Link pin shims with angled bushings

[hars550]

I have angled link pin bushings installed on the front end.
Do I still use the total of 10 shims per link pin or would I
have to add more because of the angled bushings?

[hardingfv32-1]

Has the mating surfaces of the upright been machined/milled to match the angle of the bushings?

Brian

[hars550]

No but I am trimming the shims a little to prevent binding. No time to do machine work.
I have a race in 2 weeks.Just need to get them so I have play

[hardingfv32-1]

You will probably use about 7-8 shims. You want at least one shim in all cases between the bushing/upright and the control arm. The number of shims is not really relevant as long as you get the camber you want and can fit the retaining/locking bolt.

Brian

[brian]

I concentrate on not preloading the spindle against the turkey leg. With two shims on the outside top, I install enough shims to make contact between the lower spindle and turkey leg. Any space in the lower connection will result in having to preload the assembly in order to install the pinch bolt.

Once assembled, I put the car on the ground, without the shocks installed, and tighten one pinch bolt at a time to make sure there is no binding. If you tighten all four you will have to search to find the offending connection. More often than not, the binding will be caused by a turkey leg contacting the outside edge of the carrier (dog bone). You will have to grind a taper in the turkey legs to provide clearance.

Without facing the carrier to compensate for the inclined bushing, you will have to run a slightly looser link pin adjustment.

[billinstuart]

Brian is dead nuts correct. This is one of the most mis-understood aspects of the link pin front end..you can NOT adjust camber with shims..they simply allow the bushings/pins to move as they should.

[hardingfv32-1]

So them is there a variety of offset bushings for different camber angles? Front camber is one of the most important suspension adjustments. Are you telling me we are stuck with the camber our used parts give us?

Brian

[hars550]

Thanks guys
This really helped

[FV80]

So them is there a variety of offset bushings for different camber angles? Front camber is one of the most important suspension adjustments. Are you telling me we are stuck with the camber our used parts give us?

Brian

I think you'll find that front camber is NOT one of the most important things. If you ever take a look at your front end (usually in a picture) under heavy load in a high speed turn, you'll find it with significant POSITIVE camber no matter WHAT its static setting. If it's NOT positive, then you are a LONG way from getting the most out of your tires ...

Steve, FV80

[Ed Womer]

Hey guys, I have a problem that I think I have had all year and didn't notice until mid summer, but one, just one link pin is backing itself loose while on the track. The other three are fine and maintain their adjustment. Anyone know why the one is moving? I did replace the link pin and pinch bolt and put some slight marks on the link pin so it would grab better but it still moved.

Ed

[Terry Abbott]

I have had the same problem as Ed in one of my cars the last 2 races and i also changed the parts but still came loose in the race ....

[problemchild]

Ed and Terry,

I think those new Goodyears have too much front grip for the pinch bolts.

[Matt King]

I have had the same problem as Ed in one of my cars the last 2 races and i also changed the parts but still came loose in the race ....

Make that three of us. It's the upper lefthand link pin on my car.

[Bill_Bonow]

Ball joints will solve that problem

[problemchild]

Hey guys, I have a problem that I think I have had all year and didn't notice until mid summer, but one, just one link pin is backing itself loose while on the track. The other three are fine and maintain their adjustment. Anyone know why the one is moving? I did replace the link pin and pinch bolt and put some slight marks on the link pin so it would grab better but it still moved.

Ed

I don't think this is a new issue. I have had it happen occasionally on different cars over the years. Sometimes, you just get a combination of parts that does not want to stay tight. Switching parts around and probably running looser is the remedy.

If desperate .... tack it. Some of the FST guys are having to tack in the Chinese ball-joints that fall out. Atleast the loose link pin keeps the wheel attached

PS .... another PITA fix is increase the qty of shims so that the loosening pin is at the end of its adjustment range.

[hardingfv32-1]

Steve

"If it's NOT positive, then you are a LONG way from getting the most out of your tires ..." I do not understand this statement. Are you implying that positive camber is good?

Brian

[hardingfv32-1]

Link pin movement.....

How about changing the surface condition of the link pin and control arm by sand blasting. A better surface for retaining the pin.

Brian

[Rickydel]

Brian,

What Steve is saying, that under heavy side load, the outside tire will go way positive regardless of what your static setting is.
Yes, we would all like to keep the negative camber we dial in through the corners, but the suspensions we work with just will not allow it.

Ricky del

[brian]

Brian, there is some adjustability in the shims but very little before the assy starts to bind.

Steve, much of the positive camber we're seeing in pictures is caused by flexing of the lower turkey leg. We at BRM Engineering have a fix for this problem. Watch this winter for a new bolt-on solution for this problem.

Link pins will loosen if the bushing itself is worn out and allowing the pin to wallow. This wallowing combined with side loading will push the pin out every time. It's likely time for new bushings. If you get a lot of wiggle in the pin whie inserted in the bushing, replace the bushings.

BRM will introduce another new approach to front camber this winter. We're a little busy getting ready for the Runoffs but wil have several new chassis products soon.

[hardingfv32-1]

Sounds like Steve thinks that the front tires make their best performance with positive camber. That would be news to most racers. That is why the request for clarification.

The amount of positive camber you end up with is determined by the amount of static negative camber you start with for a given amount of side load.

Brian

[tiagosantos]

The way I understood it, is that if you're using the full grip out tires give us, your suspension will be going all out of shape anyway, whichever static camber setting you use.. And that if this ain't happening, you're not going fast enough

Great thread though, this explains why my front suspension feels "stiff" or sticky, for lack of better vocabulary. The previous owner kept telling me that you adjust front camber by moving shims around, so I guess that's exactly what he did. It does move around freely if I make everything looser, but I'll play around with it this weekend and see if I can get it better now that I have a better idea what's actually going on

[hardingfv32-1]

If you are not going to use the shims to adjust the camber, them what are you going to use? Do you have a number of pre-bent control arms? 2-3 sets of assembled uprights with various angled bushings?

Very short sighted, those who insist on staying with the link pin front end!

Brian

[FV80]

Steve

"If it's NOT positive, then you are a LONG way from getting the most out of your tires ..." I do not understand this statement. Are you implying that positive camber is good?

Brian

Come on Brian... I'm certainly NOT implying that positive camber is GOOD - just that you can't have it at speed in a corner in a vee - at least not with the standard flexible turkey legs we've all been using for the last 45 years .... that is, unless 'Mac' shows us something new at Elkhart . A 'bolt on fix' for flexible turkey legs ... sounds interesting. If it works, then <tongue in cheek> there will, no doubt' be a RUN on them as it will become a "MUST HAVE" update ... and therefore we should immediately outlaw it, right? I'm confident that it would also lead to all kinds of new development work and expense. Here, we've all learned how to set up and drive these beasts for all these years ... with this new fix, we'd have to start over and use some of that setup info the FF/FC/etc guys have been using. Who knows, it might even make the zero roll rear obsolete! .
Steve, FV80

[hardingfv32-1]

"just that you can't have it at speed in a corner in a vee" What is it? Negative camber?

What is wrong with our flexing control arms? In general do we not have good car balance with our current setup and tires?
Would you not say that our tires were/are developed with our current suspensions in mind?
What is the benefit of better camber control at the front?
Do you think you can find a better setup at the rear to match the proposed increased grip at the front?

Brian

[FV80]

"just that you can't have it at speed in a corner in a vee" What is it? Negative camber?Brian

Yep - I meant "it" as negative camber in a high speed turn .. in a Vee ... with decent tires and a decent driver.

What is wrong with our flexing control arms? In general do we not have good car balance with our current setup and tires? Brian

NOTHING (within the parameter of the current rules). Balance? Some of us do and some of us don't.

Would you not say that our tires were/are developed with our current suspensions in mind? Brian

Yep (nope?) - I would say that YES - tires were developed for what we have had as of recently...flexing turkey legs....

What is the benefit of better camber control at the front? Brian

Potentially better handling ... that's what the vastly MORE EXPENSIVE race cars have, so it MUST be so...

Do you think you can find a better setup at the rear to match the proposed increased grip at the front?
Brian

I doubt it, but that won't keep people from spending mucho dollares to try to find it...

Steve, FV80