TR7 brake pipes and nut sizes

[Colin Lindsay]

I'm replacing brake pipes on the TR7 and while I'm using 3/16 kunifer the original pipes seem much thicker on the outside. The stuff I'm using is 0.028" and it's the same as I use on  the Heralds.

Two things: does anyone know the spec of the original brake pipes, and secondly, can anyone confirm that the brake pipe ends are M10 metric? The originals are badly worn but they're longer than any of my spares and I've confused myself by trying to buy them online. Can anyone confirm what exactly is needed?

If I fit the long versions, as fitted when I got the car, there's a lot of thread left over. I do have short versions but am wondering what difference it will make if I fit those, if any?? Any thoughts?

 

[Pete Lewis]

the short are fine providing they dont  have the head  bottom out 

no idea about TR7 being   metric or unified 

pete

[Colin Lindsay]

Thanks Pete; I'll experiment on new cylinders off the car before committing. I'm more or less sure they're metric M10 but as usual wanted a second opinion before starting and finding out the hard way, like I usually do.

[Pete Lewis]

i would hazard a guess the  7 is manly  metric  most of the manufacturers changed to metric in the late 70s

unf sleeves used to have a small groove in the hex  and zinc coloured ?   plated to ID them , metric often a passivated  a more gold  tint  colour 

pete

[poppyman]

Do a double check Colin, the metric nuts fit the unf thread in a cylinder..... untill you tighten it up    The metric female nuts have a less conical head, if you have one of each together you will see what i mean. The short one in the picture is metric. The long one i would say is imperial . Can you show a pic of a female union on the car?

Tony. 

[Colin Lindsay]

Double and treble check, Tony - the last thing I need is stripped threads when all else is singing along.

Does this pic tell you anything? Brake union to flexible hose; the other ends of the pipe are to the cylinders only with male connectors so this is the only female at the rear.

 

[poppyman]

Hi Colin, that is a metric union, so i cant see them mixing the threads up on the car?  It's just that normally the long metric male union dont have that shoulder on the end? As Pete say's just watch those small unions dont bottom out..... But looking at the long one , it has'nt gone that far in.  So yes, go for metric   

Tony.

[poppyman]

PS, If you look at the female union on say the Herald, you will see the difference.

[Colin Lindsay]

Thanks Tony - yes the Herald ones are more conical, and of course I have dozens of those. I'm going to try to source identical male unions to those removed, but it will take up to a week if ordered online. That short one is M8 but is all my local factors have in either male or female. Brake pipe manufacture is a dying art, it seems.

It's a strange setup - there is one flexible hose to the short pipe in my last photo, which goes to a wheel cylinder, but then in place of a bleed nipple there is a long pipe that runs over the diff to the other wheel cylinder which has the only bleed nipple. Basically you bleed the entire rear axle through one bleed nipple.

[Pete Lewis]

That  was a common practice in the day.

It works with only 3

Pete

[Colin Lindsay]

Some owners in recent times have advocated splitting the pipes with a union, and having one pipe to each cylinder, plus a bleed nipple at each. For simplicity's sake I'm going to remake the original setup then see how easily it bleeds. If I get to the stage of requiring brakes I'll be far on from where it is now!

[poppyman]

My Dolomite is the same Colin, bleeds very easy as i have just replaced the rear cylinders.  Some people in the TDC have done what you suggested with a T-piece but found it made no difference to anything.

Tony.

[hugh]

Having re-piped several tr7's they are indeed m10x1 standard metric unions the shorter ones are fine and the cross axle type rear pipe causes no problems, if you convert to rear disc use a 3 way union  and separate pipes as the calipers will have bleed nipples and don't like the daisy chain pipe

[Colin Lindsay]

Got it sorted; I've used the original system as (for now) I'm keeping the rear drums. I've remade the pipes in kunifer and had immense fun with a vice-mounted pipe flarer that makes superb flares in seconds with no effort whatsoever. If I could work up the enthusiasm to rust-proof the underside I'd have had the axle refitted weeks ago.

[Emrys Parry]

On 13/09/2019 at 17:47, Colin Lindsay said:

Thanks Pete; I'll experiment on new cylinders off the car before committing. I'm more or less sure they're metric M10 but as usual wanted a second opinion before starting and finding out the hard way, like I usually do.

My '81 TR7 has a label on the passenger side engine compartment stating that the brake fittings are metric