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11,472 Posts
The recommended tranny oil, when the Smart was under the distributership of Penske in the U.S., was considered by many as the incorrect fluid version (a GL-5 and not a
GL-4,and it not backwardsly compatable, like engine oil), as noted elsewhere in his forum. (perhaps others can help me out here). if this was true then the fluid was doing nasty things to the gears, like excessive etching, and maybe also (I have no proof) getting into the electric shifter motors interior and mixing with the carbon powder residue from the brushes. I am hoping that replacing what was possibly a GL-5 oil with a with a GL-4 (only) oil, that this gunking issue will be resolved. Gear teeth design I have no knowledge of...sorry. But there appeared to be plenty of carbon left on the brushes of my motors.
The "recommended" oil is the Castrol BOT328. This is the ONLY oil recommended.

After much to do, it was found out by one of our members, that this was the ONLY oil that Getrag tested the tranny with .... so .... it was the ONLY oil "recommended" :rolleyes:

Go figure :wow:

338 Posts
ours is '08 as well, just at 20K and no trans related problems but will keep a close eye

it has dawned on me that smart owners are the new age british sports car enthusiasts - they're fun to drive but you need to work on them from time to time

thanks for the great info

1 Posts
Reading this thread 10/18/2018. No posts for 5 years, could it be everyone solved their problems or something else like Smart has become a orphan in the USA?

Have 08 with 79K and just started with the shifting problems, will take a look the shifter motors and try the fix suggested, since the dealer is 50mi away and $$$ trying to jack my enthusiasm up.

Premium Member
61 Posts
Hooray, I received the three of death yesterday, followed the advice from this tread and now my baby is back and running strange. Thanks, all and the pictures were a hundred percent helpful. although there was no oil or gunk in the motors but I cleaned them and she is back.

190 Posts
Discussion Starter #71
Pictures at an Exhibition 01

Ok, first let me get this out of the way - my note, "all they did was install the 2012 hardware...???? - care to elaborate?" was for Toslow, at post #20.

Here's the picture of the transmission motors's vent with oil spewed debris on the exterior of the housing:

Pictures at an Exhibition 02

Next is a picture of both transmission motors before removal. This view is with the engine hatch off, I am standing behind the smart looking into the engine hatch with the air intake baffle off. (also be sure to seal the air intake into the engine to prevent any debris from getting into the carb/fuel injection ports.)


Pictures at an Exhibition 03

Right side electric transmission removed. Remove both motors and the housing as one would be easier (4 screws) than this, but was exploring in small steps at this point.


Pictures at an Exhibition 04

Dirty housing, gunk mix of transmission oil and carbon from motor brushes.
Also the 4 magnets are shown, and the rubber plug at the end of the motor housing can be removed by your fingers before you (carefully!) pull the housing off the motor. The magnets provide strong resistance as you pull it apart.


Pictures at an Exhibition 05

Dirty motor - what I failed to photograph was the gunk that I just knocked into the garbage can - this is just the debris left behind! Really, easily a couple of ounces. The left side motor wasn't as bad, but still needed cleaning.


Pictures at an Exhibition 06

Cleaned motor - I flushed the housing and motor with "CRC QD Electronic Cleaner" found at the auto-parts store. Also used this stuff for the wire connectors, both sides


Pictures at an Exhibition 07

Geared end of electric motor - This is where I suspect the oil is getting in. I used a cotton swab and applied a thin layer of automotive grease around the gear on the bearing seal in an attempt to slow the progress of any future oil from seeping through.


Pictures at an Exhibition 08

Electric motor ready for re-assembly. Note rubber o-ring in place on housing and the 4 screws with Permatex threadlocker (I used medium strength blue) on it.


Pictures at an Exhibition 09

Gasket material on housing: I used "Permatex Ultra Black maximun oil resistance RTW silicone gasket maker", available at auto-parts store in 0.5 oz tube


Pictures at an Exhibition 10

This the opening in the manual transmission after removal of the electric motors assembly. I kept it covered with kitchen plastic wrap to keep the crap out as I cleaned around it. Drain the oil and open the overflow plug too from below. Once you are ready to reassembly use this opening to simply pour the new transmission fluid in, until it flows out the overflow port. I used Red Line Synthetic MT-90 75W90 GL-4 (Amazon, couldn't find it locally). I am hoping this will prove to be a better fluid than what was in it before, it could be that I had (I bought this car used) Penske's crap in there (see elsewhere in the forum on how they approved their GL-5 junk for this tranny). Maybe why this failure happened.

I used the threadlocker on the bolts holding this together too. I also noticed none of the bolts were difficult to unscrew - i.e. they were not highly torqued like most engine parts in other cars are. I also carefully lightly lubed with a di-electric grease the rubber bushings on the electrical connectors after cleaning them with the spray cleaner, to help seal out any rain & snow spray. (Note how the connectors are exposed to the road below!)

This completes my DIY pictorial project of my electric transmission cleaning procedure. Sorry about the delay, I wanted to be sure the problem was resolved for good.


152 Posts
there we go....much thanx !!...i worked for hours trying to get that F-ing intake manifold out yesterday....finally cut it to pieces with sawzall.....going to make my own intake tube today.....i didnt take apart the motors yet...just cleaned the connections.....prolly also thinking bout the gearshift module under the
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