drilling brake T's - have i done something stupid?
MikeR - 3/4/08 at 07:53 PM
For five minutes this seemed a good idea. Then when i'd done it i'm sure i've been stupid.
Brake T peice. the hole for fastening to the car is imperial. About 7.25mm. Bugger it i think, i'll just drill it out to 8mm. So i do.
Now i'm thinking i've enlarged the hole and therefore taken brass away from the actual bit that stops the brake fluid going everywhere.
Doing my best to guestimate i think there is still 2.5mm of brass between the brake fluid and the mounting hole.
It will be ok, won't it? (cause it if will, i'll be doing the other one tomorrow night. Also just realised i can measure the thickness
accurately tomorrow as well).
Answers on a post card to the usual address 
ChrisGamlin - 3/4/08 at 07:58 PM
Probably fine but is it worth the risk, just find an imperial bolt or just use a 6mm bolt (and a washer if necessary), more than man enough to hold
something like that in position.
blakep82 - 3/4/08 at 07:58 PM
i personally wouldn't have, but i guess it should be fine.
ie, whats the wall thickness of copper brake pipe?
[Edited on 3/4/08 by blakep82]
r1_pete - 3/4/08 at 08:32 PM
The metal round the fluid path is now 0.375mm thinner, these castings are quite meaty, I don't think you'll have a problem. The fluid
drillings are only small, I doubt you are anywhere close to break through.
andyd - 3/4/08 at 11:40 PM
How much are they? If not much then just cut it up and see how much material there is left then you'll know for next time.
I must say they've always struck me as being quite over-engineered so I'd reckon you'll be ok.
Also another thought just struck me... fit some temp pipe/tubing and pressure test in some water? If you see bubbles then it'll leak fluid? Or is
that just me talking balls at twenty to one in the morning? 
Mr Whippy - 4/4/08 at 07:59 AM
quote:
Originally posted by andyd
Also another thought just struck me... fit some temp pipe/tubing and pressure test in some water? If you see bubbles then it'll leak fluid? Or is
that just me talking balls at twenty to one in the morning?
pressure test? arn't brakes working a 1000's of psi?
02GF74 - 4/4/08 at 08:04 AM
quote:
Originally posted by MikeR
Doing my best to guestimate i think there is still 2.5mm of brass between the brake fluid and the mounting hole.
copper brake pipe is 3/16 in or 4.7 mm.
Assuming a 1 mm hole and I think it is bigger than that, there cannot be more than 1.88 mm of metal either side of the hole.
But what I don't know is how copper compares to brass under pressure.
Don't worry about it as long as your brake fluid lamp works! 
MikeR - 4/4/08 at 08:17 PM
recon after measuring tonight i've got 2mm of brass.
I think i'll be ok. might do the other one now!
foes - 4/4/08 at 11:15 PM
yep i'm sure 2mm wall thickness is more than enough but why drill it out in the first place..? its not taking any load so a smaller bolt would of
been fine....
MikeR - 5/4/08 at 12:17 AM
yeah it would have been fine - but with the 8mm bolt in an 8mm hole it just locates it that much nicer.
rusty nuts - 5/4/08 at 08:14 AM
Whats wrong with a 7mm bolt?
MikeRJ - 5/4/08 at 05:00 PM
quote:
Originally posted by rusty nuts
Whats wrong with a 7mm bolt?
Nothing apart from availability of nuts and bolts and taps etc. compared to 8mm.