Discussion
Would it be feasible to fit ABS to a car that never originally had it?
I assume you would need an ABS unit that has a stand-alone ECU which the wheel sensors connect to.
I also assume some juggling of caliper sizes may be required to get similar pressure ratios to the donor, and the hubs will need appropriate toothed rings.
Is it doable?
Have I missed anything vital?
I assume you would need an ABS unit that has a stand-alone ECU which the wheel sensors connect to.
I also assume some juggling of caliper sizes may be required to get similar pressure ratios to the donor, and the hubs will need appropriate toothed rings.
Is it doable?
Have I missed anything vital?
Does a model of the car in question exist that DID have ABS? In which case, you just need all the parts from that model to fit to yours. If not, then i wouldn't recommend fitting the ABS from another car or model as there is likely to be a significant mis-match between the systems and physical layout etc
It's a thought experiment. I have a mk1 MR2, and am looking at upgrading the brakes, due to
a) The performance has been upgraded, with more planned at some future time
b) The rotors getting harder to find, and
c) The standard brakes are overly front biased, so the front end locks waaay early.
I know the various options ie different pads front/rear, and playing with different calipers, but as I was browsing disk catalogs, I realised that the mk3 mr2 had similar weight, similar weight distribution, and similar disk sizes.
It should also have similar weight transfer under braking.
Hence the (more generic) question.
I do control systems for a living, so I know roughly what the ABS is doing, but have no idea how flexible the control algorithm is.
It must at least be able to cope with the 15% full - empty difference, plus worn tyres on one or other end.
The main issue I can see is that the ABS systems I have looked at have no rear proportioning valve(s), so I assume that's built in to the valve block.
Even if it's feasible, I don't think I will do it, but I want to explore the possibility.
a) The performance has been upgraded, with more planned at some future time
b) The rotors getting harder to find, and
c) The standard brakes are overly front biased, so the front end locks waaay early.
I know the various options ie different pads front/rear, and playing with different calipers, but as I was browsing disk catalogs, I realised that the mk3 mr2 had similar weight, similar weight distribution, and similar disk sizes.
It should also have similar weight transfer under braking.
Hence the (more generic) question.
I do control systems for a living, so I know roughly what the ABS is doing, but have no idea how flexible the control algorithm is.
It must at least be able to cope with the 15% full - empty difference, plus worn tyres on one or other end.
The main issue I can see is that the ABS systems I have looked at have no rear proportioning valve(s), so I assume that's built in to the valve block.
Even if it's feasible, I don't think I will do it, but I want to explore the possibility.
JD Classics retro-fit ABS to Mk.II Jaguars so I'd have thought it possible.
I'm quite interested in this too for my early Shogun that just loves to lock up its rear tyres on the merest suggestion of precipitation; the later model came with ALB and four wheel drive - which was quite an achievement in 1990 - and I've wondered just how feasible it might be to swap hubs/timing rings, brake discs (drums on the back) and fit all the ECU and other controls.
Suppose the real sticking point would be the enormous cost of getting it all fitted and the difficulties in setting it up correctly.
I'm quite interested in this too for my early Shogun that just loves to lock up its rear tyres on the merest suggestion of precipitation; the later model came with ALB and four wheel drive - which was quite an achievement in 1990 - and I've wondered just how feasible it might be to swap hubs/timing rings, brake discs (drums on the back) and fit all the ECU and other controls.
Suppose the real sticking point would be the enormous cost of getting it all fitted and the difficulties in setting it up correctly.
Max_Torque said:
You'd definitely want to be at least starting with the ABS from a mid engined car then!
Hence the mk3 MR2 donor idea. 
As far as I can see, it doesnt have to be a middie, as long as the weight transfer is similar, ie cg vs wheelbase / roll centre, although I know that's a grave simplification.
AW111 said:
Max_Torque said:
You'd definitely want to be at least starting with the ABS from a mid engined car then!
Hence the mk3 MR2 donor idea. As far as I can see, it doesnt have to be a middie, as long as the weight transfer is similar, ie cg vs wheelbase / roll centre, although I know that's a grave simplification.
(and yes, you won't lock wheels, but then again, you won't actually stop either)
It's doable - but would be a lot easier if you could steal all the bits from a similar car which had ABS as standard...in this case, I guess a Corolla? ...not sure if they ever came with ABS though?
You'd need the hubs (with sensor wheel and pickup) ABS pump/modulator/pedal/reservoir etc, and the computer.
Then you'd simply fabricate the whole shebang in your mid-engined rust box.
Everything is possible with enough effort. but I'm not sure it's worth it. Just buy a newer car
You'd need the hubs (with sensor wheel and pickup) ABS pump/modulator/pedal/reservoir etc, and the computer.
Then you'd simply fabricate the whole shebang in your mid-engined rust box.
Everything is possible with enough effort. but I'm not sure it's worth it. Just buy a newer car
iva cosworth said:
Way too much work IMO.
Even fitting it to a car where it wasn't specced but others might have it is just a whole lot
of work.
New hubs,driveshafts,masses of wiring.......
Why new driveshafts?Even fitting it to a car where it wasn't specced but others might have it is just a whole lot
of work.
New hubs,driveshafts,masses of wiring.......
You can get shrink-fit ABS rings in many sizes & teeth : we use them at work.
If I did it I would look at machining the hubs to take an appropriate ring. I would still need to fabricate brackets for sensors and run some wiring / plumbing, but that's not such a big deal.
I have already fitted a different engine / ecu, and a 6 speed 'box converted to reverse the shift linkage, so minor fabrication is not an issue.
The only real mechanical difficulty would be finding calipers that fit, if the original ones are the wrong piston size / ratio for the ABS system.
Toyota generally are pretty conservative with their electronics, and (used to) have a stand-alone ECU for nearly everything, but I think the ABS ECU would have to be pre-CANBUS : that's probably a bridge too far.
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