Balljoint Compatibility

[DrewP]

Are the balljoints for a '73 the same as the '75 and later style that goes all the way through to the 900's?

I have not been able to find out for sure, and need at least one for my '73 LE, and don't think I have the ability to do a complete 900 swap in the 10 days I am home for Christmas. Just looking for a definitive answer. If I don't hear tomorrow I will just snag an extra 900 one from the junkyard and have a looky myself!

Best,
Drew

[Crazyswede]

I am pretty sure that the balljoints are the same from 69 until 93 and 94 on the convertible.

[paulh]

yes, theyre the same, the tie rod ends are different before 73 though, assuming you have an original rack.

Paul

[DrewP]

Thanks guys!

Merry Christmas and Happy Holidays!

Best,
Drew

[allessence]

Since this has been brought up.

Is the taper / length for the SAAB standard? That is the threaded part.

What I am asking is Luke used some Jaguar ball joints on his A arms. Is there other alternatives? Which maybe a better choice If I make up some CRmoly ones?

[DrewP]

Do you have one out? I don't have one I can measure here, but I'd bet that it's an even degree # taper, looks to be a 4 or 5 degree or so to me?

If you have one, you could measure the dia at the small end where it transitions to threads, and the big end, and the length, and figure out the angle. What good that'd do you I can't say, none of the OEM part catalogs are going to list it by taper angle and dia (probably the dia at the center of the interface in the receiving bore in the upright).

If you know the taper angle though, you could call up race supply houses and get balljoints though, be more expensive than OEM ones I bet.

I think Luke used those Jag ones because the spherical doesn't cantilever out away from the mounting, it's aligned which gets rid of the bending moment put into the upper one coming off jumps. For a street car I think the stock ones would fine, since the largest loads being reacted are the braking loads, and those are bending in the sturdier direction, forward and backwards in the plane of the arms.

You have a place to get 4130 tubing arms heat treated that you trust? We are about to run a batch of tension tests on some 4130 tubing samples for the Formula team comparing differing degrees of welding ability and of post-weld treatment, I will put up results from our real-world testing if you like.

Best,
Drew

[allessence]

if you could post your results that would be great.

I was actually going to fab up a jig and run thru the process of destructive testing until I found something that worked. be it more bracing, etc.

What your suggesting would be easier.

I have been reading a lot one the subject of tig welding on 4130 and it seems that with careful attention to heat input and small weld heat affected zones, one can expect decent results.

[DrewP]

Jennifer,

I will put up results when we get them, in the mean time, I am going to post my response in a new thread specifically about welding, I don't think that there is one here yet.

It's located here:

SaabRally Welding Thread

On a related note, our shop at school just got a Miller Dynasty 200, and I have been playing with it this weekend, and I am really really impressed. I learned on a big old Hobart Cyber-Wave 350, which is a great powerful machine with 400 amp capacity, water cooled torches, and high frequency start, but there's no AC wave modulation or offset control, just 'Max Clean' and 'Max Penetration' settings that favor the positive or negative half-cycle, so I have been having lots of fun with some 6061 scraps and 5356 filler we have around with the new miller. It's also freakin' tiny!

Best,
Drew

[Geoff]

Its funny this thread got resurrected because I was just looking at alternative ball joints the other day.

The Jaguar joints that Luke used are basically the same thing as the SAAB joints, just different mounting points for different load distribution. The taper, start diameter (diameter of the start of the taper), and length are the same (I believe).

When looking at other ball joints, I did see once a reference to the taper being "1/6". I think 1:6 is a pretty standard taper but who knows if its standard across the automotive world.

I've been looking at ways to build custom upper arms for coil overs and use ball joints that can take the loads from a rally car. One thought was to use something similar to what 1 ton trucks use.

But I'd have to find one with the same start diameter and length. I think the ones on my Ford van have a larger start diameter and the length might be larger too.

There are also Uniball joints that could be custom fitted to a custom A-arm. Something like this:



That way you'd be able to customize your taper and length.

It probably makes the most sense to go with a Jag joint or the stock joints if you're not going to be bottoming out the suspension over jumps.

[allessence]

The Ford truck ones are huge!!!

I was looking more for the act of something a little stronger and then also for the extended axles i'll be putting together this summer.

I'll be going with coilovers front and rear with a little more travel though I won't be doing any big jumps anytime soon.

Call me crazy (which I am) but if the A arms are lenghtened than the pivot point angle will also be changed which leads to axle/a arm geometry being more smooth/ less angle for the amount of travel. This will lead to more axle travel with less geometry change at the end of the axle geometry. Thus lessening the change in camber/center line angles.

I have looked at these: http://www.joesracing.com/

look under aarms and components.

[DrewP]

Geoff or Luke,

Do you know how much steer angle you guys see on an 'average' stage rally (I know an 'average' one doesn't exist, but an estimate?

Even better, do you know what the steer angle at the wheel is? Do you ever have it cranked over to full lock?

Best,
Drew

[Geoff]

The websites that sell these things need some more information. A drawing would be nice because without dimensions you have no idea if it will work for you and I don't really want to spend hundreds of dollars buying random ball joints. At least places like that you could call them and get some info.

It looks to me that the nut on top would prevent the joint from moving much...

Drew: It depends on the event, the surface, the car setup, and your skill. Normally you wouldn't be at full lock unless you had the car out of line... which can happen easily and often. You'd have the wheel at more of an angle than in regular driving though, or at least more of an angle with more speed and throttle than regular driving. In rallycross you end up at full lock a lot more often than you would in rally because the course is a lot tighter. But it also depends on the factors above. When I first started rallycrossing I had the car at full lock on almost every turn. Now that my skill level has increased and I've sorted out the car setup better I may go to full lock on 5% to 25% of the turns (course dependent) and in the turn the wheel would be at full lock for a short time vs. when I first started and was at full lock through half the corner.

[DrewP]

I ask because there might be ways to re-orient the balljoint / outer bearing assembly to get rid of the bending load going into the balljoints. Most larger race sedans and formula cars have their outer balljoints oriented with the bolt axis horizontal where it has to support the suspension loading through the pushrod or coilover mount or whatever.

Most off-road race vehicles I have seen still use balljoints though, road cars almost exclusively use spherical bearings in double shear lugs because there's less required misalignment from steer angle and suspension travel, and the assemblies are lighter and can be packaged tighter to the wheels, and because they always make custom uprights anyways. I'd be hesitant trying to make new front uprights for the Saab, but it could definitely be done.

Obviously you'd have to select bearing with enough mialignment that you don't have them binding up.

Best,
Drew