Spacing Caliper mounts?

[N94]

So today I wanted to put on slotted rotors I got a while ago (EBC slotted and dimpled). Then fit well but when I went to put the brake calipers back on they wouldn't fit/line up with the rotor. Looking closer it appears that the aftermarket rotors sit out a little further than the stock rotors (as in the top hat depth is different.

My question is, could I use spacers (washers) so that the calliper mount sits out a bit further so the brakes will fit on the rotor?

[cbauto]

Pics.

[Hondarally]

Firstly, have you confirmed through measurement that the rotors are in fact different? Measure the mounting flanges of the 2 rotors to accurately work out the difference. This will then tell you what thickness shim to use the space the caliper out. It's not something as simple as the caliper needing to be pushed back onto the slide pins? (embarrassing, but you wouldn't be the first person to make that mistake).

I wouldn't be using washers as a spacer. If you get some steel shims made up (make sure they're flat) to the right size, this will be much safer. Make sure that the shim has full contact on the caliper mounting lugs to maximise the spread of the load. Remember, it's not the shear strength of the bolts that hold your caliper in place, but the friction between the caliper and mounting ears. Hence you need a good, clean contact surface with no high spots.

How far do you need to space the caliper? I'd say a couple of mm should be OK, but much more than that and I think you'll start loading the bolts / structure up too much in bending (without actually doing any calculations to confirm)

[curtis265]

Did you push the brake pads back out?

[EKVTIR-T]

Try to squeeze the pistons in and give it another go

probably the old rotors were thin as fuk and the piston was quite far out

[Hondarally]

Reading your posts at ClubITR it seems that the thickness of the mounting flange is different in the 2 rotors you have. This is odd, as it is a critical measurement, and should not vary with different manufacturers (for the same part No.). Note the comment at ITR about the JDM and AUDM rotors being different, this is true, but the JDM rotor is over 10mm taller than the AUDM rotor - this would stand out like dogs balls without installing them. The stock Honda rotor has a flange thickness about 6-6.5mm. What's the thickness on the new rotor you have?

I came across this same problem with a 300mm brake upgrade for my EK. I found rotors that were perfect (off another car) but they have a 4mm thicker mounting flange, moving the rotor 4mm further away from the caliper. Using a 3mm shim this corrects the problem enough to be workable, but not ideal (haven't driven the combo yet to see what effect the spacers have - minimal, I'd suspect).

I suggest you contact the rotor manufacturer and discuss with them - if the difference is significant.

[Limbo]

I would machine the caliper, a lot more safer.
I had to take off 2.5mm from the ITR caliper for ITR rotors and caliper to fit onto an EK4.


I've seen some people do the washers, but I wouldn't trust my life to a couple of washers.

[Hondarally]

OP seems to have gone to ground, but if you're still reading, make sure you check caliper bolt lengths if you're going to space calipers. The bolts are only just barely long enough in a stock situation. If you space the calipers further out, then you run the risk of stripping threads as you won't have enough thread engaged in the caliper.

Limbo - agree about washers being a (very) bad idea. However, machining the calipers will move them the wrong way based on what OP is saying. Need to space them out, rather than moving them in.

[N94]

Sorry for the delay. Work and whatnot caught up with me. I've compared the 2 rotors side by side and the top hat on the oem rotor is definitely higher than the one on the ebc ones. There is only a couple of mm difference though.

I will pull apart the brakes in the next week or so and take some pictures.

Hondarally where abouts can I go to get shims made up?

I bought them secondhand of this forum and was told they ran fine on the seller's friend's car.

[Hondarally]

I cut mine out of 3mm mild steel plate (300 grade). Depending on what thickness you need, you can buy steel shim material of varying thicknesses. The thin stuff (<1mm) can easily be cut with tin snips. Much thicker than that and you need a hacksaw or cutting disc. Better to make up the thickness out of a single piece, rather than stacking heaps of thinner shims together. If you google shim manufacturers, there are a few specialised companies around the country who can make shims to order. Most of them cut them with laser or water cutters.

Note I haven't tested my setup out yet, so can't confirm that it will work / there won't be too much flex etc. I think it will be OK, but would want to test before saying all's good.

[N94]

Would making up a shim not be the same as using a steel washer? Apologies for the ignorance.

[Hondarally]

The big (and important) difference is that a shim spreads the load evenly across the full contact area between the caliper and mount. A washer won't do that, even it it's truly flat (which they usually aren't). You need to maintain the contact area in the bolted join to keep the join working properly. Using shims reduces the effect of spacing out the caliper.

One day when I have time I'll do some quick calcs to work out the effect of shimming calipers, and see how much of an increase there really is in bolt stress (if any) and the surrounding steelwork.

Have you got any information on the rotors you have (part No's etc.)? If they are a couple of mm shorter as you say, then they might work well with a 300mm Civic upgrade I'm trying to sort out. Can you take exact measurements for us and report back?