dgz924s

What is involved with this job? How is the A arm made stronger? TIA Dal

tinman944

I have done them in the past by welding a strip around the edges and then supporting the sway bar mount with another piece of material

dgz924s

Here's what sparked my interest. Per a conversation with a name witheld, he mentioned that in my upgrade to do this work to a arms. He spoke something to the effect " weld a piece of rebar to the groove in the arm, from where there is the 1/2 hole to the rear of the arm" But not real sure I understood him right. I didn't know if he mean't the bottom or top of the arm. But the manner in which he stated it there was a groove designed for this reason already there to add strength. So I am trying to see if any reality to this. But as advised elsewhere here to just replace them and carry a spare set of arms. Cheap and makes for any easy fix! Thanks Dal

tinman944

I agree to carrying a spare...not sure if I am a true believer in stiffining of the steel arms. Putting rebar on the edge sounds as a very crude way of modifying them.But I suppose you work with what You have.
I have started making arms out of chrome moly steel tubing..I have been using a set for years with no problems.We have been thinking of going into production of them as there is really no affordable replacment out there

Matt

First question - what kind of driving are you going to be doing? For frequent track driving, there are some specific mods to the control arms that will help prevent them from breaking. For street driving, I don't think there's reason to bother. r AX I dunno, I imagine it's possible to break one, but the consequences are minimal, so it's probably not worth the effort.

Vulnerability is largely a question of swaybar size versus spring rate. The arms tend to break across the point where the swaybar mounts, mostly as a result of excessive swaybar stiffness as compared to spring rate.

Post a little more about how the car is used and the rest of the suspension setup.

Matt

dgz924s

The car is used for the track. See below for set up.....Dal

Matt

Dal,

Our setups are somewhat similar, I'm running 325lb springs/29mm torsion bars, Racer's Edge sphericals, Koni Yellows, Weltmeister sways set somewhat less than half stiff, 225/50/16 front tires, 245/45/16 rears.

The steel control arms that fail generally break across the point where the swaybar attaches. It seems more common on cars with soft springs and stiff swaybars, which make sense when you look at the mechanics of it - under high cornering loads the stiff swaybar acts as a fulcrum, and the control arm wants to bend/break at that point.

The fix I'm familiar with is to form lengths of 1/8" or 3/16" x 3/4" steel bar stock to fit along the entire front (straight) and rear (curved) edges of the control arm, and weld them on with continuous beads along the top and bottom edges. This provides a lot more strength where needed to resist bending across the swaybar mount point, and also ties the upper and lower control arm stampings together. Some folks reinforce the horizontal areas around the swaybar mounts, but I haven't found this to be necessary.

I have run with these modified arms more than 50 hard track days. I always inspect them carefully for between events (most recently, tonight) and they're fine.

I don't like the rebar suggestion at all. Mainly because I don't think the round stock will provide as much stiffness in the critical plane, it's a lot heavier than necessary, and it just seems like a sloppy approach.

Don't forget to wire brush and paint the arms after having them reinforced to prevent them from rusting.

Hope this helps.

Matt

User 41221

Don't forget to seam weld the control arms before you weld the steel bar stock on to them. the seam welding makes a pretty big difference in the shear strength of the unit as a whole.

Regards,

dgz924s

Great info guys! Thanks! Not sure about the rebar I think he was just mentioning something similiar to that or I just heard wrong. But this answers the question! Dal

Matt

You probably heard right on the rebar - some people have used it. One reason is that it is relatively easy to bend, which when you think about it, doesn't say much about its suitability for the job -

M758

I have about 15 races on my stock steel arms.

I have the weltmeister sway bars and 350 lbs springs. There does not seem to be any problem so far.

I run 225/50 R15 Toyo RA-1's and the car is about 2450 lbs. I also have not seen any issues with weltmeister sway bars and stock steel arms on any other 944-spec car.