# Rear Brake Conversion



## FatKidsCruze (Sep 2, 2011)

Best bet is to find out part #s for an LTZ as they come with discs from the factory. If they are like most car makers you should be able to order the parts and swap them over. 

Im not stating that is all you have to do only thats where I would start if attempting the same. I've done rear disc conversions on Hondas and it wasn't all that hard. The hardest part was routing the ebrake cables. Oh and you'll also want to use an LTZ Proportioning valve to get the proper power distribution.


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## sciphi (Aug 26, 2011)

Neat! Let us know how it turns out, and what hurdles to watch out for! 

The only snag might be the slightly different rear suspension setups the Eco has over the LTZ. The Eco has a regular twist-beam, while the LTZ has the Watts-link twist-beam.


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## FatKidsCruze (Sep 2, 2011)

That was my thought as well different suspension setups may be a pretty big hurdle. But then again maybe not research will tell though!

Hmm better yet just find a wrecked LTZ In the salvage yard pull the whole rear suspension including rear hubs and swap it out on your Eco.


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## iCruze2 (Dec 16, 2011)

FatKidsCruze said:


> That was my thought as well different suspension setups may be a pretty big hurdle. But then again maybe not research will tell though!
> 
> Hmm better yet just find a wrecked LTZ In the salvage yard pull the whole rear suspension including rear hubs and swap it out on your Eco.


I wish I could "like" this, hahaha


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## H3LLON3ARTH (Dec 16, 2011)

Thanks for the advice i know i will have to put the master cylinder off the ltz to for the reason that the two sectioned brake fluid resivors are for front and rear brakes.


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## maven (Feb 27, 2011)

You dont need to "make" anything, its a bolt on affair with all GM parts.


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## Skilz10179 (Mar 22, 2011)

maven said:


> You dont need to "make" anything, its a bolt on affair with all GM parts.


That's exactly what I was going to say.


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## 72oly300 (Apr 9, 2011)

How do you know the mastercylinder needs to be changed? Generally, GM front drivers are a "x" split, not front/rear. There are no proportioning valves anymore. Just curious. I would check to see if the m/cyl p/n is different. If so, it could have a different fluid reservoir size to compensate for different fluid volume needs for the calipers vs. drums.


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## iCruze2 (Dec 16, 2011)

iCruze2 said:


> I wish I could "like" this, hahaha


Oh wait I can!


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## Skilz10179 (Mar 22, 2011)

FatKidsCruze said:


> That was my thought as well different suspension setups may be a pretty big hurdle. But then again maybe not research will tell though!
> 
> Hmm better yet just find a wrecked LTZ In the salvage yard pull the whole rear suspension including rear hubs and swap it out on your Eco.


The Eco has the same suspension minus the watts link, it shouldn't have anything at all to do with the brake system.


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## FatKidsCruze (Sep 2, 2011)

Well there ya go! Now just go get ur parts Op and enjoy your new rear discs.


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## ShyEco (Dec 14, 2011)

They did it - SEMA 2011 - R Miller Chevy Cruze

You could look into the Wilwoods.They are a USA company and have a huge inventory. You can pretty much pick and choose what parts you want and put everything together if they do not have a kit. May need to make some custom hats for the rotors and mounting brackets for the calipers, but any machine shop could do that.


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## maven (Feb 27, 2011)

Or you could go with GM parts which have properly sealed calipers and are designed to work with the car from the get go, disc brakes on the Cruze just bolt on, its not like a Cobalt with a different rear axle between drum and disc cars


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## FatKidsCruze (Sep 2, 2011)

maven said:


> Or you could go with GM parts which have properly sealed calipers and are designed to work with the car from the get go, disc brakes on the Cruze just bolt on, its not like a Cobalt with a different rear axle between drum and disc cars


This is making me want to swap mine out...


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## maven (Feb 27, 2011)

FatKidsCruze said:


> This is making me want to swap mine out...


I already have it planned for when I get mine.....that is if they dont come out with a "big block" version before I buy one. If they dont verify at least 200hp or more version for 2013, Ill probably just buy a 1LT late in 2012.


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## H3LLON3ARTH (Dec 16, 2011)

well because the master cylinder and the resivour on top are different its like that on every car that has rear disc brakes how do you think the fluid get to the back brakes.


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## maven (Feb 27, 2011)

H3LLON3ARTH said:


> well because the master cylinder and the resivour on top are different its like that on every car that has rear disc brakes how do you think the fluid get to the back brakes.


Are you serious? these arent the days of full drum brake cars where we have single outlet master cylinders. Cobalts all use the same master cylinder regardless of brake system(10.2" disc w/drum, 11" disc w/drum, 11" frt/rr disc, 11.6" frt/rr disc, and Bremob frt/rr disc), and Im almost positive though I have checked part numbers, that Cruzes do as well.


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## NBrehm (Jun 27, 2011)

i looked at this briefly and decided ti wasn't worth the money unless you found a wrecked Cruze, But from what I ventured you need
calipers
Rotors
Pads
Backing plates
wheel hubs
rear brake lines

Think that is all it really takes, the master cylinder is the same, as is the ABS block. There is no proportioning valve to worry about


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## maven (Feb 27, 2011)

NBrehm said:


> i looked at this briefly and decided ti wasn't worth the money unless you found a wrecked Cruze, But from what I ventured you need
> calipers
> Rotors
> Pads
> ...


That sounds right except for the hubs. Could you explain why you believe you need hubs? I have zero reason to believe that to be true.


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## GoldenCruze (Dec 18, 2011)

The brake cylinder issue can be verified at a parts counter. If the same master brake cylinder is supplied for either the rear drum or rear disk setup, then there ya go.


But there is a fly in the ointment that hasn't been mentioned yet. That's the antilock system and the computer control that goes with it. A conversion from drum to disk could throw that out of whack.


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## maven (Feb 27, 2011)

Any difference between the two calibrations is likely to be minimal. And worst case scenario is that anti lock events take a few more milliseconds before the valve work gets the desired results. There's no difference in the "fly in the ointment" in this scenario than there is when you run a non stock sized tire. All the abs system does is monitor and control brake pressure based on wheel deceleration rates. If its locked it block edal pressures and releases the apply pressure, once its not locked it reapplies pedal pressure . Hold/decrease/increase/repeat. It doesn't care what is providing the friction. On the street you would likely NEVER notice a difference. On the track?maybe.....but who is road racing their cruze right now ?


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## NBrehm (Jun 27, 2011)

maven said:


> That sounds right except for the hubs. Could you explain why you believe you need hubs? I have zero reason to believe that to be true.


You appear to be correct, GM has them listed as separate parts, one for disc, one for drums but if you chase the part numbers they are the same. I'd check at a dealer to be sure, don't know why they would have them listed as separate parts but with the same number

Edit: also forgot the caliper brackets


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## H3LLON3ARTH (Dec 16, 2011)

well now that ive looked at it i dont think it will be all that hard see this is why i like forums and this is one of the bes ive joined the hubs are the same and all you have to do is see if i have a place to put the caliper braket thats the biggesty issue everything else is rather bolt on thanks for all your input opefully it will be together on my 2012 cruze in about 2 monthst depending on if willwood or brembo can help me with a caliper choice and rotor choice because if i do this i dont want stock whats the poin in that


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## NBrehm (Jun 27, 2011)

Ahhh well than you can throw out everything we just discussed because there could be numerous changes with aftermarket brakes.


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## maven (Feb 27, 2011)

H3LLON3ARTH said:


> well now that ive looked at it i dont think it will be all that hard see this is why i like forums and this is one of the bes ive joined the hubs are the same and all you have to do is see if i have a place to put the caliper braket thats the biggesty issue everything else is rather bolt on thanks for all your input opefully it will be together on my 2012 cruze in about 2 monthst depending on if willwood or brembo can help me with a caliper choice and rotor choice because if i do this i dont want stock whats the poin in that


tHE POINT IS THAT YOUR CAR IS STOCK WITH DRUM BRAKES SO switching to OEM discs isnt stock.... :lol: But seriously, aftermarket brakes that will last as long as GM stuff are going to be retarded expensive, and will offer very little performance upgrade for their additional cost. Go with GM hard parts and quality friction (Hawk, Cobalt, Carbotech, PFC) and youll have all the rear brake you need. Now for fronts Id want to see about using Camaro rear brembos, or Cobalt fronts. Or go big (and therefore very heavy) and get Regal front Brembos. The Cruze isnt fast enough to need more brake than the Cobalt SS, its Brembos would be an awesome upgrade.


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## maven (Feb 27, 2011)

sorry about the caps....unintentional


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## H3LLON3ARTH (Dec 16, 2011)

Well I'm road racing my cruze this weekend in albq nm uf all goes

Sent from my R800x using AutoGuide.Com Free


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## Evofire (Oct 3, 2013)

gonna bring this back from the dead...Here is what i have got so far....

Drum Brakes

Disk Brakes..


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## Evofire (Oct 3, 2013)

After my research today. Here is what i came up with for the things that would need to be bought.

The hubs are the same, as are the ABS sensors. Everything else would need to be changed. This is all from GM parts direct, and includes everything needed (that is not already on the car) except the pads. Now mind you, these are whole sale prices, and dont include shipping. For things like the rotors, and calipers, I am sure they are cheaper at the local parts store.


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## NBrehm (Jun 27, 2011)

So when all is said and done you will be out $700-$750? That's A LOT of cash for a meh upgrade. I'd still hit the junkyard circuit and look for a whole rear axle. Willing to bet it will be a lot less money and a much faster install. Just bolt it in, swap out the brake lines and done.


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## H3LLON3ARTH (Dec 16, 2011)

NBrehm said:


> So when all is said and done you will be out $700-$750? That's A LOT of cash for a meh upgrade. I'd still hit the junkyard circuit and look for a whole rear axle. Willing to bet it will be a lot less money and a much faster install. Just bolt it in, swap out the brake lines and done.


Oh yea about $500 AT THE MOST on the rear axle I couldn't spend $700-$800;for no benefit. 

Sent From My Galaxy Note 3.
Which is bigger than my hand.


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## nprice (Nov 18, 2013)

such an awesome thread. Great homework everyone. I may make the conversion because I just hate that every time I clean my wheels I see drums.


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## Evofire (Oct 3, 2013)

i forgot lots when i priced this out...total is **** near 1000 with bolts and sliders and spacers and shims...


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## NBrehm (Jun 27, 2011)

Evofire said:


> i forgot lots when i priced this out...total is **** near 1000 with bolts and sliders and spacers and shims...


Ahhh the devil in the details. Still worthwhile if you get a used rear axle assembly IMO. Only way I would do it.


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## Evofire (Oct 3, 2013)

NBrehm said:


> Ahhh the devil in the details. Still worthwhile if you get a used rear axle assembly IMO. Only way I would do it.


There are a lot of little things that need to be known about ones car before anyone just goes and buys parts. There are 2 or 3 RPO codes for rear axles with different wheel and brake setups. 2 axles (15 inch wheel option) take one hub, and 1 axle (16 inch wheel option) takes another. However, my car has the RPO for the 15 inch options, but I have 16 inch wheels. So its not that simple.

Basically I took my VIN to the dealer and me and Jan sat down and went through each IPB (illustrated parts breakdown for you non air force guys) in the computers to determine and verify what would be needed. He printed me out a quote, and I have everything saved to know what I need. However, someone with a LS car might need more or fewer parts then I do. For me, this setup would cost me right under 1000 dollars for JUST PARTS ALONE. And that is at my dads wholesale price. Then there is the ABS module calibration, because of traction control and stabilitrack. which we verified that the calibrations are different. Which he said would probably be charged as an hour of labor + a charge for the calibration. All in All, this is an EXPENSIVE upgrade for just looks.


It is my opinion that the rear drums will perform just as well over the life of the car, and probably NEVER need work except parking brake adjustment. These aren't race cars with 250+ HP. The factory brakes are fine. IMO, one wouldn't NEED to worry about brake upgrade (besides maybe better pads and rotors) until HP is doubled to the wheels. I upgraded my brakes on my Supercharged Sunfire to Wilwoods all the way around, and even with double the HP of the car in its stock form, it was still over kill. They have been on for 85k miles, and the rear shoes still look brand new almost.


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## NBrehm (Jun 27, 2011)

You are making the assumption that you "need" to take it to OEM standards to make it work. I will guarantee you can bolt any of the rear axles in with little to no modification and have them work just fine. Only thing I would worry about is the ABS system with disc vs drum. The rest should work fine with small, if any modification. There can be many different reasons for RPO codes and part numbers to differ, does not mean it isn't compatible. Engines are a fine example of this.


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## Evofire (Oct 3, 2013)

NBrehm said:


> You are making the assumption that you "need" to take it to OEM standards to make it work. I will guarantee you can bolt any of the rear axles in with little to no modification and have them work just fine. Only thing I would worry about is the ABS system with disc vs drum. The rest should work fine with small, if any modification. There can be many different reasons for RPO codes and part numbers to differ, does not mean it isn't compatible. Engines are a fine example of this.



Um. I'm not sure what you are saying....bolting a used rear axle, or buying all the parts new, either way would be taking it to OEM specs, (for a version of the car). But for it to be proper, and maybe even pass inspection in certain areas, the calibration would MAKE it OEM specs. Remember that with todays computers, the slightest thing can throw a code. It wouldnt surprised me a a drop in line pressure could throw a ABS code, or something like that. Thats the only reason i posted what I did. My post just states how I would do it.


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## NBrehm (Jun 27, 2011)

What I am saying is you will be able to bolt your 16 inch wheels to a 15 inch wheel hub part number with no issues, stuff like that, so there wouldn't be a point to changing them. That's where sometimes it pays to gamble. The electronics on the ABS system may be identical (I haven't checked), my concern would be the block and how it regulates the fluid. You need a lot more fluid travel for Calipers then wheel cylinders so they may be different. That's why I am saying there is a high probability that even though there are different part numbers they may be interchangeable with each other. That's why if I was going to do this swap I would start with a stock Z-link disc brake axle and figure out what I needed from there when I could compare them side by side.


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## Smurfenstein (Nov 16, 2011)

A long time ago, back in 2012, I did the same thing as you Evofire, and got about the same response.

There are two main axle types for our cars, one only has the mounting points for drums, while the other has mounting points for both. I do believe that there is a third axle that is LTZ specific and only carries the mounting points for discs, but since we're starting with drums this has absolutely no bearing on the swap.

As for parts needed, rotors, calipers, mounting brackets, bolts, new flexible brake lines(caliper to hard brake lines on the axle), new brake master cylinder or pump(discs require more fluid to operate than drums), and a brake cylinder/ABS tune(tell your car that discs are back there to pump more fluid).

And to add to the beating of whats probably then 20th dead horse by now, unless you're dead set on having discs for show its not worth it. Discs in the rear of our car makes ZERO performance gain over the drums simply because so much weight is up front, that the drums exceed the limits of the rear's braking capability, and so even though you can have more braking power with upgraded discs/etc., you wont actually gain any overall stopping power.


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