Dually rear end swap question

[rusty ol ranger]

Thanks for the clarification, I was hoping it wasn't really necessary.

Unfourantly it is.

I know when the sensor quit on my 97 F250 it wouldnt even shift outta first and if i bumped it manually it shifted so hard it barked the tires

 

[lowspeedpursuit]

If you want to know what will happen 100%, go unplug your RABS sensor and drive around the block.

If you go into limp mode or lose something important, you'll have to keep it working. If you lose ABS and that doesn't bother you, you can do whatever you want.

 

[wellcraft]

I guess this is what I will need but something that somehow works with that old diff.

rear differential drive shaft speed sensor kit - Google Search

 

[don4331]

I guess this is what I will need but something that somehow works with that old diff.

rear differential drive shaft speed sensor kit - Google Search

That's almost exactly what I made.

I worked in an engineering design house at the time - with access to CAD/mills/lathes/breaks/welders/etc/etc in the protoshop. (The MTB tandem was built at the same time).​

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Converting to a lower-tooth-count tone ring on the driveshaft is brilliant, but I guess I don't really understand why it works? Not sure if this is a derail, since it seems like OP cares very much about keeping ABS.

I get that both setups are 29 pulses/output shaft rev, and I guess maybe the computer can track output shaft revs via the speed sensor?

I would have said input shaft, not output.

The 108/3.73 is just an example. If I had 4.10 gears would have been 108/4.1 = 26.4, so 26 teeth on the tone ring. Not quite as nice, but close enough to convince the computer the rear axle was turning the correct speed. Divide by the appropriate number for the ratio you are using and machine the corresponding toothed ring. Note: While this works fine for my '98 with just RABS, full ABS would freak at the difference at highway speeds. <In theory, there is a way to tell the computer you have a 7.5" (102t tone ring), then 102/4.1 =24.9, close enough to 25 that ABS should be happy. But I didn't have to sort that out in Forscan>.​

Note that I never said I have a Toyota rear axle. I tried, but I could never find one for the price I wanted to pay (>$300 * 7 - 14 x 5J Toyota dually rims really slowed me down).

I found that the dually Sprinter vans came with 16x5.5J rims. OEM tires on the Sprinter were 215/85R16. 205/65R16 looked more appropriate on a 2wd Ranger, IMHO. So, think Ford 9" with Chevrolet Dana 44 front axle spindles hubs (gets 6x5.5 pattern/effectively they make it full floater) then adapters to the 6x205 pattern for the Sprinter rims. Caddy Eldorado calipers work with discs on the hubs and provide both regular & parking brakes.​

The snout on the 9" makes for easy mounting of the sensor.​

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Just properly proportion the rear brakes before driving on gravel.​

 

[lowspeedpursuit]

The 108/3.73 is just an example. If I had 4.10 gears would have been 108/4.1 = 26.4, so 26 teeth on the tone ring. Not quite as nice, but close enough to convince the computer the rear axle was turning the correct speed.

Sorry, I don't know anything about how anything works.

What I don't understand is, if the ABS computer in a given truck cares about seeing a pulse rate that's dependent on your gear ratio, why doesn't ABS fail if you regear that truck?

Like if my truck came with 3.23, and I regear to 4.56, that's 108/3.23 = 33 -> 108/4.56 = 24, a 27% decrease. If what my ABS computer wants to see is "33 pulses at the RABS sensor per whatever denotes one rev at the VSS", I would expect it to freak out.