Z4 hubs on z3 info

[Markiemark88]

I know this has been posted a million times but I am wanting to narrow the rear track of my Z3 coupe I know that I can change the Z3 hubs for Z4 hubs and this narrows the track each side. What all else is needed besides the hubs? I’m new to the chasis so bear with me lol.

 

[Delk]

You most likely you will need to repalce the rear wheel bearings at the same time. Other then that its just a disc with a smaller top hat. I did it years ago to get better wheel fitment but have moved on to different brakes. I dont remember the specific brake disc but google should be able to help.

 

[Markiemark88]

You most likely you will need to repalce the rear wheel bearings at the same time. Other then that its just a disc with a smaller top hat. I did it years ago to get better wheel fitment but have moved on to different brakes. I dont remember the specific brake disc but google should be able to help.

Thank you yes I’ve done some research but I keep finding I need to mill down the brake rotor to use the existing caliper and the axle bolt there’s no way to lock it in place with z4 hub.

 

[Delk]

Disc bolts straight on and axle fits the same.
Not sure about trimming down the diameter. You could check the drawings for the two discs and check the dimensions. Brembo has good online drawings for all their discs.

I originally did the modification to go with E36 328i vented rear discs and calipers. Required a home built adapter but worked really well. I had 330 brakes in the front and going to slightly larger vented brakes in the rear was a benefit. I also wanted large tyres and wheels and the extra 22mm per side with the Z4 hubs made it much simpler to find wheels that fit with the backspacing.

My car is now turbo charged so I needed even more. Next was Porsche 992 four pot Brembos on all four corners. Fronts again were easy with off the shelf adapters. Rears were a lot more work with custom hand brake shoes and adapters. For my car it was worth the effort and they work great.

 

[Lee]

I've done this change a couple of times for people running Z3M wheels on non M zeds. As said above, bearings, hubs and discs. All very simple. I think the first set I did we turned down the z4 disc as its slight larger. We did find a disc that was straight swap last time but it's been years since I've done this swap.