CTS-V Brake Upgrade Spacer Question

[[email protected]]

We're doing some R&D on this brake upgrade and we've encountered a curiosity.
We've got all the relevant parts (2g knuckle, CTS-V caliper, Cobra rotor, wheel spacers) and when we assemble everything (using a 5mm spacer between the hub flange face and the rotor) we find that the rotor does NOT locate to the centerline of the caliper. We find it's off by about 1.4mm (such that a 6.4mm spacer, NOT a 5mm spacer would be required to match the centerline of the rotor to the centerline of the caliper). We tried it with several different combinations of rotor, caliper, knuckle (to ensure there were no oddball parts) and got the same figure each time.

As far as we know, the adapters CTSVBrakeSwap.com sells are 5mm thick. All references from all sources we've found speak of 5mm spacing/removing. Are we missing something?

Anyway, our question to anyone that has done this mod: did a 5mm spacer match up the rotor/caliper centerlines? Or for those who machined material off the caliper mounting ears, did removing 5mm match up the rotor/caliper centerlines?

The reason we're asking is that we're considering offering CTS-V calipers for sale that have had the appropriate amount of material machined off. Of course, we'd like to machine off the correct amount. There is at least one good reason to go this route, rather than spacing the rotor: it places everything (especially the caliper) 5mm? 6.4mm? more inboard and thus gives that amount more clearance for rims.

Thanks in advance.

 

[Dat240zg]

Paul:

I’m in the middle of the swap on a ‘91 TSi and have to tell you that the info that’s out there is primarily for 2g, and the people that have done the swap successfully on a 1g seemingly have conflicting info.

I agree with you - the 5mm spacer does not center the rotor within the caliper. I ground my mounting tabs down to the recommended 17mm thickness and found that that isn’t correct for a 1g. Again, my experience only - I’m sure someone else will say it worked perfectly for them. It almost seems like there are different track widths for AWD 1g.

I’ll be watching your research carefully - I’m in to the swap $500+ at this point, not including new wheels and tires.

 

[AZGSTGSX]

We're doing some R&D on this brake upgrade and we've encountered a curiosity.
We've got all the relevant parts (2g knuckle, CTS-V caliper, Cobra rotor, wheel spacers) and when we assemble everything (using a 5mm spacer between the hub flange face and the rotor) we find that the rotor does NOT locate to the centerline of the caliper. We find it's off by about 1.4mm (such that a 6.4mm spacer, NOT a 5mm spacer would be required to match the centerline of the rotor to the centerline of the caliper). We tried it with several different combinations of rotor, caliper, knuckle (to ensure there were no oddball parts) and got the same figure each time.

As far as we know, the adapters CTSVBrakeSwap.com sells are 5mm thick. All references from all sources we've found speak of 5mm spacing/removing. Are we missing something?

Anyway, our question to anyone that has done this mod: did a 5mm spacer match up the rotor/caliper centerlines? Or for those who machined material off the caliper mounting ears, did removing 5mm match up the rotor/caliper centerlines?

The reason we're asking is that we're considering offering CTS-V calipers for sale that have had the appropriate amount of material machined off. Of course, we'd like to machine off the correct amount. There is at least one good reason to go this route, rather than spacing the rotor: it places everything (especially the caliper) 5mm? 6.4mm? more inboard and thus gives that amount more clearance for rims.

Thanks in advance.

I would def be interested in purchasing the ctsv calipers pre cut to fit a 2g instead of having to use the 5mm spacers from ctsv swap. Please let us know if you start offering that. I have (2) 2G Eclipses I would purchase for.

 

[AndrewD5418]

I've been looking to do this swap too.
However it may be more beneficial to find a rotor that works with the proper height, size, and width.
Even if the pattern or bore is off that could be redrilled and opened up. Brembo allows you to search rotors thru their database with rotor specs

 

[talon77]

I'll see if I can dig up some pics, but I recall machining 5mm off the caliper definitely does not center the rotor.

 

[[email protected]]

We checked again more thoroughly and it looks like we're happy with the figure of 6.1mm (+/- 0.1mm). There's no way it's only 5mm. That's a fiction.

We've decided that's too much to machine off the calipers. We've also decided that's too much to "lose" on thread engagement of the stock wheel studs. Of course, one solution is extended studs. We're leaning towards a hybrid solution: machine some off the caliper and the rest made up with a spacer.

We suspect everyone (including the companies that used to offer the upgrade) knew it was more than 5mm but also knew more than 5mm was too much to lose from the caliper and too much to loose from thread engagement and more than a 5mm spacer would require extended studs.

There's something else many might not be aware of: the rotor the CTS-V calipers were fitted for were 32mm thick while the Cobra rotors are 28mm thick. Couple the thinner rotor with the additional amount off center, how far are the outboard pistons going to protrude (especially as the pads wear)? So much so, they "fall out" of the caliper? We aren't sure, but we know we sure don't want to take a chance.

 

[rabenne]

We checked again more thoroughly and it looks like we're happy with the figure of 6.1mm (+/- 0.1mm). There's no way it's only 5mm. That's a fiction.

We've decided that's too much to machine off the calipers. We've also decided that's too much to "lose" on thread engagement of the stock wheel studs. Of course, one solution is extended studs. We're leaning towards a hybrid solution: machine some off the caliper and the rest made up with a spacer.

We suspect everyone (including the companies that used to offer the upgrade) knew it was more than 5mm but also knew more than 5mm was too much to lose from the caliper and too much to loose from thread engagement and more than a 5mm spacer would require extended studs.

There's something else many might not be aware of: the rotor the CTS-V calipers were fitted for were 32mm thick while the Cobra rotors are 28mm thick. Couple the thinner rotor with the additional amount off center, how far are the outboard pistons going to protrude (especially as the pads wear)? So much so, they "fall out" of the caliper? We aren't sure, but we know we sure don't want to take a chance.

Your hybrid solution is exactly how I tackled the issue. I used 3mm spacers and took the rest off the caliper mounting tabs. I didn't like the idea of taking that much material off the mounting flange (yes, I know it works for some .)

 

[talon77]

I did the hybrid solution myself and was using 2.5mm spacers along with the machining. I'm not in love with the spacers though because it pushes things out just enough for the wheel to no longer be hubcentric . I also ended up getting 1mm thick titanium brake pad shims from Girodisc to help make up for the thinner cobra rotors.

 

[Dat240zg]

Paul: was looking for rotors that may better fit the bill for a 1g and found this: https://www.brakepartsinc.com/raybestos/catalog-part-search.html?PartNumber=680497R

They're cheap enough that I may give this a shot. Measurements look good, better thickness, a 14” rotor alth a bit heav (5 lbs).

 

[[email protected]]

Paul: was looking for rotors that may better fit the bill for a 1g and found this: https://www.brakepartsinc.com/raybestos/catalog-part-search.html?PartNumber=680497R

Not sure what the intention of using that rotor is? With the 1994-04 Cobra rotors (330mm) the pads are located pretty much exactly where you want them: right at the outer edge of the rotor. Smaller diameter and the pads overshoot and bigger diameter the pads undershoot. A slight undershooting of the pads is tolerable if it's only slight, otherwise, the rotor won't clear the caliper radially. There's no issue at all with the diameter of the 1994-04 Cobra rotors. If you could find a rotor with the swept area somehow in a more desirable plane, that might be helpful. Not sure if the rotor you referenced is on a different plane or not? You'd probably have to get one to see.

If someone could find a rotor with the swept area running in a more desirable plane, that would be very useful. I suppose the CTS-V rotor would probably fit the bill, but that has other issues. We may look into how much modification would have to be done to that rotor. That may be a solution of sorts.

 

[Bedicine]

Paul, Did you find a solution for this? Just ordered the CTS V Calipers and wanted to see what the consensus is now.

 

[[email protected]]

Yes, we're going with the hybrid solution: machining some material off the calipers (about 3mm) and making the rest up with a spacer (about 3.1mm).

We're currently having a run of spacers made. After that, we'll need to machine at least one caliper and then test fit the whole works on a knuckle. Not sure of the timeline for all that, but it'll be a few weeks at least.

 

[Bedicine]

If you need a test vehicle or calipers I’ve got a brand new set here and a car on stands .

 

[NeMiZiS]

I did the swap on my 1g I didn't measure the spacers before the install.

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[99gst_racer]

I did the swap on my 1g I didn't measure the spacers before the install.

Got a pic that shows how far the wheel/tire protrudes from the fender? Right now, that's my only concern with using the spacers for this swap. I'm thinking I might machine the calipers instead.

 

[rabenne]

@99gst_racer
My 2g with 3mm spacers, 17x9 enkei wheels. I did spacers front and rear to keep track width consistent front to rear.

Just leaving this here for reference

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[99gst_racer]

@99gst_racer
My 2g with 3mm spacers, 17x9 enkei wheels. I did spacers front and rear to keep track width consistent front to rear.

Just leaving this here for reference

You did the CTSV brake swap using 3mm spacer behind the rotor? And no machining to the caliper mounting ears?

 

[rabenne]

No, that would not center the caliper over the rotor. I did 3mm spacers and machined the rest (about 3mm), like RTM is planning for their kits.

 

[NeMiZiS]

You did the CTSV brake swap using 3mm spacer behind the rotor? And no machining to the caliper mounting ears?

Thread '1G CTS-V Brembo swap offset questions' https://www.dsmtuners.com/threads/1g-cts-v-brembo-swap-offset-questions.536688/
I posted more pictures on this thread.
I say 5mm but I honestly don't remember if I measured them or not.
No machining I just used the spacers in the kit.

 

[Jairo97talon]

I did the swap on my 1g I didn't measure the spacers before the install.

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I also did the swap and I just used the spacers from the kit. Side note isn’t the bleeder supposed to be on the top to let out the air?…

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[NeMiZiS]

I also did the swap and I just used the spacers from the kit. Side note isn’t the bleeder supposed to be on the top to let out the air?…

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Yes the bleeder should be at the top.
I mounted them backwards first attempt, I realized before I got to the other side.

 

[99gst_racer]

So, just thinking aloud; As an alternative to machining on the caliper, wouldn't it also work to use a 2-pc rotor and turn the backside of the hat down 3mm? Then just run a 3mm hubcentric spacer?

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[[email protected]]

We didn't tackle this project with a Wilwwod rotor in mind for basically 2 reasons:
1. They are expensive
2. We would have to start from the beginning, finding a rotor of the correct diameter, thickness, and determine the offset.

The Wilwoods we stock for 2g are too small at only 12.2". These calipers require a rotor around 13" diameter. Also, we already stock the Cobra rotors as we use them in a lot of our other brake upgrade kits and we already have the hubcentric rings for them.

 

[Stunn3r]

Hey Guys,

I'm so confused right now. My research led me to believe this is a bolt on mod for a 1G with the right parts.
I currently have the whole brake kit (Caliper, Rotors, SS Lines) including the big brake adapter kit https://ctsvbrakeswap.com/collections/mitsubishi/products/1g2g-dsm-big-brake-kit-adaptor

How was this person able to install this BB kit with no issues as described above?

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Thanks.

 

[bastarddsm]

I'm just gonna put this out there, but if you are running the car hard enough that you need that much brakes, you shouldn't be running spacers. Also It's really hard to find wide wheels that actually fit. Nothing has enough offset, and spacers will make that worse.

third point, if you are going through the trouble of making spacers, it's not much more trouble to just make a rotor hat to use wilwood rotors. Wilwood rotors are not that much money.