# Tesla electric caliper as a Parking Brake



## Lowcoe (Jul 3, 2020)

Quick google search gives a couple options. I’ve emailed Scott Bauer at Postal Mopar a couple times and this may be an option…
















This Wilwood caliper based kit could work…


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## Lowcoe (Jul 3, 2020)

For the cool factor the Tesla electric caliper is the way to go. The question is how to control it. It comes with 4 wires. 2 heavier ones, which when 12 v is applied will either activate or release the caliper piston depending on polarity. 2 fine wires are the main topic of discussion here.


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## Lowcoe (Jul 3, 2020)

To control the unit there is an off the shelf solution from Pantera Electronics the more I think about it it’s actually pretty robust and may be worth the money as it is feature complete.


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## Lowcoe (Jul 3, 2020)

In the discussion started on the other thread TeZla had some great points. The only thing I would say was I was only looking for a parking brake. I wouldn’t want to rely on the unit as my only source of braking. I actually am thinking of an iBooster down the road as a separate project. 



TeZla said:


> electric calipers aren't that simple. I've seen someone use a pair of automatic power window close modules to operate their caliper. On the bench, its great, works perfectly. It was enough to convince me it was feasible to fit electric calipers as part of my diy.
> 
> There are things that need to be considered in its operation.
> When engaging (clamping) you need to sense the motor current. The current draw when the motor is running is fairly constant, but when it finally clamps and builds pressure, the current spikes as the motor is loaded up. When it spikes, you need to cut the power to the motors, otherwise you risk burning them out. The e brake motor module used on a lot of Japanese and Euro calipers (TRW?) seems to be a fairly common fail point, so they are probably quite susceptible to over current burning them out over their normal operating life.
> ...


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## Lowcoe (Jul 3, 2020)

My initial thought was, Why can’t I have two buttons, one that powered on the caliper by applying 12v and one that applied it in the reverse polarity to release and just call it good?

Remy_martian said


remy_martian said:


> Maybe put a diode and power resistor on the actuate direction to make sure it'll release. Or maybe that's built into the mechanism.
> 
> Early Model S had a separate ebrake caliper. Newer has it built in to the hydraulic one.


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## Lowcoe (Jul 3, 2020)

Brian said 




brian_ said:


> It might seem that way, but it's not that simple. Here's SuperfastMatt's take on the subject, illustrating what TeZla explained:
> Tesla-Jag Gets The Red Carpet Treatment
> There are different versions of parking brake controls in different Teslas, possibly even within the same physical caliper design.


 Great video. I’m getting interested in arduinos. Also liked the idea of adding an obd2 dongle to access the canbus info and display it on a phone or tablet. May be a great substitute for the $3500 unit I paid PolyKup for but never received. Oh wait that’s a different thread…


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## 57Chevy (Jan 31, 2020)

If you haven't experienced a driveshaft parking brake being applied while at speed, it is quite terrifying as the wheels hop and skitter all about the place. I'd suggest keeping it super simple, an electric window switch is about all you need. The increase in current when applied cuts off the power, just like when the window is fully up.


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## Lowcoe (Jul 3, 2020)

I like that tack. E bay $12 window switch ordered. If it doesn’t work I have a quote for the $400 Pantera controller…


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## 57Chevy (Jan 31, 2020)

worth a shot for twelve bucks. There are a heap of different ways the current is cut off in the automatic systems so it might need more than just the basic switch to have it automatic. I read about somebody doing it with a window switch but can't find the reference now.

Could also use it as simple human-in-the-loop but that would require a small amount of operator awareness since it would be possible to both leave the brake partially on and also burn out the motor from holding the switch on for a long period.


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## TeZla (Feb 18, 2021)

Lowcoe said:


> In the discussion started on the other thread TeZla had some great points. The only thing I would say was I was only looking for a parking brake. I wouldn’t want to rely on the unit as my only source of braking. I actually am thinking of an iBooster down the road as a separate project.


Nothing, not even tesla use a fully electric brake, Its always hydraulic. The electric component is only the handbrake. (and ibooster)
If your only using the caliper as a park brake, there are probably more compact options out there if you didn't want the use the whole bulky tesla caliper.
with it mounted as a pinion brake, were you planning on using the hydraulic part as well? or just keep the factory landrover drums? Willwood do a E brake caliper thats specifically for the park brake.





Wilwood Disc Brakes - Electronic Parking Brake Calipers


Wilwood Engineering manufacturers a wide variety of different lightweight, high performance, and extremely durable aluminum calipers in small, medium and large sizes. Electronic Parking Brake Calipers




www.wilwood.com





They also do a caliper control box, but not sure how it'd interface with anything non wilwood? The calipers look like they use the TRW motors, with the standard 2 pin plug





Wilwood Disc Brakes


Controller EPB-Dual Caliper, brake hardware, hardware, cap, cable kit, parking brake, push rod, parking brake kit, pedal, clutch, pin, clevis, eyelet, lever, bushing, knob, actuator,620-15487




www.wilwood.com





Also, as a thought to consider, Im helping my friend making a V8 SWB land rover. We had the same handbrake issue once we put the V8 in, the drum fouls on the mid chassis crossmember. He ended up using an off the shelf land rover disc brake handbrake conversion, Bought fromthe UK somewhere I think? That could be an option for you, as in the caliper bracket and mounting position?
Disc Handbrake Conversions - Paddock Spares - Paddock Spares (This one I think?)

Also, have you seen this thread?


https://www.aulro.com/afvb/the-modified-zone/187685-electric-park-brake-conversion-defender-2.html?s=10cc0c10cf84763419eeab6c50c68d53


They don't really talk much about the electric caliper, But there are pics of the X-Engineering brake caliper conversion


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## Lowcoe (Jul 3, 2020)

Some of these options still seem to use the original gearbox, this has been removed. The willwood options don’t have any particular cost savings so kinda puts me back to square one. I do appreciate all of the options tho. Nice to have everything in one thread….


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## Lowcoe (Jul 3, 2020)

57Chevy said:


> worth a shot for twelve bucks. There are a heap of different ways the current is cut off in the automatic systems so it might need more than just the basic switch to have it automatic. I read about somebody doing it with a window switch but can't find the reference now.
> 
> Could also use it as simple human-in-the-loop but that would require a small amount of operator awareness since it would be possible to both leave the brake partially on and also burn out the motor from holding the switch on for a long period.


Seems like a simple 5 amp fuse could avoid catastrophe if the operator was unawares….


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## 57Chevy (Jan 31, 2020)

Even better, a self resetting fuse. I'd imagine the brake caliper will draw about 20-30A stalled as a guess


https://www.jaycar.com.au/medias/sys_master/images/images/9590464086046/SF2325-dataSheetMain.pdf



[edit] just looked at the Tesla wiring diagram and it used two 20A fuses, one in the main supply and one in a redundant supply, to power both calipers so that would indicate that the power is less than 10A per caliper


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## Lowcoe (Jul 3, 2020)

Nice! I couldn’t find these diagrams!


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## 57Chevy (Jan 31, 2020)

available from where all sorts of things are shared, pm me if you want a pdf.


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## Lowcoe (Jul 3, 2020)

Ok so happy to report Sucess using a 10 amp resettable fuse and a 2 way toggle switch to reverse current polarity easily does the trick! I started with a 5 amp resettable switch. If you lean on that hard it will trip the fuse. Switching to the 10 amp fuse and leaning HARD until you obviously hear the brake fully clamping or releasing does not trip the fuse!


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## Lowcoe (Jul 3, 2020)




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## Lowcoe (Jul 3, 2020)

Boom. $300 bucks saved. Figured it out before window regulator switch even showed up using a more authentic looking old school switch I had laying around…. Cost $10 for an assortment of resettable fuses …. Making up for that $3600 that PolyKup shafted me for …. Not bitter….


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## remy_martian (Feb 4, 2019)

Looks like the premium caliper senses the current for consistent clamping force.

My concern with your technique is not being able to release the parking brake with a lower 12V battery voltage than when you set the brake.

For your next experiment, clamp at 13V, release at 9V...if it does, Bob's your uncle.


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## 57Chevy (Jan 31, 2020)

do you have any warning light output from the calipers? What happens if the driver doesn't fully release it and goes for a long drive?


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## TeZla (Feb 18, 2021)

57Chevy said:


> do you have any warning light output from the calipers? What happens if the driver doesn't fully release it and goes for a long drive?



Ohh, i've seen the results of this haha.

Back when I was silly enough to turn spanners for everyone else, We had a bunch of Mercedes Sprinter vans come into the workshop for a recall, They were retrofitted into ambulances for the Victorian Ambulance Service. The outfit that did the retrofit managed to disconnect the handbrake warning light on the dash of every single one they did, so we got the recall job to fix the wiring problem and replace the rear brake rotors and handbrake shoes. The paramedics would often forget to disengage the handbrake all the way because it was located so low on the floor, It actually took leaning sideways on the seat to really put it down. The engine was plenty strong enough to overpower the handbrake and they'd drive away, the shoes inside the drum would burn out and cook the rotors. The worst one we had got so damn hot it actually split the disc from the rotor hat, Boom, no more rear brakes and a fully floating rotor.

A tourquey electric motor should have no problems at all overpowering the handbrake...


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## joekitch (Sep 13, 2013)

in for updates
the stock parking brake on the c3 corvette is legit dangerously bad, would very much like a good electronic caliper for not much cash


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## remy_martian (Feb 4, 2019)

Is that by design or is yours simply not properly adjusted?

The caliper is the easy part. You need to find a way to mount it.


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## joekitch (Sep 13, 2013)

Trust me, c3 owners have been trying to adjust their parking brakes for dang on 52 years no without much success

Mounting a parking brake caliper I'm not too worried about tbh, sendcutsend to the rescue


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## brian_ (Feb 7, 2017)

joekitch said:


> the stock parking brake on the c3 corvette is legit dangerously bad, would very much like a good electronic caliper for not much cash


Ah, the infamous rotor-hat-as-drum design. My Toyota van has that - I hate it, too. This system was largely replaced by the type which integrates a mechanical parking function with the hydraulic cylinder of a sliding caliper (originally by pull cable, but now usually by caliper-mounted electric motor)... but that doesn't work with an opposed-piston (fixed body) caliper and a separate parking caliper (which is what Tesla did initially in the Model S) is certainly a valid solution.


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## Lowcoe (Jul 3, 2020)

Bobs my uncle….


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