Big Brake Upgrades via the BMW G series catalog

[razorlab]

I wonder if the fitment this has to do with the barrel design on the stock supra wheels?

Maybe, I didn't even attempt to put on of my 18's on but I can measure the barrel of the OEM 19 and some of my 18's.

Here are more photos of the GX M cars with 18's:

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[i3igpete]

. I'm curious though, if the caliper is pushed slightly further from center, that means the pad wouldn't be making full contact with the rotor. I wonder if the fitment has to do with the barrel design on the stock supra wheels?

Thinking out loud here, another possible way to tell if it's the bracket would be to check the caliper-to-barrel radial clearance at caliper edge and center. if it was me, I'd use a round wood dowel or something from home depot and sweep it around.

if the edges are tighter, then you know it's the bracket's fault. if everything is even all the way around, it's the barrel's fault.

edit: flip what I said above around, two offset nested Circles will have the smallest radial clearance at the center of eccentricity

 

[razorlab]

Thinking out loud here, another possible way to tell if it's the bracket would be to check the caliper-to-barrel radial clearance at caliper edge and center. if it was me, I'd use a round wood dowel or something from home depot and sweep it around.

if the edges are tighter, then you know it's the bracket's fault. if everything is even all the way around, it's the barrel's fault.

Somebody else can do that. Already invested $550 and a couple hours of my time. On to the next thing.

I have some GX M rear calipers in red if anyone wants them cheap. Front caliper is pretty destroyed, got lucky and found that for $150 for test fitting.

 

[NK_SUPRA]

Hello, I am reading this thread with great interest.

Probably, but isn't the brake caliper installed backwards?
I think the caliper installed on the Supra is for the right side.

I think the piston gets bigger and bigger in the direction of rotation.

I tried to draw a line to the ones that are easy to understand in the photo of only the wheels.
Please take a look for reference.

Sorry if I'm wrong.

 

[razorlab]

Hello, I am reading this thread with great interest.

Probably, but isn't the brake caliper installed backwards?
I think the caliper installed on the Supra is for the right side.

I think the piston gets bigger and bigger in the direction of rotation.

I tried to draw a line to the ones that are easy to understand in the photo of only the wheels.
Please take a look for reference.

Sorry if I'm wrong.

yes it was installed on the wrong side but it doesn’t matter as the caliper is a mirror. Same proportions on both sides. You can see this in the clearance top to bottom. It’s exactly the same.

 

[NK_SUPRA]

I see, it looks like the bracket offset is the problem.
thank you.

 

[cbrummell]

yes it was installed on the wrong side but it doesn’t matter as the caliper is a mirror. Same proportions on both sides. You can see this in the clearance top to bottom. It’s exactly the same.

just speculating but it appears the caliper was upside down when you test fit it.

is it possible the mounting holes are slightly different position top and bottom and that was what caused it to be pushed out? just doesn't make sense why it's so far off compared to G8X.

p.s love that you are trying this and thank you for investing your time and money for our benefit!

 

[razorlab]

just speculating but it appears the caliper was upside down when you test fit it.

is it possible the mounting holes are slightly different position top and bottom and that was what caused it to be pushed out? just doesn't make sense why it's so far off compared to G8X.

p.s love that you are trying this and thank you for investing your time and money for our benefit!

Someone already mentioned that. The caliper is a mirror. I measured everything and the clearance was the same on both ends. The only thing that made it “upside down” are the brake hard line and bleeders being upside down.

 

[Z4m40i]

just speculating but it appears the caliper was upside down when you test fit it.

is it possible the mounting holes are slightly different position top and bottom and that was what caused it to be pushed out? just doesn't make sense why it's so far off compared to G8X.

p.s love that you are trying this and thank you for investing your time and money for our benefit!

The only thing I can think of is that the drop center of the OEM wheel is either more towards the center of the barrel, or there is a barrel taper that doesn't maximize the wheel diameter.

Could be worth investigating, but the whole point of this for me was to have a budget friendly brake upgrade. If there is an incompatibility with OEM wheels for the supra folk, it kind of defeats the purpose if you have to also upgrade your wheels to fit a brake kit. At that point, there are probably more reasonable brake upgrades if you're spending all that cash.

Thanks again, Razorlab, for investigating the "M" brake side of things. I tried to contact that other z4 owner about their m4 brake setup as they use an OEM z4 wheel. Unfortunately, they don't know many details as they purchased it as a kit.

 

[cbrummell]

Could be worth investigating, but the whole point of this for me was to have a budget friendly brake upgrade. If there is an incompatibility with OEM wheels for the supra folk, it kind of defeats the purpose if you have to also upgrade your wheels to fit a brake kit. At that point, there are probably more reasonable brake upgrades if you're spending all that cash.

i think a 19 inch titan7 or rays wheel with less barrel taper would fit these brakes no problem and i'm planning on changing wheels anyways so that's less of a constraint for me.

i can get a set of these calipers for $1500 so i'm seriously considering this route!

 

[razorlab]

I’ll measure the barrel of the oem 19’s this weekend

 

[Todday1]

I will add that if anyone wants a custom made wilwood kit i can connect you with the person who makes custom race kits that did this one. It required me buying the front and rear knuckle / hubs so he could use them to measure and machine brackets and engineer fitment etc. so he had the specs done. These are 15” rotors front and rear. Calipers are 6 piston front and 4 rear. But the brake pad is same for both, however the fronts will accept the .080 thick pad and.670 rear. This eliminates the parking brake. The main reason I went this route is then you have easier access to reasonable replacement parts. These fit on 18” rims. Radial mount kits do require some shims to get them centered and the height correct. So is not just plug and play. Also is not really a set up for street driving but if you have a track dedicated car then you may be interested .

 

[razorlab]

I will add that if anyone wants a custom made wilwood kit i can connect you with the person who makes custom race kits that did this one. It required me buying the front and rear knuckle / hubs so he could use them to measure and machine brackets and engineer fitment etc. so he had the specs done. These are 15” rotors front and rear. Calipers are 6 piston front and 4 rear. But the brake pad is same for both, however the fronts will accept the .080 thick pad and.670 rear. This eliminates the parking brake. The main reason I went this route is then you have easier access to reasonable replacement parts. These fit on 18” rims. Radial mount kits do require some shims to get them centered and the height correct. So is not just plug and play. Also is not really a set up for street driving but if you have a track dedicated car then you may be interested .

This thread is for OEM upgrades. Plenty of aftermarket options available. My personal experience with wilwoods made me vow to never come close to them again.

 

[Z4m40i]

I was concerned the adapter brackets might have been the issue since they’re advertised for the m5 f90 rotor (395mm). I was able to reach out to a different supplier for these kits, and the adapters look to be similar in size. It leaves me to think that the caliper mounting position is not the issue and it is the wheel. I’m curious if your 18” aftermarket wheel would have cleared now. This is a pic of that kit on what looks to be a 3 series 19” wheel.

 

[razorlab]

I was concerned the adapter brackets might have been the issue since they’re advertised for the x5m caliper (395mm). I was able to reach out to a different supplier for these kits, and the adapters look to be similar in size. It leaves me to think that the caliper mounting position is not the issue and it is the wheel. I’m curious if your 18” aftermarket wheel would have cleared now. This is a pic of that kit on what looks to be a 3 series 19” wheel.

I didn't buy the 395mm adapters. I bought the 380mm adapters.

I should have test fitted my 18's but i was in a rush getting the car prepped for a track event, that ironically got cancelled.

I'll measure the OEM 19's barrel and some of my 18's and compare.

That photo is a M340i, which shares the same hub as ours. So yea, something isn't adding up with my test fit. lol

Got info on the other supplier?

Now I am really confused, here is a G30 (5 series) with the 395 adapters with 395 rotors fitting under 19's... lmao

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