rx7 series3 brake upgrade
 

Hi all I am just building a rx7 series 3 race car I have some 4 spot series 4 calipers just wondering what hubs and rotors will fit onto the series 3 strut and I want to keep the 4 stud. Cheers

Nothing but series 3 fits, I don't think. They have the inner bearings of a series 1-2 and the outer bearings of a series 4-5.

I have not tried it yet so I can't account for what happens to bumpsteer or Ackerman, but you can use the whole series 4-5 upright with a Mazda 3 ball joint. It presses into the 1st gen control arm and is the same pinched stud as the 2nd gen. Then you have to try to hunt down four lug hubs.

ive seen pics of cars with the FC hubs, i'm not sure what they do to get it on the car, as PJ says one bearing is the same, one is not, so you need to do something. it also needs a caliper bracket, but that is just a flat plate, pretty simple

This is a similar answer to one I gave on the AusRotary forum.

You can't fit FC hubs onto s3 struts.

As hinted at above, you can adapt an FC strut to a series 3 lower control arm and steering arm using a modified FC upright/knuckle. You basically press out the ball joint of the 1st gen lower control arm and replace it with one from a Mazda 626 that fits an FC knuckle (don't know which year you need), then use an adjustable steering arm linkage to suit.

This is described in this thread here:

S5 front struts and brakes into a s3 - AusRotary

and here:

https://www.rx7club.com/1st-generati...es-fb-1116397/

The problem with this approach is that the bolt pattern, track and offset will not be the same as stock. In the US, non-turbo series 4 FC came with a 4x 114.3 hub which would keep the same wheel bolt pattern as factory series 3. However, these weren't available anywhere else in the world. All Aussie FCs used the 5x114.3 pattern. I managed to hunt some down for my FC subframe conversion and import them from the US. They can be found, but it will take time and money. The advantage of a factory FC strut is a much bigger stub axle than series 3.

Alternatively, there are numerous workshops in Australia that make custom billet hubs that allow you to FC or FD brakes onto a 1st gen stub axle. With a custom hub you can retain series 3 bolt pattern and use whatever offset and track you want. Good hubs also use bigger replaceable bearings which represent an upgrade on 1st gen units.

Also, from a fitment and availability perspective, FD calipers are superior. They are lower profile and more easily fit aftermarket wheels, plus FC calipers are rebuild parts are getting very thin on the ground in Australia. FD is much more common. I realise you have the FC calipers already, but something to consider.