7 replies to this topic

[I hate Brian]

Hi all is it best to take the front to rear brake pipe behind or in front of the rear subframe just looked at tow different pic see attached which is the preferred method?

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[nicklouse]

original is between the shell and the subframe as per the lower image.

[minimans]

Two choices of battery cable fitment in those two pictures too!!!

[tiger99]

So that you can remove the subframe easily from time to time, (as well as for plain simple originality) it should be as per original, rising between heelboard and subframe (not chafing against the subframe in the gap!), then it turns horizontal, pointing backwards, and should have 1.5 turns in a loop in the vertical plane, with the end then pointing forwards to the T piece or limiter valve. The reason for the loop or really a coil is to accommodate subframe movement without fatiguing the pipe, and is a very good reason why copper pipe should not be used. The original "bundy" pipe is adequate to cope with repeated minor flexing, as is Kunifer, the preferred material on safety grounds. The 1.5 turn coil would be about 3 to 4 inches diameter. You make it by winding the pipe, by hand, around a suitable circular former such as a bit of pipe of approximately the right size. The flexing results from subframe movement on its mounting rubbers, and is of course worse for later models with the horrid rubber mounted front subframe and larger, softer rubbers in the front trunnions of the rear subframe.

 

I have seen some Minis where a replacement pipe had been fitted, probably the genuine BMC article and correct length as they were bundy (long before Kunifer was widely known or spivs started selling unapproved copper) and was in a very long loop in the vertical plane where the coil should have been. Probably adequate as regards flexing but not good looking at all. It reminded me of the end of a trombone. I assume that whoever was fitting them simply did not know about the reason for the extra length.

 

(Hint: If you fit old style trunnions and bushes to the front of your rear subframe, unless you have exceedingly well developed senses you will not detect any extra noise or vibration, but a person of average sensitivity will usually be able to detect marginally better handling.)

 

I don't know if all Minis had the coil in the pipe there, but all of mine certainly did, including the ancient MK 1 van.. The same is done on various other vehicles where minor movement is required. Early Triumph Heralds even used a multi-turn coil in the clutch line rather than use a flexible hose, the coil being oriented such that it worked like a coil spring, extending and retracting as the somewhat feeble torque rocked the engine on its mounts. Running any metal pipe from shell to any sort of rubber mounted subframe without a flexible hose or a coil is asking for trouble. The rubber mounted Mini front subframe uses a carefully routed pipe with enough free length to flex a bit, from the limiter valve down to the subframe. That is why the pipe is more or less hanging in mid air. Tie it down and bad things would happen sooner or later. (Another good reason for solid subframe mounts? Possibility of neater pipework!)

[richmondclassicsnorthwales]

and the meaning 

[lawrence]

I think what tiger is trying to say in a convoluted way is leave a bit of slack in the brake line to lower the change of fatigue cracking of the pipe.

 

Put the pipework so you haven't got to bend it to removed the rear subframe and do what you want with the battery cable just make sure everything is tidy so it lowers the chance of snagging on stuff on the ground or pipework etc rubbing on things

[tiger99]

I was actually also talking about originality, for which there was a good engineering reason, not obvious unless explained. If you make it look original, it will also be functionally correct, and safe, in this instance. If you don't have the coil to allow flexing, it will also not look original. Therefore both requirements coincide, albeit for true originality you would use Bundy pipe rather than Kunifer, if you are into that level of detail. Some people are.

[I hate Brian]

Thanks for the info guys