Shims

[Chittad]

Hello everybody

I have gone through almost all the threads on this forum discussing shims. I have a fair bit of idea about how to use them to adjust my camber/caster - placing them behind the clevises, calculating how much is the change per insertion/removal of shim and keeping one parameter independent of the other.

We are probably going to use inboard rodends and outboard sphericals.

Can somebody please share some photographs preferably photographs of somebody adjusting the shims? That will be helpful since I am not still not comfortable with the fact that everytime I want to change my camber I will have to unsrew - add a shim - screw it back.

Vineet Bhandari
Raftar@IIT Madras

[Chittad]

Hello everybody

I have gone through almost all the threads on this forum discussing shims. I have a fair bit of idea about how to use them to adjust my camber/caster - placing them behind the clevises, calculating how much is the change per insertion/removal of shim and keeping one parameter independent of the other.

We are probably going to use inboard rodends and outboard sphericals.

Can somebody please share some photographs preferably photographs of somebody adjusting the shims? That will be helpful since I am not still not comfortable with the fact that everytime I want to change my camber I will have to unsrew - add a shim - screw it back.

Vineet Bhandari
Raftar@IIT Madras

[exFSAE]

Why aren't you comfortable with it? Shouldn't take that much iteration to find a pretty good camber setting.

That's how we did it. Loosen or undo the bolts, add or remove shim, and tighten it all down. Doesn't take all that long.

The more important thing to make sure you can change quickly are springs, bars, and dampers.

[Chittad]

We are a first year team and are relatively inexperienced. Just thought a photograph would be helpful.

[vandit]

tell u what ...use the search option about something 'fsae west pics' or 'fsae pics' ....there is guy who has shared a zip file with millions of pics of FSAE competition....u might be able to design ur whole car out of that

[Drew Price]

Chittad,

Our upper ball-joint carriers bolt to the uprights, and you shim between them to add positive camber (static setting is pretty negative, and you adjust to kick it back out).

The thing you want to think through is how you will add or take away shims. Most camber shims have slotted bolt holes so that you don't have to take the bolts completely off to change shims, just loosen them, pull the components slightly apart, slide the shims in or out, and then re-torque. Sort of like these:

http://www.tannerracing.com/images/Chassis_Set_Up/Camber%20Shims%202.jpg


Best,
Drew

[Chittad]

Thanks a lot. I got that.


I plan to have a threaded insert into the wishbone tubing for our inboard rodends. I dont know if this is very dumb of me but I have spent quite a bit of time on this one -

With just a threaded insert (I think) I would have to remove the bolt of the rodend unscrew/screw it and put the bolt back. Or is there anything simple by which you can just use a spanner and alter the lengths without dismantling the whole thing?

Vineet Bhandari

[RacingManiac]

http://www.fsae.utoronto.ca/2007/pictures/2007%20Construction/Upright01.JPG

My 2007 design, note the aluminum clevice and the box steel upright. In that pic there are no shim inbetween. We make our shim out of sheet aluminum ourselves. The clevice is secured to the upright via 2 bolts.

As to your last question, you could use a turnbuckle, which is basically a piece with 2 threaded ends, one side CW and one side CCW thread. Use with jam nuts you can just undo the jam nuts and turn the turnbuckle to extend or retract the length. However putting multiple threaded portion in bending is not something I'd recommand....

[Chittad]

So unless somebody uses a turnbuckle one has to dismantle the whole thing.

And about the rodends in bending, I think it has been already discussed in some other thread that a rod end along the axis of the wishbone tubing will have very minimal bending loads.

[fade]

This (http://www.fsae.me.washington.edu/fsaewest2007/othercars/pages/IMG_0490.html) is the design I used for the cars i worked on. To speed up adjustments during testing make sure you can get a socket/wrench on the fasteners that hold the ball joint to the upright with the wheel mounted. Also make sure the shims can be removed with the wheel on. I used a tab with a hole so you could use an allen wrench or pick to pull the shim out. For caster adjustment the inboard clevis could be removed and rotated 180 deg which moved the ball joints in plane. Im Not sure what your using the turnbuckle for. There is a place which sells turnbukcles (called jackscrews) You can also make them using a RH bolt drilled and tapped for a LH rod end and using a RH tap in your tie rod as in the pic.