Alan C.

Ran the brass ball cups with stock arms on my 86 based GT3S. 800/900 F/R with no problems for 3 years. You know what they say about God looking after little children and .............

Another item to add to you list might be the arms which Kokeln is now marketing. I've seen them and they look to be well made.

FD Frank

While the charlie & fabcar arms are very pretty and no doubt and elegant solution, the Blaszak reinforced steel arms are wicked strong, servicable, relatively inexpensive & don't bind the ball joint pin like the stock arms or bind on the crossmember like either the charlie or fabcars can (can't remember which). I have no affiliation w/ Markus, I have just had good results with these arms on a drive to track car with #400 springs & HARD track use.

Good luck with your prep and remember... keep it simple; work on your improving your driving, suspension & motor...in that order.

Frank

GeoffD

Ditto what Frank says above. I have many race miles on Blaszak arms and have replaced a number of ball joints when they developed a little play. It's real easy, take three bolts out, off with the old and on with the new. I have #400 springs, a 30 mm sway bar, all spherical control arm bushings, use sticky tires and the car is very low.

gd

GeoffD

p.s. I worry a lot more about my early 944 type spindles than my control arms.

gd

tifosiman

Sorry to resurrect an old thread.....................but I read this one awhile back and thought of it this weekend.

On the way home from the autocross event last weekend, my 944 had a slight shimmy in the front end. It sat in the garage until I had the time to get it up in the air this weekend and check it out. I really thought that I had something amiss with one of the tie rods on my manual steering rack, so I checked them first. No play.

Then I checked the ball-joints. The drivers side was totally shot, chunks of sharp brass sticking out (what remained of the top SSI race) and lots of play. The passenger side was not much better. This only from 15 months worth of use...............25 or so autocross events and around 4-5K miles. The car has 400lb springs and a 30mm front sway, lowered but not excessively. I really thought that the SSI kit would last longer than that, but I guess there is truth to the fact that the hardened steel pin, if not perfectly smooth and polished, will work-harden the brass to the point of failure. There really is not much travel in my suspension system, so the pin never did strike the outside of the socket on the a-arm like you would see on a lowered car with softer springs.

I just ordered the upgraded GCK kit (I did have the shorter SSI pins before) with the longer pins and alu-brass bushings to rebuild the arms. More than likely as a stop gap until I get some Charley Arms or equivalent.

Has anyone else experienced a failure on the longer pins, like the one mention of it in this thread (was that a rennbay pin?)? Does going to the 19mm pin size of the Charley Arms (and drilling out of the spindle/pinch mount) really take care of the pin failure issue? Wouldn't it also be a matter of the material make up of the pin?

jerome951

Yes, pin strength is definitely a function of the material (and quality of the material) used.

I haven't heard of a Charley pin breaking nor an OE Fabcar pin. Apparently there were some aftermarket pins available to fit the Fabcars that had some issues.

RedlineMan

Hmmm...

And yet again RedlineMan is seen to cast an uninspired Bronx Cheer for the fickle alloy control arm, and give another confident nod and thumbs up to the pedestrian and under-appreciated VW Rabbit control arm.

All this horsehockey is precisely why I build my own control arms!

Jack667

horsehockey???

Is that near Horseheads?

Larry Herman

I thought that it was near Chemung! Anyway, the real point here is that the stock ball joints, no matter how you rebuild them, are unsafe for the track. Maybe some people out there have gotten lucky, but there have been too many failures to take a chance with this. Any purpose build arm for these cars with a quality ball joint is required for the track.

tifosiman

OK, got it. Do you mind if I ask a few more Q's?

What defines a quality ball joint? I assume that the longer ones are more prone to breaking/bending than the shorter ones? Are the 19mm pins the only ticket, or are there pins that are stock-sized that are good?

I'm confused because when people speak about 944/951 alu a-arms, there 3 distinct and sometimes related failures:

1. Bushings go out and cause play (and eventual failure)
2. Arm cracks or allows the ball to pull out.
3. Pin breaks

How does a custom-made a-arm take care of the breaking pin issue, unless the pins are superior? And, if you source a better pin, why can't it be used in the stock arm with a good rebuild kit? If one kept up on the maintenance (ie inspected the joint for play) and the arm didn't get whacked by the pin from suspension travel or bottoming out, and the pin is a quality piece, is it still unsafe?

Thanks!

superloaf

I just installed some Rennbay track (brass bushing, stock ride height) ball joints and I believe Travis said they were working on a kit with larger pins. Not sure how close to market it is though.

Since I haven't seen the larger pins up close I wonder how that solves the problem though. I'm assuming the pins break where they are smaller just before forming the ball--but if this area is thickened, wouldn't it then bind sooner causing too much stress on the joint and creating a failure?

Larry Herman

Whew, that's a lot to answer. Maybe I should start by explaining that I initially felt that rebuilding the stock ball joint would be fine. After all, I have 34 years experience working on cars and have good mechanical knowledge. After installing the first kit with the plastic bushings (the stock ones were plastic too) and seeing them fail immediately, I examined them to see why they failed. The stock ball cups got worn from the failing stock bushings. So the new bushings expanded to fill the worn spaces and immediately created slop and failed.

Then we went to the SSI brass cup bushings, and used a rock hard epoxy to fill the voids, and create a solid backing for the bushings. An alternative would have been to machine the arm cups and get custom bushings made up, but I felt that this might weaken the arm too much. This time the bushings did not fail, but the pin, which had a circular groove machined in the top to hold it in, broke at this circular groove and pulled out of the strut.

It was not worth taking a 3rd chance...we got lucky twice. The Charlie arms have spherical bushings that are robust and easily examined and replaced. The hardened pins are thicker, and only have a small groove machined in one spot to lock them into the strut. There may be other systems out there that work as well, and that's fine, but I am not arbitrarily trusting my son's life to them. I know that what we have on the car will last.

Skip Wolfe

Tifo,

I think it is a matter of what the stock arms were designed for - definitely not to be rebuilt and run on a suspension with spring rates 2.5 times greater than stock. I think you will be constantly chasing the weak link. Replace the suspect bushings and the pin become the weak link - replace that and the lack of articulation or the fact that the arm itself has experienced 15+ years of cyclic loading becomes an issue. The Charlie Arms on the other are designed specifically for track use and to be servicable. The spherical bearing setup is definitely a more robust tried and true component vs the ball/bushing design of the stock unit.

I have seen the Finite Element Analysis on the Charlie Arm and it is very nicely design. I also talked to Charlie regarding the pin diameter and it was his feeling that the 19 mm pin is absolutely essential, and actually got mad when I asked him if he offered a 17mm unit that would fit in the stock spindle. I have no regrets in getting the Charlie Arms and think you are taking a risk by trying to bandaide an inherently weaker design.

Alan C.

Well,
I guess I am the exception to the rule. I used stock arms on my GT3 for 3 seasons with the bronze bushings and had zero problems. And I was using 800 LB springs in the front.

Would I do it again, probably not.

tifosiman

OK, well all of this talk of failure has at least convinced me to pursue the purchase of charlie arms or equivalent. I already ordered the Rennbay GCK kit with the Alu-Brass bushings, so once that comes I will rebuild my arms with those as a stop-gap for a few months (I won't be doing another DE until the fall anyway).

So, the next question is which aftermarket arm is recommended and the price? I seem to recall that the "charlie arms" are NLA, so that option is probably out. What is the feedback on the Blazack arms and the Kokeln arms? Does anyone know what price range those fall in? I honestly want to stay away from the early steel arms that have been "boxed" and modified. Running such a large sway in the front kind of turns me off to that idea (no offense intended to those that have done that).

Looking at this from another direction.................I have always found that fixing one thing often leads to finding the next weak link. In this case, would drilling out the 951 spindle to 19mm to accept the larger pin cause a potential issue there? Jeez, this is neverending!

(sorry for all of the questions)