John Speake

OK, I must have misremembered. I may have been thinking about UK market cars from 84> I think it was an option up to some date and then became standard fitment. I will have to look up the tech Bulletin.

John Speake

I will have to check out the tech info I have on this. Logically what Colin is saying seems correct, but I am not sure if anyone has tried it.....

You will need to use the later type sensors as they are the correct ones to fit your MY91 hubs. You donor S2 is MY85 so I think they are the later sensors, you will need to check PET to confirm.

Vilhuer

Number of teeth is about double or half depending on which combo is used. What happens when ABS brain gets twice or half number of pulses? It will think cars speed is 2x or 1/2x. When car is doing 150mph it will either think its doing 300mph or 75mph. Will ABS work right at 300mph?

Vilhuer

It rains in UK.

Lizard928

Erkka,

The later cars had less teeth, so it would receive less pulses per RPM.

However the way that the system works is that if it senses a variation in pulses side to side, or front to rear that it pulses the fluid to either the front or the rear or both at the same time.
The early ABS systems (all 928s) are very simple devices. Given that the teeth are less on the later hubs, it will read as going slower, but it should still engage the system completely normally.

While there were yes early and late sensors, they should be interchangable, they all generate the same sine wave pulse which is sent to the brain. If you can use the sensors that you have now though, I would.

John Speake

OK, As of MY 86 all Euros had ABS as standard. From 84>>>> all UK cars had ABS... For 8-86 in mainland Europe ABS was an option.

For MY86 the numner of teeth on the hubs changed from 90 to 45. The wiring haness connectors for the sensors also changed. The ABS ECU changed at the same time, and Porsche insist that the correct unit is used to match the hubs/axles.

The speed sensors appear to also have changed in length for MY 86, and so Geoff's sensors will not fit the 91 hubs as far as I can see (assuming he can get them out of the old hubs.

Maybach_Man

thanks to all for your trouble!!!

so....in a nutshell, if i put the 91 hubs and sensors and change the control unit for a 91 also.......it should work.........right???

John Speake

As I mentioned, you may have to do some modification on your 84 S2 harness to connect up the 91 sensors.... but otherwise you will be OK.

If you can successfully extract your MY84 sensors, they are now NLA so could be saleable.

I can supply the correct sensors.

Maybach_Man

thanks john... how much are the sensors????