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opinions on rear disc conversions

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TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
I think that anybody wanting to keep the stock rear end is going to want cheap. The other problem is anybody wanting rear discs has already upgraded to Woody's kit, which isn't much of an upgrade. That means this kit needs to use small rotors to not throw anything too out of whack. Once I get done doing the legwork and tweaking things, Glen will be the one doing the machine work. You can buy the finished product from him, just like many of you have done with his front brake kits. Given the fragility of the stock rear end, anybody that needs real big brakes has most likely already gone to the Ford 8.8. This kit will be for the 90% of you guys that just want something better than the stock drums.

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RossL Silver Member Ross LoMonaco
NJ, USA   USA
In reply to # 1503840 by TR8todd I think that anybody wanting to keep the stock rear end is going to want cheap. The other problem is anybody wanting rear discs has already upgraded to Woody's kit, which isn't much of an upgrade. That means this kit needs to use small rotors to not throw anything too out of whack. Once I get done doing the legwork and tweaking things, Glen will be the one doing the machine work. You can buy the finished product from him, just like many of you have done with his front brake kits. Given the fragility of the stock rear end, anybody that needs real big brakes has most likely already gone to the Ford 8.8. This kit will be for the 90% of you guys that just want something better than the stock drums.

Who is Glen? Where can I learn about the front brake kit you describe above?

TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
Heading over to Glens today. I'll have him chime in on this thread so you can PM him. Here's a teaser for big brakes on a Ford 8.8. This will be going behind my LS3 6 speed combo.

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tr8 Paul m
ottawa, ON, Canada   CAN
Next size larger is an anchor!!

bowen6951 Avatar
bowen6951 Gold Member rob bowen
Fontana, CA, USA   USA
I have Glen's big brake kit and could not be happier (feels like the car can do stoppies) it really is a bolt on kit he even made the new hard lines I needed. He is a really nice guy to deal with and willing to make changes or additions you want.

Todd,
isn't it going to cost about the same for the brake conversion as to put an 8.8 in? Thanks, Rob


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Bergie Bob Berg
Powell, OH, USA   USA
Good idea Todd....my vote would be all new parts as a complete DIY kit with wilwoods so maybe offer two versions- fits OEM 13 inch wheels and upgraded for 15 inch wheels bigger caliper.

TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
Glen and I played with the Nissan parts. They can be made to work, but we both agree that we want to have a look at Mustang rear calipers before we go any farther. He has Mustang calipers on his Mustang 8.8 with BMW 320i front rotors. Odd combo, but necessary. Mustangs only had drums on 4 lug axles. 5 lug axles got discs. He was able to use calipers from a 5 lug axle, but needed to find a 4 lug .5" solid rotor with plenty of meat of the face to drill new bolt pattern. We want to see if that formula will work on the wedge axle as well as it does on the Mustang axle. Once the Nissan rotor was installed, it looked small. Its basically the same diameter as the TR drum. I think stepping up to the .5 rotor from the Nissan's .38" rotor is a good idea. On Glen's car, he used shortened a Mustang brake cable, so if we go that route, at least one of the hurdles has already been figured out.

Swapping in a Ford 8.8 axle opens up all kinds of rabbit holes to go down, so the cost to do so can range from $1000 to more than $2500. It also requires some serious skills to narrow a rear end. The only reason to do a Ford rear end is if you do it as part of a total package upgrade to the car. Do you have a big HP engine? Do you want a limited slip rear end? Do you want disc brakes on the back to match the big brakes you have on the front? Those are all reasons to swap. If you are like 90% of the wedge owners and are just looking for better, safer, more modern brakes, then this will a great kit for that. If you are building a race car, these will certainly be better than the stock drums, but they will not be part of an ultimate brake kit. Honestly, how many of you guys are going to be doing repetitive wo downs from 100 plus mph? There is a big demand for a bolt on rear disc brake kit in the wedge world, and franky, I'm surprised nobody has stepped up and developed one yet.

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TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
Wilwoods are not really an option because they don't offer a suitable caliper with a mechanical brake lever. Need to keep an Ebrake for a street car, so we are looking at repurposing OEM calipers. You want to build a race car, then Wilwoods are great for that. They are also great for the front of the car where there is no need for an Ebrake. I have seen them used on the rear of a street car before with a second set of spot calipers, but who really wants to look inside a wheel and see two calipers on one rotor. Imagine how many stupid questions that set up would create at a car show.

sbs Avatar
sbs Steve S
Todd, how does the height (45mm) of that Nissan rotor look to you?

I'm doing some brake catalog reading and don't need an exact number at this point, but a ballpark.

From the pictures it looks like that's as high as you'd want to go, and you could probably go a little shorter depending on caliper and wheel. But pictures lie...

So I think I'm looking for rotors with 30-45mm height. What do you think?

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tr8 Paul m
ottawa, ON, Canada   CAN
Here is something from facebook


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sbs Avatar
sbs Steve S
Updated to reflect lessons learned in later discussion.

For the rear I'd want a rotor that has a centerbore smaller than the TR so it can be made hubcentric without an extra ring. There aren't a lot of those.


The miata happens to be one, and you get the benefit of a huge selection of rotors for that car.


Some possibilities:

94-05 miata front non-sport rotor
255 x 20mm vented, 45mm height, 55mm CB
$10

88-96 vette rear caliper
1x40.5mm piston
$72

90-92 Isuzu Impulse rear rotor
256 x 9.1mm x47.25mm, 57.02 CB
$6

94-00 miata rear caliper
1x32mm piston
$80
See issues with miata calipers discussed later in thread.

Two VW calipers that should work with the above Isuzu rotor:

2000 Jetta rear
1x41mm piston
$53

2008 Jetta rear
1x41mm piston
$97

1995 Paseo front rotor
243 x 18 x 48mm vented, CB 55
$11

2000 Mustang rear caliper (base, GT)
1x38mm
$75



Prices are for the cheapest option at rock auto. For calipers, they're for the cheapest option that says it includes the bracket.



Edited 4 time(s). Last edit at 2018-01-29 07:29 PM by sbs.

TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
Sorry guys, I dropped the ball on this one. Been swamped with work. No time for anything else right now. Wrecked the wife's Rover three weeks ago and don't even have time to look for a replacement. For now, she and my daughter will have to share a car.

sheetsofsound Avatar
sheetsofsound Brent Taylor
New Westminster, BC, Canada   CAN
Sorry to hear about your Rover. I hope no one was seriously hurt and that everyone`s back on the road soon.

In reference to Steve`s post, I used 2000 Miata calipers I got off craigslist. They have the brackets. I used the Miata cables with some modifications. The rotors are off a Honda Civic. I had just about a millimeter taken off the centre bore of the halfshafts in order for the rotors to be hubcentric. I also had the studs offset drilled out to 100mm so I could find more common wheels. While not road tested yet, the parking brake works nicely.

In hindsight I would pick different calipers, probably from a VW Jetta that have the bracket on the top. I was not able to put the calipers where I planned because the Miata bracket shape ended up dictating the caliper location.




Brent

sbs Avatar
sbs Steve S
Brent,

Is it the parking brake cable entry position that's driving the caliper position?

What year are the Civic rotors? (So I can find out what the rotor height is)

Thanks!

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