3-Link Retro Fit Banana Bracket Attachment Question

[Jim Doak]

Following installation of a new under car exhaust system on my old Mark 1, I've freed-up space behind my rear axle allowing me to install a 3-link rear suspension system. (I'm currently running a 4-link.)

I ordered my 3-link kit from Factory Five on Monday and have been researching the installation; particularly the attachment of the banana bracket onto the rear axle. I've downloaded Mark Reynolds' Breeze instructions and plan on welding the banana bracket onto the axle to prevent the bracket from slipping on the axle housing. However, my question pertains to welding the inner edge of the bracket that butts up against the differential housing. Since they're dissimilar metals, I'm not sure about welding the bracket onto the housing.

I was thinking about trimming about a 1" x 0.125" notch on the inside edge of the banana bracket which would allow me to weld the bracket to the axle housing. I found a photo on the forum and edited it to show where I plan on welding. (Weld the entire outer edge of the bracket; a couple of plug welds on the front side of the bracket, and the 1" x 0.125" notch on the inside edge of the bracket.)

What do you guys think?

[NAZ]

If all you're trying to do is keep it from rotating on the axle tube you can weld the clamshell to the axle on one side with 70 ksi filler using a .125" fillet and that should be plenty. Throw in a couple of rosette welds like in your photo and that will give you piece of mind. A .125" fillet 4.2" long (less than half the circumference of the tube) with ER70S-2 will result in a tensile strength of that weld that far exceeds the torque load on the bracket. Only welding the clamshell part of the bracket allows you to replace the main bracket if it gets damaged. If you want to weld to the center section casting you can do so using 99% nickel filler and a process I can detail for you if you desire. It's expensive (filler is ~$100/lb) and time consuming and you'll need some special tools. DO NOT weld the casting with fillers used for mild steel or stainless steel. I've been welding cast steel and cast iron for over a half century and made a good living as a professional welder. I've made all the mistakes a welder can make with cast iron and cast steel so save yourself some heartburn and don't weld cast unless you know the proper process.

[Yama-Bro]

Great advice NAZ. I've been wondering about the same thing. I especially like the advice of only welding the clamshell to the axle to make the bracket replaceable. Good idea. You refer to rosettes. Are those the plug welds that Jim shows in his picture? Also, when welding this much, is there any concern of warping the tube? Thanks!

[NAZ]

Yes, the rosette welds (AKA plug welds) are same same. There is a concern over welding the tubes that close to the center section as any warping in this area will be magnified at the hub end of the housing. I use a fixture to help prevent warping when welding axle tubes. Here are photos of my welding tubes to the housing in a fixture. However, if you go slow and weld an inch at a time and let it cool you will minimize warping when welding just the clamshell section.

6820768208

[initiator]

Great info from NAZ - this approach was the route I took, and the bracket is rock-solid. I don't plan on road-racing, so did not go to the extra effort of building up the axle tube near the housing (per Breeze instructions) before attaching.

[ehansen007]

You seem like you're a pro at welding but for the rest of us, if you just alternate sides and keep it from getting too hot you'll be fine. A couple of tacks will be enough to keep it from sliding around. I bent the hell out of mine autocrossing and just ordered a new one and installed.

[CraigS]

Or you can go here and order their braces.
http://www.vintageperformancemotorcars.com/
and eliminate all the concern over proper welding technique. W/ the wall thickness of the pieces forming the clamping tube portion of the banana, I think the braces are a better design.

[AC Bill]

I made my own upper brace, that goes from the top of the banana bracket down to the control arm bushing eye on the pumpkin. As Craig say's, it alone will prevent any rotation on the axle tube.
This is not my design, (or my picture), but it illustrates really well, how the brace is incorporated, if members are wondering.

[SteveHsr]

A little weld on clamshell and a brace.
Steve

[CraigS]

Mine looked much like AC Bills. But one needs to be able to weld to do it this way. And I would bet I spent maybe 4-5 hours creating mine. The downfall of the VPM is the price of the rod ends and that special machined piece that fills in the ear on the diff. The advantage of the VPM pieces is they will fit easily since they are adjustable.