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M46 overdirve removal[200/1982] posted by Randy on
Monday, 7 February 2000, at 2:19 p.m.
It would appear that if I want to enjoy the increased performance of the 10w30 synthetic oil in my M46 I'll have to remove the overdrive and replace the gaskets between the two overdrive components. The synthetic oil is pouring out along one of those gaskets. I guess that is why the previous owner had heavy weight gear oil in the transmission.
1. I've had the rear housing off of several AW70 transmissions to replace the bushing and seal. Is this job (removing the rear half of the overdrive unit) similiar?
2. After removing the driveshaft and crossmember is it necessary to remove the shift lever to get the transmission to drop down enough to remove the back half of the overdrive?
3. I read in Bentley's about relieving the internal torsional stress. Any other tricks to removing the rear portion of the overdrive unit? Looks like five (or was it six?) 13mm nuts. Can I just seperate the two halves of the overdrive and leave the front half in place and simply remove the back half to get at the "gasket/spacer/gasket" combination that is giving me the leak?
Thanks for any insight into this new learning experience. Seems like it might just be easier to go back to heavy gear oil and wait until it needs a clutch to change the gaskets!
Randy
Re: M46 overdirve removal[200/1982] posted by abe crombie on
Monday, 7 February 2000, at 3:33 p.m.
The leakage is most likely from the upper two nuts/studs on the OD unit. These are sealed with cone shaped nylon pices that get forced into threads.
Clean it up and then drive a block and see if it leaking there. If so then you only need to remove nuts and clean the stud and case with brake cleaner spray and then apply sealant (silicone, permatex, etc) to the studs liberally and then re-install nuts.
If you have to remove OD then just before you lift car kill it in reverse so that the splines in OD will unbind from the trans output shaft.
The OD will slide right off if this is done.
Re: M46 overdirve removal[200/1982] posted by Randy on
Monday, 7 February 2000, at 4:32 p.m.
Abe,
It is leaking between the two halves of the overdrive unit as opposed to near the end of either of the top studs/nut combinations. I've tried to include an image here with an arrow showing the seam that is leaking.
When you say "kill it" do you mean stall it in reverse while I have the brakes applied (as opposed to shooting it through the ECU)? Thanks for your help (again).
Randy
Re: M46 overdirve removal[200/1982] posted by duane on
Monday, 7 February 2000, at 9:11 p.m.
Randy,
The leak appears to be at the forward edge of the brake ring. To remove this the six nuts must be loosened a little at a time since there is spring pressure from sliding member pushing the three sections of the housing apart.
Abe was correct in watching for the two nylon cones under the top two nuts. On some older models two copper washers were used instead. Either will work.
The trans only has to drop about two inches at the back to allow separation of the OD case. No need to remove anything except the driveshaft.
Duane
83-245 LH 2.0 M46 191xxx
85-245 LH 2.2 AW70 133xxx
Overland Park, Kansas
The OD Guru (Laycock only)
Re: M46 overdirve removal[200/1982] posted by sydney on
Monday, 7 February 2000, at 9:22 p.m.
I gather the running in reverse before dismantle will accomplish the same as running in 4th with o.d. engaged and then pushing in clutch and allowing the drive train to come to rest on its own. I used the latter method and found the o.d. separated nicely on an 80 240. ...syd