W124 cluster update DIY
 

Many posters here have noted the improved lighting in later W124 instrument clusters due to better light pipes. From the local Pick and Pull I got a cluster (case only $20) out of a '91 300E and swapped it for the original in my '87 300D. The cases are identical except for the light pipes so the instruments swap with no modifications at all.

If you are going between gas and diesel you must remember to swap the right hand strip of film that has the labels for the idiot lights, so that it has a glow plug symbol instead of a "Check Engine" note. Pull out the gasser strip with a pair of needle-nose pliers and stick in the one for the diesel.

The pictures show the improvements in the light pipes.

The first two pictures show the change in the thickness of the plastic, allowing more light to be transmitted to the instrument faces. The second two pictures show how my old cluster had partially melted (PO tried bigger bulbs that got too hot for the plastic). The new case has a cutout to allow the bulbs to get some cooling air.

Finally, note the rubber piece in the last picture. There are four of them that help hold the cluster in the dash and they often fall off. You can move them from the old case to the new one. I attached them with Gorilla Glue. I'm still missing one but that's better than missing three.

Jeremy

I replaced the bulb in one side of my cluster with a new OE one, and a couple of the vent lights, and found them to be much much brighter than the old ones with somewhat dark glass (from years of sputtering filament). Replaced the rest of the bulbs with new ones, very significant difference.

I'm guessing the new cluster is better still, but the old '87 lights up very well with fresh bulbs, I run with them dimmed a little.

Good work, Jeremy! I love the amount of light a new cluster provides over the old one Wow! a huge improvement!
Mercedes finally got it right, after all these years of suffering with poorly lit 123's :mad: its a real joy to drive my 124! :):)
here's a pic showing a legend strip being removed from the 124 cluster (long nosed pliers are just out of the pic)

Amazing!
 

A couple of nights ago I had a chance to drive the 124 for the first time since installing the later model cluster case. The improvement in lighting is amazing -- I can even read the trip meter now. Even with new bulbs in the old case the illumination was not very good (mine not only had the small light pipes but had been damaged by PO-installed high wattage bulbs). Now it's like a spotlight was turned on. Certainly one of the best $20 I've spent on this car.

Jeremy

It looks like I'm getting a late model W124 cluster on my next trip up to a Pick'N'Pull. The P.O. of my 300TDT put 194 lamps in my cluster and melted the light pipes. I put the proper lamps back into the cluster but it is still real dim.

Great info guys! I have been looking for a solution to my dim cluster lighting.

-Steve

The next question is, where in the model years is the break point between the thin and thick light pipes? The cluster case that I got was from a '91 E300 gasser so the break came before that. Anyone know?

I just picked up a cluster case from a 1989 300E and it had the thicker light pipes. So it looks like the thicker pipes were used in 1989 (unless the case was swapped, but not highly likely). I think this weekend I'm going to install the case, and hopefully the cluster dim lighting woes will be solved.

It's pretty easy to swap out the gauges in the case. There are only 8 screws (4 on the speedo, and 2 on each side instrument set) holding the electronics in to the case. The case I got was in pretty good shape. It only had a minor ding in the upper right front window area and one of the light pipes was slightly yellowed/melted. I can't complain for $5.99. If I find a better one I'll swap it out again.

-Steve

I was at the PNP this weekend. I didn't have access to this thread so I didn't know how to identify the redesigned light pipes. The 4 124s had their clusters removed and partially to completely disassembled so I couldn't be sure which housing came from which car. Can someone confirm that I'm looking for thick light pipes as in the second picture vs skinny light pipes as in the first picture as the way to identify the newer style housing?

Thanks,
Sixto
87 300D

the thicker plastic light pipe is the later style. I think they began using these in 1989, but there may have been some in '88
I have a housing to put in my wife's '87 if the numbers mean anything on it I can take a look for you.
(the paper tag usually has the K code on it, that identifies the speedo ratio)

Cool. As long as I know thicker is what I'm looking for, I'm good.

Can the light pipes be transferred to the older housing or do I have to use the newer housing? Asking in case the older housing has a cleaner screen.

From the PNP on Commerical in San Jose, I have a gasser left gauge set I found inside but not attached to an 87 gasser for a economy/boost gauge conversion. Might as well hold off for the light upgrade.

Sixto
87 300D

The light pipes are held down by a white cover that is molded onto the housing in several places, I can't even budge itand I don't see one in the picture of the old version housing (above)
The pipes travel from the outside rear into the inside through some hidden passageway and looks like its very much a part of the housing assy.
Just find a complete housing and swap the instruments over. I think you should hold off for a new version if you ever plan on driving much at night

I would say that the light pipes cannot be swapped. Since the newer cluster is the same size on the outside, the extra room has to come from the inside of the case.

More cluster pictures. Thanks for the write up Jeremy. I can't wait to drive at night now.