I bought seats on CL and used one of the motors to replace the up down worm gear. Wasn't difficult. Didn't do the front back.

 

Yeah my local junkyard sells the seat bases for about $25. I know the ZJ bases fit the WJ once you swap the mounting brackets and are more stout. Does the ZJ also use plastic drive gears? I don't really want to be doing this again in two months.

 

I actually started a thread the other day with a link to their page. I have used them for my Mustang and the parts are better than anything you will find at a junk yard. Chances are the part you are removing that's just as old as the one you are replacing will fail the same way too. Plus I don't know how junk yards are in your area but over here in Miami they are hot as hell and full of mosquito's. So fighting to get a seat out that is stuck in one position because there is no power is just too much of a PITA for me when I can just order a new part to my door. As far as replacement instructions, someone actually did a whole write-up on replacing that gear. I remember seeing it while searching for something else.

http://www.2men1garage.net/Jeep-Grand-Cherokee-1999---2004-Parts.html

 

Seat drive repair tips

I actually started a thread the other day with a link to their page. I have used them for my Mustang and the parts are better than anything you will find at a junk yard. Chances are the part you are removing that's just as old as the one you are replacing will fail the same way too. Plus I don't know how junk yards are in your area but over here in Miami they are hot as hell and full of mosquito's. So fighting to get a seat out that is stuck in one position because there is no power is just too much of a PITA for me when I can just order a new part to my door. As far as replacement instructions, someone actually did a whole write-up on replacing that gear. I remember seeing it while searching for something else.

Jeep | Two Men One Garage

Thank you Ghost_5oh for the link to "Two Men, One Garage" in Georgia - Two Men One Garage | Aftermarket Power Seat Repair Parts

The company was most helpful in repairing the seat drive gears even though they didn't have the exact parts listed for my wife's 1996 Grand Cherokee Ltd, they knew just what to do to modify parts they did stock so the GC's seat could work again. 2M1G were very patient and understand about fielding amateurish questions, too. They offered to modify two of their JEEP-6 parts on their lathe to match the 1996 GC -- these fit perfectly.

My wife's 1996 GC had driver seat problems where the seat moved back and forward, but would jam every few inches of travel; releasing the seat forward/backward button then pressing it again would move it another inch or two. On disassembling the forward-back worm shaft, one plastic gear within the right-angle gear case was cracked in multiple places and the steel shaft was spinning inside the broken plastic gear. The other side gear had one radial crack and mostly worked except when the load was heavy, like when the car was pointing up a steep incline.

I published "A Few Tips and Things to Watch Out For" on power seat repair that I discovered the hard way in a later post. See A Few Tips and Things to Watch Out For later in this thread.

JPC

 

I just found the instructions on their website for getting the drives out of the seat track. It makes sense how to get it apart and I should be able to do it pretty quickly. You're absolutely right about installing old parts in the seat. If I didn't intend to keep the Jeep for a while or if I had more time for a trip to the junkyard I could see installing a used seat base. Basically none of these Jeeps have had their seat tracks maintained and I know mine didn't have a lot of wear. The plastic must break due to age as much as miles moving the seat back and forth.

 

Can you tell me where you found these instructions? I have some old seats and the grease in the gears is rock hard. Without removing the gears from the entire assembly, I can clean out two of the three that I can get access to but the other faces the seat frame. To reach it, the gear assembly (has all three included) needs to come off the frame assembly.

 

I finished this fix today. The new jack screw drives were easy to install and work perfectly. Both of the old plastic gears were cracked and one had stripped teeth. I imagine the gear cracks which spreads the tooth spacing and strips the teeth off.

I highly recommend the kit to fix a jammed seat.

 

I finished this fix today. The new jack screw drives were easy to install and work perfectly. Both of the old plastic gears were cracked and one had stripped teeth. I imagine the gear cracks which spreads the tooth spacing and strips the teeth off.

I highly recommend the kit to fix a jammed seat.

Glad to hear it went smoothly.

 

Hows this holding up? My drivers seat died today.

Also, how are these better? Aren't they still just plastic gears?

 

Still works perfectly.

 

Somehow I lost everything in one go. Front back and up and down.

 

Somehow I lost everything in one go. Front back and up and down.

that seems more power or controller problem than 3 motors failing at the same time.

 

No, I get about 1" of forward and backwards and then it jams. Up and down is jammed completely. I can hear it engage. I bet it tried to move into a preset position with a bag behind it in the way or something. I'm really careful about leaving space back there but it's not really on my wife's radar.

 

No, I get about 1" of forward and backwards and then it jams. Up and down is jammed completely. I can hear it engage. I bet it tried to move into a preset position with a bag behind it in the way or something. I'm really careful about leaving space back there but it's not really on my wife's radar.

I bought left and right seats from a partout and took all the motors and heaters out for spare parts. Sold the frames to people that theirs were cracked. Driving the roll pins out to remove the motors is the hardest part of the worm gear replacement or motor replacement.

 

Wj rear motor gear parts



I agree on removing the roll pins. My shop CD does not cover seat motor removal. My passenger seat on my 02 Limited will move forward and back no problem. I can raise and lower the front of the seat no problem. Lost ability to raise and lower rear of the seat. Motor works but nothing else.
Went to disassemble one at junk yard to see why my seat failed.
In the rain, something we have not seen much for some time, I worked from inside the Jeep to figure out what I needed to do to get the rear motor out.
I was not prepared to remove the two roll pins. So I used the tools you see in the first picture.
There are two roll pins positioned as seen in the third picture. One is solid. Easier to get at. I used a small Phillips screw driver as a punch and a pair of pliers as the hammer to get it out. It ruined the screw driver. But it was stripped anyway. The other pin is an actual roll pin. Hollow in the middle. I used the socket tool, since it had a solid tip and was small enough to reach the pin through an access hole. It got the pin started but was not long enough to push it out. I used the pliers to cut the tip of a finish nail I found in a truck nearby to get the pin out.
As hard as I tried I could not unscrew the large plastic gear and screw out of the steel rod. The other end of the screw had a metal stop that would not screw out of the rod far enough for me to attempt to remove it. Still not sure if it is pressed onto the screw or unscrews itself. So I recovered the assembly.
Since I have not disassembled my own seat yet I recovered a spare short plastic screw and the outer plastic screw housing just in case.

 

Finally had time to remove the seat. Nothing was broken. Probably jammed from wear, excess play and old grease.

Packed it with new bearing grease and good as new.

 

So glad I found this thread because I am having these seat problems. Found a seat track assy at pull yard but it has same problem of not moving front or backward. I have taken it apart and the drive gears are cracked and slipping on the shaft. I need only the drive gear but may have to purchase the whole kit to get the gears.

 

After looking at the prices for those "parts" , I'd go with junkyard seats. Ouch.

 

Junk yard plastic shaft & gears proved to be junk



I did obtain a junk yard seat power mechanism from a 1994 Chrysler LHS that I harvested the black plastic drive block after I had stripped out the threads on the 1996 Grand Cherokee's. This LHS seat mechanism came from a vehicle with only about 10K miles on it.

After diagnosing the inboard forward-backward seat adjustment double-helix worm shaft having a damaged plastic gear on the end, I pulled the corresponding part from the LHS power mechanism (LHS shaft is about 1.5 inches longer) to take it to my machinist to be cut down to match the GC then slot for the snap ring. While degreasing the shaft and plastic gear I noticed a clean, sharp, wide crack radiating out from the shaft to the valley between two gear teeth. My thinking is that age and 25 years exposure to grease caused the plastic to shrink, thus causing the crack. Both left and right side LHS parts were cracked in the same way.

Yes, $120 with postage did seem expensive, but so is downtime on the wife's GC, and working on the seat mechanism is likewise time consuming and time is money. Lastly, it's reassuring to know we now are riding on fresh newly made parts.

Something further I picked up on while studying Two Men One Garage's website and speaking with owner "Barry" - they try to improve on the original parts when needed. If you check their website, they offer several bronze or brass gears to replace the OEM plastic gears because the plastic gears have proven to not stand up. I feel better about spending our money with people that really try to do things right.

 

Go to the bone yard and get a couple of tracks just in case one doesn't work. Take one apart at a time so u have one to go by. Also take a 12v or 18v battery from a drill and some wire with alligator clips. attach the clips to the seat wiring to move it forward and backward to get to the bolts which i think are 14 or 15mm.

 

Makita 14.4 Volt Battery to Test Seat Motors



That is exactly what I did, using a Makita 14.4V battery, to test and position the seat motors. The track bolts in our 1996 Grand Cherokee are Truss Head Torx T50 10mm with a 1.5mm pitch, 11mm in length.

Four long black plastic bearings strips snap into the upper (moving) seat track, allowing it to slide backward and forward over the fixed bottom track. These plastic bearing strips take most of the wear. The 1994 LHS bearing strips, four per track, interchanged with the 1996 Grand Cherokee.

It's important after reinstalling the seat to immediately reprogram the seat position memories. The seat motor counts the number of rotations to position the seat for DRIVER 1 and DRIVER 2. It's unlikely after replacing the gearing that the gears and motor will still be synchronized. If it's off enough, when the DRIVER 1, DRIVER 2 or the key fobs is pressed, the seat will run into the stop at the end of the shaft and stall, possibly damaging itself.

Renewing the track lubrication with a light coating of white lithium grease eased things noticeable, and all the mechanism pivot joints and metal worm gears were lubricated with BoeShield T-9.

 

I just pulled the worm drives out of my ZJ. Gears on one track on each side are broken.

Looks like I'm going to buy a set of these.

http://www.2men1garage.net/99-04_Jeep_For-Back_Gears-a.jpg

 

Actually they said I need the Jeep 6.

 

I got a set of from Gruven Parts, Both gears are solid brass, worked out really well. gruvenparts.com/xj-cherokee-grand-cherokee-seat-height-gear-set/

 

I had my passenger seat stop working front/back recently. Also my driver up/down wasn't working in the rear. Found these posts and was about to buy the replacement worm gears. Found it very frustrating and annoying that the plastic gear cracks then gets teeth broken off, and you can't just buy a new plastic gear for a reasonable 10 bucks each or something. looking at $100 per seat just for back/front. up/down is at least $60 a seat from my searches. I decided to try something first.



What I did is first removed all loose pieces from the damaged area missing the teeth. I scraped at it pretty good to make sure it was sturdy. Then I sanded the area with 200 grit sandpaper. cleaned it with IPA. then I took some of my kids play dough, made a small cigar shape with it, and pressed it onto the side of the gear with the good teeth making a mold. I pressed the dough under on the bottom side and cut it from the top of the teeth so the cavity was open on top but closed on bottom. I took the mold and dry fit it over the damaged area so I could mark the section with missing teeth. Then I used some JB weld and filled the teeth in the marked section. I put a little JB on the gears damaged area because it seemed to go a little lower than where the mold touched. Put the filled mold over damaged area and pressed firmly. I then let it sit for 2 days. The play dough hardened and broke away from the JB weld fairly easily. I used a sharp knife to clean up and shape the new teeth. it wasn't pretty and wasn't a perfect fit but it worked and has been working for a few weeks now. I did this to my driver side up/down gear as well. When I took the driver front/back apart they worked but both had huge cracks. I sanded and filled the cracks with JB weld for insurance. of course cleaned everything thoroughly and used super lube on all moving parts. I don't move the seats around a whole lot and not my daily driver so I can't say for sure how long this will last but so far so good! I already had JB weld, sand paper, and play dough so this fix only took my time. The first time I tried this I used JB weld PlasticWeld. It has been working but the teeth did seem more flexible than when I used original JB weld. I will update if I notice any problems with my repaired seat tracks.