AW4 Date/Era Conversion

[ChillyB]

Have a 4WD AW4 for my 1995 conversion to 4WD. The transmission is a 99 and so has an output speed sensor that produces four pulses per rev instead of the one pulse per revolution that my TCU is expecting.

I removed the t-case, then the output adapter housing, then removed the reluctor. I figured to eBay myself an output shaft with the correct single-pulse reluctor and swap just reluctors (hoping same length And ID. Anf I guess I'll need a sensor unless the RWD sensor is the same as for a 1995 4WD by some miracle.

 

[lawsoncl]

Buried in this thread are posts from guys who have done this already, swapping parts from the earlier to the later.

Thread 'Everything you ever wanted to know about the AW4'

Jan 27, 2011

I've gotten enough questions concerning AW4 specs and "will x year AW4 fit into x year XJ?" that I figure I should probably just write it all up once and for all... so here goes!

The AW4 transmission was used in 4.0L equipped XJs from 1987 through 2001. It was also rarely used in 2.5L equipped XJs with the automatic transmission option, 1987-1990*. It has 3 regular forward gears and 1 overdrive gear, along with a torque converter containing a lockup clutch. Gear selection is part hydraulic and part electronically controlled via solenoid valves. Shift firmness is controlled by a...

• kastein
• Replies: 771
• Forum: OEM Tech Discussion

 

[ChillyB]

Buried in this thread are posts from guys who have done this already, swapping parts from the earlier to the later.

Thread 'Everything you ever wanted to know about the AW4'

Jan 27, 2011

I've gotten enough questions concerning AW4 specs and "will x year AW4 fit into x year XJ?" that I figure I should probably just write it all up once and for all... so here goes!

The AW4 transmission was used in 4.0L equipped XJs from 1987 through 2001. It was also rarely used in 2.5L equipped XJs with the automatic transmission option, 1987-1990*. It has 3 regular forward gears and 1 overdrive gear, along with a torque converter containing a lockup clutch. Gear selection is part hydraulic and part electronically controlled via solenoid valves. Shift firmness is controlled by a...

• kastein
• Replies: 771
• Forum: OEM Tech Discussion

Read it several times. The reluctor swap was vague and pics are all red X for me. So while it's very helpful there are still information blanks. That's OK, I'll refigure it out all over again.

Questions I will need to amswer:
1. Is early reluctor a direct swap with the later? Logic tells me it would be silly to change transmission output shaft dimensions just to change reluctor so probably the same. A comprehensive parts list of both years would confirm by comparing output shaft part numbers. But I don't have that information.

2. Did tailhousing adapter change from 95 to 99 when the sensors and reluctor changed? Frank's writeup didn't say he changed the adapter, others have suggested a different housing was required. But I think they based that on Frank's article, which actually doesn't say that he changed housings. When I checked eBay last the adds didn't indicate year cutoffs, though many sellers aren't well informed. Since I'll likely need a sensor anyhow I'll just buy one and see if it fits.

 

[ChillyB]

Well well well. Here's sensor socket from my known 1999 housing.


Here's a screenshot of an eBay add.


Note the retaining screw position. It's different. Not sure if it matters? Add says 1984-2001, like most adds for such housings.

 

[ChillyB]

And FINALLY a seller who seems to know. One add specified 87-96, stating sensor hole is smaller and clocked differently. So I bought that and a tailshaft with the older type reluctor.

 

[Unclewolverine]

Yes, the housing, wheel, and sensor have to be changed.

 

[ChillyB]

Here are differences in output housing. Tag shows unofficial years, sensor hole ID measured by calipers, which is not very accurate.

Note that center-to-center distance from sensor hole and retaining screw are different. The new type could be sleeved with a hole drilled and tapped in the unused boss. The old type could have sensor hole drilled out but there is no aluminum within reach for retaining screw.


EBay seller FN Jeep is the only add for one of these that recognizes they aren't all the same. Not affiliated, but they were knowledgeable on this matter, packed the item well, and shipped quickly.

 

[ChillyB]

I now have two options: I can maybe convert the 99 transmission to work on my 1995 by changing output shaft, output housing, and splicing old sensors to new. While some old threads say this is easy (splicing is indeed easy), I have not found details on how to map wire colors. So maybe not my favorite option.

Other option is to convert the 1995 RWD transmission to 4WD. Except for Speedo sensor, remainder is native to my Jeep so less wiring uncertainty. The odometer reads 340K. No idea if transmission has been rebuilt but it works very well, perhaps because it was a gently used RWD jeep.

A third option is to but a period-correct 4WD transmission. May still so that to save time, though I'll admit to being intrigued to convert a RWD because everybody has been unwilling to attempt this job.