needing advice on front diff replacement

[khartley]

I am needing to tear apart a 2g awd tranny due to a blown front diff.

I have a 1g fwd turbo tranny lying around, and was wondering what all parts I can rob off it to put in the awd tranny. Is there any possible way the front diff from the fwd tranny will work in the awd? Are the gear hubs the same?

I am also wondering if I should take everything to a shop to have the parts replaced, or if this is something I can do myself. As far as swapping parts goes, I'm ok with that, but I heard something about shims needing changed and stuff like that, so I'm just curious if I can easily screw this up.

Thanks.

 

[twicks69]

The front diff on AWD vs. FWD are different. The case, ring gear and bearings are different.

You need an AWD front diff case, and roller bearings. The FWD uses tapered roller bearings.

As well, the AWD front diff is set up with 0.003-0.005" endplay, whereas the FWD front diff is set up with preload due to the different style bearings.

If you need one, I have probably 25-30 units on the shelf -- totally ready to go with good bearings and ring gears. PM me if interested.

As for the removal/install, I can post up a step-by-step if you want, along with all the special tools.

 

[twicks69]

Here are the instructions for the front diff replacement:

Download the transmission service manual for your trans -- W5M33 --
http://www.3sx.com/faq/manuals/Service-Manual-Transmission-FWD-Mitsubishi-Manual.pdf

Then, get the tools required for the job:

Special tools:
snapring pliers - Proto 250G works excellent
seal puller - double hook style
OTC 1122 bearing splitter and OTC 7393 push-puller (do a google search) -- for removal of 5th intermediate gear
36mm socket (end shaft nuts)
12mm socket
14mm deep socket
17mm socket
19mm socket
24mm deep socket or wrench
swivel-head socket attachment
short 3-4" extension
6" extension (use with 14mm deep socket to remove case bolts)
2 prybars
1/2" impact or cordless impact
3/8" impact or cordless impact
3/8" ratchet
3/16" roll pin punches
hammer or mini-sledge
dead-blow hammer
Ultra Grey or black RTV silicone
Brake-cleaner for degreasing purposes

These are the majority of the tools required for teardown.


For W5M33 transmissions:

Drain the transmission, and place the trans on a work surface with the bellhousing side facing down. You will still get more gear oil out of the trans, so use some towels to plug the driver-side axle seal, and have extras under the output shaft area.

Now, remove the 5th gear cover (9 short bolts and 2 long bolts) with a 14mm deep socket, manually shift the transmission into reverse (or you can use a roll pin punch and hammer and remove the roll pin from the 5th/Rev shift fork and manually shift the transmission into 1st and 5th) to lock the transmission. Unstake the shaft nuts first before trying to remove them!! You will damage the threads on the shafts if you do not do this!! I use a 3/16" flat head screwdriver that is a straight blade and i grind it down to have a wide and a narrow angle chisel tip on it. It should fit right into the shaft detent slot and hammer the detents outwards. Then, using a 1/2" impact and 36mm socket, remove the end shaft nuts from 5th gear and 5th intermediate gear.

If the 5th/Rev shift fork roll pin is still installed, shift the transmission into reverse so you have more access to the roll pin to hammer it out. Remove it using a 5mm or 3/16" roll pin punch and hammer. It is best to use the pin punch and pound the pin outward as you may get it stuck in the hub assembly if you don't know what you are doing. There are three variations of 5/R shift forks, the 1989-1996 ones all have the roll pin centered with the shift rail detents and if you pound it inwards it will jam the roll pin into the 5th/Rev hub, you need to go from the backside and hit it outwards, and then use a vise grips pliers and grab onto it and rotate it while pulling it out. The 97-99 style shift fork has an offset roll pin that you can hit straight through and it will not contact the 5th/Rev hub.

Using two small prybars, gently seperate the 5th/Rev hub and slider by placing the prybars between the 5th gear and the 5th gear synchro so that you do not damage the 5th gear synchro. Evenly and gently pry upwards while guiding the 5th/Rev shift fork upwards off the shift rail. Once the hub and slider assembly has been removed, remove the 5th gear and 5th gear split needle bearing.

Using your snapring pliers, remove the viscous coupler snapring, and use your two prybars to remove the viscous coupler, then use your pen magnet and remove the detent ball from the output shaft.

Now, remove the 5th intermediate gear; NOTE THE ORIENTATION OF THE 5TH INTERMEDIATE GEAR FOR REASSEMBLY. It should be easy to remove by hand, or hard to remove requiring special tools -- DO NOT PRY THE GEAR OFF!!! YOU WILL CHIP THE TEETH! Use the proper tool. That would be an OTC 1122 bearing splitter and OTC 7393 push-puller tool by inserting the jaws on the top flange of the 5th intermediate gear and then remove the gear.

You should now have everything off of the 5th gear side of the trans case.

Remove the reverse switch and crush washer (24mm wrench/deep socket), remove the reverse lockout bolt and crush washer (19mm), remove the three shift detent poppet plugs (14mm)/springs/detent balls (using a pen magnet), and reverse idler gear bolt (14mm or T50 Torx depending on year trans, next to front differential passenger-side axle seal).

Remove the intermediate case section gently by hitting the triangular point of the case with a dead-blow hammer upwards to break the RTV silicone bond, then using two prybars evenly spreading the case gently upward. With the bearing plate removed, you can now pull out the center differential by hand.

Next, remove the main case section by removing all the 12 case bolts with a 14mm deep socket and swivel head attachment. Once removed, use your two prybars and evenly and gently seperate the case section by starting at the pry point by the clutch fork boot and then working around the case with your prybars to seperate the section from the front differential and the bellhousing.

***NOTE THE ORIENTATION OF THE REVERSE IDLER GEAR and shaft bolt hole!!*** You will need to have the reverse idler shaft oriented properly so that the reverse idler gear shaft bolt properly reinstalls -- note the direction that is required so it matches up with the transmission case for easy installation. Pull the reverse idler shaft, reverse idler gear and reverse lever key, then use your 12mm socket and and swivel attachment with a 3" extension and remove the two bolts holding the reverse idler lever.

Remove the front differential, output shaft and output pinion shaft and needle bearing. Remove/clean/inspect output shaft and front differential and all other components.

If necessary for cleaning purposes or further inspection, follow the instructions below to remove the gear clusters:

Now, using your 3/16" or 5mm roll pin punch, remove the roll pins for the 1/2 and 3/4 shift forks. Using your hands or gently using small prybars, orient the 5th/Rev rail end first by pulling upward and away from the shift selector (away from the other two rail ends). While the 5th/Rev rail end is up/away, do the same with the 3/4 rail end so that it clears the shift selector assembly. With the 1st/2nd rail end, go the OPPOSITE DIRECTION and gently move it away from the other two rail ends so that you can slightly modulate the shift selector to clear all three rail ends. Pull up. All the gear clusters and shift rails/rail ends/forks will come up as one single unit.

Reassembly:

Reinstall the output pinion shaft and needle bearing with output shaft, then the front differential (and put the shim on the top roller bearing).

Assemble the gear clusters with the shift forks just like how you removed them originally. Reinstall the cluster assembly, modulate the shift rail ends just like how you removed them to get them all back to centered orienation with the 1/2 on the left side of the shift selector, the 3/4 on the center of the shift selector and the 5th/rev on the right side of the shift selector in the neutral position.

Reinstall new roll pins.

Reinstall the reverse linkage arm and 12mm bolts - 16-18 lb/ft torque. Reinstall the reverse linkage key, idler gear and slide the idler gear shaft back into the oiling detent with the bolt hole orientation towards the front diff properly so it aligns with the main case section.

Reinstall the output pinion shaft, needle bearing and output shaft at the same time as the front differential.

Reinstall the trash magnet.

RTV silicone the case section flange evenly with a thin bead of Permatex Ultra Black or Ultra Gray RTV silicone. Otherwise, using your finger, evenly spread a thin coat on the case section flange so that all contact area is evenly covered with the RTV silicone. Let cure for 15-20 minutes to tack, then install the case section.

Reinstall the case section making sure that you have the magnet tray reinstalled and the black plastic oiling guide reinstalled on the case section.

Reinstall the reverse idler gear bolt to 32-39 lb/ft torque. (Tapered end bolt with aluminum flat washer).

Reinstall the 14mm bolts that attach the main case section to the bellhousing to 29-32 lb/ft torque EVENLY.

Reinstall the 19mm reverse lockout switch bolt (19mm head with spring-loaded detent ball on the end and aluminum flat washer) to 22-25 lb/ft torque.

Reinstall the 24mm reverse switch (plug head with 24mm hex-shape body and aluminum flat washer -- DO NOT FORGET THE WASHER or you will have problems shifting into 5th/Reverse) to 22-25 lb/ft torque.

Reinstall the center differential, then RTV the intermediate case section, let cure and reinstall the case section.

Reinstall 5th intermediate gear and 5th gear split needle bearings/5th gear. Reinstall the 5th/Reverse hub and slider gently/evenly with 5th and reverse synchros oriented properly so it does not bind up or get damaged. Slide the hub and slider back on WITH THE 5th/Rev shift fork at the same time being installed onto the 5th/Rev rail.

Reinstall the 5th/Rev shift fork roll pin.

Reinstall the viscous coupler detent ball, and align the detent on the output shaft with the detent ball to recess it -- you can use a 1" thick block under the transmission bellhousing to space it, then use a prybar to act as a lever to raise or lower the output shaft to make this easier. Then, reinstall the viscous coupler so the detents match the detent ball keyway. Install a new viscous coupler snapring.

Manually shift the transmission into reverse (OR like last time, before reinstalling the roll pin, shift the transmission into 1st manually, then into 5th gear with your hand engaging the hub/slider onto 5th).

Install new end shaft nuts to 102-115 lb/ft torque.

Ping the detents with either a punch/hammer or a small point punch on an air hammer GENTLY for both end shaft nuts.

RTV transmission case flange for 5th gear cover. Let tack 15-20 minutes before reinstallation.

Be sure your reverse wave spring is still in place and reverse synchro is properly reinstalled.

Be sure that you have the roll pin back in the 5th/Rev shift fork, and that the transmission is back in the neutral position.

Reinstall 5th gear cover and 14mm bolts to 26-30 lb/ft torque.

This is a quick rundown of directions for replacement of a front differential (and disassembly/inspection) for an AWD turbo 5-speed transmission for a 4G63 AWD turbo DSM 1991-1999.

 

[khartley]

WOW, thank you for all that info. I have replaced the center diff with the tranny still in the car, but I managed to screw that up because it pops out of reverse now. But that being said, since I have to remove the tranny to replace this front diff, I will be able to do a better job. Very interested in some awd tranny parts from you. PM pending...