View Full Version : Brake rotor help

09-28-2006, 11:46 AM
I am hoping someone on this forum may know what British car has this size brake rotor.(see sizes below). Our RF 80 Van Diemen formula ford is said to use a stock british car brake rotor, possibly a Trimuph GT6.The main issue is the height of the “hat” which is much shorter at only ½ inch. Any help in resolving this issue would be greatly appreciated.
Current rotor dimension are
Hat height = .50”
Hat I.D. = 2.62”
Hat dia 5.45”
Worn rotor thickness .31”
Disc dia = 9.75”
Bolt circle = 4 X 3.75
Stud hole = 3/8”
I attach pictures of the rotor.

09-28-2006, 02:40 PM
Not only the hat dimensions but the rotor diameter are different in a Spit and the GT6 rotors.

You might slide over to the Apex Speed forum in the FF/CF section and see if there is any thing else that might be close but I really doubt it.

09-28-2006, 04:32 PM
Could be a tr7 or tr8. I'll measure them up when I get home and let you know. The only other car that uses a 4 X 3.75 is a Lotus.

09-28-2006, 07:11 PM
The hat dim is much to short for a TR8 (I've got new TR8 rotors on my bench right now, hat dim from rotor surface is like 1 5/8")

09-28-2006, 08:12 PM
With such a short distance between the hat face and the rotor face, how can you get a caliper in there without it hitting the wheel? A rotor like that must have come off of a car with inboard discs. My guess would be Jaguar or possibly a TVR 280i.

09-29-2006, 08:06 AM
Thanks for the info. The same request is on Apex Speed. So far it looks like a custom hat rotor combo. The current rotor is a one piece and had to come from some car. I will keep searching. Will post if I ever find the part.

09-29-2006, 08:46 AM
I can't be certain ("old-timers' disease") but I *think* I remember Jag rears as having no "hat"... and if TVR used them, I doubt it would be exclusive to that particular marque. Can't find my E-type manual ATM.

I'll be curious to find out what it is from.

09-29-2006, 04:27 PM

Some Swifts also use the same rotor.

this whole flog was laid out in the old FF Underground board...thats how long ago.....

Even IF.......they came off a car (which they didn't)knowing the Brit kit car guys they would use some obsolete /low volume rotor and the cost still would be $70 each due to the low usage/volume...which is about what they cost in the UK. /ubbthreads/images/graemlins/england.gif

It's a set of rotors or a set of tires...I understand pricewise.

There is a way out......a run maybe 500 rotors..........a good grey iron is a must as they are a lightweight solid rotor......no country of Undetermined origin. For a $17K investment you can corner the market. Actually there is one compant in the US that would do a run of maybe 150 pieces.....the freight is still a killer.

09-29-2006, 08:25 PM
Thanks for the info. So you are saying they are custom and not found on any production car. Humm. So we should make a bunch and sell them. Interesting. I need to know what is a good "gray iron"? What type of steel - grade? I work in the aerospace industry and have access to a machine shop so making a few would not be a major issue.

This internet thing always amazes me. Many Thanks

10-02-2006, 04:50 PM
You have to find someone who is proficient in casting rotors in small qualtities. Casting tooling and getting parts on the floor is the hard part....anyone with a program and a VMC can make the chips.

What you are trying to do is compete with an existing product of which there are many sellers. Thye only thing you will have to offer is price and at the end of the day when you have parts you have to make something on them.

You can spec good parts from China or India....or Turkey. But you have to have the testing facilities in place especially in the first two. For just a few hundred parts even in their labor/material rates it still doesnt add up.

Oce again I'll say that your dealing with a very small market ...try running the numbers of how may pieces you can sell in a year and the R.O.I.