work of the car ( i have a few inches i can move it in) (but obviously will have to ensure i dont come in too close and touch the brake caliper)

 

so how i do go about finding an alloy? they seem to be selectable on the car they will be going on, rather than putting in the data i have.

 

i have thought about machining the hub on the 5 series rear end from 74.1 to 72.6. that would mean standard 3 series alloys would fit on the hub. this would mean i could have ET40 offset wheels on the back, and hope that brings them in closer to the body work.

 

im a bit stumped.

[IanS]

I Think that the 5 series is wider than the 3 series. So your rear axle is wider and might make it very hard to get the rubber under the existing wheel arches.

How about extending the arches out instead?

Edited June 1, 2014 by IanS

[Guest mcramsay]

i did think of that, but to be honest wouldnt have a clue where to start.

[fry61]

Your idea of machining the rear hubs seems best as less than 1mm of steel removed from radius -- the ET difference should bring the tyres 20mm closer into the bodywork. IMO

[Guest mcramsay]

thats what i think i will do, however will that not bring the "spokes" of the alloy wheel closer to the brake caliper? thats the only thing i cannot work out. does increasing the offset (moving the tire back into the arch and closer to the suspension) will that bring the spokes closer to the brake caliper?

[maccavvy]

idealy you need 3 series wheels as the spokes are further out away from the caliper and machine the center. as you've noticed youll have caliper clearance issues with 5 series wheels and machining the back down and then youll have to stretch tyres.ok in the modified world not so good look on a kit

[Guest mcramsay]

You sure it's not the other way around?

[Guest mcramsay]

Ok so managed to get my hands on a set of 3 series alloys on eBay tonight! Collected them 30 mins ago! Only 70 quid!! Going to machine one of the hubs down at work tomorrow. Hopefully will find out tomorrow if things are going to fit or not. If not I'm going to have to extend the arches some how... Really don't want to do that. The problem is everything on the net is about moving the wheels further out of the arches! I think I'm the only person trying to bring them in!

[maccavvy]

when I got my new wheels they were of an offset that brought the spokes further in. ie lower number. so I had to fit spacers to take them back out..

 

off sets can get confusing easily and quickly .

[fry61]

Answer will be to buy some " Negative Spacers " Craig. You know the ones --- like the "blue amps" you were sent out for as an apprentice.

[Guest mcramsay]

Way hey, found, bought and collected the 3 series wheels yesterday, and machined the hub this morning ( clocked it up in a 4 jaw chuck to keep everything concentric) fitted it all tonight and it looks like it's going to work, wheel now sits under the arch.