Axle choice is excellent these days. The Drive Shaft Shop can make just about anything you want, and can handle just stupid amounts of power. With a good differential and axles, the weak link becomes tire traction. And that’s a good thing. When you snap an axle, lots of bad stuff happens.
Like most everything else, I don’t believe in skimping here. Get axles that are rated for a little more power than you expect to make. Not just at the initial build, but including future builds. The additional money is small, the work is the same, and breakages will be really expensive. Never buy cheap parts, they’re too expensive.
Previously, axles for a project like this would be basically Ford parts, with a custom built center axle shaft. That’s what I have in my FFR Cobra. This works really well, and no need to change if that’s what you have.
But these Ford parts are getting scarce. So The Drive Shaft Shop are using something else. It’s a Porsche type joint, with a bolt on stub for the differential. There are a couple of advantages to this. First, the parts are easy to come by. Second, changing from 28 to 31 spline is an inexpensive and easy job.
Quality parts for the uprights are simply a phone call away. FM, Boss Frog, and V8 Roadsters all have the right parts sitting on the shelf, waiting for you to buy them.
A small problem arises when putting this all together. The axle boot supplied comes very close to contacting the shock body on the right side. On the left side, it actually does contact it. Within a mile, the boot will tear. Before assembly, I replaced the boot with an Audi part, Beck/Arnley 1032952. Swapping boots on these new axles is a real chore. The Ford axles come apart very easily. But not these. I had to take them to a local drive shaft shop to change the boots, and they had a hard time. If I were ordering new axles, I would specifically request these boots. Since these are standard Miata swap parts, I’m surprised they don’t do this.
The rest of the assembly is basic Miata stuff. I opted for the heavy duty hubs and bearings for racing use.
The lower arm to spindle fastener is a very long bolt, and is frequently bent in heavy duty use. Getting a bent bolt out of there is difficult. Be sure to place the bolt in with the bolt head in the front, and the nut in the rear. If you have to use a BFH to get that bolt out, it will be much easier.
I tore another boot last week end. It’s tough to keep a CV joint boot alive on the track. Adding zip ties to boots will help. but they can still tear. The inner boot tore because it was not assembled correctly, and the band cut in to the boot. The outer boot tore due to centrifugal forces, I guess.
Anyway, getting another outer boot is not easy. The Beck/Arnley part referenced above is not available. I couldn’t find an aftermarket replacement. So, I ordered a couple from the local Audi dealer – PN 4EO498203. They are made for the 2000-2010 Audi A6 Quattro, 2004-2010 Audi A8 Quattro, and the 2002-2004 VW Passat. Cost is about $43 each from Audi. I ordered two, so I would have a spare.
9/16/16 More Boots on the Ground
This is turning out to be more trouble than I thought it would be.
I did manage to find ONE B-E boot from e-bay. That arrived yesterday. It’s a dusty box, so it’s been sitting around for a while. Fortunately, the seller didn’t know how rare it was. I probably would have paid twice as much for that part.
The parts I ordered from Audi arrived today. Unfortunately, they are not the correct parts. Not their fault, they sent what I ordered. I’ll contact the Audi dealership in Lakewood on Monday and see what they have. In the mean time, I can at least get the torn boot fixed.