ACR calipers w steel rotor upgrade on my 13 GTS

[pony23]

I decided to do a big brake upgrade on my 13GTS. It really bothered me that all the other cars out there come with big rotor, 6 pot caliper setups (Challengers, Mustang, Camaro, Vettes, etc) and the Viper coming with the tiny rotor, 4 pot setup (until the ACR). I saw the swap that was done on here converting over to the ACR carbon brakes, that is out of my price range. After looking at kits out there and the fact that I prefer factory equipment, that led me to do the ACR calipers with the steel rotor conversion. Plus I think I can make the kit cheaper than buying one already built. I put this on the gram, but this is a little more in depth. Here is the parts breakdown.

Right ACR caliper 68270298AA - $604
Left ACR caliper 68270299AA - $604
Caliper hardware kits 68203105AA - $22 x 2
Girodisc ACR steel rotors - $1400
EBC yellow stuff pads DP41853R - $167

That totals out to about $2819 not including shipping and taxes.

https://i300.photobucket.com/albums/nn30/dsg03vert/2013%20viper%20gts/F426C83C-4D9D-4F62-A321-D12ED7261C96_zpslraobjej.jpeg (https://s300.photobucket.com/user/dsg03vert/media/2013%20viper%20gts/F426C83C-4D9D-4F62-A321-D12ED7261C96_zpslraobjej.jpeg.html)

Man these calipers are beautiful. After my initial mockup I noticed that the lower section of caliper hits the knuckle a little bit. It requires a small amount of the bottom of the knuckle to be clearanced. Being it is made of aluminum it was easy to do either with a file or a grinder and sanding wheel. I didn’t even have to sand into the area where the two surfaces meet up. The knuckle is much larger than the two mating surfaces.

https://i300.photobucket.com/albums/nn30/dsg03vert/2013%20viper%20gts/1292EA3D-E55C-4902-BA53-A01549F82111_zpsx18xaytw.jpeg (https://s300.photobucket.com/user/dsg03vert/media/2013%20viper%20gts/1292EA3D-E55C-4902-BA53-A01549F82111_zpsx18xaytw.jpeg.html)

https://i300.photobucket.com/albums/nn30/dsg03vert/2013%20viper%20gts/77F26457-451D-4942-8D2B-D8BC0087584D_zps4ea7jd97.jpeg (https://s300.photobucket.com/user/dsg03vert/media/2013%20viper%20gts/77F26457-451D-4942-8D2B-D8BC0087584D_zps4ea7jd97.jpeg.html)

[LATAMUD]

I've heard the ACR front knuckles were different, I've looked them up and don't know why. My guess was they had longer mounting points to push the calipers outward more to accept the 15.5" rotors. Do the ACR calipers bolt up to the standard knuckle with the ACR 15.5" rotors? Or do you need to space it out the 3/4"? I was installing an 8 pot setup on my Gen4 but was talked out of it due to ABS bias issues for the track. If this works as is without knuckle or spacers needed I'll probably go this route. It was the knuckles that were holding me back.

[pony23]

I went with the Girodisc rotors because they match my rear rotors pretty well. They do weigh in more but that’s understandable being they are 15.5” in size over the stocks which are only 14”. I personally don’t care about the few extra lbs. but that’s me.

https://i300.photobucket.com/albums/nn30/dsg03vert/2013%20viper%20gts/69A23714-39A9-4459-9F5B-13BA92D68A6A_zpsyqfmh3s6.jpeg (https://s300.photobucket.com/user/dsg03vert/media/2013%20viper%20gts/69A23714-39A9-4459-9F5B-13BA92D68A6A_zpsyqfmh3s6.jpeg.html)

https://i300.photobucket.com/albums/nn30/dsg03vert/2013%20viper%20gts/B3BCFCBA-B91C-4A82-AE09-8488C7D8D89E_zps6sjxtuvq.jpeg (https://s300.photobucket.com/user/dsg03vert/media/2013%20viper%20gts/B3BCFCBA-B91C-4A82-AE09-8488C7D8D89E_zps6sjxtuvq.jpeg.html)

https://i300.photobucket.com/albums/nn30/dsg03vert/2013%20viper%20gts/4A659C47-1B7F-4DF8-96E0-E3812979425D_zps0bxymvvf.jpeg (https://s300.photobucket.com/user/dsg03vert/media/2013%20viper%20gts/4A659C47-1B7F-4DF8-96E0-E3812979425D_zps0bxymvvf.jpeg.html)

https://i300.photobucket.com/albums/nn30/dsg03vert/2013%20viper%20gts/B22E7C11-0058-435F-9AD5-CD752B31AD2B_zpsgmej6hrr.jpeg (https://s300.photobucket.com/user/dsg03vert/media/2013%20viper%20gts/B22E7C11-0058-435F-9AD5-CD752B31AD2B_zpsgmej6hrr.jpeg.html)

[pony23]

I've heard the ACR front knuckles were different, I've looked them up and don't know why. My guess was they had longer mounting points to push the calipers outward more to accept the 15.5" rotors. Do the ACR calipers bolt up to the standard knuckle with the ACR 15.5" rotors? Or do you need to space it out the 3/4"? I was installing an 8 pot setup on my Gen4 but was talked out of it due to ABS bias issues for the track. If this works as is without knuckle or spacers needed I'll probably go this route. It was the knuckles that were holding me back.

All you have to do is clearance the bottom of the knuckle to bolt it up.No spacers needed.

[SLP]

Great idea. Does anyone know if there are any other differences between ACR/nonacr knuckles? Also, I take it these won't fit behind 18" front SWIIs and instead will require ACR sized wheels?

[pony23]

i decided to go with EBC yellow stuff pads for now. They came recommended from a few people that I know. After talking to the guys at Girodisc, they informed me that I must use a pad that is FMSI 1405 in shape to clear the rotor hat. So any pad will work that is that shape with these rotors.

https://i300.photobucket.com/albums/nn30/dsg03vert/2013%20viper%20gts/8799580C-7863-4993-8C42-B82F5A08BFD3_zpsw0qid1t0.jpeg (https://s300.photobucket.com/user/dsg03vert/media/2013%20viper%20gts/8799580C-7863-4993-8C42-B82F5A08BFD3_zpsw0qid1t0.jpeg.html)

Everything cleared my 19” wheels nicely with plenty of room to spare. Now I just need to bleed the system and bed the pads. Just have to wait for spring to come here in New England.

https://i300.photobucket.com/albums/nn30/dsg03vert/2013%20viper%20gts/CB8BF609-F700-4F78-BE32-E3E17CA83F3A_zpsm96df5hk.jpeg (https://s300.photobucket.com/user/dsg03vert/media/2013%20viper%20gts/CB8BF609-F700-4F78-BE32-E3E17CA83F3A_zpsm96df5hk.jpeg.html)

[pony23]

Great idea. Does anyone know if there are any other differences between ACR/nonacr knuckles? Also, I take it these won't fit behind 18" front SWIIs and instead will require ACR sized wheels?

1of1TA1.0 also used the stock knuckles in his upgrade. https://driveviper.com/forums/threads/15131-ACR-CCB-s-on-non-ACR-Gen-V

[LATAMUD]

Thanks all! Definitely happening on my car this summer.

[sharmut]

If I recall correctly it was the rear knuckles that's different.

[LATAMUD]

If I recall correctly it was the rear knuckles that's different.

I saw that in the linked post. I'm thinking up a way to make a bracket to space out the e-brake caliper.

[pony23]

I saw that in the linked post. I'm thinking up a way to make a bracket to space out the e-brake caliper.

You don’t need to touch the rear brakes using the steel front rotor. The rear can stay as is. Can always look at that down the road if you want to upgrade the system to carbon at a later date. I thought I read that Racing Brake had a fix for that too

[BSLSK]

Did you notice huge improvement after the upgrade?

[dsp300c]

so this is to replace just the front only on a base model srt? nothing needs to be done to the rear? i currently have stock sized Stoptech rotors on front and rear.



EDIT: think i found my answer. acr has 4 piston rear and 6 piston front. so putting 6 piston up front would look similar to the acr. i may do this so the wheel is filled up more on my 19" front aftermarket wheels.

[pokeyl]

I know this is an old thread but were did you get the ACR caliper from? I have a set of ACR steel rotors at the house now.

[TBSH]

Badass swap for sure!

[pony23]

I bought them directly from mopar. It was from one of the many online sellers.

[pokeyl]

I had to pay 800 per caliper, but I also picked up a used set or CCM Rotors.
I'll use the CCM for auto-x and street
Iron for High Speed events, 800 for new rings I can do.

I'll stay iron only in the rear for now.

[No hemi]

Great Info, will be doing this to my car hopefully soon!!

[viper04]

Nice Post, good info.