Identify this mystery part from 717.4 - PeachParts Mercedes-Benz Forum

Greg in Oz · #1 03-14-2006, 12:37 AM

I changed the fluid in the 5-speed manual gearbox (717.413) in my 1990 190E-2.3 Sportline on the weekend. This was the first time I have done so since purchasing this car a few years ago.

The fluid was clean and the small amount of fine metal filings on the drain plug magnet appeared normal. The larger broken item which appears to be a spring stuck to the magnet certainly did not appear normal

! The gearbox appears to behave perfectly normally and has not changed in behaviour since I have owned the car. For all I know this broken spring may have been there for many years.

Can anyone identify the item (see photos)? I have looked at the diagrams in the EPC but cannot see anything that looks exactly the same. There are some springs associated with the selector mechanism but none looking quite like this.

Thanks,
Greg

t walgamuth · #2 03-14-2006, 07:58 AM

a tranny expert but i have had a few apart. i cant imagine what it is. i suppose it is possible it fell in during assembly at the factory and has no place in your trannny. seems unlikely.

i suppose if it is shifting alright i wouldnt lose any sleep over it.

tom w

mbdoc · #3 03-14-2006, 08:11 AM

The synchronizer rings are retained by those "spring" rings.

MB number 123-262-01-93 or 123-262-02-93

kidMoBile · #4 03-14-2006, 05:29 PM

I've spent the last two days browsing through a book entitled "How to Rebuild and Modify Your Manual Transmission". Got it from Amazon.com for about $16. Very interesting reading. That looks like exactly what MBDoc says. If these trannies are similar to the one detailed in the book, this is one of two spring clips that sit inside a synchronizer assembly (one synchro assembly is shared for gears 1 and 2, another separate assembly is shared between gears 3 and 4, still another separate one exists just for overdrive. Reverse may or may not have one....probably not). The spring holds a small metal thingie in place inside a small hole in the synchro ring...the thingie is what allows the synchro to do what it's supposed to do. There are two springs and two thingies per synchro assembly. Could be that you have one of your synchro assemblies working with only one spring and one thingie instead of two. If this is actually a synchro spring, then you're talking about splitting the transmission case and rebuilding to fix it, I think.
Sorry about the anti-technical talk. The book is not in front of me. I can refer to it and be more specific if you'd like.

Brian

Greg in Oz · #5 03-15-2006, 06:24 PM

Thanks for those replies. I have gone back to the diagrams on the EPC and looked at the springs (A123 262 0193 and A123 262 0293) associated with the synchros. They are circular in shape. The spring I have found strikes me as possibly being much the same shape it originally was. For it to have been distorted to this shape (from a circle) within the transmission would surprise me. You see, it is very stiff and springy and I believe any attempt to bend it significantly from its original shape would cause it to break (as one end of it already has - see smaller section in photos). I also notice that its shape is very symmetrical and all of it except the ends is perfectly flat in one plane. Could those synchro spring rings really end up so well formed into this shape? Its present shape appears intentional.

With regard to the operation of the synchros, they seem faultless (although I am in the habit of double de-clutching down shifts from spending my early driving years in a car with lazy synchros). The only gear that is occasionally baulky is reverse, requiring the clutch to be engaged briefly again before reverse can be selected. I can't remember if reverse in this transmission has synchro, I know some do now.

Getting back to the broken spring, the closest match I could find on the EPC was either part of the shifting fork assembly A124 260 0730 or the spring A124 993 0325. Even these are not the same shape in the drawing as the item I have recovered from the magnet in my transmission. Whilst the EPC diagrams are only approximate, I usually find the basic shape of parts appear correctly.

Again, thanks for the replies.

Greg

kidMoBile · #6 03-15-2006, 06:40 PM

I just ordered a CD-ROM which goes through a step-by-step rebuild of a 717.430 transmission (1986 300E), which likely is nearly the same beast as what you have. I'll take a look for you when it arrives. You're right....for a synchro spring to be distorted from a half-round shape to what you have in nearly perfect fashion seems impossible.
Brian

mbdoc · #7 03-16-2006, 08:06 AM

Have had many of those MB manual transmissions apart!

That is a common problem.. The part number(s) that I listed is the part that you are seeing!

Greg in Oz · #8 03-16-2006, 06:55 PM

Thanks Brian and thanks MB Doc,

Amazing that it ends up that shape. I will optimistically make the assumption that it was like that when I purchased the car over 3 years ago (on the basis that I have noticed no change in its behaviour during that time) and that it will continue to operate well for a long time time to come.

Greg

chuni959 · #9 11-14-2007, 08:33 PM

MBDoc, do you have any other suggestions (besides 4x4abc.com) for getting a repair manual for a 717.432 out of my 190e 2.6 5-speed? Or perhaps you could tell me why it clunked very harshly during shifts? It never slipped out of gear, just harsh shifting. I am getting ready to put it back in with a new clutch, pressure plate and T/O bearing. I just want to make sure the tranny is ok