Vertical Timing Gear Thrust Bushing - shimming

[awolff280sl]

Can someone point me to a kit that would work to press out the brass bushing in the thrust piece?
I want to sandwich a shim there.
Or maybe I should find a machine shop.
Thanks.

[Mike K]

Isn't it less hassle and easier to replace it with a new one? I replaced mine not too long ago, I paid about EUR32.00 for it.
It took me about 1/2 an hour to do the job.

[awolff280sl]

Yes, it is good to replace it, but this does not guarantee that the vert gear's end-play will then be in spec (0.1mm - 0.25mm).
In my case, I still have about 1.5mm of vertical endplay with a new bushing. This is likely the result of gear wear plus wear of the other thrust bushing under the other end of the tach shaft.
By keeping the vert end-play closer to spec, I expect to reduce the wear rate on the gears.
About 12,000 miles ago I put a copper injector seal (1.5mm thick) on the vertical gear, as suggested in the forum, to reduce the end-play I had at the time. When I did a routine maintenance check again recently I found that the excessive end-play was back to about 1.5mm. I removed the vertical gear and found that the copper shim was totally gone, but there really wasn't any significant wear of the brass thrust bushing itself that I could see.
Nevertheless, I bought a new thrust bushing and this still gave me 1.5mm of vertical end-play. So this time I want to shim under the thrust bushing itself, if I can press out that bushing. I'm going to try a 2 jaw gear puller to push it out.
For now, I put a new copper injector seal back on the vertical gear shaft. It may be my imagination, but I my tach needle is rock-steady at idle as compared with before this shim.

[Mike K]

OK great.  I found the same thing when I replaced the bushing, tach needle seemed steadier than before.

[ja17]

Hi Andy, You can get hardened steel or stainless steel round metric shims from McMaster Carr in various thicknesses. 14mm is the correct ID.

https://www.mcmaster.com/catalog%2f125%2f3362

[Benz Dr.]

Sounds like the copper seals that are used under the fuel injectors that we've been using tend to wear out and slowly disappear into dust. Not really the kind of stuff you want floating around in your engine although the oil filter would catch some of it. This might require a rethink.

[ja17]

Yes on that Dan, however in a way the original brass bushing is doing the same thing as it wears, probably slower. It is important to make sure the mating parts are made nice and smooth before assembly with any shim. I bought a selection of hard steel shims from McMaster Carr that I am using these days. When possible it is always best to replace with a new thrust bushing but even these need shims sometimes.

[awolff280sl]

Thanks Joe.
I had a machine shop press out the brass bushing and put a 1.0mm shim under its collar and pressed it back in.
I'm still not quite at spec, so I ordered some hardened steel shims as you suggested for on top of the gear collar to make up the difference.

[Harry]

I am about to reassemble my engine (1966 230SL), which will include checking this end play.  How is that best done, and where does the shim go that is being discussed here?

Thanks.,
Harry

[66andBlue]

JA17 described the procedure here: https://www.sl113.org/wiki/Electrical/RevCounter#TachBushing
also read this: https://www.sl113.org/forums/index.php?topic=12014.

[Harry]

Thanks Alfred!

[ja17]

Yes thank you Alfred, your the "master" at finding these "posts from the past"!

[mbzse]

Isn't it less hassle and easier to replace it with a new one?.../...

Some more info on the tach drive parts including pictures of new and updated parts from M-B in this posting:
https://www.sl113.org/forums/index.php?topic=27931.msg201026#msg201026