Anti lock brakes

[MdR]

Can anyone give me a good reason why it would be difficult/dangerous to modify/fit an ABS system from a production vehicle? :befuddled
I reckon a vehicle from mid/late 80s that ideally had no engine management as such & had ABS as a factory cost option would be the best bet. This (in theory!) would have an entirely separate ABS brain, loom, modulator etc. that I could rob & fit to a Beetle. I know that UK spec twin carb Honda Concerto fits this discription (might have electonic ignition).
I already have 944 discs/calipers on all four corners so fitting the later front ABS sensor ring would be no hardship. I figure the rear ABS ring could be fitted to the CVs or the stub axles (I don't know how the Porsche factory did it on 944s).
OK so 'sensible cars' are front engine etc. so weight transfer would be different, but surely all ABS does is sense the wheel(s) are locking & pulse that hydraulic circuit.
I'm aware that there are different ABS systems 3 channel 4 channel, split diagonal etc. is there anything else to bear in mind?
cheers
Martin :haveadrin

[samcat]

If you are fitting the sensor rings, you could (in theory at least) fit traction control as well as ABS... Althought that may be a little bit more involved (engine management or how?)....

I cant help on any of the problems with fitting it though... Just you got me thinking (always a dangerous thing!).

Good luck. And put an article together once you've done it and submit it and it can be put up here...

Sam C

[Da1Duc]

Well here are the potential pitfalls:

The most ABS systems are designed/ tuned for a certain wheel size, thus it knows the vehical speed. This will be a problem if you change wheel size and cannot recalibrate the ABS (Much like the guys putting huge mud tires on an pickup).

The other issue is that the ABS system is designed for the weight distribution of the car it was intended for. Thus look for the ABS from a car with similar weight distribution.

Finally, you will want to make sure you get the sensors correct, ie the number of ticks per revolution of the wheel. You can use this in combo with a different wheel size to get the system back into sync.

It would be simpler to develope a custom controller to do what you want, unless you had access to customize the ABS box (usually through a company diag tool).

Hope this helps.

Derek

[Michael Ghia]

I sold a 968 setup to a buddy a while back which has ABS sensors on it. He plans on using the setup with the 968 ABS brain and pump.
When Porsche introduced ABS to the 944, they used new rear arms and hubs throughout. The ring is on the CV joint and the sensor is fitted to the arm from behind (if I can remember right).
Steel arm 944's were before ABS so they never had provision for it.
I'd use the Porsche stuff... should work well.
MG