www.RX7fb.com

Sounds like mix and match is a pretty solid none-starter.

Would a 13" wheel fit an S3 rear axle (with adapters for the wheel bolts/studs)?

I know the brakes are bigger, but how much bigger? Is it just the larger fronts that won't fit inside a 13" wheel ?

John

I didn't think series 3 front brakes were any bigger than series 2? On saying that never personally compred them.

the s3 brake calipers are definitely bigger... I've had the s2 and s3 front brakes side by side and compared them... the pistons are exactly the same size and the same rebuild kit can be used for both s2's and s3's but the body of the s3 caliper is bigger to accomodate the bigger and thicker brake disc.... I read somewhere that this was also the reason for the change on the s3 to the 14" wheel as the larger brakes wouldn't fit inside the existing 13" factory wheel.... how true that is I don't know.
Going back to the axle swap, the mounting points for the brake carrier are the same so what's to stop us fitting the s2 brakes to the s3 axle, drilling the hub and setting the pcd to suit the 13" wheel?.... assuming that the smaller wheel is hub-centric and the offset is ok?

Johnnyboy wrote: Back on my favorite subject again. Any idea if there is any other difference between S2 and S3 driveshafts ie. apart from number of splines? Is the diff housing the same size? In other words, could we put an S3 diff and driveshafts into an S2 Axle?

As I understand it the overall track was the same between S2's and S3's, the suspension mounts are all the same, Just the hubs and brakes we different (and of course the Diff and driveshafts...)

John

an interesting thread on this subject here...
http://www.ausrotary.com/viewtopic.php?f=4&t=211133

ian65 wrote:Do they fit only s3 axles or s1 & s2 as well?

Apparently Phantom Grip makes a LSD conversion for open diffs that supposedly fits into both all FB axles.

And there are some guys over at the AusRotary forum that in ther signatures and some posts

http://www.ausrotary.com/viewtopic.php?f=4&t=211133 mention running with guru lsds in their S2s...

This is totally new to me and really worth investigating further.

Cant seem to edit..

Compared to Guru (http://www.xtremerotaries.co) anything is worth trying before shelling out for that AU$ 1990...

With the Phantom Grip stuff being €275 for FB... that's cheaper than finding a suitable S3 donor...

None of us wanted to go near the phantom grip LSDs after reading about them.

It's a real bodge, but look at the price.

The design is pretty simple, but if you're just looking for the added grip in slippery conditions (rain, snow) then it ought to hold up if you're not putting too much torque on it..

But I see your point, Im just a beginner when it comes to drivetrain mods and what works and what fails...

We are doing some research over here and this is what we've found.

• There is little or nothing on a S3 axle that will bolt straight on to a S2 axle
• S3 axles are wider WMS-WMS compared to S2
• S3 axles have thicker diameter drive shafts than S2
• S3 axles have 26 splines compared to 24 on S2 and old skool Rxs
• Mazda shipped old-skool Rx's with LSDs
• S3 open diffs and LSD diffs are the same size as the S2 counterparts
• By switching 2 gears (part number coming) from a S3 LSD you can put it in your S2
• Miata 7" diffs fit into the S3 (read above) and can use the drive shafts
• Many other 7" diffs from Mazda should fit into the S3 axle (possibly a driveshaft issue say b2600 diff or other UTEs)
• The internal space of the S2 and S3 diff house should be the same

Given that all it takes for a S3 LSD to fit into our S2 (possibly even S1) is a pair of gears, the same should apply to Miata diffs or even possibly any other 7" diff from Mazda
we will meassure a B2600 diff that a friend is fitting into a b1600 axle to put into is 818 to get the physical dimensions of the diff.

I will contact my local mazda dealer to see if the S2 LSD gears (which used to be sold separately) are available from mazda.
I will do my best to get ahold of the specs for those gears and get a quote form a few workshops aorund here to see if anyone can make a few sets.

As soon as i can get my hands on any other 7" Mazda diff that looks like it could fit I will try to do the same for those gears.