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 Brake Drum Ventilation Holes
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Westbury

United Kingdom
578 Posts

Posted - 01/07/2018 :  11:21:40  Show Profile

Hello, Chris.( MG Maverick)

Hope you received my Email and pictures.

Cheers,

Chris.
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MG Maverick

United Kingdom
889 Posts

Posted - 01/07/2018 :  11:44:35  Show Profile
Good Morning Chris, Yes, thankyou very much. Currently attending to an elderly Aunt who has just suffered a stroke.

Will reply, Many Thanks, Chris

Chris

J2353
J4129
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Peter Green

United Kingdom
1592 Posts

Posted - 01/07/2018 :  22:12:48  Show Profile
Chris (Westbury)

It looks as if your wheel center are touching the brake drum, I hope it is not.

Peter

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Westbury

United Kingdom
578 Posts

Posted - 02/07/2018 :  10:21:24  Show Profile

Thanks, Peter.

I haven’t finally fitted the drums yet. I merely placed the drum in place for illustrative purposes only but full marks for observation !

Best regards,

Chris.
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Bruce Sutherland

United Kingdom
987 Posts

Posted - 02/07/2018 :  21:31:35  Show Profile
Please,
Does anyone have FACTUAL EVIDENCE (NOT hear-say or opinion) of the benefits to braking performance by drilling holes in either the the drum disc or back plate?
i.e. merits and de-merits (pros and cons)?

Bruce. (PB0564)
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Bruce Sutherland

United Kingdom
987 Posts

Posted - 13/07/2018 :  21:31:34  Show Profile
So it appears that no one has any factual evidence for any benefit to brake performance by drilling ventilation holes in the drum disc or back plate!!!!????
Is this just a 'period' 'fashion' modification?
Seems likely that water and road dirt ingress would be more deletarious!

quote:

Please,
Does anyone have FACTUAL EVIDENCE (NOT hear-say or opinion) of the benefits to braking performance by drilling holes in either the the drum disc or back plate?
i.e. merits and de-merits (pros and cons)?

Bruce. (PB0564)



Bruce. (PB0564)
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PeterL

United Kingdom
1181 Posts

Posted - 13/07/2018 :  22:20:47  Show Profile
Unsprung weight...
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Bruce Sutherland

United Kingdom
987 Posts

Posted - 13/07/2018 :  22:44:54  Show Profile
quote:
Originally posted by PeterL

Unsprung weight...



un-sprung weight/ braking performance - more effective for the driver to lose a pound or two.
Factual evidence, NOT opinion PLEASE.



Bruce. (PB0564)
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Westbury

United Kingdom
578 Posts

Posted - 13/07/2018 :  22:51:17  Show Profile
Hello, Bruce.

If I dare to pass a comment, I would suggest that the fact that so many top marques such as Alfa Romeo, Maserati, Mercedes and Talbot Lago regularly used ventilated drums surely speaks for itself.

Chris.
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rodamos

Australia
10 Posts

Posted - 14/07/2018 :  04:42:53  Show Profile
To be a bit anoraky I could point out that the driver (of whatever poundage) is sprung weight
A more serious comment I could make is that I noticed on one of my cars (not MMM) with holes in the brake drums that there was evidence from blistered paint that perhaps heat path was affected, resulting in potential distortion. Not hard evidence I know, just more conjecture
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Bruce Sutherland

United Kingdom
987 Posts

Posted - 14/07/2018 :  21:50:54  Show Profile
[/quote]
If I dare to pass a comment, I would suggest that the fact that so many top marques such as Alfa Romeo, Maserati, Mercedes and Talbot Lago regularly used ventilated drums surely speaks for itself.
Chris.
[/quote]

Chris,
Quoting drum brake ventilation holes by other continental manufacturers is ‘hearsay’ NOT Factual.

Comparison of stopping distances/brake fade after repeated stops from a designated speed with/without drum brake ventilation holes might constitute factual results.

When tasked with performance comparisons between different brake specifications in a professional capacity, a reliable method was to use brake dynamometer results where all parameters – speeds, loads, cooling airflow, etc – were closely and repeatably controlled and monitored, to give credible brake performance comparisons.

As opposed to the centrifugal cleaning/dispersal effects of water and dirt ingress with disc brakes, such ingress into a drum brake begs concern, which in the absence of accurate quantifiable brake performance improvement for drum brake ventilation holes, makes the addition of drum brake ventilation holes questionable – a 1930’s period style/fetish perhaps? (for use in dry/clement continental weather?).

To repeat my original request for FACTUAL data for the advantage to brake performance with drum brake ventilation holes - can anyone provide this, please?


Bruce. (PB0564)
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rustcollector

United Kingdom
363 Posts

Posted - 14/07/2018 :  22:19:41  Show Profile
The addition of these holes is to allow brake dust to escape not as a weight saving advantage.
My bsa gold star has them from the factory and fitted with core plug like blanks so the owner has the choice whether he wants the vents or not.

A couple of points come to mind, these vents are used on racing vehicles, so a different requirement to a road vehicle. Also brake pads are exposed to water and road debris and don’t seem to suffer.

Just my opinions and not wishing to start a war.
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Westbury

United Kingdom
578 Posts

Posted - 15/07/2018 :  09:53:59  Show Profile
Sorry, Bruce.

Look at any period books and photographs and you will see countless examples of competition cars with drilled brake drums, that is a fact.

The Mercedes Team cars in the 1930s, as an example, were highly professional in their approach (probably an understatement !) and certainly every consideration would have been applied by them to the last detail in the design and construction of their cars in their zeal to annihilate any opposition.

I must humbly accept that they knew enough about motor technology to take every advantage wherever possible and drilled brake drums was just one example.

Chris.
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paul55

Luxembourg
560 Posts

Posted - 15/07/2018 :  10:14:05  Show Profile
Just a thought, if you have vented drums, would it not also be better to have air scoops on the back plates? This would allow air flow through the brake assembly hopefully blowing out any dust and water. Without back plate scoops I think that water and dirt could be trapped inside.

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MikeR

United Kingdom
73 Posts

Posted - 15/07/2018 :  10:30:35  Show Profile
Bruce,

Again no factual data. The attached picture shows a Maserati brake drum with vent holes which certainly do not look like an afterthought nor fashion statement.

Whilst reducing unsprung weight would seem positive I am sure that the small difference in handling (for my J2 at least) would not be evident - the same would be seen that better heat dissipation may not give a noticeable improvement in braking for normal road use.





Regards
Mike

J2 - J4351
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