Fuel & Brake pipes
 

Hi can anyone tell me the size of brake and fuel pipes they are using on the MX5 builds, I had a quick look today at my brake master cylinder and it seems to have two different size pipes which don't appear to be Metric.

Regards Mick.

One of them is probably 4.7 mm, it's the standard brake pipe size. For fuel I just used 8 mm copper pipe out of a hardware store and 8 mm internal rubber hoses (Sierra build though).

I used 3/16" for the brake lines, and 8mm for the fuel.

Hi skov did you use the mx5 master cylinder?.
I have seen 3/16" pipe with 10mmx1mm fittings on EBay but I don't think the connections to the master cylinder are Metric, one of the connections says 1/8 something can't read it properly.

Regards Mick.

Yep, I used the MX5 master cylinder. Can't remember what size the fittings are but they're definitely metric.
Sounds like you might be missing the little adapter that converts the larger fitting to the same size as the others:

Thanks for that information, I will check it again it seems that I have another part on mine than you have in your pic maybe I don't need part.
And thanks also to you alga.
Regards Mick.

Ah, have you still got the funny brake bias thing attached?
I junked mine.

Two pipes coming around reservoir to a tee piece on a bracket and three pipes off it two slightly smaller than the other one is this not needed then, do you fit a bias part somewhere else or is one not needed? There's labels on mine saying front rear etc.
Regards Mick.

Yeah, that sounds like the brake bias valve.
It looked like it was going to be a pain to fit, so I got rid of it and stuck a mondeo valve in the rear line instead.
As it happens I failed IVA because my rear brakes were far too weak :rolleyes:
I took the Mondeo valve out and replaced it with a bit of brake line and passed.
The rear brakes on the MX5 are a bit pants at the best of times, which is why I guess a bias valve isn't needed.

Cheers skov I will have to think about it a bit more because I'm using the MX5 pedals and maybe the servo.
Regards Mick.

I would be very surprised that all the connections are not metric on the MX5 :confused:

I just double checked in the data bases I have for brake lines and in-board brake pipes : everything is always metric M10x1.00 all around on all Mazda (except in the 70's, some models use M10x1.25, but it is not your concern :p )

The 1/8 thingy you saw can be either 1/8x28 BSP (parallel thread) or 1/8x27 NPT, (tapered thread). In both case, "1/8" has nothing to do with the diameter of the thread in inches, it is just an appellation (1/8 BSP is 9.73mm out. diam. on the male part, and 1/8 NPT is 10.29mm)

But again, I would be extremely surprised that one of these 2 threads has been used on the MX5!

You can start by carefully checking the diameters of the ports of your M/C. Here are some useful data's:
M10x100: male OD = 10mm, female ID = 9mm, 10 threads on 10mm
1/8 BSP: male OD : 9.73mm, female ID = 8.56mm, 28 threads per inch
1/8 NPT (tapered) male OD (middle of the threaded part)=10.29mm, female ID=8,41mm, 27 threads per inch.

If you find a port which is not M10x1.00 on the MX5 brake circuit, I would be very interested to know where, and what thread it is please :)

Thanks, and good luck ;)

Sometimes jap pipe ends do not have the small unthreaded portion at the end of the fitting so the normal 10x1 mm will not seat properly and some have OP 2 concave on the pipe just to confuse the issue a little more