Anybody use balljoint extenders?

[Dingis]

Hey,

I would like to thank everyone, (especially flogger, dubdrvrkev, WWR, samrabbit, etc) this has been an awesome thread.. I've heard alot of people say "lowering your rabbit won't help turning" and now I can totally see why. I'm definantly going to look into this for my rabbit. You all rule.

[BFDeihl]

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I've seen balljoints shear during race conditions. Even the larger later model joints. I like the idea of relocating them so the arms are parallel-- but I'm not so sure I am sold on extending them...

just my $.02

What kind of racing conditions??? I know (and race with) several people that race A1 VWs in SCCA (ITB, ITC, HProd) and I have never heard of anyone shearing a ball joint from stress. And these are some fast cars w/ very sticky tires.

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Bill, The ball joints I saw sheared off were in Vince Lociciero's shop. At the time he had quite a bit of race hardware laying around from all around the country.

I'm unsure of the class, and I hesitate to say GT4, (since I did NOT see the actual race) but I DID see the aftereffects. Face it, VW engineering must have had a concern with stresses too as they upsized the STOCK balljoints during the run of the Rabbit.

Sure, there is an advantage to correct geometry-- I'm just cautioning that you may want to think twice about how you go about it. Extending the shaft of a ball joint (as a few of these designs do) MAY not be the right way.

As usual YMMV.

[phrankentruk]

That's what I was worried about. When I did mine I hadn't actually heard of anyone doing this. We kind of stood around and said, "well they LOOK pretty strong." My hope was that they'd bend before breaking. The thought of what a sheared ball joint extender would do to the front of my Caddy makes me cringe. I did progressively harder stops and several inspections before relaxing about it. I wanted to wait a year or so before posting because of this. It's been about 1 1/2 years now and about 20-30k mi. with no problems. But then I'm not running slicks.

I'm going to make a page showing my whole setup and I'll post a link here next weekend.

[the12for12]

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I'm going to make a page showing my whole setup and I'll post a link here next weekend.

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we'll be waiting...

[KelRox]

Very interesting information here! I like it. I'm looking forward to more info!!

[dubdrvrkev]

I will be waiting for the upcoming web page as well. Should spark the minds of all of us who are into racing or even just proper handling cars.

[Mk1Racer]

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you guys are amazing.
i just learned more in 10 minutes of reading than i have in 2 years of auto x.

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Good, solid, tech stuff like this is one of the hallmarks of the A1 forum!

This is one of the best threads I've seen in a while. Nice work guys, keep it up!

BF,

It's really hard to say. If it was a GT4 car w/ a redesigned suspesnion, but using stock ball joints (why, I have no idea), maybe it wasn't built right. And, was the ball joint failure the cause, or a symptom of some other failure/shunt?

And, it's not reall extending the shaft of the ball joint, more like stacking one on top of the other. If it's good steel (CrMo maybe?), and it's machined properly and the tolerences are tight, shouldn't be a problem. I forget the exact size, but I think it's on the order of 12mm. Takes a lot to sheer 12mm of good steel.

[vdubspeed]

Regardless of the outcome of this post (if these are good or bad) I've already begun to make a pair. What I did was I went to my parts Scirocco 16V and I took off the balljoints and the knuckle. The plan is the cut off the ball joint end that slides into the knuckle. I'll then cut the part off the knuckle and put it under the first part I cut off. Using a mig, I'll weld that BABY THICK!!!!!! If done properly and welded cleanly, the extender will just be a piece of a knuckle with the shaft of the ball joint on top.

Does this sound worthy of spirited driving in my Rabbit. My GTI is screaming to be lower in the front!!!!!!!

I'm stoked!

Jason

[samrabbit]

one more thing I should mention. ......hehe.

if you go too low and start angling the ball joint alot, it is possible to bottom it out when you hit a big bump, and the resulting shearing/popping out from the upright will happen. it has before.
if you put in raised camber plates to get more travel, you better get some longer uprights too to keep the balljoint angle in a good spot.

the carrera plates which I use have an offset on top, so you can use them one way for camber setting or spin them 90 degrees for caster adustment.
if you use them in the longitudinal position(caster), you can still use the strutt camber adjusters on the upright to set static camber.

the too low balljoint scenario did happen at limerock on a prepped 944 and he rolled it and more. air time too.

if you really want to see firsthand what the dynamics and stresses are on a balljoint with spacer setup do the following...........
pick a nice bolt from your collection. put it in a vice.
try bending it right on the vice surface......thats called shear(the way the balljoint and upright are designed to work).
now go up about an inch or two, and try bending that bolt. it bends.
the spacer makes a shear connection into a bending arm.
when you introduce race tires and high loading, with nice bumps thrown in, things get magnified. and street conditions are far worse than a fairly smooth racetrack.

do it safe.

[WackyWabbitRacer]

Samrabbit is correct about the increase in the shear load as the length is increased due to a longer moment arm about the force.

My custom fabriacted bearing housing extenders were made of high quality steel, TIG-welded to the bearing housings with a special filler rod for the dissimilar metals of cast iron to steel.

I also inspect the entire suspension and retorque everything after each race weekend. If the weekend is a double race event, I will retorque and inspect on Saturday night.

As a suspension is more modified, more frequent inspections are required to insure that all components are still functioning right. Cheers, WWR.

[phrankentruk]

Maybe the setup is different on the Porsche but I think the angle is the same as it would be on the stock setup. OH maybe you're talking about the caster, I think I get it.

I wouldn't feel comfortable at all with welded together joints. Just think of what would happen if you were hard braking into a fast turn and hit a pot hole or a dog or kid showed up and that baby let loose. It's a scary thought.

I think the race track would be more stressfull because the loads being put on the extender are a function of tire traction. Repeated braking at the limit with slicks would be more than street tires with some bumps thrown in I would think.

[verboten1]

>metallurgist here, mine are just 4140, if i recall correctly,
not heat treated, and held up to a STIFF suspension and horrible roads

[kmead]

If you look carefully, you can see that they put a subframe across the engine bay behind the engine. The subframe carries the lower and upper a arms, the Mazda Miata has a similar arrangement of the a arms in front (without the Honda spring/shock attachment of course). They also cut quite a bit out of the inner fender well to make the room. I suspect (not being able to see the complete solution) that they tied into the longitudinal bars that go from front to rear in the engine bay and carry the crash loads from the bumper system. Quite a good idea actually.

[dubdrvrkev]

Here is some better pics of the mounts:

This car is very well built, I would like to be able to put the kind of money and time into my car that is in this car.

[pastpargolf]

Best thread on this site!

And remember when making backyard balljoint extenders, they support some signifigant loads, accelerating thrust, brakeing, cornering ect.
What I'm saying is if you ball joint snaps on the highway or in moving traffic......nothing good is going to happen.

Caster question, what effects will adding caster have? Cornering camber?
The rate at which camber changes during cornering? Anything else??

Mercedes have lots of positive?? caster??

[WackyWabbitRacer]

From my reading of various suspension books, an increase in caster will help to slightly decrease the amount of positive camber gain of a MacPherson strut suspension when the strut is compressed due to cornering loads. Unfortunately the geometry of a MacPherson suspension results in a positive camber gain...just a part of the design. However a little more caster reduces the curve of the positive camber gain. Unless you go with double A-arms, like in the picture of the Rabbit, you and I are stuck with a positive camber gain with the VW. Regards, WWR.

[kwenzel]

Greetings -

I thought I post a couple of thoughts to this thread, since several pictures of my car (the E Prepared Rabbit with the twin a-arm suspension) have been posted. On the subject of ball joint spacers: yes, using these can be fraught with peril if they're not made properly. I know of at least three instances of failure, and in each case they were either made of a material inadequate for the task or not engineered properly (in particular, the junction between the "post" and the body of the spacer better have a proper radius, rather than being a sharp bend - as far as the material goes, 4140/4142 is a good choice, but I *really* recommend heat-treating). Dave Stone is the guy behind Performance Machine Works ( http://www.pmwltd.com ), and I don't know of any installation of his spacers that has experienced a failure, to date (both autocross and club racing cars). His work is not cheap, true - but nothing good ever came of a divorce between an upright and a control arm... The benefits of spacers are quite large (if it's legal in your class, of course - and I should add that I'm not sure why anyone would bother doing this to a street-only car), but think very carefully about the issues. If you're machining a set yourself, it might be a very good idea to at least call Stone and talk to him about the issues before deciding to tackle it yourself.

ps. More pictures of the twin-a-arm Rabbit (in various stages of construction) can be seen at:
http://kwenzel.rmsolo.org/epimages/

[kwenzel]

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If you look carefully, you can see that they put a subframe across the engine bay behind the engine. The subframe carries the lower and upper a arms, the Mazda Miata has a similar arrangement of the a arms in front (without the Honda spring/shock attachment of course). They also cut quite a bit out of the inner fender well to make the room. I suspect (not being able to see the complete solution) that they tied into the longitudinal bars that go from front to rear in the engine bay and carry the crash loads from the bumper system. Quite a good idea actually.

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Close - the upper a-arm pickup points are just below the longitudinal frame members, and are actually attached to a bit of the stock frame that curves above the halfshafts on each side. At first, the only extra bracing that existed was the vertical piece that you can see between the halfshaft and the trigger wheel on the crankshaft. Later, Dave Stone added bracing from the backside of these pickup points to a plate on the firewall (braced back to the cage on the other side) which was also attached to the longitudinal fame members. The lower pickup points are in essentially stock locations, but are also supported by bracing to this plate - so, it's kind of a combination between the stock frame and additional bracing/subframe.

[Mk1Racer]

Definately a top-flight job!

[Mk1Racer]

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I know of at least three instances of failure, and in each case they were either made of a material inadequate for the task or not engineered properly (in particular, the junction between the "post" and the body of the spacer better have a proper radius, rather than being a sharp bend

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This raises an interesting question. I would think that you would either want the 'junction' to be square, so you would ensure good contact between the spacer 'body' and the bottom of the knuckle. Or, you would want to chamfer the bottom of the knuckle to 'accept' the radius at the 'junction'. I'm thinking that the later is probably the better choice as I'm not sure what kind of stress risers, etc. that you would see at a square 'junction'.

Any mechanical engineers care to comment?

[WackyWabbitRacer]

Bill, a radius is definitely preferred as a square cut will introduce a stress riser area which is then subject to cracking. Regards, WWR.

[dubdrvrkev]

I will post some text I found on http://www.ground-control.com

Tech Talk - Caster

A short dissertation on CASTER, the most misunderstood of the three front wheel alignment angles, with regard to production based roadrace cars.

Of the three main front wheel alignment angles, camber, caster, and toe, it is certain that caster is the most confusing and most subtle, and therefore the most misunderstood. This subject requires a working knowledge of racecar front end geometry as found in one of the many books available, some of the best of which are listed below.

Camber is the angle at which the top of the tire is tilted in, as viewed from the front of the car. As the front tires are turned left and right, the camber changes slightly because the pivoting points for the tire are not vertical as viewed from the side. If the car has positive caster, as most every racecar does, the topmost pivot is behind the lower pivot and this causes the tire to tilt in more at the top as the tire is steered inward. This small amount of negative camber gain is the most common reason for the popular misconception that a lot of caster is a good thing.

While it is true that most cars DO handle better with more caster than the factory spec, and many handle well with as much caster as possible within the limitations of the body structure, it is definitely a fallacy that "more is better".

The most confusing thing about too much caster is that the car can FEEL better, but actually be slower on the track. This is aggravated by the possibility that the car can feel so much better that the driver actually goes faster, even though the bumpsteer and corner weights are made worse. This occurence is the driver's problem for not going fast enough to begin with and there are books for that too.

Changing caster primarily affects four things, high speed stabilty, camber gain, bump steer characteristics and relative corner weights (wedge). There is no disagreement that high speed stability is a good thing, so extra caster is a plus there. Camber gain with extra caster just happens to be in the direction we want, more negative, so that's good too, however the amount is usually greatly overestimated as shown in the example below. Bump steer however is affected adversely, but this can be changed, however I have seen many racers get caught out by this one. Corner weights are the big problem with too much caster, as extra caster definitely affects an otherwise balanced racecar for the worse.

What occurs with extra ("too much") caster is that more and more weight is transferred off of the outside front and inside rear tires, while this may at first sound good because taking the load off the outside front CAN be good, the reality is that the outside rear tire will be doing too much work in the middle of the turn, so steps then taken to alleviate this will cause a corner entry push. Additionally, on any rear wheel drive car the inside rear tire will be light and won't come off the corners well. Remember we're talking about a well balanced car here, not a car where this extra caster covers up a sway bar or spring problem.

There's nothing like a good example so here are some actual numbers from the use of data acquisition, a set of electronic scales and an alignment machine. With caster + 3.5, camber -1.5,when the tires are turned 7 degrees as typical for sharp hairpin, the camber gain was 0.35 degrees (not much!) however the corner weights changed by 22 on just the outside rear tire. With caster +5.0, camber -1.5, and 7 degrees toe-in, the camber gain was 0.50 degrees (still not much), but the corner weight changed 35 lbs. on the outside rear tire, which is just too much. The most interesting item in these examples is actually how little the camber gain changed. This stuff applies equally to FWD and AWD cars, but for slightly different reasons.

This page is for thinking purposes only, and of course you may find totally different results, but all engineering students who feel typically argumentative are cheerfully advised to get out of the computer lab and race something, instead of E-Mailing me about why their theories disagree.

Books: Race Car Engineering by Paul Van Valkenburg, any Carroll Smith book, How to Make Your Car Handle by Fred Puhn, and the new Don Alexander book is way better than the old one.

And this also from the same website:

Tech Talk - Bottoming out of the front suspension

The single most common problem we encounter on race cars is bottoming out of the front suspension. It is suprisingly difficult to detect sometimes. This problem can really frustrate you, in fact, a frustrated team and driver can be one of the symptoms that the car is bottoming out! Most cars have more rear suspension travel, so bottoming out of the rear suspension is less common, and is actually easier to detect because of severe and sudden oversteer. Bottoming out of the front suspension can be much more subtle and gentle.

I have listed the most common symptoms and causes separately, with the most common listed first.

Symptoms of bottoming out the front suspension.

The car is unresponsive to changes made to the front suspension. A particularly good clue is that softening the front sway bar makes the car understeer the same or worse.
The car understeers more if you try to go faster, especially in mid-turn after the chassis takes a set. Don't confuse this with braking too late.
The car understeers more after only 2-3 laps. This is a sign that the front tires are overheating very quickly., indicating that the cars is way too stiff, perhaps because of bottoming out.
Just to be sure, wrap a nylon tie around the strut or shock, to indicate travel, then drive a few test laps. Absolutely avoid any bump or curb which would artificially push the nylon tie to the top of the shaft, and then pull in to see if the nylon tie has been pushed to the very top. This may mean driving off line and slowly everywhere but the places where you suspect bottoming.
Causes

The most common reason for bottoming out the front suspension is that the car is simply too low for the existing front strut or shock length. This is true even with very stiff springs. See our catalog for solutions.
Bump stops could be too long, especially stock hard rubber ones that can steal 2 or 3 inches of travel. Bump stops should benefit the car, not make it worse.
Front spring rate is too soft. Especially common with street springs that have been cut. This can be especially confusing because all the books say that stiffer front springs will make the car push, which is not always true.
Front springs coil binding. This is rather uncommon, but it does happen. You can see this by looking carefully at the individual coils where they could touch.

I am not posting any of this as my opinion just as text that you can take what you want from it. I would like to keep the technical aspect of this thread alive.

Also as a thought, if a GB was organized would $275 a pair seem fair to you for the extenders?

[MiCrO]

some thing i found http://forums.vwvortex.com/zerothread?id=237742

but i know that WAY back in the day probably like over a year ago somone posted a link to a suspension site, they didnt specialize in vw's but they sold them....

[kwenzel]

Regarding caster - GC's article has a decent description of the dynamics of the situation, but I should note that their view on it (that is, somewhat negative) is not universally shared. My personal experience with it has been that (particularly on a strut-based VW, although I run a fairly large amount of caster on the twin a-arm car) the more caster you can get, the better. The dynamic weight jacking is definitely more significant than the camber change, but it's quite beneficial for a front-heavy poor-suspension-geometry car like a Rabbit. What's more, it acts like a dynamic swaybar, in a sense - the effect of overloading the outside rear (really, the outside-rear-inside-front diagonal) is more pronounced in lower speed corners when you've got the wheels steered more. This is helpful, since typically a car set up to be neutral in high-speed corners will tend to push in low-speed corners.

Regarding a sharp junction between the post and body of the spacer - I think I mentioned that this is exactly where they typically fail, when designed in this manner. Not just bad, but BAD. Stay far away from any built in this manner.

Lastly:

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Also as a thought, if a GB was organized would $275 a pair seem fair to you for the extenders?

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If the "you" in that sentence is referring to me, sure, I guess, but I'm not the fabricator. Dave Stone is the guy to talk to. I agree with the other posts that say these things can be made cheaper - but again, this is not an area where I would be trying to skimp on materials or craftsmanship.

Kevin Wenzel
EP 117 - Open 440

[flogger]

Kevin Wenzel posting on the Vortex? Did hell freeze over???

For anyone who doesn't know, he's a former national champ in SoloII and a bit of a guru when it comes to autocrossing A1 VWS. Kevin, I bow in your general direction...

Kevin, I always pictured the weight jacking affects of increased positive caster to be even more beneficial on open dif cars than LSD cars (speaking in the front-end heavy VW world). I'm thinking specifically in terms of STS vs FSP differences. Have I got this right? I would think that the wider wheels in FSP with wheel centerlines further from the hub would increase the effective amount of weight jacking slightly, but that still, peglegged cars would benefit more (especially at corner exit). Am I missing out on seeing other typical class setup differences that would make this not true?

[verboten1]

roger brown (vw caddy)has the plans and materials an tooling to make the units i have, he may still be interested in making them for you guys, ...everyone backed out last time thoiughj

[MiCrO]

for $100 i would sure buy a set

[dubdrvrkev]

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If the "you" in that sentence is referring to me, sure, I guess, but I'm not the fabricator. Dave Stone is the guy to talk to. I agree with the other posts that say these things can be made cheaper - but again, this is not an area where I would be trying to skimp on materials or craftsmanship.

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Well I didn't mean you in particular I was refering to the people who have expressed interest in them.

I agree that CG's article made caster seem like an almost unimportant set-up change. But a few people showed some interest so I thought I would post it anyway.

Do you use shortened A2 strut housings on you car? What are your thoughts on that route?

[phrankentruk]

I'm not an expert but I wouldn't feel comfortable with the ones that slip over and use set screws. Mine are clamped on with the bolt similar to the picture of the ones at the beginning of this thread. Also, the ones shown with the set screw have that sharp angle.

[Mk1Racer]

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Bill, a radius is definitely preferred as a square cut will introduce a stress riser area which is then subject to cracking. Regards, WWR.

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Pretty much what I thought.

[2L Bunny]

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he may still be interested in making them for you guys, ...everyone backed out last time thoiughj

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We did? Last I knew my co-driver is still looking for a set. We were gonna buy 2 maybe 3 sets.
later,

[dubdrvrkev]

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We did? Last I knew my co-driver is still looking for a set. We were gonna buy 2 maybe 3 sets.
later,

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Are you still interested? They wont be $100/set, but like I posted earlier maybe around $275 and they WILL be the ones that are pictured in the first post of the thread.

IM me if you are interested.

[seako_916]

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I have a set i will sell, not as heavy as those, but still worked great

[Modified by verboten, 12:28 AM 1-6-2003]

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hey jason,are those just steel???no urathane or anything like that??
looks like theres just a set screw on them,if so,i could make something like that at work no prob...

Brett

[VWJerm]

ok so I have read thru most of these posts, here is what I gather.
If'you're going to lower the rabbit heavy duty, the easiest way to keep it handling well is to use balljoint extenders and a modified/flipped tie rod to minimize bump steer. Am I way off here? I realize that there are some better ways that require alot of fabrication, but I'm thinking of using the balljoint extender route.

[WackyWabbitRacer]

A word of caution with the fabrication of ball joint extenders or spacers. A properly built extender requires a good design and correct tolerances, the right choice of steel, and a proper method of clamping. Otherwise, the result may result in breakage and severe consequences.

These extender devices are not something that an average individual can build in their home garage. Knowledge of machining, material strength, and perhaps even heat treating is required.

Definitely do not take any short cuts. Modifications of any suspension always cause a subsequent compromise of the original design. Be smart and play safe. Regards, WWR.