Rear drum brakes - why?

Faults and Technical chat for the Volkswagen ID.3
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Deleted User 1011

Post by Deleted User 1011 »

Anyone know the engineering explanation for the use of rear drum brakes on the ID.3? They seem to work well enough yet are something I thought long-discarded. Just curious!

MotMot
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Joined: Fri Jun 11, 2021 2:04 pm

Post by MotMot »

Well - as the motor is in the rear wheels - all of the regen braking is done via these. So they don’t need as much braking ability or power as the fronts. If you drive gently they may never actually be used / except for thr handbrake/auto hold.

If I’m feeling charitable - I’d say this was a sensible engineering solution. Rule of parsimony - don’t over complicate things.

If I’m feeling cynical I’d say it was to save money 😁

Some pros and cons found here: https://haynes.com/en-gb/tips-tutorials ... rum-brakes

One big advantage is you don’t get brake dust crap all over your nice clean wheels (or released into the general environment for that matter..).
Deleted User 1011

Post by Deleted User 1011 »

Many thanks - now you've pointed out the regen factor I can see, yes, of course, hefty 'sudden stop' discs aren't unnecessary. I surprised, though, that drums would be cheaper. Having dismantled/rebuilt/adjusted umpteen drums in my long-gone motorcycle days I'd have thought them far more complicated - and thus more expensive? - than the relatively simple discs. But yes, no brake dust crap is a definite plus! Loving my week-old ID.3 and gradually getting better at using and understanding it ...
Deleted User 192

Post by Deleted User 192 »

Last edited by Deleted User 192 on Sat Jul 10, 2021 7:15 am, edited 1 time in total.
monkeyhanger
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Post by monkeyhanger »

Unless you're driving around in a seriously powerful car, the back brakes are doing very little apart from stability (pseudo diff braking inside wheels on an aggressive turn) and handbrake duties. I've owned plenty of disc all round cars and every time you clean them you can see a negligible amount of brake dust on the rear wheels vs the front.

All the ID3 wheel designs are very closed in for aerodynamics, is you're hard pushed to notice the rear drums anyway.
Cupra Born V2 e-boost 230ps Aurora Blue, replaced ID3 PP Family

Audi S3 - because I hate rapid charging for long distance driving.

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MotMot
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Joined: Fri Jun 11, 2021 2:04 pm

Post by MotMot »

Great links. Tl;dr

The continental drum brakes are sealed units that only require servicing after 150 000 km..
Statten
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Joined: Tue Mar 09, 2021 8:39 pm

Post by Statten »

Has anyone noticed a slight creaking when braking and moving from Auto Hold? I feel like I’m only hearing it when in B mode, just as I’m coming to a stop using the brake or pulling away from Auto Hold. I feel like it’s the drum brakes as opposed to the front discs.
MotMot
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Joined: Fri Jun 11, 2021 2:04 pm

Post by MotMot »

Statten wrote: Sat Jul 10, 2021 10:22 am Has anyone noticed a slight creaking when braking and moving from Auto Hold? I feel like I’m only hearing it when in B mode, just as I’m coming to a stop using the brake or pulling away from Auto Hold. I feel like it’s the drum brakes as opposed to the front discs.
Yes. Totally. That’s what I thought it was too.
Deleted User 192

Post by Deleted User 192 »

Statten wrote: Sat Jul 10, 2021 10:22 am Has anyone noticed a slight creaking when braking and moving from Auto Hold? I feel like I’m only hearing it when in B mode, just as I’m coming to a stop using the brake or pulling away from Auto Hold. I feel like it’s the drum brakes as opposed to the front discs.

Same on the Golf, both on Auto Hold and when the automatic parking brake releases when you first start the car and move off.

I don’t think it’s worth worrying over.
Statten
Posts: 23
Joined: Tue Mar 09, 2021 8:39 pm

Post by Statten »

scott28tt wrote: Sat Jul 10, 2021 8:38 pm
Statten wrote: Sat Jul 10, 2021 10:22 am Has anyone noticed a slight creaking when braking and moving from Auto Hold? I feel like I’m only hearing it when in B mode, just as I’m coming to a stop using the brake or pulling away from Auto Hold. I feel like it’s the drum brakes as opposed to the front discs.

Same on the Golf, both on Auto Hold and when the automatic parking brake releases when you first start the car and move off.

I don’t think it’s worth worrying over.
Good to know — i was wondering whether to flag it with my dealer. The trim of the left rear light came off when i opened the boot after only having the car for a week, i've clipped it back in but it's not flush like the right side so i want them to check it out so i was going to chat to them on the brakes but it sounds like it's probably a common thing.
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