Vibration after installing RX7 brakes and a 5MM spacer

[e30gentry]

I finally got my kopi alpina wheels back from being refinished and installed my RX7 bbk with 5MM spacer and now I have a very horrible vibration in the front end above speeds of 30mph. I know the wheels are straight and true so I am assuming something with the brakes or the spacer.

[jlevie]

The hubcentric bore on some wheels needs full depth engagement of the hubcentric ring to center the wheels. A 5mm spacer may not leave enough of the hubcentric ring exposed, the wheel won't be centered, and that will cause vibration.

[flash 23]

^^ dead on, as always. you can also check if it is the tires. double check on balancing etc.

[e30gentry]

I used our hunter road force balancer so the tires and wheels are good. There have been some people that use a very similar set up as this.

[Massive Lee]

Some wheels will accept safely a 5mm spacer, some won't. As was said, enough of the hub must "penetrate" the wheel's center bore so that the wheel remains hubcentric. If the bore has a large engagement bevel, then it won't work. If the wheel has a small engagement bevel. It will work. You can extend the hub with "hub extenders".

One very important element I missed. The VW Corrado rotor hat is about 1mm thinner than a BMW hat. In many cases, again depending on the bore's shape, the wheel will not fully seat on the hat and will be very wobbly. This has been mentionned many times over the past years.

I have 1,5mm spacers that solve the problem. Those are specific to VW rotors fitted to e30 hubs.

[e30gentry]

Some wheels will accept safely a 5mm spacer, some won't. As was said, enough of the hub must "penetrate" the wheel's center bore so that the wheel remains hubcentric. If the bore has a large engagement bevel, then it won't work. If the wheel has a small engagement bevel. It will work. You can extend the hub with "hub extenders".

One very important element I missed. The VW Corrado rotor hat is about 1mm thinner than a BMW hat. In many cases, again depending on the bore's shape, the wheel will not fully seat on the hat and will be very wobbly. This has been mentionned many times over the past years.

I have 1,5mm spacers that solve the problem. Those are specific to VW rotors fitted to e30 hubs.

I am interested tell me more how much?

[Massive Lee]

I am interested tell me more how much?

First, remove a front wheel, and confirm that the VW hat's mounting surface is below the centering hub because the hat is thinner. :p

BTW I have those 1,5mm spacers with 66mm center bore, as well as thin 3mm spacers with the usual 57.1mm bore. Maybe 5mm is too much for your wheels.