10/1/16 – Axles and Boots
I have learned from experience that keeping axle boots alive on the race track can be difficult. The high speeds lap after lap tends to destroy them. I couldn’t find much information about repairs, so I built this page for others to use.
I purchased the axles from V8 Roadsters a company that specializes in putting V8’s into Miata’s. They get the axles from The Drive Shaft Shop , who makes all kinds of heavy duty drive shafts and axles. I’m using their axles in my Cobra, too.
I’m not really sure what the inner joint is from. But, there’s an interference problem with the boot and the shock body. I am using an Afco shock, which seems to have a bigger body than most other shocks. But the boot slightly touched the shock on one side, and came really close on the other side.
I replaced the boot with an Audi part, and that gave it plenty of room. This new boot is from Beck-Arnley, PN 103-2952.
After the last track day, I found a small hole in this boot. Unfortunately, this part is no longer made!
I ordered a new boot for an Audi A6 Quattro, and got the wrong one. I’m sure it would fit the axle, and without the Afco shocks it would probably fit the car. This new Beck-Arnley part I managed to find on E-Bay. The box was pretty dusty, so it had been sitting around for a while.
The search continues. Sigh. I contacted Brayden Peters, at Prestige Imports , a VW/Audi dealership in Lakewood, CO. All I needed was the correct boot. He could find the boot, but could only order it as part of a kit, which includes the bolt and other small stuff. Kind of expensive, too, at $48 each. I didn’t need them right now, but I ordered two for spares.
SupaDupaSteve found this part number for me. Looks good, and considerably cheaper than from Audi. Go to www.FCPEuro.com. Look for PN 4b0598203. This is a Rein aftermarket part, and lists for $9.49. Is it as good as the Audi part? IDK, but’s cheap enough that I might just have to buy a couple and see what comes in. FCP Euro also lists the original Audi factory piece, PN 3b0598203, for $40. Thanx, Steve. 🙂
The Drive Shaft Shop used to use Ford tri-lobed CV joints. But these joints have become nearly impossible to come by. So they (and pretty much everyone else) have started using Porsche joints. The upside of that is parts are easier to come by. The down side is that they’re kind of expensive.
So, you can use pretty much any Porsche boot. They all seem to have the same dimensions. Some are taller than others, but I’m not sure that really matters. The metal base plate does come in different sizes, so be careful about that. I purchased these boots for a 1976-1984 Porsche 911. The boot works. But the base plate does not. Not a big deal, I’ll just use the old base plate.
The boot on the right was sent to me from The Drive Shaft Shop, Interparts BT-273. The base plate is CV1018. The boot on the left is the Porsche boot, PN 86145. Notice how much smaller the base plate is. The single base plate was part of the original assembly. Swapping the base plates is simple.
OK, now that we have all the right parts, we can do the assembly. It’s not overly difficult. The only “special” tool you need is a medium snap ring pliers. This is a very messy job, too. The moly grease for the joint will really stain your hands. I wore rubber gloves for this job. I also used a bunch of paper towels to control the mess.
These are all the parts, and the order that they go in. Take a close look at the Porsche CV joint, second component from the left. Notice that there is a groove on the outside, close to one end. That groove goes toward the axle stub. If you get it backwards, it will still work, but you will lose some articulation.
Start by sliding the boot on to the axle. Move it down a ways so it doesn’t get in your way. Fill the CV joint with appropriate grease. Here it’s half filled, so you can see what it looks like. Then slide the joint on the the axle shaft. Pay attention to that groove!
Once the CV joint is in place, install the snap ring
Don’t use too much grease, or the weight of it will tear the boot at high speed.
Now you need to move the boot and base plate in to place, and install the rear seal, and that other metal plate. There is no gasket, but you need to seal these metal joints. Otherwise it will fling grease everywhere. It’s quite a mess. Be sure to clean both surfaces well.
When you put the backing plate in place and push the bolts through, some of the grease and silicone will spooge out on the end of the bolt. Wipe that off! The bolt holes are blind. You could crack the part or not get the bolt tight due to hydraulic pressure.
Once you finally get it bolted together, it looks like this!
I use cable ties to hold the small end on the shaft. You could also use hose clamps. Also, by placing the cable tie in the middle of the boot, it gives the boot some additional support and helps prevent tearing. I went through 3-4 boots before I figured that one out.
We went through the entire 2017 race season, 7 race weekends. Not a single leak. I probably shouldn’t say that out loud. Didn’t have to do anything to the axles or boots. The cable ties are holding it all together. I’ll let you know if that changes.