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-   -   Speedometer help needed (https://volvoforums.com/forum/volvo-240-740-940-12/speedometer-help-needed-98534/)

duke fame 12-05-2018 11:14 AM

Speedometer help needed
 
I recently swapped a '92 ABS rear with my failed 91 (no ABS) rear axle. The wagon runs great although I appear to be travelling everywhere at 120 MPH.
It seems that the '92 with ABS sends abs signal in addition to speed. It also appears that swapping the switch will not work as the internal reader is not the same mechanism.

Any ideas for work arounds? Do I need a new cluster or can I manage this in some other way?

WAGON 1991 245 no abs.
Axle 92 with ABS.




pierce 12-05-2018 03:22 PM

IIRC< the ABS and non-ABS have different 'tone wheels' with a different number of pulse counts per turn. short of swapping speedos, yeah, nothing you can do. you'd have to disassemble the whole differential to swap the tone wheel inside.

act1292 12-06-2018 06:04 AM

Either that or get a speedo cluster from a '92. You might want to check out this link:

Electronic Speedometer Notes

I vaguely recall reading somewhere about modifying the cluster to work with a different tone ring. You may also want to read up on Dave Barton's page (DaveBarton.com). I believe he had articles relating to the different tone rings as well.

duke fame 12-06-2018 12:17 PM


Originally Posted by pierce (Post 468211)
IIRC< the ABS and non-ABS have different 'tone wheels' with a different number of pulse counts per turn. short of swapping speedos, yeah, nothing you can do. you'd have to disassemble the whole differential to swap the tone wheel inside.

I'm not in any way interested in disassembling a differential. Looks like an instrument cluster is the way to go.

duke fame 12-06-2018 12:21 PM


Originally Posted by act1292 (Post 468230)
Either that or get a speedo cluster from a '92. You might want to check out this link:

Electronic Speedometer Notes

I vaguely recall reading somewhere about modifying the cluster to work with a different tone ring. You may also want to read up on Dave Barton's page (DaveBarton.com). I believe he had articles relating to the different tone rings as well.

I'll look around for that modification. I'm more of a nuts and bolts guy then an electronics guy. I'm certainly not about to bench test a speedometer...I'll hit up the WWW for an instrument cluster.

pierce 12-06-2018 12:54 PM

the mod is basically a phase lock loop pulse divider unless the ratio is integer, then its a simple digital divider. they sell these as a module for the custom vehicle world to deal with different tire sizes that you can setup for any percentage correction you need.


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