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V rear calipers on a Vsport? Will it work?

39K views 168 replies 24 participants last post by  Lifespeed 
#1 ·
I was considering picking up a pair of V2 rear calipers and swapping for the stock units - Anybody know if it's a direct swap??
 
#2 ·
I have thought about this as well. I still haven't confirmed it. However some websites that show compatibility say it is not compatible. But I don't even think they would've tried to find out.

Also there is talk about how it's not too smart to change the brake bias on the car.
 
#3 · (Edited)
Also there is talk about how it's not too smart to change the brake bias on the car.
This...,,if you want V brakes do all of it....rotors and calipers, front and rear....or at minimum if the rotors are compatible calipers only.....otherwise your monkeying with a Nurburgring tuned brake setup, no need to throw that out of whack, plus you'd also likely be throwing stabilitrak and ABS out of whack too....going from a single piston sliding caliper to a 4 piston unit is a huge change and balance will be changed for some weirdness, partly due to clamping power, and partly due change in fluid use..... the amount of fluid used to move 4 Pistons vs 1 would at least triple and change pedal travel and add mushiness

You'd still affect the pedal changing all 4 but at least you'd be balancing out rear changes with similar changes in front

keep the parts that relate to each other together for best results

Doing this right....can also help make best use of a wheel tire upgrade later down the road

Stock the V-Sport brakes are excellent, and are even better with the optional performance pads.....so the only reason I see for upgrading the rear only is cosmetic....but this would not work cosmetically either since V-Sport Brembos are gray but V Brembos are silver, gold, or red, so Unless you paint all 4 after upgrading rears only you'd be going from a meh looking rear brake to a goofy looking brake system
 
#6 ·
in that case i wouldn't even bother with trying to figure out Cadillac OEM Brembos and call a brembo distributor and get some 2 pot calipers that fit the V-Sport
Auto part Brass Metal

....a 2 piston Brembo is a nice upgrade from the 1 piston floating GM rear brake and should balance decently with the 4 piston front already installed on the car.....remember, the V-Sport front caliper is essentially the V rear caliper, so doing 4 pot in the front and 4 pot in the rear could get weird for the car but 2 pot rear and 4 pot front is a common pairing...you end up with the same setup as the WRX STI
 
#15 · (Edited)
and the size of the floating caliper piston?....since OP doesn't like the look of the floating and wants a brake upgrade to correct the issue....i suspect your arguments are moot because he can't help but increase 'effective' piston area because he'd be adding an entirely unused size....case in point....a typical GM floating piston is around 40-45 mm this will give an area of 1589 mm (using 45mm to be generous to your argument) and the dual pot brembos i suggested looking into are 2x36 mm which gives us an area of 2034 mm....which takes us right back to the beginning before this effective area talk.....this change leads to more pistons, which changes the equation for the entire braking system, which could get weird
 
#16 ·
Piston count non-issue aside, your math is wrong; as stated earlier, you have to double the sliding caliper piston area to come up with effective area. The single 45mm piston in a slider would give you an effective area of 3179 sq mm. Your 2x36 is going to be woefully inadequate.

But FWIW, I don't think the V-Sport piston is that big. I can't find that diameter with a few quick searches, but based on a quick eyeball of the externals, and a data table of rear sliding caliper single piston diameters for GM cars over the past 30 or so years, I'd wager it's closer to 40mm, give or take a couple. A 40 mm piston calculates to 1256 x 2 = 2512 sq mm. A two piston fixed caliper would of course have to be the same 40 mm diameter for the same clamping force. A 4 pot fixed caliper with 28mm pistons would be within about 2 percent of the same area. Either of those would certainly be within the realm of available aftermarket caliper configurations. But the mounting bracket pieces would most likely be the long pole in the tent... I checked Wilwood for instance, and they have no bracket kits for the CTS, front or rear.

I'm sticking with my original statement, quoted here for your convenience :) "But you have to remember it's total piston area per caliper that's the key factor, regardless of pot count...."
 
#21 ·
In the first four examples, the fact it's not mentioned is certainly not proof that it's not valid. But from the 5th link (where you say they "partly" agree with me), they do mention it, you just have to be able to read and comprehend. :) Here's the quote from the Wilwood paper:

"A calipers piston area is calculated by finding the total piston area from one side of the caliper (this is true for a single piston caliper also)." (underscore emphasis mine)

What this says is that if you want to compare floating and fixed caliper piston areas on an even basis, you only look at one half of the caliper - ignoring the fact the floating caliper only has piston(s) in one side.

I did a quick search on the subject and came up with this site which deals with actual calculations. It very clearly spells out the need to double the piston area on floating calipers. In fact it's mentioned twice...

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Edit:

And another calculator complete with a note (under "Terms and Values Explained") that states exactly what I've been saying from the get-go. Here's the quote:

"Note: multi piston calipers express their values using one HALF of the caliper body. This accounts for the floating aspect of the single piston caliper. A six pot caliper would be 1.625/1.125/1.125" for example. True clamping force would be double that but also double the single piston of a floating caliper taking into account the 'pull' of the outer pad to the rotor surface. Using total area (all six for example) would require you double that of the floating caliper also- thus the net result is the same whichever way you do it."
if by comprehend you mean make up stuff they didn't say, you'd be right...but like i said they partly agree with you by saying one side, but they don't say multiply by two, and neither does your quote from them say it....you were reaching on that one

in the end we have differing information hence the :hmm:
 
#22 ·
if by comprehend you mean make up stuff they didn't say, you'd be right...but like i said they partly agree with you by saying one side, but they don't say multiply by two, and neither does your quote from them say it....you were reaching on that one

in the end we have differing information hence the :hmm:
Actually, in the end we have you refusing to believe something that is pretty much 6th grade physics. What's your opinion of the other two quotes I pointed out... the ones associated with caliper piston area calculators? They made that stuff up too? :)
 
#23 ·
Direct swap meaning what? If you mean change nothing but the caliper, no, it's not a direct swap - the V2 rear rotors are 365mm diameter vs 315mm diameter for the VSport. So, even without knowing how the offsets of the calipers compare, or how the mounting bolt spacing compares, we know that the V2 caliper would not work with the VSport rotors. You'd need the V2 rotors to match up to the calipers, but to use those you'd need to know if the parking brake diameter is the same, and if the rotor/hub offset would match up right.

Basically, I think the only way to answer the questions would be to buy the parts and do a test fit. A V2 rear caliper can be had for ~$165 via Amazon Prime - take some measurements, return it if you end up not needing it. You'd just be out the shipping cost. A rear rotor can be had for ~$35; again, if you don't need it, return it.


This...,,if you want V brakes do all of it....rotors and calipers, front and rear....or at minimum if the rotors are compatible calipers only.....otherwise your monkeying with a Nurburgring tuned brake setup, no need to throw that out of whack, plus you'd also likely be throwing stabilitrak and ABS out of whack too....going from a single piston sliding caliper to a 4 piston unit is a huge change and balance will be changed for some weirdness, partly due to clamping power, and partly due change in fluid use..... the amount of fluid used to move 4 Pistons vs 1 would at least triple and change pedal travel and add mushiness.
Without knowing the piston diameters involved you can't make that sort of statement.

in that case i wouldn't even bother with trying to figure out Cadillac OEM Brembos and call a brembo distributor and get some 2 pot calipers that fit the V-Sport
View attachment 410049
Did you bother to check to see if Brembo even offers such a thing?

remember, the V-Sport front caliper is essentially the V rear caliper
No, it isn't. The VSport front caliper is significantly larger. Compare a FMSI D1001 pad vs a D592 pad and you'll see.

so doing 4 pot in the front and 4 pot in the rear could get weird for the car but 2 pot rear and 4 pot front is a common pairing.
Again, the number of pistons has nothing to do with this, it's the area of the pistons that matters. My V1 came from the factory with 4-piston Brembos front and rear and that wasn't weird at all.

it's actually more than piston area....it's piston area, volume of fluid required for a given travel of pistons in calipers (slave), # of pistons,
All of which is the same thing.

volume of fluid displaced by plunger/piston (master), leverage applied to plunger (travel & length of lever which is typically a brake pedal or brake lever) , and force applied to lever.....its because of these factors i said the brakes will get weird
How are any of these factors being affected by changing the rear calipers? :confused:

if by comprehend you mean make up stuff they didn't say, you'd be right...but like i said they partly agree with you by saying one side, but they don't say multiply by two, and neither does your quote from them say it....you were reaching on that one

in the end we have differing information hence the :hmm:
Denrael is correct, you are not. If you understand how a sliding caliper works then it's obvious why you have to double the piston area; the force generated by the piston(s) acts on both sides of the rotor. So when you're comparing fixed vs sliding calipers, you either double the sliding caliper's piston area, or you only use 1 side of the fixed caliper.
 
#25 ·
Meanwhile, even ignoring the dimensional aspects (mount bolt spacing, offsets, parking brake, etc.), I think we have an answer to the OP's question. It appears the V-Sport rear caliper piston is 43 mm, so that puts us at 1451 sq mm, vs the V2's 28/32 mm pistons at 1419. This is only 2+% less area with the V2 caliper; not a bad match, so far, so good. But assuming we use the matching 365mm V2 rotor, we introduce a 50mm difference in diameter, which is going to upset the balance significantly. I don't know the exact effective radii (measured at the center of the respective pads) of the two setups, but my guess is it would be enough to generate something on the order of a 15-20% increase in braking torque. Not good... at least not without a corresponding braking torque increase at the front end of the car.
 
#28 ·
:want:This is good stuff though. It gives us answers from people that know their stuff. A debate is always good because the best answers will come out in the end. I'm not a brake caliper genius so I like to hear all aspects of a debate. I won't really know though until I see someone change out the rear calipers because this is something I would like to do.
 
#43 ·
BTW - HOW do you get pictures uploaded here. Every time I try it says they are too big?!
It said they were too big because they were too big. The "Manage Attachments" box tells you exactly what the size limits are - 1024x768, 390.6kb. Your first two images are 1066x800. There are a bazillion programs that will resize JPEGs - I would think a Mac would do it automatically if you just say, "Steve Jobs' ghost, please resize my images." :p

Here is a link to the pictures of my car with the calipers. Let me know what you think and if you have any questions!
I replaced the links with the actual images embedded into the post. If you go to your images on postimage.org and click on the "Share" button, you're provided with a variety of ways to share the images. I copied the "Direct Link" and put tags on either side. That embeds the image directly into your post, and that way people don't have to click a link to open up another site to see your pictures.

[QUOTE="jasonwoodard, post: 16058970, member: 946417"]And it seems I was able to save the photos small enough to get them to upload here too[/QUOTE]
Actually, you saved them [I]way more than[/I] small enough! :lol: I don't know what you used to resize them, but going all the way down to 320x240 is overkill.



OK, picture discussion aside, let's get back to the brakes ...
[QUOTE="jasonwoodard, post: 16054025, member: 946417"]I was told by an engineer very familiar with the system that it is. In addition, the current gen rear Camaro SS caliper is a direct swap and so is the current gen rear Corvette caliper on base models.[/quote]
I don't understand what that engineer was saying. Those calipers might bolt up to the spindle just fine, but they're not a direct swap; as already discussed in this thread, those calipers are all designed for significantly larger rotors (365mm on the CTS-V and Camaro, 338mm on the base C7).

[QUOTE="jasonwoodard, post: 16054025, member: 946417"]I have installed the later on mine - pictures forthcoming.[/QUOTE]
So what rotors size are your rotors? Did you upgrade to larger rotors to match the C7 rear calipers, or do you have massive pad overhang using the stock VSport rotors with Vette calipers?

[QUOTE="jasonwoodard, post: 16059274, member: 946417"]I installed slotted rotors as part of the kit. Plus, I went with a 17" front caliper and the OE rotor was 18" so it would have had to be changed anyways.[/QUOTE]
:confused: 17" caliper and 18" rotor? Can you explain what you mean by that? The stock VSport rotor isn't anywhere near 18" (or 17", for that matter).
 
#34 ·
I am a Windows guy and know a little about MAC because I have to use it at work. I did a Google search for "photo editor software free download mac" as key words and found this site. Not sure if this one is free but you can try it to see if it will work the way you want. If not try one of the other free editors from this sort of search. "Google is your friend!" :)

https://itunes.apple.com/us/app/fotor-photo-editor/id503039729?mt=12

Here is another site that boasts 10 different Free editors for MAC

http://www.apartmenttherapy.com/10-free-photoshop-alternatives-145709

BTW - The hosting site is probably a place you can load your photo then use a link on this forum to open the pic, at least this is my guess as I have not tried this.

Good Luck
 
#35 ·
Martinm is right. The hosting site gives you a link that is compatible with the forum. When the code in the forum site sees a link it knows it's not supposed to write out a link for the users to see, it's supposed to show the picture that the link goes to. That way, cadillacforums.com doesn't have to use their space to store your photos.

It's better that way. When they want them so small for uploading they lose detail. Use a hosting site. I don't know others, I've used photobucket for probably a decade. It's free
 
#47 ·
I didnt drive it long enough with the old brakes to really do a comparison. But I have to believe that changing the stock rears out with 4 pot fixed calipers is a huge step up. And the slotted rotors have to help. I am very happy with the current system, although the brake dust on the front means it needs a good bath every week or two!

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Hi. You can get this as a kit from the dealership MINUS the rear calipers. Those are not available. That was a purely custom setup because I worked at the manufacturing plant :)

Now, if you want to buy a set of rear Corvette calipers, you will have this same setup. The only problem is the logo. It will have the Corvette logo. It takes a lot of work to get those off but it is possible. Then you could buy a good brembo logo that is hi-temp resistant or simply leave it bare.

But the front red calipers and the slotted rotors are an upgrade kit at your Caddy dealership.

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Hi guys. I have been offline for a while. new job keeping me going long days.

I am no engineer, so excuse the lack of technical description here. But this is basically what I did to this car.

The front calipers and all four rotors are an upgrade kit available through GM.
The rear calipers are current gen Corvette and Camaro rear calipers. They have a Cadillac logo on them, which is not available on the market. I had that custom made.

The rotors are undersized yes. But its the kit that was available. I chose not to buy larger rotors for simplicity and cost.

Make sense?
 
#48 ·
The rotors are undersized yes. But its the kit that was available. I chose not to buy larger rotors for simplicity and cost.

Make sense?
The unanswered question in my mind was brought up by AAIIIC in an earlier post and is important enough to bear repeating. Did you end up with pad overhang on the rear brakes, using the stock rotor with a caliper designed for larger diameter rotors? If so, how much?
 
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