MadaboutKitcars

Has anybody fitted ABS? I saw the WK guy doing it and just wondered if it is easy to do.

Someone might be able to confirm this:

I heard there were issues with using the ABS from a donor. The theory being that the ABS was designed for a 1400kg (eg) car not a 500kg and the system is calibrated set on certain criteria, one of them being weight.

For this reason I have been looking at the WK? build with interest.

Anyone able to shed any light?

I was wondering exactly the same thing. Bit like Airbags. Not allowed by SVA as the airbag system transplanted into a donor is not designed for that car.

I am also very interested as I would like ABS when I start my build.


Mike.N

I spoken to a few people and all think weight will affect the ABS system.

This: http://www.stoptech.com/whitepapers/abs_bigbrake_122701.htm was posted on another forum.

It doesn't really refer to weight, but does make quite interesting reading about changing things in the system.

ABS

Thanks to all for the discussion on this link. I was naively going to just fit the ABS thinking that if I could solve the mechanical problems of fitting the sensors everything else would be simple.

I guess this means I need to go for the non - ABS approach but that too has problems. I believe that the master cylinder is different for non-ABS cars anyone know if this means I have to chnge to a different master cylinder and will it fit the same servo or do I need a new one of these too!

Also I was banking on the ABS preventing the the front wheels locking cos they are much more lihgtly weighted than before - does this mean a brake balance system and where do I get one cos its not part of MArlin's kit (apparently!!)

Help gratefully recieved

After reading the linked article I wouldn't necessarily go off the idea of using the donor vehicles ABS system.

It seemed to me that problems are only encountered with the ABS if you change dramatically the brake components. If you retain the original donor's brakes without increasing calliper or disk size it should all work the same.
The one thing you have changed though is the weight of the vehicle.
This I would of thought will have an effect on the ABS, in that the brakes will pull the vehicle up quicker because the car is lighter.

Though I bet the software program is the same for all models of the same car, be it a bog standard 1.1 R25 or a fully kitted 2.0 TD pulling a lot more weight about.
Taking this forward a good analogy in weight of the vehicle as a variable would be when towing a trailer or caravan.
Worst-case scenario therefore could be 1). a car (R200/25) one day being driven solo by a 50kg women and 2). the next day the same car towing a 500kg* caravan and with 5 rugby players in the car itself. Now that must be a weight difference of over 1000kg! This indeed would be more of a weight difference than our 5exi transplant!

*This is just a guess, as I do not know the weight of caravans (but it cannot be that far out) or even the max weight a R200/25 can tow.

Would be very interesting to hear from a braking specialist/boffin.



Mike.N

Tim

I wouldn't necessarily go off the idea of fitting the ABS. As I have already said, WK? have kept the ABS on their build.

All I (& I think others) am trying to do is learn if there are issues to be taken into consideration.

As Mike says, it would be interesting to hear from someone who knows.

The problem with this analogy is that a caravan has it's own brakes. But I agree with the car gaining weight carrying heavy loads etc. But it would be good to find out with someone in the know who has done it. Or is there a way of getting in contact with the WK guy to find out how the ABS is working out?

I asked Marlin the questions about the ABS below is their reply - which makes things a bit clearer

1) Can a car with ABS from the donor vehicle get through SVA - will it be disqualified because its much lighter than the donor and this messes up the algorithm that drives the ABS systme? YES AS THE WK CAR SAILED THROUGH WITH NO PROBLEMS AT ALL

2) This seems to have been OK for the Which Kit guy but the mag has not yet got to the SVA story and sometimes different inspectors have different approaches.

3) If you dont fit the ABS, the master cylinders are different. Does this means a new master cylinder from a non-ABS car or is the ABS one OK. If a non-ABS master cylinder will it fit the servo? THE MASTER CYLINDER STANDARDLY USED ON THE ABS SYSTEMS ARE SIMULAR EMOUGH IN THIS CIRCUMSTANCE TO BE CONSIDERED THE SAME. THEREFORE IF USING IT IS WHAT YOU WANT TO DO YOU SHOULD NOTICE NO ADVERSE EFFECT.

4) Finally, if we dont have ABS then how do we stop the front wheels locking under braking cos its all much lighter than a Rover - does this mean having to have a brake balancing system or has MArk thought of all this and will it just work. WITHOUT ABS THE FRONT WHEELS OF THE CAR WILL LOCK BEFORE THE REARS (AN SVA REQUIRMENT). IF FROM A PERSIONAL POINT OF VIEW YOU WOULD PERFER THAT THIS DID NOT HAPPEN SO QUICKLY MARLIN CARS CAN SELL YOU AN ADJUSTABLE BRAKE BIAS VALVE, THIS HOWEVER MUST NOT BE FITTED FOR THE SVA TEST FOR THE REASON THAT IT IS DRIVER ADJUSTABLE. PRICE FOR ADJUSTABLE BRAKE BIAS KIT WILL BE £120 PLUS VAT

Thanks for that Tim.

Have I got this right - the SVA requires the front wheels to lock first?

Has anyone thought of emailing WK? with a nice technical question about the ABS?

I would, but I think Mr Filby has something against me, since I met him at Donington last year.