ABS unit for fiddle brakes ?

[CompoSimmonite]

I would like to use my Marlin Roadster for gentle green laning. It's a trials design so is more than tough enough Easy to raise suspension for extra ground clearance.

One thought is fiddle brakes to assist if one wheel starts spinning in mud / snow etc. Next thought is could a ABS unit be used, with surplus outputs blanked off, so (rather than the normal pair of additional master cylinders for operate rear brakes when in "fiddle mode") a simple 3 position sprung return switch (left brake operated, neither brake operated, right brake operated) used ?
Basically a manual traction control.


Paul h

 

[AndyStobbs]

Not sure what you're asking, but you would have to manually energize the valves in the ABS unit. Got one in bits at the mo, will get you some pictures if you're interested. I'm certain the valve block is still around, but think the coils might have gone out already. Will check anyway if required.

 

[FranV8]

The old Bosch 2 units have three channels, and I've got the pin outs for the ones used in 80's Corvettes. The valve and pump unit is quite simple, and it's an add on system so if it's offline you just get normal brakes. The solenoids, 3, energise with 2.5amps or 5 amps to select hold and depressurise. Probably could be made to do what you want. The system was fitted to all sorts, I think the 3 series BMW's were one fitment.

 

[bricol]

I think you'll find you need a bit more control then simple on/off - otherwise simply locking one wheel under power will simply kick the other one into wheelspin. And break the diff ;-)
Investing in a decent 12V compressor to quickly blow tyres up and something to let tyres down quickly in the first place will help maintain progress in the first place - I've run down to 2 psi when regs allowed - but you do have to treat tyres as consumable items - although the two punctures I've suffered on events weren't when running silly low pressures.
Bri

 

[CompoSimmonite]

I think you'll find you need a bit more control then simple on/off - otherwise simply locking one wheel under power will simply kick the other one into wheelspin. And break the diff ;-)
Investing in a decent 12V compressor to quickly blow tyres up and something to let tyres down quickly in the first place will help maintain progress in the first place - I've run down to 2 psi when regs allowed - but you do have to treat tyres as consumable items - although the two punctures I've suffered on events weren't when running silly low pressures.
Bri

Thanks.
I don't want to compete in trials. At present I've got a Mahindra MM540 Jeep but am thinking of getting rid and just having the Marlin (plus other "dailys" - Skoda Fabia and Smart Fortwo). I therefore want something that I can venture down the numerous green lanes around here seeing my health is such I can't walk them anymore. One near to me I've even managed in my Smart Fortwo - and also in my Class 3 mobility buggy.
When it comes down snow is a BIG problem here as it's such a hilly area. Being able to lock a spinning wheel for a few seconds to get out of situations, both snow and mud, is my aim rather than anything more serious.

Paul H

 

[CompoSimmonite]

Found an "autopsy" of a Bosch ASB unit -

Doesn't look like one would be adaptable for my needs.
I assumed, wrongly, the motor worked a pump but it seems it just provides a tiny bit of oscillation via small valve that pulses the brake pressure. I'd need something that provided enough pressure to operate a wheel cylinder.
Back to the drawing board
I suppose I could use two electric handbrake units as they are basically just small winches that pull on the cable. If I had one to each wheel then a 3 way switch could select both (as handbrake - operated by another switch) and left or right handbrake cable.

Paul H

 

[AndyStobbs]

Units with TC are capable of building pressure to operate a caliper/wheel cylinder. Also look at BMW pre-charger pump.

 

[PhillipM]

Most electronic handbrake mechanisms are far too slow and clunky for the kind of response you want from a fiddle brake - you'll have stopped or slithered through the bit you want before they finished actuating. What's wrong with a pair of handles and some cylinders?

 

[Fintray]

Would it be possible to fit an air or electric operated diff locker to your vehicle?

 

[Cobbler]

Hi Compo,
On the trials car I built,I piggybacked onto the handbrake cables, so it left the hydraulics intact for MOT. There are so many Marlins on the trials scene now, someone must have sorted the best way to do it. As stated before, you need the braking effect to be progressive to be effective. You don't want to lock it up, just apply braking force, then it try's to drive on both wheels.

Have you thought of an LSD?, is yours a Marina Axle? should have thought one would be available. Save a lot of messing about.

Cobbler

 

[Robotstar5]

Look at traction control rather than ABS, my car applies the brakes to a spinning wheel using the ABS plus a pump I assume to supply fluid pressure. You could try the "old" method, left foot braking while applying power, the brakes will slow/stop the spinning wheel so diff transfers drive to the other.

 

[the snooper]

the ford focus has traction control built into the abs pumps on some models the gear is one from memory so it would be just a case of mounting pump and sensors then connecting pipes and cables, the ecu for the abs is on board the pump so I don't see a problem in being able to transfare it

 

[DrNik]

Early ford rs turbo and the like had belt driven abs, which could be utilised

 

[Robotstar5]

Early ford rs turbo and the like had belt driven abs, which could be utilised

Surprised you haven't got one in your loft somewhere

 

[DrNik]

Cheeky......

 

[FranV8]

I think the video shows a Bosch 5 abs unit, they do traction control also so can apply either rear brake. The two is simpler, and does have a pump built in too.

But you could work without a pump, apply brake and use the ABS to release the brake in the gripping side.

 

[AndyStobbs]

I think the video shows a Bosch 5 abs unit, they do traction control also so can apply either rear brake. The two is simpler, and does have a pump built in too.

But you could work without a pump, apply brake and use the ABS to release the brake in the gripping side.

I thought the 5.x units had four channels? Even the 4.x units have four channels.