How close is too close for a brake caliper

[1jz68u]

hi,
i have some track rims that i put tires on today in preparation for the track day tomorrow and there is not much of a gap between the caliper and the face of the rim and by not much i mean driver side = 0.5mm and pass side = 0.15mm (measured with spark plug feeler gauge).

i did test fit the rims and new it was close but didnt think it was this close. now will the calipers expand more that this amount tomorrow and therefore hit the rim?

i have purchased some spacers but would prefer not to use them if i dont have to.

i asked the tire guy and he said that if anything the caliper will get further away from the rim as the pad wears down, so on that basis he is an idiot and will not be doing any work on my car.

so can anyone help?? a quick answer would be good also as the track day is tomorrow.

thanks

[1JZ-Rolla]

sliding caliper, or opposed multi-pistons is probably the most relevant first question?

Yes, if a sliding caliper, then clearance will increase with pad wear, hopefully before caliper expansion with heat causes problems

Is anything stopping you from shaving a small amount of material (say 1.0-1.5mm) from the caliper at its closest point tonight before the track day? A flat bladed large file would do the job, unless you have some pretty brembos or something and don't want to uglify them

[1jz68u]

dont really wanna shave them i have pretty supra brakes

multi piston.

[piggy]

i have a fingernail between my caliper and my rims

[1JZ-Rolla]

Since they are multi-piston I now know why you don't want to return to that tyre guy what a moron!

[Hiro]

if a sliding caliper, then clearance will increase with pad wear, hopefully before caliper expansion with heat causes problems

You just hope that the pads aren't currently worn enough so that the clearance disappears when you put fresh pads on....

[whatthe?]

Dont worry, the insides of the spokes will clearance the calipers after a couple of hard laps

[JustenGT8]

^^^ yup what he says....ie they will touch so use your spacers

[RobertoX]

Don't forget that the rims, hubs etc will bend a little under cornering, not sure if it will take up 0.5mm but I guess you'll find out.
You wouldn't need a very large spacer at all to give reasonable clearance.

[MWP]

Normal play in the wheel bearing will easily make it move around more than 0.5mm as well.

[1jz68u]

i do have a spacer but its a 5mm one and my wheel studs don't look like they will be long enough. Oh well am taking them tomorrow so will work it out then.

[1jz68u]

ok im at the track, we put the spacer's on and one of the wheel studs is missing the thread from the top so one of the wheel nuts on the side that is rubbing won't go on. So will 4 wheel nuts be enough? This is gay.

[PeteH]

Hi,

Ummm no....4 nuts is not enough......and it sounds as though even if you could get all 5 on you don't have enough thread anyway......well not with the spacer in there.

Pete

[1jz68u]

there is about 5mm missing of the end of the stud.

[JustenGT8]

Don't bodge stuff to get yourself on the track...this approach will bite you.

More planning and less impulsive buying tis the only way