V2 rotor/caliper retrofit for V1 cars
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Re: v2 calipers on v1????
Allow me to merge your post into the "V2 rotor/caliper retrofit for V1 cars" thread that was literally the top thread in the Performance Mods forum when you decided to post a new thread.
Bump for some brake rotor updates. I initially did my conversion using the original OEM 1-piece "co-cast" rotors. Then GM started offering the 2-piece Brembo rotors, so I've acquired a few sets of those over the past few years. Regardless of whether you use the 1-piece or 2-piece V2 rotors, if you intend to use them on V1 hubs, you have to enlarge the center bore (from 67.4 out to 70.7mm), and you have to redrill the bolt pattern to get your 6x115.
Recently, as I was browsing around for brake parts, I discovered something kind of curious. The V2 2-piece rotors are ACDelco 177-1145/1146. I thought that the ATS-V used the same brake setup as the V2, but it turns out the ATS-V has different part numbers for the 2-piece front rotors - 177-1193/1194. According to the specs I can find (clicking the "INFO" button on each part on Rock Auto), they're the same size - 370x34mm - so that made me wonder about the different part numbers. The only thing I can figure is that the hat offset is different; that's one spec that isn't listed for both rotors on Rock Auto (it shows the ATS-V rotor "height" is 2.4", but height isn't listed for the V2 rotors). Someone on LS1tech pointed me to centricparts.com, and sure enough, the specs they list there show the ATS-V rotors have a 10mm different offset (more on that in the pics below).
Similarly, some V7 Vettes (the '15+ C7 Grand Sport package) also run a 370x34mm 2-piece Brembo rotor. It's slotted, but apparently isn't directionally vaned, as I'm only seeing 1 part number - 177-1174. Based on the centricparts.com data, the offset of the GS Vette rotor is the same as the V2 rotor.
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I ordered 1 of each of the GS Vette and ATS-V rotors so I can compare them to the V2 rotors I've already got. In the case of the ATS-V rotors it's basically just for the curiosity's sake, as the rotors (at this point) are more expensive than the V2 rotors. The GS rotors are also more expensive, but if someone wants slotted rotors for the V2-calipers-on-a-V1 setup, then the GS rotors might be a way to get there.
I received an ATS-V rotor and a couple of GS Vette rotors and pulled them out of the boxes for a look.
- The ATS-V rotor hat visually has more offset than the V2 and Vette rotor hats. The rotor ring appears identical to the V2 rotor ring, with directional vanes.
- The GS Vette rotor hats appear to be the same offset (to the naked eye) as the V2 rotors, so that's good. The rotor ring is non-directional; it uses pillar vanes that look very similar to the original co-cast V2 rotors (this style). I have a couple of those co-cast rotors that I picked up last year when Amazon was doing the 20% off ACDelco deal, I'll have to pull one out and compare side-by-side with the GS Vette rotor.
Most importantly (for my purposes, sticking with 6-lug hubs), the GS Vette rotor hats have the same center bore as our V1 hubs (testing with an old hub I've got with all the studs knocked out). That makes modifying the rotors to fit the V1 a much easier/cheaper evolution, as I don't have to pay a machine shop to enlarge the center bore of the rotor from 67.4mm to 70.7mm, and instead just have to redrill the bolt pattern. That's something I'm able to do myself.
As of today the GS Vette rotors (ACDelco 177-1174) are ~$15ea more expensive than the V2 rotors (ACDelco 177-1145/1146) on Amazon, but that cost difference is more than made up for by not having to pay for machining. And as many of us have seen, the price of ACDelco stuff seems to bounce around quite a bit on Amazon, so in a few months the Vette rotors may be cheaper. (Or the V2 rotors may be $75ea cheaper instead of $15, who knows?!)
Some comparison pics.
First, ATS-V vs GS Vette rotor. Centric's catalog said there's a 10mm difference in offset, and you can see that pretty easily with the naked eye:
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The GS Vette rotor with one of my modified V2 rotor hats:
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Visually they look like the same offset, which jives with what Centric's catalog says:
![]()
And a straight edge across the two looks purty good:
![]()
Here you can see that the GS Vette rotor has the same type of non-directional, pillar style cooling vanes that the original V2 co-cast rotors have:
![]()
Recently, as I was browsing around for brake parts, I discovered something kind of curious. The V2 2-piece rotors are ACDelco 177-1145/1146. I thought that the ATS-V used the same brake setup as the V2, but it turns out the ATS-V has different part numbers for the 2-piece front rotors - 177-1193/1194. According to the specs I can find (clicking the "INFO" button on each part on Rock Auto), they're the same size - 370x34mm - so that made me wonder about the different part numbers. The only thing I can figure is that the hat offset is different; that's one spec that isn't listed for both rotors on Rock Auto (it shows the ATS-V rotor "height" is 2.4", but height isn't listed for the V2 rotors). Someone on LS1tech pointed me to centricparts.com, and sure enough, the specs they list there show the ATS-V rotors have a 10mm different offset (more on that in the pics below).
Similarly, some V7 Vettes (the '15+ C7 Grand Sport package) also run a 370x34mm 2-piece Brembo rotor. It's slotted, but apparently isn't directionally vaned, as I'm only seeing 1 part number - 177-1174. Based on the centricparts.com data, the offset of the GS Vette rotor is the same as the V2 rotor.
I ordered 1 of each of the GS Vette and ATS-V rotors so I can compare them to the V2 rotors I've already got. In the case of the ATS-V rotors it's basically just for the curiosity's sake, as the rotors (at this point) are more expensive than the V2 rotors. The GS rotors are also more expensive, but if someone wants slotted rotors for the V2-calipers-on-a-V1 setup, then the GS rotors might be a way to get there.
I received an ATS-V rotor and a couple of GS Vette rotors and pulled them out of the boxes for a look.
- The ATS-V rotor hat visually has more offset than the V2 and Vette rotor hats. The rotor ring appears identical to the V2 rotor ring, with directional vanes.
- The GS Vette rotor hats appear to be the same offset (to the naked eye) as the V2 rotors, so that's good. The rotor ring is non-directional; it uses pillar vanes that look very similar to the original co-cast V2 rotors (this style). I have a couple of those co-cast rotors that I picked up last year when Amazon was doing the 20% off ACDelco deal, I'll have to pull one out and compare side-by-side with the GS Vette rotor.
Most importantly (for my purposes, sticking with 6-lug hubs), the GS Vette rotor hats have the same center bore as our V1 hubs (testing with an old hub I've got with all the studs knocked out). That makes modifying the rotors to fit the V1 a much easier/cheaper evolution, as I don't have to pay a machine shop to enlarge the center bore of the rotor from 67.4mm to 70.7mm, and instead just have to redrill the bolt pattern. That's something I'm able to do myself.
As of today the GS Vette rotors (ACDelco 177-1174) are ~$15ea more expensive than the V2 rotors (ACDelco 177-1145/1146) on Amazon, but that cost difference is more than made up for by not having to pay for machining. And as many of us have seen, the price of ACDelco stuff seems to bounce around quite a bit on Amazon, so in a few months the Vette rotors may be cheaper. (Or the V2 rotors may be $75ea cheaper instead of $15, who knows?!)
Some comparison pics.
First, ATS-V vs GS Vette rotor. Centric's catalog said there's a 10mm difference in offset, and you can see that pretty easily with the naked eye:
The GS Vette rotor with one of my modified V2 rotor hats:
Visually they look like the same offset, which jives with what Centric's catalog says:
And a straight edge across the two looks purty good:
Here you can see that the GS Vette rotor has the same type of non-directional, pillar style cooling vanes that the original V2 co-cast rotors have:
I finally bought a postal scale, so I can get more accurate weight information for relatively light stuff like this. Adding to what I posted 4-1/2 years ago...
OEM V2 1-piece co-cast rotor: 25.5# (demonstrates how well the co-cast design saves weight - only 0.4# heavier, despite a rotor that is 15mm larger diameter and 2mm thicker)
OEM GS Vette 2-piece rotor: 23.75#
OEM ATS-V 2-piece rotor: 27.5#
The only V2 2-piece rotors I have on hand are used, so the weight would be off by some amount. I think my current track rotors (which are on the car) are the least worn, so I'll weigh those when they come off the car; should be able to do that tomorrow.
The 4# difference between the GS Vette and ATS-V rotors caught me by surprise. There's obviously a little extra weight in the ATS-V hat, and the Vette rotor loses some weight with the slotting, but I would think the majority of the difference is due to the different rotor ring styles (curved vane vs pillar vane). That leads to an interesting question: Is it better to have 3-4# less unsprung & rotating weight, or is it better to have a rotor with more mass to handle the thermal loads?
OEM V1 1-piece rotor: 25.1#
OEM V2 1-piece co-cast rotor: 25.5# (demonstrates how well the co-cast design saves weight - only 0.4# heavier, despite a rotor that is 15mm larger diameter and 2mm thicker)
OEM GS Vette 2-piece rotor: 23.75#
OEM ATS-V 2-piece rotor: 27.5#
The only V2 2-piece rotors I have on hand are used, so the weight would be off by some amount. I think my current track rotors (which are on the car) are the least worn, so I'll weigh those when they come off the car; should be able to do that tomorrow.
The 4# difference between the GS Vette and ATS-V rotors caught me by surprise. There's obviously a little extra weight in the ATS-V hat, and the Vette rotor loses some weight with the slotting, but I would think the majority of the difference is due to the different rotor ring styles (curved vane vs pillar vane). That leads to an interesting question: Is it better to have 3-4# less unsprung & rotating weight, or is it better to have a rotor with more mass to handle the thermal loads?
2007 SRX4 Sport V8 Magride, 1975 Coupe deVille, 2013 CTS-V Coupe
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306 Posts
AAIIIC,
Thanks for all the great info. Sorry for reviving a very dead thread, but this is good stuff.
I’m looking to install V2 brakes on my gen1 SRX. If I’m understanding this correctly, I should go with C7 GS rotors (drilling them out for the 6 lug pattern), drill out the mounting bolt holes to accept the larger bolts, but I’m unclear as to what the best solution is to address the slight offset between caliper and rotor? Additionally, I understand there are some additional hurdles with the rear brakes?
Any help would be appreciated!
Thanks for all the great info. Sorry for reviving a very dead thread, but this is good stuff.
I’m looking to install V2 brakes on my gen1 SRX. If I’m understanding this correctly, I should go with C7 GS rotors (drilling them out for the 6 lug pattern), drill out the mounting bolt holes to accept the larger bolts, but I’m unclear as to what the best solution is to address the slight offset between caliper and rotor? Additionally, I understand there are some additional hurdles with the rear brakes?
Any help would be appreciated!
Funny that you've bumped this thread, because I've just finally revived this topic myself. 
After posting all that info back in 2017, I really hadn't done anything with the rotors, because I had some modified V2 rotors on hand for track duty and was able to use those through the 2018 track day "season". In 2019 I didn't get to any events, and this year I haven't done any events ... until next weekend. I had used up the V2 rotors, so it was time to figure out using the Vette rotors. This evening I installed my modified V2 hats onto the Vette rotor rings; I still need to drill the 6x115 pattern onto the Vette hats, so I'll then have 2 sets of hats with the proper bolt pattern.
.) Everything should line up fine. The only thing I can think of is that I have brake cooling ducts installed, and those sandwich between the hub and knuckle; the aluminum is thicker than the steel ABS wiring bracket that was originally sandwiched in there, but that little difference hasn't impacted anything.
After posting all that info back in 2017, I really hadn't done anything with the rotors, because I had some modified V2 rotors on hand for track duty and was able to use those through the 2018 track day "season". In 2019 I didn't get to any events, and this year I haven't done any events ... until next weekend. I had used up the V2 rotors, so it was time to figure out using the Vette rotors. This evening I installed my modified V2 hats onto the Vette rotor rings; I still need to drill the 6x115 pattern onto the Vette hats, so I'll then have 2 sets of hats with the proper bolt pattern.I'm not sure what offset you're referring to. (I say that without remembering what I may have typed here in the past
.) Everything should line up fine. The only thing I can think of is that I have brake cooling ducts installed, and those sandwich between the hub and knuckle; the aluminum is thicker than the steel ABS wiring bracket that was originally sandwiched in there, but that little difference hasn't impacted anything.The V1 and V2 rear brake setup is the same (other than the obvious bolt pattern difference). I installed the V2 rear calipers just because I wanted the matching yellow calipers all around. I can't speak to any hurdles on the SRX, like if the parking brake is a different size or something like that.
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