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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
Lets say I spent some time and came up with a simple easy to install rear disc conversion. What would you guys like to see? I could go cheap and make something up out of junkyard calipers with integral Ebrake arms. I could go Wilwood Dynalite calipers with aluminum hats and separate single piston brake caliper. Would you rather have something you could scrounge around and find the parts yourself, or a full bolt on with all the thought taken out of it? How big would you want to go? Small enough to fit under stock wheels or slightly bigger and need 15" wheels. Obviously a rear disc conversion needs to somewhat interface with a front disc upgrade. I would say that the disc needs to be able to use stock and 4X100 bolt patterns, so I'd start with a 4X100 disc and have 4 new holes drilled in it. There would have to be some machine shop work involved. Finally what would you want to spend on such a thing? Lots of people are spending $900 plus for the questionable ones available for the fronts. Really surprised someone hasn't done this before other than a few internet how it was done articles.

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TR3barton Avatar
TR3barton John Taylor
Greenfield, MA, USA   USA
Good Morning Todd,

I would like a system that used the stock wheel bolt pattern. The weak offering of 13inch tires and since both of my cars have 15inch wheels would certainly lean towards 15inch stock pattern. I think such a system should use a mass produced rotor and caliper with the Ebrake built in. The rotor should be “smaller”. Again as for my cars they both have Woody’s front kit. The FHC coupe came with an AP front set but I wished both cars to be the same. I sold the AP system to someone in Alabama. ?

I would reduce the thought to the welding of a bracket to support the caliper plus what ever for the Ebrake.

Seems to me that I recently saw a “rat rod” with an Ebrake caliper on the drive shaft that was hydraulic. The master must power off the handle. If so I wonder how long it would hold?Looking at the Wilwood catalog I see several options that would make this work but complicates the install. One of my cars has a stock drive shaft the FHC is the heavy duty cross joint style. I modified the bolt pattern of the rear flange. So I have two different bolt patterns. I will try to add a photo.

If the rear Ebrake caliper is mechanical then one would need cables likely produced in small quantities. This issue will be the cost, should not be a stunning price, but might still lead to a bolt on system.


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TR3barton Avatar
TR3barton John Taylor
Greenfield, MA, USA   USA
Todd,

I have like many of the listers present have driven lots of cars with varying brake capacities. I own a 1986 Jaguar XJ-6 and a few years ago sold a V12
XJ-S. These cars have the same brakes. They are really impressive for a general 4500lb passenger car and certainly have the feel and performance of out braking either of my TR8’s.

It would be nice to have that confidence feeling in an “8”.

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M1kem3 Avatar
M1kem3 Michael Rawlins
San Antonio, TX, USA   USA
I'd be interested in a full, bolt-on kit that will work with the original wheels. I heard about a company in Britain that is working on a complete kit, and I am still thinking wether it's worth buying or not. More stopping power definitely won't hurt, but wear items such as pads and modified rotors should be readily available to anyone who would buy the kit.

sheetsofsound Avatar
sheetsofsound Brent Taylor
New Westminster, BC, Canada   CAN
Anybody that is going to the trouble to change the bolt circle to 4x100 is probably going to be comfortable with doing stuff that requires more modifications. For example, I changed one of my cars to 4x100 and moved to 15" wheels. I came up with something that used off-the-shelf parts (Miata calipers, Miata parking brake cables, and Honda Civic rotors), a bracket of my own design, and a cable system hook up that is also my own. My main point is that for people going to bigger wheels and bolt circles, they are maybe more likely to be good with more fiddling than a bolt-on, no-thinking-required, option.

My other car has the stock bolt pattern and wheels. Something using off-the-shelf parts that would fit under the 13" wheels may not be possible, but that is the route I would favour because of cost. When it comes to the stock wheels, I'd be more interested in a full bolt-on kit and agree with Michael's words in the previous post.

There is a company called Scarebird Brakes that does disc brake upgrades using off-the-shelf parts. They sell kits for a few British cars, although not the TR7/8, alas.



Brent

darrellwalker Darrell Walker
Vancouver, WA, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
Hi Todd,

My preference would be a complete kit, or a partial kit that includes any custom and custom machined parts, with a parts list for any off the shelf parts to purchase directly.

I would pay $1-1.5K for an all inclusive kit. I would expect the total expense for the partial kit (kit plus what I have to get) to be a few hundred less. I would prefer something with Wilwood parts, but off the shelf new/rebuilt components (Miata or something similar) would be OK too. Maybe a few hundred dollar premium for using Wilwood parts.

Fitting under 15" wheels is fine with me, I would want stock bolt pattern. Should be sized to work with the typical front brake conversions.

-Darrell



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA

midgetwidget Avatar
midgetwidget Doug J
Woodland, UT, USA   USA
Please keep me posted Todd. Your Front Brake suggestion looks great on the LeMon's car. We are hoping to race it in Denver next month. Rear brakes would be greatly appreciated.
Stock bolt pattern, under 15 inch wheels.



Edited 1 time(s). Last edit at 2017-05-04 01:02 AM by midgetwidget.

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Gt6s Avatar
Gt6s Laurence Cochrane
Newtownards, UK   GBR
1972 Triumph GT6 MkIII "2600 EFI"
1973 Triumph GT6 MkIII "2500"
1976 Triumph Spitfire "Sixfire 2500"
MGF rear discs fit the bolt PCD perfectly I will be buying a pair for my EFI Gt6. I already have a set of MGF calipers to do this. A lot easier to get MGF rear discs here in the UK Any UK motor factors will get them.

Laurence

ROAR Mihael Rogers
Arroyo Grande, USA   USA
Most of us don't need brakes that will last the 24 hours of Le Mans, Even for autocrossing they only have to last a few hard stops, For those that do track days--what's insufficient?? I recall the red glowing disks of the Jags that still worked-- do the rear drums fade under track racing? seems about ANY rear disks would serve 95% of us, adding weight to the live rear axle would be a consideration when adding big disks there.
cheers;
ROAR

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darrellwalker Darrell Walker
Vancouver, WA, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
In reply to # 1454735 by Gt6s MGF rear discs fit the bolt PCD perfectly I will be buying a pair for my EFI Gt6. I already have a set of MGF calipers to do this. A lot easier to get MGF rear discs here in the UK Any UK motor factors will get them.

Laurence

Good thought on the discs. What do those go for in the UK?



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA

TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
A little prodding from Darrel got me back on to this again. Enough so that I spent a couple of hours in the junk yard this week. I dropped $20 and came home with a rear caliper and rotor from a 2001 2.0L Nissan Sentra. Same setup was used on 2.0 Altimas and the Infinity G20. Looks like they are plentiful and cheap. Found replacement rotors as cheap as 12.95. Center bore of rotor is slightly larger than the center of the wedge axle so that is taken care of. Lots of blank face on the rotor so drilling 4 new holes at 4X95.25 is a possibility. Need to head over to Glens and have hime drill the 4 new holes so I can slide the rotor over the wedge axle and mock up a bracket. Once everything is mounted securely and I can have a proper look at it, I'll decide if this rotor is good enough or if I should look for a better rotor candidate. Also found a VW caliper that is pretty much the same as the Nissan caliper, but its aluminum. Honestly the Nissan one is cheap and pretty lightweight in its own right, so I'm going to run with it. At least the ball is rolling. Nissan rotor is 260mm by 10mm solid. Caliper has a built in lever that rotates when the brake is pulled, so its a combination hydraulic/mechanical setup. Not sure yet if it can be adapted to run with a stock brake, but thats the ultimate goal. At this point, I'm sure it will work with an aftermarket Lokar cable like the ones we run on the Ford 8.8 rear ends, but I'm trying to keep this as cheap as possible for you guys.


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RossL Silver Member Ross LoMonaco
NJ, USA   USA
Cheap is good.............how does this work with the front brakes? Do you have to upgrade the front as well for balance?

midgetwidget Avatar
midgetwidget Doug J
Woodland, UT, USA   USA
You just need to install a proportioning valve for balance,
Tide, thanks for doing the legwork on this I look forward to hearing what you find out.

Ron Avery Ron A
Oxnard, CA, USA   USA
I have 15" wheels and Woody's Wilwood front brake kit. ( it is being installed now).
I would love a bolt on kit complete . I think around $1000-1500. Would work for me.
Thanks for thinking of this.



Ron
1980 TR 8
1965 E-Type Jaguar
2016 Aston Martin Vantage GT
Oxnard, CA



Edited 1 time(s). Last edit at 2017-12-21 11:11 PM by Ron Avery.

sbs Avatar
sbs Steve S
I missed this thread the first time around.

Building my own brake conversion is probably a year away, so if you came up with something suitable in the meanwhile I might be interested in buying the adapters.

My wish list includes aluminum calipers, 4x100, suitable offset for +35-40 wheels, fits under 15x7 wheels, integrated cable-actuated handbrake (similar to what you have there).

My initial plan is to use PBR calipers (found on Vette, F-body, Mustang, among others) and a two-piece rotor.

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