Drilling (midyear) frame; securing TA slotted shims w/cotter key

[Jeff S.]

I'm looking for response from those who have actually accomplished drilling the kick-up frame section for acceptance of shim-retaining cotter key ('69-'70 & on style) with body-on-frame, completed car configuration. I know how to locate the hole's position & yes, how shims "... cannot come out ..." if tapped down into the frame pocket, etc, etc.

If you have photos, illustrations, narrative of how to accomplish while protecting the body/wheel well opening fiberglass, that would be helpful. Would a 3/16" dia, 12" length, aircraft extension drill bit be appropriate? Does the body-on geometry allow drilling the hole 'straight thru' the outboard and inboard frame rail metal, while remaining perpendicular to vehicle axis?

Shims are the typical aftermarket slotted, stainless, 4-1/2" o/length. Thanks in advance.

Jeff

[Edward D.]

Re: Drilling (midyear) frame; securing TA slotted shims w/cotter key

I routinely do this on drivers that I am doing a 4 wheel alignment on when I replace the old style two hole shims with the fork shims. Yes, your 12" 3/16 drill bit is the right tool to use. You will need to protect the front of the bodywheel well with thick duct tape or some sheet rubber taped on. Your drill thru may end up not quite perpendicular, I find this varies car to car, but you will be able to get the safety cotter pin thru and really it will not be off by enough that you can really see it. Also, make sure you clean out those lower pockets and the drain holes are clear, shims must tuck down into pockets, I see lots of them filled up with crud. Last tip is to put the cotter pin thru the frame holes and shims before you tighten the pivot bolt castle nut and lock the shims in place.

[Jeff S.]

Re: Drilling (midyear) frame; securing TA slotted shims w/cotter key

Thank you, Ed; this confirms what I thought to be the case.

I'm assuming it's the drill chuck that endangers body wheel well -- particularly when 12" bit is near full travel & driving into inside wall. I have access to 3/16 x 18" aircraft extension bit, HSS - probably M2 or M7, 118* point angle (v. 135* typical, 12" bit). Would you think this would achieve better perpendicularity & less potential fiberglass interference? It might also be a "handful" to control from scratch, but perhaps by using the 12" to make OB side hole, then switching to 18" bit to continue thru IB side?

[Edward D.]

Re: Drilling (midyear) frame; securing TA slotted shims w/cotter key

Jeff,
Actually the 12" bit is long enough, your drill chuck will get close to the fender lip so don't be too aggressive in pushing the last part thru lest you go too far and hit the fender with the chuck. The biggest issue is your drill shaft rubbing the fender lip, thus you need to protect the fender lip to prevent friction from the shaft damaging the paint. Even with shaft right up against fender you will likely still end up with holes that don't line up quite square across the frame, but it will be close enough.

[Frank D.]

Re: Drilling (midyear) frame; securing TA slotted shims w/cotter key

I routinely do this on drivers that I am doing a 4 wheel alignment on when I replace the old style two hole shims with the fork shims. Yes, your 12" 3/16 drill bit is the right tool to use. You will need to protect the front of the bodywheel well with thick duct tape or some sheet rubber taped on. Your drill thru may end up not quite perpendicular, I find this varies car to car, but you will be able to get the safety cotter pin thru and really it will not be off by enough that you can really see it. Also, make sure you clean out those lower pockets and the drain holes are clear, shims must tuck down into pockets, I see lots of them filled up with crud. Last tip is to put the cotter pin thru the frame holes and shims before you tighten the pivot bolt castle nut and lock the shims in place.

Absolutely - I used shop air at the bottom of that vertical drain spot just below and rearward of the shim cavity and blew out an unbelievable amount of crud!