ATS Brembo Offset Bushings

[SecondhandSnake]

I'm planning on making my own offset bushings for the ATS Brembo calipers. The main thread is pretty cluttered with all kinds of other information so I thought I would split off discussion here.

For the S&S kit- are those still using the Brembo 14mm bolts versus the Cobra 12mm?

Does anyone have the offset measurements on them? I've got the X-axis offset measurement (how far they need to go inward) but not the Y-axis (up/down, radial distance). I know it's mentioned there's only 1mm or so clearance with 17" wheels and those bushings, so I'm trying to plan mine accordingly.

As far as making them I'm going to give it a shot filling the stock inserts and then re-drilling them with as much offset as I can run with a 12mm bolt. If that isn't sufficient I'll have to see where else I can pick up some distance on the caliper and spindle.

 

[SecondhandSnake]

Update on measurements-

I used a spare GT caliper and bracket I had laying around for some base measurements. All measurements in imperial (because 'merica, convert to commie units at your leisure.)

GT caliper:
Distance between inner edge of bolt holes - 4.720"
Top of bolt hole to highest point on caliper (height) - 3.732"
Inner diameter of M12 bolt hole - 0.402"

Brembo caliper:
Distance between inner edge of bolt holes - 4.600"
Top of bolt hole to highest point on caliper (height) - 4.100"
Inner diameter of M14 bolt hole - 0.470"
Insert outer diameter (w/o knurling) - 0.798"
Effective wall thickness of insert - 0.163"

The difference in bolt centers between the two means you need to either offset or slot the holes 0.06" (appx 1.5mm or slightly less than 1/16".)

It also means that you're going to pick up only 1mm or less in the radial direction without significantly modifying the caliper or spindle. Judging by the fact the S and S kit doesn't alter the caliper hole, that gives you an idea of what offset it may give you.

Looking at the caliper you definitely could hog out the caliper a little to get more height clearance. You could then add in material to the bushing, which would also create an anti-rotation feature.

I'm going to try checking some measurements on the car and see if I can do it without modifying the caliper with 17x9" aftermarket Cobra wheels.

 

[03' White Snake]

I ground the clearance hole in the ATS caliper to maximize the rotation of the insert. I practically have zero pad hang off now. I don’t see how you can fill a 14mm tapped hole and offset it for a 12mm bolt hole. The stock bushing is not large enough for this.

I designed my own offset bushings, but when I had them quoted, it was cheaper to buy the S&S ones. I did not want to run any spacers, so I paid a machine shop $100 to remove the 0.050” from the mounting surfaces.

 

[SecondhandSnake]

Putting an offset for a 12mm bolt in the original 14mm bushing is the easy part. But as I mentioned above it's only going to get you a relatively small offset.

The whole reason I'm looking to make them myself is the local machine shops are swimming in so much business they won't even quote you for less than a thousand pieces, if they return your call at all.

That information is helpful though. It's looking increasingly likely I'll have to go that route for clearance on my wheels, but we'll see when I get a chance to measure everything on the car. In that case I'm guessing it will be something like a 6mm vertical offset, 1.5mm lateral offset, requiring the caliper hole to be ground out some (as you did), then material added to the bushing, making it more of an oval shape.

 

[03' White Snake]

Putting an offset for a 12mm bolt in the original 14mm bushing is the easy part. But as I mentioned above it's only going to get you a relatively small offset.

The whole reason I'm looking to make them myself is the local machine shops are swimming in so much business they won't even quote you for less than a thousand pieces, if they return your call at all.

That information is helpful though. It's looking increasingly likely I'll have to go that route for clearance on my wheels, but we'll see when I get a chance to measure everything on the car. In that case I'm guessing it will be something like a 6mm vertical offset, 1.5mm lateral offset, requiring the caliper hole to be ground out some (as you did), then material added to the bushing, making it more of an oval shape.

Do you have a set of ATS calipers in hand yet? or are you going off of images. The stock bushings that come in the ATS have 14mm hole in the center. The offset of 1mm (0.039") on the bushing cannot be re-drilled for a 12mm hole. 95% of the holes would be inside of each other leaving no material for new threads. This means the bushing that comes in the caliper is junk. Cannot be reworked to accomplish what needs to be done to align to the spindle. You could drill and file the spindle to use the 14mm bolt possibly. That is not what I wanted to do. I did zero modification onto my spindles.

You need to match center to center of the spindle bolt holes onto the caliper itself. That is the point of the offset. This distance is 2mm different from the spindle to the caliper. Hence the 1mm offset needed in the bushings. Then you can worry about clocking the insert to lower the caliper onto the rotor for wheel clearance. Below is the insert I designed.

With the 1mm offset, you clock them towards each other, this now gives you the correct center to center to match the spindle. I started the bolts thru the spindle, clocked the bushings in the calipers and started to tighten the bolts, pulling the inserts into the caliper (just to start). Removed from the car, and finished pressing in the bushings. By clocking them like this, I guaranteed the caliper was going to sit as low as possible and still have the correct center to center pitch on the bolts to align to the spindle.

Hope this helps, and good luck. Cost wise, you cannot beat the S&S kit. I went down the same road as you are already. I was quoting much smaller quantities than 1000 pcs too. I was quoting 20 pcs.

 

[SecondhandSnake]

All these measurements have been with my own calipers.

Just to clarify this isn't making offset bushings to use a 12mm bolt that thread into the existing caliper and bushings with a 14mm thread. This is taking the existing bushing, pressing it out, filling the thread with weld until it's a solid bushing, and redrilling/retapping it to M12.

Basically I would end up with a bushing exactly like yours.

Although from what I was gathering from other people's experiences, even with those offset bushings that don't require spindle modification, it would still require some pad trimming and may not clear 17" wheels as is.

 

[SecondhandSnake]

Update: It does work. I've been running them for about a year or so. I'll have to dig up my measurement sheet for the exact dimensions but it is pretty tight to the calipers on the stock 17" wheels with stick on weights.