Rear Disk Brake Conversion Pt 1

[TCMach]

Well I'm learning not to trust the databases that auto parts dealers like AutoZone and Napa offer to the public. It seems pretty clear that there are different rotors on the GT mustang and the cobra, but everything I was seeing yesterday said they shared the same caliper. Something motivated me to look at rock auto's catalog and I am glad I did. It seems there are different calipers for these different applications. I have been thinking I needed to use the caliper from the GT, but it is a really tight fit on the Toyota rotor. The cobra has a thicker rotor and now I know it probably has a caliper more suited to that application. The calipers looks very similar and the mounting surfaces do too, but I can't really tell from these pictures if the cobra caliber has a wider slot for the rotor. At first I thought it did but can't really be sure from the pictures The rock auto catalog also shows that these two different calipers use the same 2.5 inch piston and rebuild kit/seals. This is got me wondering if the calipers are the same and only the bracket is different. So tomorrow I'm off to a local wrecking yard that has the cobra calipers.

FYI from my time in the Mustang world (had a Mach1 which shares the cobra brakes). Cobras just have thinner pads, quoted from SVT forums.

The only thing the same between the rear brakes on a GT versus a Cobra are the calipers as you mentioned. The Cobra rotors are larger and they are vented as opposed to the solid GT rotors, which makes the Cobra rotors thicker and the pads are thinner,(less material) than the GT pads, to allow them to fit between the caliper and rotor.

'93 Cobra R: 13x1.1" vented rotors, PBR dual piston 38mm unit from Corvette (interchangeable with Cobra and Bullitt calipers). 10.5" rear vented disc.

'94-95 V6 & GT: 10.8x1.0" front rotors, 66mm single piston calipers. Rear single piston 38mm Varga caliper, 10" solid rotor

'94-98 Cobra, '95 Cobra R: 13.0x1.1" KVH rotors, 38x38mm dual piston PBR calipers. Rear single piston 38mm Varga Caliper, 11.65" vented rotor

'99+ V6 & GT: 10.8x1.0" front rotors, 44.5x44.5mm dual piston PBR calipers. Rear single piston Varga caliper, 10" solid rotor

'99+ Cobra: 13.0x1.1" Brembo rotors, spec'd 40x40 mm dual piston PBR calipers. Rear single piston 38mm Varga Caliper, 11.65" vented rotor

'00 Bullitt Mustang: Same brakes as 94-98 Cobras (unique red PBR calipers with running horse up front, same varga caliper in rear painted red.) Rear single piston 38mm Varga Caliper, 11.65" vented rotor

'00 Cobra R: 13.0x1.1" Brembo rotors, Brembo 4 piston calipers. 36x40mm pistons. Rear disc the same as the stock '99+ Cobras​

 

[sleepydad]

Well I'm learning not to trust the databases that auto parts dealers like AutoZone and Napa offer to the public.

Man your killing it. I finally found somebody to waterjet my brackets so... I never really questioned the clearances. Everything just seemed to fit really nice so I just kept going. I will be curious to know how well things work out with the different part combos.

I used to fish steelhead in the root river over in Racine.

 

[WrenchTech]

Man your killing it. I finally found somebody to waterjet my brackets so... I never really questioned the clearances. Everything just seemed to fit really nice so I just kept going. I will be curious to know how well things work out with the different part combos.

I used to fish steelhead in the root river over in Racine.

Truly original thinkers are very rare, the rest of us stand on the shoulders of those who've gone before us. I was inspired by what you and rockdawg did. I even modeled the brackets out of eighth inch hardboard laminated into a 3/8 inch thick workpiece like you did. This project also got me to buy a used Milwaukee portable bandsaw. That and a 4 inch carbide tipped holesaw are what I used to cut my bracket out of 3/8 inch steel. The bandsaw is a real game changer. I am looking forward to buying a table to mount it in.

And now I have solved the bracket clearance problem. As promised, my local AutoZone came through with overnight service to get me a caliper bracket for a 1998 Mustang Cobra, and as I suspected, it fits the GT caliper perfectly and it has a wider gap to accommodate a thicker rotor. I said earlier that I had read that the GT and the Cobra use the same caliper. That was true. They also use the same brake pads*. The difference is in the caliper bracket. The bracket that comes with the GT caliper is made for a 14 mm thick rotor. The bracket that comes with the Cobra caliper is made for an 18 mm thick rotor. The brackets are available separately from most auto parts stores for around $20 dollars plus a six dollar core charge. And of course you can buy the correct assembly, caliper and bracket together or even buy them as a loaded assembly caliper bracket and pads.

This evening I have installed the modified assembly along with my custom made bracket and the fit is perfect. The rotor is well centered within the caliper bracket and the clearance is good. I would offer a picture, but that stuff is outdoors and the lighting is inadequate for good picture taking. I will take care of that tomorrow. Happily, I can move on with my restoration and upgrades, the ultimate goal of which is to get a 2.0 l turbo diesel out of a 2004 or 2005 Volkswagen Passat installed in my truck this spring. I am hoping that Diesel Conversion Specialists will have their adapter plate for the "R" series five speed manual transmission available after the first of the year.


Pictured below are the two brackets side-by-side, with the GT bracket on the left and the cobra on the right.

* the GT in the cobra use the same pads as far as I can tell from looking at Rock auto's catalog. TCMach says the pads are thinner on the cobra. I think it's possible that they were available at sometime, maybe from the OEM, but I haven't found evidence yet that you can get thinner pads in the aftermarket.

 

[WrenchTech]

I'm thinking about the parking brake cables and the hydraulic lines next.

I ordered the Mustang rear parking brake cables yesterday, there are two, one for each side, and each is about six feet long. Right now I am thinking I will just use about 16 inches of the sleeve and slightly more of the cable to connect the Mustang calipers to the Toyota rear cable assembly, which I am going to use largely in the stock configuration, mounted as it is on top of the rear axle housing. It is looking like I might have to swap the calipers side for side and mount them pointing towards the front of the vehicle in order to get the best routing of the cable.

I also ordered some Mustang brake hoses that will bolt to the calipers with a 10mm banjo bolt on one end and get adapted to the Toyota 10mm inverted flare brake line fitting on its other end.

I am using Rock Auto for most of the parts I need, some of which have already arrived. Other parts, like the center bolt for my leaf springs, a part for mounting my new Nipondenso fuel pump and a full set of axle flange to bearing case bolts are coming from ToyotaPartsDeal.com and may not arrive until after Xmas.

 

[WrenchTech]

I also ordered a second caliper. I saw it on eBay with a low price, free shipping, and the claim that the part is rust free. That could have been a mistake. It's been 3 days and I haven't heard a word from the seller which is an auto salvage yard in Grand Prairie,Texas that has a lot of negative feedback..

I would like to get that part soon. My rear axle is out of my truck. I have sandblasted and pickled it. It is all ready for paint. I would just like to do any last minute welding that might be necessary for brake line tabs or any brackets I might need for the parking brake cables. I have to have this thing rolling pretty soon because I'm in the process of moving. Luckily I have a friend with a farm who lets me store vehicles on his property.

I am also eager to get started on a number of other Toyota projects that I have planned, including an engine swap for this truck, and a transmission swap and replacing the cylinder heads for my 1989 4Runner. The 4runner has the 3vze V6 which has a couple of valves that are not sealing well and which are causing low compression in 2 cylinders. Anybody who knows anything about the 3vze knows that you can hardly afford to be down two cylinders on that engine. I am pretty much through with the 3vze, but I happen to have a pair of cylinder heads with only 110k miles on them that are in very good shape. That and the manual transmission swap will help me to breathe new life into the 4Runner until I can decide what engine I would like it to have for the long haul. I have everything I need ready to go for the transmission swap.

 

[ThePurposeIs]

I'm not sure how taboo reviving old threads is considered... Sorry in advance but there's some really intelligent people in here so maybe I should DM all of them? Will everyone in this thread see that I am posting this? I can add some info others might be looking for so should I start a new thread? I am pretty new to posting on forums.

I have a 99 2wd from my sister (she drove it with no maintenance through college in Austin, TX) so I have performed maintenance on just about every in (okay maybe foot) of the truck. 231mm 04 Tundra front brakes, new oem 04 tundra rear wheel cylinders. I deleted ABS and reused factory hardlines with 76 Blazer MC running rear brakes hardline into the cab with wilwood proportioning valve (so I can adjust on the fly) with a 10lb wilwood prop valve going to rear brakes. My sister drove the leaking diff (from paper diff seal that no mechanics ever found somehow!!!) to the point where I now have a diff whine (doesn't sound bad or like its getting worse too quickly) and after taking everything apart my driver axle seal has now started leaking. Apparently the axle seals require special tools (local 4runner shop says they are still working on creating a tool and say I should just buy a used, non-leaking axle and swap it in)

I don't have great access to a welder (I'm sure I could find a local guy to do small jobs) and I'm kinda torn on what direction I should go. Diff whine means new diff? Or just rebuild? Pretty good junkyards in the Dallas area. But I would still like to upgrade to locker. I'm thinking about everything that needs work on my rear end and could I just swap in something different? I would even be okay with swapping to rear leaf springs if it meant I could get a good rear end with good brakes etcetc. My plan with this truck is stay 2wd for a while and maybe go 4wd in future. I understand 4wd is much more capable but I mostly use this truck to deliver dairy from small farms with small to potentially larger trailers. I think brakes are most important part of a car so whatever I do to the rear end I would like to keep them good. The 04 tundra rears are actually working fine (I can lock them up with the 31 street tires currently on it) but upgrading to calipers sounds fan-****in-tastic, especially if I could tackly my diff issue. Rear leafs sounds awesome but I don't wanna reinvent the wheel and people seem satisfied with the coils. I haven't found any full rear axles with locker at junkyards but maybe I could just rebuild my differential (not sure how that works or if driving it with low oil has destroyed it) to save some money. Should I buy a used axle or find a shop that knows how to change the rear bearing?

Again sorry to revive an old thread if that's not something that's considered good etiquette or whatever. I can throw up pictures of anything I've done if ppl wanna see.

Thanks!!!!!!

 

[Rockdawg84]

I'm not sure how taboo reviving old threads is considered... Sorry in advance but there's some really intelligent people in here so maybe I should DM all of them? Will everyone in this thread see that I am posting this? I can add some info others might be looking for so should I start a new thread? I am pretty new to posting on forums.

I have a 99 2wd from my sister (she drove it with no maintenance through college in Austin, TX) so I have performed maintenance on just about every in (okay maybe foot) of the truck. 231mm 04 Tundra front brakes, new oem 04 tundra rear wheel cylinders. I deleted ABS and reused factory hardlines with 76 Blazer MC running rear brakes hardline into the cab with wilwood proportioning valve (so I can adjust on the fly) with a 10lb wilwood prop valve going to rear brakes. My sister drove the leaking diff (from paper diff seal that no mechanics ever found somehow!!!) to the point where I now have a diff whine (doesn't sound bad or like its getting worse too quickly) and after taking everything apart my driver axle seal has now started leaking. Apparently the axle seals require special tools (local 4runner shop says they are still working on creating a tool and say I should just buy a used, non-leaking axle and swap it in)

I don't have great access to a welder (I'm sure I could find a local guy to do small jobs) and I'm kinda torn on what direction I should go. Diff whine means new diff? Or just rebuild? Pretty good junkyards in the Dallas area. But I would still like to upgrade to locker. I'm thinking about everything that needs work on my rear end and could I just swap in something different? I would even be okay with swapping to rear leaf springs if it meant I could get a good rear end with good brakes etcetc. My plan with this truck is stay 2wd for a while and maybe go 4wd in future. I understand 4wd is much more capable but I mostly use this truck to deliver dairy from small farms with small to potentially larger trailers. I think brakes are most important part of a car so whatever I do to the rear end I would like to keep them good. The 04 tundra rears are actually working fine (I can lock them up with the 31 street tires currently on it) but upgrading to calipers sounds fan-****in-tastic, especially if I could tackly my diff issue. Rear leafs sounds awesome but I don't wanna reinvent the wheel and people seem satisfied with the coils. I haven't found any full rear axles with locker at junkyards but maybe I could just rebuild my differential (not sure how that works or if driving it with low oil has destroyed it) to save some money. Should I buy a used axle or find a shop that knows how to change the rear bearing?

Again sorry to revive an old thread if that's not something that's considered good etiquette or whatever. I can throw up pictures of anything I've done if ppl wanna see.

Thanks!!!!!!

Reviving threads are fine but be sure to ask questions about what the thread is about. As far as your situation goes I would rebuild the diff and replace the axle seals. FIND A NEW SHOP!!! There is no special tool to replace axle seals. As for rear brakes I would suggest that you simply rebuild your rear brakes with good components and you will be fine. The 3rd gen rear brakes are plenty strong if you are mostly stock. and unless you are going to do a SAS don't rework the rear suspension.

Start a build thread with lots of pics and questions and you will get a lot of help.

 

[Rockdawg84]

So it’s been years since I started this project and part 2 never came. I collected parts but never got the parking brake done.... till now.

I came up with the plan and my good friend made it happen. Used stock mustang rear cables and equalizer cable. Then the stock parking brake cable was modified and a custom (angle iron) bracket was built. All came together great. I will get picks tomorrow. But glad this is done. I’ve driven without a parking brake long enough

 

[jkeith.w]

Yay!

 

[poleclimber63]

Yes!

Better late than never!! I've been checking in from time to time to see if pt2 was ever going to appear... When my rear axle seals went a few year back I saw your thread! I was intrigued. I've had my 4Runner since 2012 and did a few mods (and an engine replacement in 16')and have been considering more in depth mods lately, now the kids are out of College. Now that I acquired a welder, other metal working tools and have more time, this mod might be on my agenda. Nice to see you figured a solution to the E-brake!
Thanks for keeping this thread alive!
I did come across a post a couple of years back where a guy in the UK did a disc brake conversion--- he replaced the entire rear end with a Prado rear end! Not that us N. Americans have access to these without a ton of huge shipping costs!

Anyways, I await your pics with anticipation!

 

[Rockdawg84]

well here they are

started from the rear of the truck at the mustang caliper and ran the line up toward the front. As a note mustangs have a right and left that are different lengths. Buy 2 of the shorter ones.
Parking brake install by Sam Wright, on Flickr
Parking brake install by Sam Wright, on Flickr

Then a bracket was made for the cables to fit into. a simple piece of 1.5" angle iron was used. Holes drilled for the cables to fit into and 5 holes drilled so the bracket could be riveted into the floor support. Nice that toyota put that there for us to use and not have to drill all the way through the floorboard.
Parking brake install by Sam Wright, on Flickr
Parking brake install by Sam Wright, on Flickr

Then we cut the equalizer cable up so we could get the bracket and the boot.
Then the stock parking brake cable outer casing was cut and we left the inner cable long. the boot was put on and attached with zip ties.
Parking brake install by Sam Wright, on Flickr
Parking brake install by Sam Wright, on Flickr

Once the length was determined the equalizer was put on the cable and cable ferrules were used to secure it on the end.

Parking brake install by Sam Wright, on Flickr
Parking brake install by Sam Wright, on Flickr

Finally everything was put together and the cable was adjusted at the handle and it actually works! I'm very happy with how it came out. there are a couple of things to finish up, like securing the cables to the rear axle better and to source a new brake handle and cup underneath since I did the shift to the side mod with the 98 handle. Over time if I don't change it out the cable will fray and I will have to modify another stock cable. Over all I think it came out great, and looks pretty factory.

Parking brake install by Sam Wright, on Flickr
Parking brake install by Sam Wright, on Flickr
Parking brake install by Sam Wright, on Flickr

 

[sotigra]

would like template or produced bracket

did you produce a template for the or sell the brakets for the calipers?

I specifically chose the calipers because they have been around forever and I should have easy access to parts. Also the mustang weighs a little over 3000 lbs and so I thought that they would be a good balance for the front 13WL's. And they have a mechanical parking brake.

So a few thoughts now that I'm all done. Except the ebrake.

Pro's
1. super clean setup and stops wicked nice.
2. easy rear pad changes.
3. I can get into the rear axle with out breaking open the brake system. I hate bleeding the brakes just to change a 3rd member.

Cons
1. expensive and a lot of work to get it done. About $560 since I bought everything new.
2. I may need to upgrade my master cylinder because the pedal is a little softer than I normally like. Maybe a 1-1/16 bore or 1-1/8. I think this is partly because I have already moved up to the 13wls and together with the rear calipers I could use the extra volume.