Strange Non-Stock swaybar configuration and front suspension issues

[maxthegearhead]

I’ve recently noticed a rubbing when I make a sharp turn left under high speed. It feels like it’s coming from the passenger side front tire area. When i pulled a wheel off and looked at the suspension I saw this. This second thinner sway bar cannot be stock can it?

Pics attached

thanks guys!

[Somjuan]

Huh. It’s very not stock. Looks like a second sway bar got added to the control arm.

[dreiermann]

That really looks like it would cause binding, being installed opposite the main sway bar like that.

[OLD MAN]

Is the stock swaybar cut? can you take a picture from the front?

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If the stock (front) sway bar is good then your front end is really stiff!

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VERY INTERESTING!

[jaredmac11]

lol I was just thinking of making the post to ask if shops/non OE parties ever rethought the suspension setup of the E21. I was thinking more of Dinan or Hartge, not a DIY solution! Looks like they made their own end links. The original swaybar goes through the control arm and I still see a bar going through the control arm... where is that going?

[amarino]

lol I was just thinking of making the post to ask if shops/non OE parties ever rethought the suspension setup of the E21. I was thinking more of Dinan or Hartge, not a DIY solution! Looks like they made their own end links. The original swaybar goes through the control arm and I still see a bar going through the control arm... where is that going?

Like this? https://store.vacmotorsports.com/vac...ion-p2170.aspx

[jaredmac11]

holy crap. I had no idea this existed. $3000....

[amarino]

holy crap. I had no idea this existed. $3000....

I think autox320 did something similar in his Return of the OG building thread.

[OLD MAN]

I think autox320 did something similar in his Return of the OG building thread.

He did.

[maxthegearhead]

The original factory sway bar (the thick one from the 323i it being a '77) is still in place and in good condition. I only noticed this suspension modification fairly recently, but i've never driven another E21 so I can't compare the handling to any other one. However, I do notice very little body roll through corners. Keep in mind my front springs are cut by one coil so that is in play as well.

[320iAman]

Maybe this was done as an answer to 55 mph shimmy.

Randy

[cgifool]

Pretty interesting solution.

I remember seeing something like this long ago on a 2002 race car built/run by "Terry & Neil's Quality Car" in Rockville Maryland.

[mxl556]

It looks like an iS rear swaybar was clamped onto the front control arms... If the factory front bar is where it should be (it looks like it) I'd remove this "mod," I am sure there will be an improvement.

Max

[maxthegearhead]

I’ll unbolt it on one side and see if it improves handling.

[Erik Dlux]

Interesting for sure....

I am doing a very similar front setup to the VACmotorsports setup. I would like to produce a kit also. Should be nowhere near $3000 though, much cheaper.

[autox320]

holy crap. I had no idea this existed. $3000....

I think autox320 did something similar in his Return of the OG building thread.

He did.

I used to give vac hell about the cost . . . common circle track parts as a "kit" lol
Dave Mcintyre had the vac setup on his E21 racer.
Biggest issue with their kit is heim in bending mounted at the hub aka Rod End In Bending (REIB). This is an engineer no-no/nogo but can still be practiced. Discussed it in my build thread and I even started with that setup. Then decided it was safer making weld on cups with larger qa1 bearings.

Even with bolts and all tubing I think I sunk $350 into my front end. Of course went further by scrapping the subframe all together and started with 1" wider front track with 1" higher front roll center correction. This allowed much lower ride height in the front and less spacers at the hub side.

The swaybar in question OP looks to be in addition to the original bar to add bar to the front. Dinan and a few oldschool pics I had they would bolt a second bar right onto the original bar essentially doubling it up. Sometimes we'd see autocrossers do this to get around rules

My circle track supply shop of choice is the oldest in the US www.speedwaymotors.com . I like to use QA1 heim joints especially the endura series. I spec the qa1 heims I want from qa1.net then order from speedway.

[autox320]

REIB; the hub connection shouldn't have threads. Period. Technically even if a ball joint(Erik) there shouldn't be a turn style threaded adjustment. Weld it up fixed. Threads and small round stock (non fixed welded solid connection; tubes) will cause stress risers and eventual failure similar to a REIB. Math backs it up but in laymen terms thought process is like this.

Quick dirty Example: We chose a high load heim/rod end in example 5/8" that handles say 10,000 lbs radial load. Sweet thats plenty, ok but axial up down when attached to the bottom of the strut is not really rated and at best most manufacturers will say 10% of radial. So we have 1000 lbs rated for strut coil bind or kerb hopping/pot hole sudden increased forces that would quickly hammer into a bent heim. But that's not the real scare factor. Think about how the entire strut suspension, tire, wheel hub assembly is riding on this single heim sideways when the most extreme forces are on it. . . braking torque. This will always fatigue the heim end just at the first thread behind the lock nut and WILL end in failure. Not right away maybe but it will happen. It may bend slightly at first but if ever tried to control a car with one control arm ball joint snapped off at the hub...yeah end of story.

Erik no hard feelings man just pointing out for safety. I'd weld that IMO or make a fixed version end with the ball joint. Keep adjust-ability at the other end for track width if want it. It's not worth a failure.

Don't do this




Do this

[Erik Dlux]

Are you trying to say that my tie rod end at the strut is not up for the task because it has adjustable threads?

[autox320]

Are you trying to say that my tie rod end at the strut is not up for the task because it has adjustable threads?

Yes. Thread behind the lock nut is weakest point. From the forward arm to the strut bottom....the ball joint threads will be stressed forward during braking trying to tear it off. The ball might not fail but the thread area could bend or shear off. IMO best case on using the ball joint is to weld the tubing onto the joint housing itself. Finding a ball joint that fits perfect on the strut is an issue and yup makes it hard to have a replaceable joint. Hence to use replaceable balljoints or spherical bearings for serviceability.

Could easily just gusset with more steel plate and seam weld joining to the forward stay piece where your clevis is bolted for the forward arm.

[Erik Dlux]

Wow! Its crazy you even think that IMO.

You think I will bend 7/8" threaded rod? The shear strength of that is 42k lbs! LOL. You think a 2500lb car can create 42k lbs on one wheel?!!

This ball joint is used on full size dually 4x4 trucks for the tie rod. I would really think a tie rod would see way more forces than where its at now. These trucks are close to 7k lbs.

Also, you have a threaded end on your chassis side.... this will see roughly the same forces as the strut side. Do you see yours failing there? Seriously, if you dont have failures with a single shear bolt at the chassis side AND at your strut side which has a lot of bolt sticking out making it really weak, I am shocked that you think you could bend a 7/8 shank. Shocked.

Braking should have almost no forces put into that lower ball joint or strut side joint, whatever you want to call it. All those forces will be on the bar that connects it front to rear. Think about it, if I disconnected the bar that goes front to rear, I could just slop that side to side control arm forward and backward as much as I want.

The only thing the side to side is really controlling is the forces that act on it from side forces, which are not too much. If you hit a pot hole like you said above, that will mostly be on the bar that runs forward to back. I dont expect there would be much side load on the wheel at all really. Surely not 42k lbs!

[Erik Dlux]

Here is a buggy I built. It has a parallel 3 link with panhard.

NOTHING controls the side to side except the panhard. Nothing.

This panhard is running a 3/4 rod end. There is only one for the axle, one for the frame unlike the BMW that has 1 per side.

So, youre trying to tell me that this single 3/4 rod end on a 4k lb rock buggy with 39" tires that goes 60mph thru 2 foot tall whoops, gets wedged in gigantic rocks, has to fight full hydraulic steering, vicious roll overs is fine but my 2, 7/8 threaded bolt on a 2500lb car that sees nothing but road is going to fail?

[autox320]

True brake forces are on the forward stay arm but only from the point which it's connected. The end under the strut is still a shear point. Not saying it won't work just not best practice. Read on REIB on baja and FSAE forums. I'm not arguing about it just pointing it out. Yes it's a fail point and always in discussion. If big enough ends used yes it can last and get away with it.

The single shear bolt on my setup is a bend point but is part of the triangle (control arm inner, clevis, +with the forward stay leg). The hub end is totally different. It's out on it's own. Just past the clevis is where I'm talking about.

[Erik Dlux]

Taking another look, there are forces on that strut end because it will have to take some fore and aft forces too because of where I put the fore/aft bar on it .I still think it's crazy to think it will bend though .

I mean really, the stock e21 control arm has a minutem diameter of .640, a good bit smaller than my .875 and it's cast, not a quality hardened piece .

[autox320]

Not doubting 7/8" is beef as hell for our little cars. It will probably hold up fine, just not best practice. Where's Retoropak? Calling Retoropak... come in man chime in here Sir lol Post some on your arms man help a brother out here

[Erik Dlux]

That's what I am not understanding . Why even bring it up if it will work just fine? I mean, isn't that the point, to make it work as good as possible?

I see more flaws in what you're suggesting than what I havehav why even consider changing to something that works worse even if it is "better in practice"? That makes no sense. It's like taking 3 steps backwards to take 1/2 step forward .