MikeR
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| posted on 4/5/06 at 09:53 AM |
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Are sierra drums lighter than disks?
Think i'm going de-dion.
So, are drums lighter than disks? If i'm going to the hassle of converting the chassis i might as well make the most of it.
Anyone with any views, hard evidence or general advice as to which is lightest and which is best?
Going to be fittnig 13" capri alloys
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flak monkey
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| posted on 4/5/06 at 10:11 AM |
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You will have trouble fitting sierra rear discs under 13" capri wheels...apparently
David
Sera
http://www.motosera.com
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tom windmill
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| posted on 4/5/06 at 10:46 AM |
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i think a while back someone did a breakdown of the weight of the sierra drums and disks and the difference was minimal maybe a search will dig
something up...
Tom
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James
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| posted on 4/5/06 at 11:19 AM |
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I would imagine the drum weighs as much as a calliper and disc.
But the disc (or atleast 4x4) drive shafts are a lot heavier.
So it probably works out around the same.
For a future car I would look at combining the bits to get the best/lightest option.. along with some alloy callipers! 
HTH,
James
------------------------------------------------------------------------------------------------------------
"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights."
- Muhammad Ali
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smart51
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| posted on 4/5/06 at 11:43 AM |
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someone weight like for like components and found that drums were almost 0.5kg lighter for the pair.
sierra rear discs will fit under 13" rims but sierra handbrake calipers will foul most wheels. The handbrake arm can be tweeked to fit some
13" rims, or you could fit a different caliper. I believe that several companies make billet alloy calipers that have been adapted for a
handbrake cable. they have a side exit arm. One of the kit car magazines did an article on them.
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Hellfire
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| posted on 4/5/06 at 12:10 PM |
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Go for the lighter diff with push-in shafts and convert the rear drums to disks. This will give you a fairly light setup if that's what your aim
is. 
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MikeR
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| posted on 4/5/06 at 12:19 PM |
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whats the lighter diff?
I'm hopefully about to win a complete rear end with drums. If fitting disks under a 13" is a problem then i'll stick with drums and
pretend they are lighter.
(done a search and found no matches)
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D Beddows
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| posted on 4/5/06 at 12:37 PM |
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I'm interested in this too - who sells the necessary bits of metal to convert push in driveshafts to disks or can you mix and match the relevant
parts from the different types of Sierra back end?
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NS Dev
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| posted on 4/5/06 at 02:08 PM |
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If you're not going sierra track then you'll need different shafts anyway (and I think you are going narrow track aren't you
Mike?)
In that case get lightweight shafts made (by you know who!), lighten the CV's (I'll do them for you Mike) and I can't see the disc
setup being any heavier, especially if you use alloy VW calipers which are as cheap/cheaper than fordy ones anyway.
I hate drums!! They are fine in terms of brake performance but just horrid in terms of engineering, horrid yucky things full of crappy bodge springs,
silly sliding bits, crappy retainers, silly self-adjusters that go wrong and all manner of other things that I would not let anywhere near my car!!
Sorry, rant over!!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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britishtrident
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| posted on 4/5/06 at 02:19 PM |
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Apart from brake fade the big problem with drums is both the drum and the brake shoes act like springs under when pressed really hard.
However for road use 9" Sierra drums are more than up to the job and will give a really good handbrake.
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MikeRJ
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| posted on 4/5/06 at 02:22 PM |
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quote:
Originally posted by britishtrident
Apart from brake fade the big problem with drums is both the drum and the brake shoes act like springs under when pressed really hard.
As do many calipers!
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britishtrident
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| posted on 4/5/06 at 02:53 PM |
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quote:
Originally posted by MikeRJ
quote:
Originally posted by britishtrident
Apart from brake fade the big problem with drums is both the drum and the brake shoes act like springs under when pressed really hard.
As do many calipers!
Nothing like as much, the major part of problem with drums is under havy braking "pressure" they bellmouth, ie the diameter of the drum
at the edge nearest the back plate increases more than the edge nearest the hub --- this really hammers the brake efficiency.
A guy I knew had the problem in a major way on a pre war MG Midget (anybody with MGCC connections will know who) came up with an ingenious way round
it he had the outer surface of the drums machined and high tensile steel bands heat shrunk over the outside.
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MikeR
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| posted on 4/5/06 at 04:16 PM |
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bugger - outbid on ebay ..... grrrrr.....
realistic price for complete rear end anyone ?
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Wadders
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| posted on 4/5/06 at 06:20 PM |
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Given what i know now, i would use a drum brake rear end cos the shafts, joints and hub carriers are all lighter, bin the drums and convert to discs
using lightweight ally calipers.
13" wheels can present quite a challenge with discs, as iv'e found out the hard (expensive) way. VW calipers will not fit under some
13" wheels. This is my final solution, using bike discs and pug 206 calipers. seems to work ok, but is not an easy bolt on solution by any
means.
 
Description
 
Description
[Edited on 4/5/06 by Wadders]
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NS Dev
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| posted on 5/5/06 at 10:07 AM |
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Not easy bolt on, but bloody nicely done mate, detail work like that makes all the difference!!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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Bob C
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| posted on 5/5/06 at 12:05 PM |
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Hi Wadders - looks like a tricky installation! Are the discs floaty (like on the bike) or bolted on? Did you turn an inward flange on the bells for
the fixings?
I did a slightly more conventional version but that involved turning up(down?)standard discs rather than using bike gear...
cheers
Bob
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Wadders
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| posted on 5/5/06 at 07:06 PM |
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Hi Bob
yes disks are bolted solid, and as you say, located by a rebate turned on the back of the bells. The Pug calipers float by design, so the discs should
be ok mounted solid.
Rattling floaters would have driven me nuts anyhow!
Cheers Nat, appreciate the kind words .
Al.
Originally posted by Bob C
Hi Wadders - looks like a tricky installation! Are the discs floaty (like on the bike) or bolted on? Did you turn an inward flange on the bells for
the fixings?
I did a slightly more conventional version but that involved turning up(down?)standard discs rather than using bike gear...
cheers
Bob
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MikeR
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| posted on 6/5/06 at 01:47 PM |
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got my sierra back end (thanks for all the help paul - really appreciated) and when the weather dries up i'll weigh the escort axle, the capri
axle and the sierra stuff to give you a final, conclusive comparison.
All will be weighed with fluids etc and i'll try and figure out the amount of force needed to lift a side of the axle for when it hits a bump.
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Oldpc
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| posted on 6/5/06 at 02:56 PM |
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back end
Hi, Mike think we had the best of the weather. Hope you find it all usefull.
I hope you wont enter me for the untidy garage competition as I would have an unfair advantage 
all the best, see you around somewhere.
Paul
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MikeR
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| posted on 6/5/06 at 04:41 PM |
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Aaah, but you're excluded on the grounds that yours isn't a garage but a Garage!
Anyway, it wasn't that untidy, you knew where everything was.
Really sold on using the air gun after using yours now. Just had mine fired up to remove prop shaft bolts on the capri axle.
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RichieC
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| posted on 7/5/06 at 07:47 PM |
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Here is the thread in question thanks to LSDWeb
Rgds
Rich
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