Good news....

I found a perfect 107 instrument cluster with 160 MPH speedo. The gauge face bears part number 107 542 28 01.

Bad news...

It came from an unknown donor.

There are no tags on the back to indicate what rear axle ratio it was originally used with....

I have attached a few photos of the cluster, including the back of the speedo itself.

On the back of the unit, the numbers '095/002 / 21' are stamped into the metal housing, followed by the charcaters 'W1155' and the numbers '9.76.'

The number '34' has been hand-written over the '21' (mentioned above) and the number '12' has been hand-written over the '9.76' described above as well. This would indicate to me the unit has been calibrated at some point, but to what specification????

below this group is a blue triangle ink stamp, with squared edges, that reads '112 1.77' and a similar looking green triangle that reads '30 12.75' respectively.

My intention is to install this into my W116 with a 2.47:1 rear axle with 205/70R14 tires and have it read correctly. I am in hopes that someone can either interpret these markings, or point me in the direction of someone who can.

Thanks very much for your help!!!!

Attached Thumbnails

       

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Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

hey good for you, thats what I was going to try also but I have never come across a cluster in a sl or sel. keep us informed

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1982 300CD Turbo (Otis, "ups & downs") parts for sale
2003 TJ with Hemi (to go anywhere, quickly) sold
2001 Excursion Powerstroke (to go dependably)
1970 Mustang 428SCJ (to go fast)
1962 Corvette LS1 (to go in style)
2001 Schwinn Grape Krate 10spd (if all else fails)

I have contacted a couple of speedo shops to try and figure out what the codes mean. I will post the answers as I get them....

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Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

You can use the maximum speed in gears as a guide to what rear ratio it is if you can find somebody with the same hash marks as this has. I believe most of the us spec 107's probly have 247 gears. I don't know about the euro cars but i suspect some may have had 224 gears if a v8 and prolly 354 if a six. that looks to be a three speed gearbox with fairly tall gears judging by the hash marks.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

That "1.77" marking is a date code which means it was made in Jan. 1977. In 1977, the 450SL and SLC were the only 107s being imported to the US market. I think the 450SL had a 3.07 rear axle at the time. The only 107 I know that had the 2.47 was the 86-89 560SL. So, I would be on the lookout for a 560SL speedometer.

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

According to the speedometer shop, the W1.115 marking is the speedometer ratio....

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

Is there a chart of ratios?????

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

Could you not just order new gears for a 2.47 rear-ended car?

http://odometergears.com/mercedes.html

I guess the trick would be to know how many teeth are on gear E3

12,13,15,16,17,18

Maybe someone over in tech help with a late 80s SL could help.


EDIT: Doh, that would only correct the odometer, the speedometer would still be off. Disregard.

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----Adam

1985 300SD 322,000

Only the 560 (and perhaps some euros?) had 2.47:1... Other ratios for earlier years... as posted by HTOWN

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RM Smith
1988 560SL

"Where is it again that we are going, and why are we in this handbasket"?

It's $165.00 to have it recalibrated by Palo Alto Speedometer.....

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

bummer, did you ask them if they could recalibrate a w123 speedo?

__________________

1982 300CD Turbo (Otis, "ups & downs") parts for sale
2003 TJ with Hemi (to go anywhere, quickly) sold
2001 Excursion Powerstroke (to go dependably)
1970 Mustang 428SCJ (to go fast)
1962 Corvette LS1 (to go in style)
2001 Schwinn Grape Krate 10spd (if all else fails)

They do them all...

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

Ok....

The 'W1155' stamped on the '107' speedo housing is a calibration code. It represents the number of cable revolutions at 60 mph. In this case, 1,155 revolutions.

The stock speedo from my '116' with a 3.07:1 axle ratio is a 'W1330' unit.

Clearly, the '107' speedo is not calibrated for a 3.07:1 axle.

If we use a simple, mathematical formula, we can get close to what the proposed axle ratio change will give us.

Since our W116 test car has a 3.07:1 axle and a 205/70R14 tire and develops 1330 cable rpm @ 60 mph, we will use this as a baseline.

To estimate the effect the new axle ratio will have on the speedometer, divide the proposed axle ratio (2.47:1) by the current axle ratio (3.07:1) and multiply by the cable rpm @ 60 mph, which in this case is 1330.

The answer is 1070 cable rpm, which means this '107' speedo would be off by 85 cable rpm.

In general, a 3.75% speedometer error is considered acceptable, which is about 50 cable rpm.

A 2.69:1 axle would yield 1165 cable rpm, so it is likely that this 107 speedo that I have, marked W1155, was originally destined to be used with an axle ratio very close to 2.69:1.

Hope this helps...Robert

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

awesome info, takes some of the mystery out of the speedos

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1982 300CD Turbo (Otis, "ups & downs") parts for sale
2003 TJ with Hemi (to go anywhere, quickly) sold
2001 Excursion Powerstroke (to go dependably)
1970 Mustang 428SCJ (to go fast)
1962 Corvette LS1 (to go in style)
2001 Schwinn Grape Krate 10spd (if all else fails)

then that seems to be the best solution, just recal the original speedo for the new axle

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1982 300CD Turbo (Otis, "ups & downs") parts for sale
2003 TJ with Hemi (to go anywhere, quickly) sold
2001 Excursion Powerstroke (to go dependably)
1970 Mustang 428SCJ (to go fast)
1962 Corvette LS1 (to go in style)
2001 Schwinn Grape Krate 10spd (if all else fails)