Author Topic: Tach Thrust Bushing (Read 18423 times)

bpossel · « **on:** August 13, 2005, 04:34:41 »

Hi All!

:?: When you replace the thrust bushing for the tach/oil pump, is there a new/redesigned tach rod that must also be purchased and installed? Or, just use the existing tach rod? From an earlier post, Hans (mbzse) mentioned a new/redesigned rod?
This is post from Hans:
"I am replacing these cross drive shafts on my car. You buy them as a pair, part No 130 050 0406. It seems M-B have identified the wear problem described by several of you in this thread, and the vertical shaft has been re-designed. See attached photo. With the new shafts you also need a new Tacho drive bushing (thrust piece). Part number for the new bushing is A615 180 0344.
On the re-designed parts, the contact (wear) area is much larger, and is lubricated more effectively.
/Hans in Stockholm"

:?: Also, what's the trick to getting the old bushing out? Mine seems to be tight. Note: 10mm bolt has been removed...

Thanks for your advice and comments!

Bob

bpossel
Memphis, TN.
1971 280SL
1997 E320

Naj ✝︎ · « **Reply #1 on:** August 13, 2005, 08:23:32 »

Hi, Bob,
Hans was talking about changing the complete gear set which is a new design and also uses a different (shorter - I think) thrust bush.

If you are just replacing a worn bush, you do not need to change the existing rod.
The adaptor on which the tacho cable fits can be screwed back in a few turns and then use a screw driver between its flange and engine block to pull out the bush. Holes on the bush and block should line up to take the set screw when refitting.

You may want to change the 'O' ring and seal:

Download Attachment:

TachoDrv12.JPG
44.68 KB

naj

J. Huber · « **Reply #2 on:** August 13, 2005, 09:29:13 »

Bob, in my case, I had some oil pooling on the tach drive and did the "thrust rod test". Movement was minimal so I just replaced the bushing SEAL. It was a challenge to get out -- I used a drill and carefully "sawed" into the side. It eventually broke up. No leak in two years.

James
63 230SL

J. Huber · « **Reply #3 on:** August 13, 2005, 10:22:15 »

I am of course talking about the rubber SEAL inside the tach drive... wasn't sure if that was clear.

James
63 230SL

waqas · « **Reply #4 on:** August 13, 2005, 10:34:40 »

Naj- do you have part nos for the seal and o-ring? Neither Ray Paul nor the local MBZ dealer were able to track them down... I need to get the real parts manual one of these days (instead of the cheesy user parts manual w/out any part # listings...) Thanks again.

WAQAS in Austin, Texas

erickmarciano · « **Reply #5 on:** August 13, 2005, 10:50:15 »

I change the bushing about 1 year ago and I also added a washer .I has no play . i just looked last night and now I have 1.5 mm play .can i leave it like this?what would make it wear so much?
thnaks

1971 280sl
1962 VW
1954 Allstate vespa
1958 gs150 vespa
1962 gs160 vespa

Naj ✝︎ · « **Reply #6 on:** August 13, 2005, 10:59:46 »

waqas,

quote:
Naj- do you have part nos for the seal and o-ring?

Part #s,
007 997 7346 seal for tacho cable
621 997 0040 O ring

naj

65 230SL
68 280SL

enochbell · « **Reply #7 on:** August 13, 2005, 11:10:49 »

Bob,

You may want to read an older post from Erik, it includes the repair I completed at ADalton's suggestion, which was to press out the old bushing, resurface the business end of it, shim behind it with aluminum, and put it back together. Worked like a charm and cost about $.65 for the aluminum washers (well, OK, so I used the savings to by a nice digital micrometer, but isn't that what this is all about?).

http://index.php?topic=3097

Best,

Greg

'64 230sl, fully sorted out...ooops, spoke too soon

bpossel · « **Reply #8 on:** August 13, 2005, 18:21:20 »

Thanks All!

I tried to remove the bushing without any luck. I am going to try again tomorrow by putting the large tach screw back in and seeing if I can get the bushing out. Maybe the bushing is swollen since it's 98 degrees here, just in my garage? Boy... it's hot here in Memphis....
Bob

bpossel
Memphis, TN.
1971 280SL
1997 E320

Raymond · « **Reply #9 on:** August 14, 2005, 00:07:19 »

Here's a creative approach. We'll see how it works. I very carefully filed the ridge off of the thrust bushing where it had worn down into the champher. Made sure the surface was flat and even all around. Then measured the play on the shaft. It was 1.98 mm. I had a machine shop manufacture a bronze bushing that was 20mm diameter (bushing diameter) with a 14mm hole, (shaft diameter). The bushing was 2mm thick and champhered. I installed it on top of the thrust bushing like a washer. It fit snugly and there is now no play. I haven't run it yet, but we'll see how this works.

This saved having to purchase a new assembly and gear or having to press out the bearing and press a new one in.

Ray
'68 280SL 4-spd Coupe

waqas · « **Reply #10 on:** August 14, 2005, 03:55:56 »

Just completed this job-- albeit with the old seal and O-ring. I'll replace those as soon as I receive the new ones.

As per Naj's suggestion in a previous post, once the 10mm bolt was out, I screwed-in the tach housing a few threads, and used a small screwdriver as a pry-bar between the tack housing and a convenient engine surface. It slid out without any significant hesitation. For installation: unless I'm mistaken, I think Joe alexander once mentioned freezing the new bushing before re-installation; on first trial, the new [room-temperature] bushing slid in relatively painlessly, with a tiny coating of engine oil around the sides.

I can rest easier now that this is done, as the old bushing had about 3 or 4mm of play!
I'll keep it around with some shims, for future use as a quick emergency fix.

WAQAS in Austin, Texas

bpossel · « **Reply #11 on:** August 14, 2005, 17:40:27 »

Finally did my tach thrust bushing today. The trick is to screw the tach housing back in. Then use a small piece of wood and a screw driver to carefully pry up the old thrust bushing. With the tach housing screwed into the old thrust bushing, the entire unit did not clear a protruding section of the engine, so had to slightly push back in, unscrew the tach housing and remove. Then pull the old thrust bushing out.

I did end up putting the new thrust bushing in the refrig, since it has been so hot here. I also put some motor oil on the new housing. It slid in like butter. I was then able to rotate it and move it into place for the 10mm bolt to go in.

Overall, an easy job, once you have done it! In summary, my old thrust bushing was worn. I also pulled the tach gear to inspect. Some of the gears do show wear, ie. they are sharp on the ends, vs being somewhat squared off on the gear ends. I simply re-installed my gear. Hopefully it will be ok?

Thanks to all for your comments and help!
Bob

bpossel
Memphis, TN.
1971 280SL
1997 E320

jeffc280sl · « **Reply #12 on:** August 14, 2005, 20:21:43 »

Sorry Bob,

Missed this thread. I did the same thing 6 months ago. I'm glad you got it done. You prefer to do things in parallel versus serial fashion. Pace yourself! Pretty soon your car is going to be finished then what are you going to do with all your spare time?

Jeff C.
1970 280SL 4-speed

waqas · « **Reply #13 on:** August 15, 2005, 23:55:52 »

Bob,

Did you notice any difference in behaviour on your tach needle? Since I changed the bushing, I've noticed a distinct tach 'bounce' across the entire range of RPMs, but especially idle, during which the needle vibrates vigorously in a 5mm peak-to-peak swing. Any ideas on what may be causing this?

WAQAS in Austin, Texas

bpossel · « **Reply #14 on:** August 16, 2005, 04:23:47 »

Waqas,

Actually, I replaced the tach thrust bushing on Sunday and have ony started the car, have not driven it. So far in the garage, at idle, my tach is stable, no bounch.

I will probably do a test run this evening to check if my tach is stable and to test out my new radius arm bushings that I installed last night. I was too tired to take a run after my work last night on the radius arms, which I started on Sunday after doing the tach bushing.

I will re-post later tonight.
Regards,
Bob

bpossel
Memphis, TN.
1971 280SL
1997 E320

hands_aus · « **Reply #15 on:** August 16, 2005, 04:27:58 »

Ok,

I read that I can do a test for play.

Other than the test what are the indicators that the thrust bush needs to be adjusted/replaced/shimmed?

Is there a rattle noise?
Is there a leak?

What should I look for?

I don't want to FIND / CREATE problems that might not exist but I am trying to eliminate a RATTLE noise that is like two washers that touch each other spinning on a shaft.

My car has 164K miles but was rebuilt by 1st owner at 93K miles in 1977.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

Tom · « **Reply #16 on:** August 16, 2005, 06:52:12 »

Bob,

If your tachometer needle is "bouncy", it could be caused by a bushing that has too much play. Could also be the cable or the gears in the tachometer could be worn.

1971 280sl Tunis Beige Metallic (restored & enhanced)
1971 280sl Tobacco Brown (low mileage stock)
1970 280sl Deep Red (Project Car)

enochbell · « **Reply #17 on:** August 16, 2005, 08:32:17 »

Bob,

If you follow this string:
http://www.sl113.org/forums/index.php?topic=3097
you will find all you need to diagnose and fix, including some great pics of an effective measurement procedure. Simple fix for play, hope it cures your rattle,

Greg

'64 230sl, fully sorted out...ooops, spoke too soon

rwmastel · « **Reply #18 on:** August 16, 2005, 21:12:27 »

quote:
Originally posted by hands_aus

I don't want to FIND / CREATE problems that might not exist but I am trying to eliminate a RATTLE noise that is like two washers that touch each other spinning on a shaft.

Has someone over-tightened the three valve cover bolts? Doing so can pull the backets up and the bracket sides can contact the cam and make noise. Remove valve cover and see how close these are.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420

bpossel · « **Reply #19 on:** August 17, 2005, 04:18:04 »

Hi Waqas,

Drove the car last night. No needle bounce.
Maybe you need a new tach cable, or still too much play at tach bushing? Maybe try a shim?
Bob

bpossel
Memphis, TN.
1971 280SL
1997 E320

Naj ✝︎ · « **Reply #20 on:** August 17, 2005, 08:35:13 »

Bob,

quote:
Some of the gears do show wear, ie. they are sharp on the ends, vs being somewhat squared off on the gear ends

Do you have a picture of the worn gears?
Would be interesting to see the kind of wear pattern you have.

thanks
naj

65 230SL
68 280SL

bpossel · « **Reply #21 on:** August 17, 2005, 20:07:19 »

Hi Naj,

I didnt take any pictures of my gear, however, there is an earlier post on this topic that shows a picture of the old and new design of this gear. If you look closely at the old gear, the gear teeth are thin, whereas the new gear has squared off ends.
Hope this helps.
Bob

bpossel
Memphis, TN.
1971 280SL
1997 E320

Download Attachment:

tachgear.jpg
36.23 KB

ja17 · « **Reply #22 on:** August 17, 2005, 21:04:10 »

Hello,
It seems apparent that new and old design parts should not be interchanged, but switched out in sets?

Joe Alexander
Blacklick, Ohio

bpossel · « **Reply #23 on:** August 18, 2005, 07:40:58 »

Joe,
I spoke to one of our vendor partners on this and here is what he said....
"When you replace the tach drive gear set, a $ 700.00 set, you need to also replace the thrust bushing with the updated version at an additional $ 80.00. You do not need to change the gear set if you are only replacing the original thrust bushing with a new original one."

Anyone else have any comments or information on this topic?
Thanks,
Bob

bpossel
Memphis, TN.
1971 280SL
1997 E320

A Dalton · « **Reply #24 on:** August 18, 2005, 07:58:11 »

What both JA and your guy are saying is that if you want to change the gear , you have to change the set , as they have to mate up for a proper match [ all mesh gear assem. are changed as sets- if you change one only, the other one will wear the new one out in short order, as the old/new contact surfaces will not mate correctly ]
And the new improved gears set requires a new thrust peice b/c the new one is a different dimension than the original [ allowing for the larger bushing surface/shoulder on the new gear]
.. but , if there is not a lot of wear on the gear assem, there is nothing wrong with just replacing the thrust piece with an original replacement [ or shimming]
The modified setup will not wear as the original does, but it takes a long time to wear one out and the original can be re-shimmed much cheaper than the mod. cost without the fear of of early breakage or oil pump drive problems .. it is just that one should do a routine end play observation when the miles get high on the replacements , even if it is the new mod....
If the gear/shaft look Ok, go with the thrust piece, but if the gear is bad , go with the complete gear set and matching thrust piece.
For those who prefer the shim tecnique over the replacement of the thrust piece, it is preferable to press the bushing out of the thrust casing and insert the shim behind the bush , as it is then sandwiched inside the unit, allowing for any type shim stock , as the original brass bush material is still the bearing surface.[which you resurface] With a shim on top of the thrust, not only is the shim wear qualities in question, but you can then get wear on both sides of the shim as it floats between the gear and the bushing surfaces. As the wear becomes larger , the gears take the extra wear as they start to lift with each drive input due to the rotational cut of the gears. So, smaller end float with best material is better all around.

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Author Topic: Tach Thrust Bushing (Read 18423 times)

bpossel

enochbell

bpossel

bpossel

jeffc280sl

bpossel

enochbell

bpossel

bpossel

bpossel

A Dalton