Rear End Question

Salvador

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I now that this question have been done all ready a few time ago, but here goes again how can I put the stock 8.8 sensor on the 9" diff??
My transmission went completely nuts, and the shifting thru 2nd its a pain in the neck, the shfting thru 3rd I have to do it manually, and the down shifting its like it have a reverse shift kit on it??
I relly hope not too go back too the 8.8". Be apreeciated fore coments or pictures iof you have any off this (Jeff or Toddt).
The lasts post off this dont have any more the pictures and I dont now were too put the plug, if its on the housing or in the third member??

Mexican PreRunner
 

jeff

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This thread needs to be added to the other FAQ's... :)

Most of the people have modified the actual 3rd member on the Ford 9" to accept the 8.8's sensors. My own projects have never needed the surgery but I've helped out a few customers back east get the 8.8 sensors working on the 9".

There are a few ways to do it... You'll either need to re-use a working tone ring and sensor from an 8.8 rear or get creative. The tone ring is located inside the 8.8's center section behind the ring gear. To have the tone ring and sensor work with the 9" you have to get the tone ring transferred over. Easier said than done but it's not really that bad. Once you get the 8.8's tone ring relocated and positioned in the 9" 3rd member you need to cut a hole large enough for the sensor to pass through. How the actual sensor is mounted is totally up to you. The 8.8 uses a single fastener that just holds the sensor in place. You can weld a bung for the sensor or come up with some other method - one guy just glued and sealed it in place with JB weld. That's a little too Arkansas Automotive for my tastes but whatever works.

Now the more creative method is to mount a tone ring off the driveshaft, either at the 3rd member or up at the transmission end. The trick is you have to come up with a tone ring that has the correct number of "teeth" so that the stock sensor is reading the correct signal. When the tone ring is mounted behind the ring gear it's turning at a slower speed than if it were mounted directly on the driveshaft. I'm not sure what application uses a tone ring that works for this kind of swap but I've heard it's been done using readily available junk yard parts. You could determine the necessary size of the tone ring using some simple math.

No pictures... the ones I had I lost a long time ago. If RDC doesn't have them from the old posts I have no idea where to point you. Someone from this site originally posted a 3rd member that had the sensor in position - maybe they will chime in and re-post the pics.

Aloha
 

Salvador

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Thanks a lot for the info Jeff, Today went too a Diff Specilists (Right!!) And The owner still dont now how it can be done this, But well a little off work I think it can be done.
Also He toll me that the Sensor it got to go about .17-.23" above off the Tone Ring, it this correct or can I have a bit more space betwen this two.

Mexican PreRunner
 

jeff

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I'm not sure what the greatest amount of distance you can run from tone ring to sensor is without error. The greater the distance the more problems you will have. Background on how the system works is helpful... distance depends on the magnetic field strength.

The sensor pickup has a magnetic core surrounded by coil windings. As the tone ring turns, teeth on the tone ring move through the pickup’s magnetic field. This reverses the polarity of the magnetic field and induces an alternating current (AC) voltage in the pickup’s windings. The number of voltage pulses per second that are induced in the pickup changes in direct proportion to wheel speed. The faster the tone ring turns, the more pulses per second. The slower it turns, the fewer pulses per second. So as speed increases, the frequency and amplitude of the wheel speed sensor goes up. The tone ring signal is sent to the ABS brain where the AC signal is converted into a digital signal and then processed. The control module then counts pulses to monitor changes in wheel speed.

Or you can look at it like this... When the wheels start to lock up the sensor picks up the tone ring has slowed too quickly or stopped spinning, if that is the case the sensor triggers the ABS computer and it engages the ABS on/off system.

That's why building one off of the driveshaft is easy to do once you figure out how many teeth the tone ring needs to have. You just weld the tone ring onto the transmission end of the driveshaft and locate the sensor within range. You might even be able to cut teeth off an existing ring (or build a ring from scratch) to get it working on a driveshaft mounted system.

Using the stock 8.8 system is still probably the easiest.

Aloha
 

Marshall

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Be aware that if you mount it off the drive shaft that the transmission will move up to an inch with stock mounts. So might want to go with something more solid or put the sensor mount off the transmission and not the crossmember. Just a thought?
 

ntsqd

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I used a 30 series 60 tooth sprocket on Ken's Automotive's Dyno. We pick up RPM for the Data Acquistion system the same way as the ABS sensor works. The one thing I did was to put the sprocket in the lathe and knock the sharp points off the teeth. I was afraid that the sensor would only see the points and might introduce some errors. B4 we really put that part of the system into service (There is a cable driven tach as well) we fed the input into an oscilloscope. Danged if the wave form generated by the sensor didn't look exactly like the complete shape of the teeth. It was as if we had unpeeled all of the teeth off the sprocket and laid them out flat like the rack of a rack & pinion.

I was looking at one of these rings in a Dodge truck the other day and noticed that it would generate a nearly true sinusiodal (sp ?) wave if the sensor is as accurate as the dyno sensor.

TS

"It only seems kinky the first time"
-- Bumpersticker seen in Lost Wages
 
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