Front Offset Spindle Bushings

[kkapelke4]

Why is the standard FV Spindle bushing offset 1.5 - 2 deg? And than we shim it to get our desired camber.

Why don't we run 3,4 or even 5 deg bushings to get the desired camber and than no special shimming required?

Post your thoughts!

Thanks

Kevin

[SR Racing]

The bushing is not really providing the camber. The shims are doing the camber. The bushing is specially designed only to prevent binding when achieving 1.5 or more degrees of camber with the shims.
YOu could easilly get 5 degrees of camber with the shims alone and stock VW bushings. But the system would be in bind.
You wouldn't want more than 2 deg of camber anyways in most cases. You would just eat up more inside front tires and not get much additional turn in exchange.

[cendiv37]

There appear to be a couple schools of thought on what should be used to control the front camber on a Vee.

If you use worn bushings (or wear them out prematurely by relieving them) you can use the shims to set camber.

However, if you use freshly reamed bushings (reamed with the std VW reamer), you can't really change the camber much without binding the bushings. In this case you buy or make fresh parts, put it all together and shim for minimum binding, not for a specific camber. You get what you get and live with it.

In either case you must make sure that the front end is not binding when you are done or you will not like it.

My $.02...

[G.B.]

As I think has been said, the commercially avaiable 'offset' bushings give about 2 degrees negative camber, which is idea for the US FV bias ply tires.

However, the Canadian radial tires really need more camber, 3 degrees or so. The difficulty is getting this without binding up the front end.

[hardingfv32-1]

You need Radial Tire Spec bushings! Must be someone in Canada that has them.

Brian

[problemchild]

You need Radial Tire Spec bushings! Must be someone in Canada that has them.

Brian

I found 3 sets last year. I could use another set, but they're on back order and I have not found another supplier.

[kkapelke4]

We got our german machinist friend to make some for us they are a total of 3.5deg offset. They are probally the nicest bushings i have seen on a vee!

If anyone would like a set our friend will make them. You can have whatever offset you want. He wants $100. They are perfect machined and reamed!!!

If I get an order in within the next couple of days they will be availble for Shannonville.

Let me know!!

Kevin

[brian]

I assume you all are talking about link pin bushings and not spindle bushings. The legality of offset spindle or king pin bushings is open to conjecture and dispute.

[kkapelke4]

Yes link pin bushings!

Does anyone run offset king pin bushings? The rules are vague. I also know there is not much meat to play with on those.

[BLS]

Per the GCR "Caster, camber, and toe in/out settings are unrestricted. Clearancing of carrier or trailing arm to eliminate binding is permitted. Offset suspension bushings and alternate locating spacers are permitted."

I've been wandering about the kingpin bushings as well. I've not had one apart in about 30 years, so I'm not sure there is much to work with. I'll find out in a couple weeks.

As I read the GCR, any suspension bushing is "permitted", which would seem to include the kingpin bushings. But I could be wrong...

[problemchild]

Clearancing of carrier or trailing arm to eliminate binding is permitted.

I would have safety concerns after clearancing the carrier enough to have no binding with 3.5 deg offset bushings.

[BLS]

I find some of the "new" terminology confusing. So I'm clear, the front trailing arms are often referred to as "turkey legs" and the carrier as a "dogbone". Is this correct?

Greg, I'm not suggesting a way to get 3+ negative camber, just responding to the question about the kingpin bushings. I can see your point about clearancing. Which brings up some of my new questions. I'll start a new topic in order not to hijack this one.

[problemchild]

I believe your terminology is correct .... although like trailing arms, there may be different interpretations.

When a class is 48 yrs old, there are no new ideas or tweeks. Everything has been tried several hundred times by somebody. To me, front camber is not a significant concern, so I have not studied the issue to know all the factors involved. I just buy commonly available bushings, get the clearancing done, and forget about it.

[hojo]

Hey Guy, what was the max camber you could get on the Jacer you ran back in 2007, to me that seemed to have the most neg camber out of all the cars i can remember on the grid?

personally going past -2 on the fronts is about as far as you need to go. anymore is not going to have the same performance increase of say going from -1 to -2.
it certainly isn't the holy grail of front grip. especially if you already have massive understeer or a bad push condition thats forcing that outside loaded tire to flop over and go positive anyway.

it would be interesting to see what -2.5 or -3 would be like on the falken radials though just to try it out. you might get an increase in turn in for a limited time throughout your 20 minute run, but it would also depend on your driving style and other front end setup as well.

[problemchild]

Why not follow the common practice of using front droop limiters to limit chassis roll and the resultant camber curves of the wheels?

[brian]

My experience with droop limiters has been mixed. I don't like the sudden stop that a limiter generates and have seen instances where the inside tire is lifted off the ground. Higher rebound on the front will slow the rate of roll and won't trigger a sudden stop of movement.

[hardingfv32-1]

"Higher rebound on the front will slow the rate of roll"

This is fine for corner entry and exit. What about the center 50% of the turn?

Brian

[hardingfv32-1]

How much front droop is provided on the average FV using droop limiters?

Brian

[hojo]

"what about the other 50%"

not important, in canada we only do things half assed eh or god will cover it. haha

[G.B.]

Andrew,

The Jacer (in its F1200 format) had 3° negative camber in each side at the front. The Kumhos didn’t like going into positive camber, so this coupled with limited droop worked very well. Especially at Calabogie in ‘07, 1.18.7. The following year with the same engine and front dampers, but on a BRD, I could not get within 1.5 seconds of my ‘07 time.

However at Mosport, the better handling was almost a disadvantage. From turns 1 to 5, I could eke out 50 to a 100 yards on the following cars , which was just the gap they needed to catch and draft passed me going into turn 8.

Since then I’ve stuck with 2° negative camber, as any more wears inside of US tires and I’ve wanted a set up that was good for both Canada and USA.

I hope that answers your question,
Guy.

[kkapelke4]

When you guys are talking about clearancing the carrier what are you doing to it?

Are you machining the inner radius of where the spindle goes over the turkey leg?

Are you putting an angle on the link pin bushing and where the link pin bushing goes into the carrier?

We have radiused the turkey leg to get rid of all edges so there is no binding when the turkey leg sits inside the spindle.

Sorry if these are stupid questions we are just trying to use common sense when making our vee parts.

[brian]

It's really two things, making the ends of the bushing and the face of the carrier on the same plane and radiusing the end of the turkey leg, usually the top one, to allow a deeper location of the leg in the carrier.

As mentioned before, the use of more or less shims is very limited and I personally only use enough shims to make up the difference top to bottom. Any more and you'll get some binding.

To check for binding, I disconnect the shocks and make sure the car is free to go up and down. If it doesn't, I loosen one link pin pinch bolt at a time and see which one frees up the front end. The pull that side apart check all the clearances and start over. Generally speaking, the first time I assemble a front end, I go through this procedure before going to the track.

Brian, regarding the "other 50%", I've always felt that the roll has stablized by that time and while it may change, it's not as significant as turn in.

[hojo]

thanks guy, you answered my question and a lot more actually

no the kumho's definietly do not like going positive camber, once the sidewall "breaks" or is over loaded, you can scrap that corner you were in and your laptime for that matter. if you go back and look at old photos of cars in corners fast cars vs slow cars you can see that evidence really well.

playing with the droop is something i'm looking to be doing more of and understanding better since i have everything else pretty well sorted to a decent degree. preventing or enabling the rear to come in or out of certain conditions in cornering and seeing what the effects area is an area for me to learn.

find a setup that gets you 150-200 feet through 1-5 at mosport and your golden!

Guy would you say that the smoothness of calabogie and its high grip level allowed you to run a lower droop setting of say -2 to -3?

[hardingfv32-1]

"preventing or enabling the rear to come in or out of certain conditions in cornering and seeing what the effects area is an area for me to learn."

And what do you consider options in the rear to accomplish this?

Brian

[BLS]

Regarding the camber change towards the positive under cornering load, does the length change of the spring pack have much effect on this? I know the spring pack length shortens as it twists which, if mounted in the bottom tube, would cause some positive camber to develop. I do not know how much the spring pack shortens and the amount of camber change which results. On my old car the springs are in the top tube which would tend to produce more negative change if this is any factor. Does everyone run the springs in the top? Does it matter?