woodsy144
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| posted on 17/7/24 at 10:12 PM |
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I might be mistaken,
I thought there were Polo EPB units out there, but subsequent searches I couldn't find them.
The Polo rear calipers I am using appears to be from a 2009 to 2014 unit.
I wonder if the Passet unit could be placed within the Polo slide unit (I might be asking too much).
Does anyone have the dimensions of the VW EPB unit??
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JAG
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| posted on 18/7/24 at 06:44 AM |
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Most of the integrated EPB calipers, from TRW say, use the same motor-gearbox unit. There is a more powerful version for heavier cars but the external
dimensions and wiring are the same - they only change the internal gear ratio.
It's a similar story for the other big player - Continental. The motor-gearbox-unit is common.
Different vehicles will have different hydraulic piston sizes - so you should select your caliper based on the hydraulic sizing and the front:rear
hydraulic brake balance.
Common piston sizes are 34mm, 38mm and 43mm.
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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woodsy144
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| posted on 19/7/24 at 01:21 PM |
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quote:
Originally posted by JAG
Most of the integrated EPB calipers, from TRW say, use the same motor-gearbox unit. There is a more powerful version for heavier cars but the external
dimensions and wiring are the same - they only change the internal gear ratio.
It's a similar story for the other big player - Continental. The motor-gearbox-unit is common.
Different vehicles will have different hydraulic piston sizes - so you should select your caliper based on the hydraulic sizing and the front:rear
hydraulic brake balance.
Common piston sizes are 34mm, 38mm and 43mm.
The vw caliper I am using is 38 diameter piston, the rod diameter is 6mm and the distance between them is approx 118mm. How does that compare to the
epb unit??
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car man
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| posted on 20/7/24 at 05:57 PM |
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Epb units a passat are 38mm.
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coyoteboy
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| posted on 21/7/24 at 09:32 AM |
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Dont forget theres a few safety features youre going to want to have. you dont want it commandable while moving, you dont want it commandable while
ign off, you might want self diag and retract for pad change etc.
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car man
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| posted on 21/7/24 at 10:08 AM |
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Wilwood do a kit https://www.wilwood.com/brakekits/BrakeKitListRear?mincatdesc=Electronic%20Parking%20Brake%20Rear%20Retrofit%20Brake%20Kit.
No speed input so you could operate at any time.
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scudderfish
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| posted on 21/7/24 at 11:40 AM |
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quote:
Originally posted by coyoteboy
you dont want it commandable while moving
You absolutely do! It's the emergency brake for when your hydraulic brakes fail.
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woodsy144
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| posted on 21/7/24 at 12:45 PM |
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quote:
Originally posted by car man
Epb units a passat are 38mm.
Any idea on what the pin slide diameter and distance is??
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coyoteboy
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| posted on 21/7/24 at 03:24 PM |
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quote:
Originally posted by scudderfish
quote:
Originally posted by coyoteboy
you dont want it commandable while moving
You absolutely do! It's the emergency brake for when your hydraulic brakes fail.
That just isnt a good idea with an epb which just rams itself on full, with a hand operated brake that you can modulate you can prevent yourself
being an uncontrolled missile. It would have to be hooked onto your ABS sensors to prevent lockup.
[Edited on 21/7/2024 by coyoteboy]
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obfripper
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| posted on 21/7/24 at 04:28 PM |
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The OE systems use an inbuilt accelerometer to stop the brakes locking when applied while moving, this amount of deceleration will be vehicle specific
to stop wheel locking when used in an emergency. The epb controller can also use any available can bus data to augment the acceleration data, this may
not be available in the event of an abs control unit failure. Later cars have the epb control integrated into the abs control unit, a failure here
leaves no secondary brake available.
The OE systems also apply the hydraulic brake in preference to the electromechanical brake when moving, which means the hydraulic brakes are still
applied in the case of a master cylinder failure. This is why for a dynamic test the EPB needs to be put into a test/bedding mode, otherwise you would
be testing the hydraulic brakes in lieu of the electromechanical brake.
I'm pretty sure all the vw group cars based on pq and mqb platforms (last ~20 years with 5 stud wheels) use a rear caliper with a 118mm slider
spacing(whether epb or not), the older platform cars used a 110mm slider spacing. There are lucas(trw) and ate(continental) variants, and both use
their own caliper brackets and pad shapes.
The oe systems also use the brake pedal operation as an interlock for the manual release of the epb, this would be easily done by needing the brake
light output to be on to activate the release switch.
Dave
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coyoteboy
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| posted on 22/7/24 at 11:45 AM |
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Interesting info on the OE, thanks!
You could indeed use an accel here, but I'd be concerned it was too variable, or at least too conservative - if I brake on a wet slick road my
slip would occur an order of magnitude lower G than on a dry grippy road. Seems you'd be leaving a lot of brake unused. A combo of both would be
nice but then you get into authority issues, but I realise not everyone has wheel speed feedback either.
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JAG
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| posted on 24/7/24 at 01:12 PM |
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All of that is true but the same is/was true of the original 'emergency brake' the park brake lever. The only real difference is/was that
the driver could modulate the brake output to provide the most braking while avoiding rear wheel lock.
For reference the legal requirement, for the emergency brake, is to provide 0.3g of deceleration. There is no requirement to avoid rear wheel lock,
because this is an emergency.
Early EPB systems used to provide an 'emergency brake' output without needing an accel' signal - they did it with a gradual ramp up of
brake output. So when the car was above a threshold speed (say 5mph from a speed sensor signal somewhere on the car) and the driver commanded an EPB
apply the EPB unit would provide a stepped apply....
5 amp apply -> 5 seconds -> check EPB switch state -> 10 amp apply -> 5 seconds -> check EPB switch state -> 15 amp apply (until
max' current)
If the driver released the EPB switch at any point in that cycle the EPB released all clamp.
For a kitcar you'd need to have a speed signal input, probably a slotted disc on the propshaft. Then the same strategy could be implemented and
would meet the legal requirement.
[Edited on 24/7/24 by JAG]
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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