Mercedes W124 front suspension swap, questions

Hello guys, I'm diving into my front suspension swap now. I think that I have the lower balljoint mounting issue worked out, I'm working on that part as I go along, should be quite simple really. Where I'm at in the planning phase is how I'm going to mount the Mercedes strut and if I even need to use the coil spring.

Here is the MB setup:




And here is the Mazda setup:


What I'm pondering, would I even need to use the coil spring if I were to retain the use of the torsion bar, or would I be able to ditch the use of the coil spring? I would be able to transfer the upper mount for the coil no problem, but on the MB it is incorporated into the control arm, and I really don't want to cut that one up and weld it to the other control arm if I don't have to. (summit aftermarket mount maybe for the control arm?)

What I plan on doing for the strut mount is to take the tower from the MB, and weld it to the Mazda, reinforcing the rest of the wheel well (somehow) in the process to handle the extra stress. I have to use the MB strut because of how it mounts to the back of the MB steering knuckle, and I'm hell bent on using the MB knuckle for multiple reasons, so no talking me out of that I will be using the Mazda lower control arm, I'll explain exactly how when I finish that part. It's painfully easy

By the way, this will be a writeup once it is completed. I fully believe that this is completely doable, and it allows for larger brakes to be used in front and a 5 lug setup

keep us posted are planning on swapping in the mb diesel?

Yup, and a few other goodies too

Need thoughts on suspension questions

Well steering MIGHT be a lot easier than I thought, it turns out that the thread size on both the Mercedes and the Mazda are the same, trouble is that the inner tie rod end on the Mazda is also left hand thread, and the outer tie rod end on the Mercedes is left hand thread, completely the opposite of what I need. To boot, the Mazda has female threads on the ends where the Mercedes has male threads on the ends.


I can combine the two, since they are the same thread size and pitch, but I get a setup that is either too long or too short for the stock setup. This MIGHT not be an issue depending on how far out the Mercedes hub is versus the Mazda, I may need the extra length if it sticks out further.

Why do I need to combine the two joints to each other? I need the Mazda sized ball for the steering component, and I need the Mercedes sized ball for the knuckle. I could bore out the Mercedes knuckle arm, but it is smaller as it is and I don't want to take out any more material if possible. Still, it does seem that enough is falling close enough into place that I can work with it no problem

bump, any thoughts on needing the coil spring if I keep the torsions? C'mon guys! I know that there is a lot of suspension knowledge here

Well I did some more work on this tonight. I am nearly finished in addressing the lower ball joint issue. Mazda ball joint is too tall, uses a lock nut and cotter pin on the top, Mercedes uses a thinner, shorter joint with a slight notch and a lock bolt to hold it in place. Solution? Use the Mazda ball joint, cut out the actual ball joint, and get it ready to press in a Mercedes ball joint

Start with 2 blown ball joints:


Cut and grind some:


Wire wheel to clean em off:


Worst case scenario, all the parts I took off were already shot and needing replacing, just put the original setup back on and have the hubs re-drilled for the Mercedes lugs.

i dont think you have to reuse to torsion bars. although they are 2 different pieces of equipment, they do the same thing essentially. if the MB didnt have em and you swap the springs i dont see where youd need them

What I'm hoping to do is to not use the MB coils, and to use the torsions instead. Since they do essentially the same thing, do you think that I can safely not use the coil springs?

so yeah, my swap just got a BUNCH easier. Turns out that Mazda and Mercedes used the same thread pitch for the steering linkage mount on the knuckles. Also, the spacing between the two holes are ALMOST alike. This means that I can use the steering linkage mount from the Mazda on the Mercedes knuckle! I will just have to have one of the bolt holes shifted approx 1mm inwards, then it will bolt on. This means I get to use stock Mazda inner and outer tie rod ends! Man this swap just keeps getting easier!!!

The hard part, I gotta find a machine shop that will do the drilling in the Mazda pieces for a good price in Rich Prick Suburbia.

I also decided that I am not going to risk using the actual Mazda lower ball joint pieces that I polished off, but instead I am going to get a set of steel ones made, I'm not too certain about pressing a ball joint (Mercedes is press fit) into cast iron, and I don't know if what I have is cast iron, cast steel, if it is safe or not, and if I can safely get the pieces bored out to the right size.

another idea that I had, take the mount points that I have for the strut, and to get a piece made that will bolt to the back of the knuckle and accept the Mazda upper ball joint, spaced at the same geometry as the stock Mazda setup.This would prevent the need to weld the strut tower to the Mazda wheel well, which I wasn't certain could be made strong enough anyways. I'm going to research this option some, see if it is cost effective or if I need to suck it up, cut a couple of wheel wells and weld the donors to my B

Hmm your going to have to use the torsions. have you thought about getting an extra set of mb and mazda tie rod sleeves halfing them and welding the 2 pieces together?just a thought