Throttle linkage balljoints - PeachParts Mercedes-Benz Forum

lrg · #1 07-25-2002, 01:15 AM

I just returned from the dealer after attempting to buy new balljoint ends for the throttle linkage rods on my 124. My 123 has metal ends but the 124 has nylon/plastic ends, two or three of which have small cracks in them. To be clear, these are the rod links that connect the IP and cruise actuator to the throttle bellcrank. The problem is that MB only sells the entire rod with both ends which is expensive. You can't buy just the ends. Has anyone ever had one of these break? I'm wondering if I'm being too anal thinking about replacing these when I only have a couple of hairline cracks. I'd hate to have one break when I'm out in the boonies somewhere but then I don't think I've ever heard of one of these letting go. Anyone had this problem?

The Warden · #2 07-25-2002, 01:25 AM

lrg, that's what duct tape is for!!

Sorry; couldn't help it...to be honest, I can't give you an answer. Maybe try a junkyard? Just a thought...good luck!

lrg · #3 07-25-2002, 01:41 AM

I thought about trying to JB Weld them but it looks like the kind of nylon resin that doesn't let much stick to it.

MVK · #4 07-25-2002, 08:35 AM

Well They have something like this listed for your car at Fastlane
But I am not sure if they are metal or Nylon
C7025-26867 Throttle Linkage Socket $2.03

Check under, Fuel Injection then under Throttle Linkage socket.

MVK

Ken300D · #5 07-25-2002, 10:42 AM

I did the same thing to my brother's car when I tried to pop off the joints to grease them. Not realizing they were plastic, I cracked one.

It's a shame if you can't just get a bunch of the threaded sockets.

If anyone orders these from FastLane please post a description of what you get.

Ken300D

lrg · #6 07-25-2002, 01:53 PM

I just ordered a couple of the ends from Fastlane. I'll give them a try and let you know how they work.

leathermang · #7 07-25-2002, 02:18 PM

Well, they probably buy these from someone... I think there was a company called " Smallparts" at one time.. think " other sources"

Hum, It did not come up on my search , but did just typing it in...

http://smallparts.com/

I have the paper copy and will look in it...

#8 07-26-2002, 12:07 PM

I've broke one of the metal ones on my 62 trying to pry it apart lol
I think your best bet would be to go to a junkyard and collect a couple.
The rods wouldnt hurt either after all you never can tell when you might need it, but all in all they are very strong parts and should really never go bad or break

j

lrg · #9 07-26-2002, 04:14 PM

Well I just got my new balljoint ends from Fastlane (nice, quick delivery by the way) and guess what? They're metal. It's hard to tell but I'm guessing the won't fit since they look a bit different. I hope to have some time to try them this weekend. It doesn't seem like that big a job but actually they're a bit tough to get at behind the intake manifold and I'm not anxious to break the old ones in case the new ones don't fit. I'll report back when I've given it a try. Thanks everyone for your help.

lrg · #10 07-27-2002, 01:04 PM

I couldn't resist and tinkered with my new throttle rod ends last night. Here's the story. On my '87 300D turbo there are three rods:

1. Throttle cable bell crank to lower bell crank (lower has bowdin cable and throttle linkage attached)
2. lower bell crank to rear IP fuel delivery lever
3. cruise actuator to rear IP fuel delivery lever

Rods #1 and #2 are the most critical and it appears the balljoint ends can not be removed on either. Rod #2 is a square two piece rod with what appears to be bonded on ends. There is a screw and nut in the middle of the rod that can be loosened to enable the rod length to be adjusted. Clearly replacing this is an all or nothing proposition. Rod #1 is the easiest to get to and in my case the one with the worst cracks. This rod is round and looks to be threaded at the ends but no amount of turning would remove the balljoints. I was afraid to pull too hard but I'm guessing that these ends too are not designed to be replaced. For now I wrapped the ends tightly with steel wire and JB Welded over it so the cracks are completely covered. We'll see how long that lasts but I'm optimistic it will be a while. I think this is the rod you want to keep an eye on if you're checking your linkage.
Rod #3 isn't quite so critical since it works off the cruise actuator. My new ends did work on this (it figures). The old plastic ones unscrewed and I replaced them both with new (right hand threaded) metal ends. I measured the old rod and adjusted the new ends to be identical and it clicked right on. Oh yeah, I also added an 8mm nut at each end to act as lock nuts. So except for rod #3 I guess you do have to replace the whole thing. For what it's worth, the plastic ends have both a Mercedes and Bosch logo on them so I think they were made up specially for these cars. I hope this is helpful to somebody. Thanks everyone for your input.

MVK · #11 07-27-2002, 05:51 PM

Thanks LRG for you feed back.

MVK

#12 07-27-2002, 07:24 PM

Be careful here, I remember a time when after a engine re-build on my 78 240D, one of the linkages came off and stuck the throttle in a wide open position. ( Happened right in front of the Ford Plant also...)I remember pushing in the clutch and the engine then red-lined, scary in itself on any engine, it reminded me of an old diesel rabbit I had that after tons of miles, it red-lined on combustion blow by one night, another scary time.

I would suggest strongly that you be very careful in cutting corners here, in my case, if I remember, is there not a small clip that keeps the ball on the socket? I think this joint can wear out after awhile if memory serves me right.

I think I also remember some old timer telling me of using grease to keep the friction down when assembling, but oldtimers may be fading my memory somewhat....

lrg · #13 07-28-2002, 02:08 AM

Chris,
I don't disagree with note of caution. I used a dab of lith grease in each ball joint but note that the plastic joints don't have a nice metal ring to lock it in but rather just a plastic ridge. I guess the ball joint can deform enough to snap in place...which mine did. The cracks I had were lengthwise...that is to say at the end that attached to the rod and parallel to the rod. Also, the rods mostly push so there is not a great deal of stress on the ends. I'll be keeping an eye on these to make sure they are OK. Thanks for the warning though.

dabenz · #14 07-28-2002, 11:22 AM

For what my opinion's worth, I'd try to figure out a way to use the metal ball ends, even if it means buying the whole rod.

I've known daBenz since it was new, and owned it outright since 1992. I imagine grease on the ball joints is the MB answer, but then you'd have to take them apart. Lubricating this stuff is part of my engine oil change routine. All the ball joints and the moving parts that they get connected to get wiped off and a few drops of engine oil get put on. I've never taken them apart, and the only failure on an associated system has been the nut where the idle speed cable ends (not due to the rods, but engine vibration on the bracket that hangs out in space).