crd flexplate

[Kidshorsesme]

Can confirm now that the used Mercedes Benz part that I sourced was a direct BOLT IN !!! This EXACT MB part number seems to be used in vehicles with OM642 from 2005 to 2021 with 5, 7 & 9 spd auto transmissions. How absolutely clever of MB to do something as 'smart' as this !

Getting it out & back in whilst on jack stands & ramps in the garage, laying on your back had its challenges. Was actually not the nightmare I was perceiving it to be. used two trolley jacks that I welded a M16 nut into the top of the cup, then bolted on a bit of 45x90 timber. Put one under the transfer case cross member & the other under the trans pan. Was quite sturdy & no chance of having it fall off.

Only moved it back about 150mm just enough to gain access to the flex plate bolts. Simply unbolted the old one, bolted in the 'new' replacement



The replacement that I sourced was in 'as new' condition. The ring gear was absolutely un marked

The one that came out was WAY worse than I could ever have imagined. I think most of this damage was from the previous starter as it was not throwing out the pinion properly. Checked the condition of this newly replaced starter & it was hardly visible of any wear on the pinion gear ... thank goodness !!!



No wonder it wouldn't crank over ???

I did re-use the original flex plate bolts to bolt on the replacement one. It was hard enough sourcing the flex plate, could imagine the drama getting new bolts ?

So hopefully this information will help other people that require a new flex plate / ring gear for their WH Grand Cherokee with the OM642 engine !

[NoviceGuy]

First of all thanks Kidshorsesme! Coming across your post guided me very easily to replace my flex plate from home, also. Took 1 full day solo, all bolted back up 5am to 5PM including trips to shops and breaks. Not rushing it.

I sourced my replacement by matching up part numbers you mentioned in your post. Ebay had me sorted for AU $167.06 including postage from Lithuania. Flex plate looks excellent and arrived within a few weeks.
Replacement: 16420300512 / 6420300512? (searching 6420300512 gives many results)
https://www.ausjeepoffroad.com/forum...9&d=1704671171
https://www.ausjeepoffroad.com/forum...8&d=1704671171

Worn/replaced:A6420300012
https://www.ausjeepoffroad.com/forum...7&d=1704671171

Background- Mine had flat spots from before I purchased the car. I ended up chewing the starter motor out on a bad spot within a week of getting her on the road. Replaced the starter motor to get me by for a while. Then carried a large 1/2" ratchet with 27mm socket to turn over the motor. If it so happened to stop in the most warn spots on the flex plate


Tools I needed outside of common hand tools:
>27mm on long ratchet (turn over crank bolt -front of motor pulley)
>T55 on a 3/8" drive (all bolts on the Flexplate- torque converter bolts and crankshaft mounting bolts)
>Grabbed a nice solid sturdy trolley jack from super cheap auto (coupled with a cheap crappy one i already had to back out the gearbox)

Surprisingly easy, my rough replacement steps and order:

1. Car ramps under front wheels and level it with stands under rear diff. Secure it well make sure its stable. (do this the day before so everything isn't 6000 degrees). Remove battery negative.
2. remove front and rear propshafts. Mark locations for correct re-fitment.
3. loosen all gearbox bolts while everything is still supported. can get to all of them without doing anything crazy. Just use a good assortment of flex drives and long bits.15mm hex i believe. All but one behind the auto trans lines can be done. Left some in with a few turns so nothing fell apart for the next steps.
4. clear all the tranny stuff that wont let you roll it back without snagging. dipstick tube, tranny lines and cap them -they'll keep dripping,selector cable bracket and linkage.
5. through the inspection gromet hole in the bottom of bell housing undo all the torque converter to flexplate bolts T55s 6 of. Rotate crank bolt 27mm to get them all out.
6. get the trolley jack supports in and make sure its sturdy. I fixed some timber to the top of mine and secured it to the trans support cross member. Tied the trolley jacks together. So, they both rolled together, I didn't have to be under the car when rolling it back too.
7. undo the last of trans bellhousing bolts leaving the crossmember bolts to last. undo crossmember bolts once everything else is out. Check over again to make sure nothing else will be an issue when rolling back.
8. Undo the crossmember bolts to unibody and roll it back (only needed 150 mm or so. Only dropped the cross member to clear underside by 5-10mm and rolled it back. Used screw drivers and timber to separate it off the rear of motor + ratchet strap to the trolley jack to reverse it back gently without being under the car.
9. Undo 6x T55 bolts and replace flex plate. I used a piece of timber on teeth of the flexplate wedged against the bell housing to stop it turning over the motor.
10. Reverse order of steps and call it a day.

Some pics:
Rolling back the gearbox- ratchet straps
https://www.ausjeepoffroad.com/forum...1&d=1704673227

Trolley jacks setup
https://www.ausjeepoffroad.com/forum...1&d=1704673227

Old vs New
https://www.ausjeepoffroad.com/forum...1&d=1704673227

Cheers!