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different sizes?
Anything and everything Herald. Talk about anything from the first 948s to the last 13/60s.
Section : Rear Axle
Rear axle, brakes, wheels and tyres.
Posted By : James Hoare, 18-Oct-2006,
11:44am
Does anyone have any experience of finding different thread sizes used for the brake drum grub screws? I'm rebuilding a halfshaft assembly at the moment,
using a mixture of salvageable parts from my assembly from the car and a box of bits (halfshaft, trunnion, hub, etc.) The problem is... my original drum
screws are too small for the threaded holes in the hubs I'm using!
As far as I was aware, these screws remained the same size throughout production. The Canley catalogue only shows one size for all models. It shouldn't be
a problem for me to work out what size they are, and find some to suit, but I would be interested to hear if anyone's had the same problem.
Cheers,
James
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Posted By : Steve Cureton, 18-Oct-2006,
04:53pm
James, I wouldn't worry too much as once the wheel is on the drum is held securely anyway.
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Posted By : Matthew Holland,
18-Oct-2006, 08:28pm
Surely these two screws are crucial for drum centralisation? Without them both in place there is no way of being sure it's on correctly and once
the wheel is tightened there's no way it'll self centralise and could give the illusion of a warped drum.
That's what I think anyway...
: )
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Posted By : Steve Cureton, 18-Oct-2006,
09:45pm
Although I have the screws fitted to my Herald I have had other cars wthout them without problem. If you're concerned then apply the hand brake
to centralise the drum while you tighten the wheel. If you're really concerned have you tried the Triumph suppliers? Failing that you could
always drill and tap the holes to take alternative screws.
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Posted By : Chris Taylor,
18-Oct-2006, 11:38pm
Strikes me that someone has stripped a thread and retapped the holes to the next larger size.
I would not worry if you cannot identify the right thread as these screws are not really essential. As other posters have said, the drum is
well secured between hub and wheel when the wheel nuts are done up, and the "braking torque" so to speak is taken by a mixture of friction
between drum and hub face and the wheel studs. It is NOT (I'm glad to say!) taken by these screws.
As regards centralisation of the drum, this is taken car of by the wheel studs and also the circular register on the hub face that matches
the hole in the front of the drum. The only useful function these countersunk screws do is prevent the drum falling off when you take the
wheel off. Especially once you've worn anything of a lip on the inside of the drum, this is NOT a likely event, and is harmless even if it
should happen. (Worst possible scenario a bruised finger?)
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Posted By : Dan Owen,
19-Oct-2006, 10:24am
I wouldn't say the screws are totally redundant. I know they're not essential but they stop the drum from wobbling around while you
adjust the brakes.
The main problem of course is when the little b@$t@rd$ sieze up despite the coppergrease you put on there! (Essential Tool
1,493,948-impact screwdriver. If you can find it...)
Mind you I still prefer them to these awful modern things that self adjust (stop you getting the drum off) and have the hub
incorporated into the drum so you get grease all over the shoes and brake dust into the hub, these are truly the work of the devil!
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Posted By : James
Hoare, 20-Oct-2006, 11:55am
Thanks to all of you for your varied thoughts on this topic. You've pretty much confirmed what I was thinking already.
Dan - I have to agree with your list of annoyances. One of our other cars is a Citroen which, although brilliantly engineered in
many respects, has the dreaded brake drums with integral bearings. Having to pull the hub just to change brake shoes is a major
pain, although the hubs are not quite as obstinate as on "our" cars!