W126 guide rod bushing... need advice.
 

I need new guide rod bushings.

I took my SD to a local indie who has done a bit of work on these old diesels.

The "retaining tab" or whatever you call it on the DS is broken off (see open rectangular hole in pic 1, and see pic 2 for example of the other side with retaining tab still in place). He says he is going to have to cut into the frame around that rectangular hole to be able to get a wrench in there in order to get the bolt out and the bracket off, and then weld the piece back in. Does that make sense? Is there any other way around this?

Thanks

whiew! that sure is a lot of rust... I would not want to drive a car that had the frame cut up. are there any better examples of 126 vehicles in your area? My parts car has less rust in that area.

From what he described, he would be cutting into the flat part around the rectangular hole, so to me, if he put it back in place, it doesn't seem it would cause any structural problems.

As for other examples... I just can't do it. This is my car and I have to live with it for now. I can't bother with buying and selling cars all the time right now.

Rod Bushing
 

I think i would order a new bolt and nut and use a air saw that has a small
metal cutting blade and cut the pieces out harber freight sell these saw's and blades
http://www.harborfreight.com/cpi/photos/00100-00199/00113.gif

I think i would order a new bolt and nut and use a air saw that has a small
metal cutting blade and cut the pieces out harber freight sell these saw's and blades


Las 769 are you talking about using the cut off saw on the bushing/bolt assembly and not cutting into the frame? I cut these bushing easily with a sawz all equipped with a metal blade. I agree I wouldn't cut into frame. Cutting bushing would then allow for easy extraction of bolt and tab.

cutting
 

yes cut the bolt not the frame

I don't quite understand...

so are you saying you would cut away the rubber part (bushing?), which the bolt is going through so that the bolt would be "available" and easy to cut through?

One question about that, however, is how would that make it any easier to get at the broken off tab inside of the frame? Wouldn't the bolt still be threaded into that tab inside? I guess I don't know exactly what the bolt is threaded through, other than the tab inside.

I have an appointment to bring this in next week to have the job done, so I'd like to talk to the mechanic some more about this before then, in case we need to order more parts.

Thanks

Don't Cut The Bolt!!!!!
 

I had the "wings" break off on one of my guide rod mounts so I opened the opening enough to get an open end wrench in there to hold the square nut. If you cut the bolt you will not be able to remove the end from the frame. Use some PB type stuff to loosen the rust on the bolt and nut, then loosen with the wrenches. Really man think before you cut!!

Yes, I think those "wings" are the same thing I am referring to as "tabs" right? That is the problem with mine (that they broke off), and I think what you are saying you did is exactly what the mechanic is suggesting doing, if I understand correctly.

Are you saying that it is necessary to do this in order to get at it?

I am wondering, to the people who suggested cutting the bolt, have you done this, or is it just a guess at something that might work?

I would tend to agree with crashone. The guide rod mount kit comes with a new "tabbed" nut.http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=23K00S4YN23W06EQVC&year=1983&make=MB&model=300-SD-002&category=L&part=Guide+Rod+Mount+Kit If you can get a wrench in there or maybe some of those needle nose vise-grips. One thing for sure, use lots of frequent doses of PB Blaster. Once you get it apart, is sure would be a good time to do some extensive cleaning and rust treatment as this is an area that takes a lot of stress.

If you DIY, use a come-along to hold the bearing carrier in place and allow you to align things to re-bolt the assembly.

Yes you have to cut a little on each side of the opening to get a wrench in there. Take a look at it with a trouble light so you can see. You don't need to cut much, a little at a time. Keep soaking with PB and use a big breaker bar to loosen the bolt and nut. Good luck.

Put some PB on there asap and let it soak in. Cut away the captive nut's opening just enough to get a wrench on it. Hope it breaks loose.

When its all done, degrease the area and treat it with Rust Cure. All of the oil film must be gone for this stuff to work. Topcoat with paint, POR.

Might be a good time to look for rust at other areas of the chassis.

Beware! Uro ain't the only one...
 

I just had a new Lemforder captive nut "let loose" in the frame upon installation.

2.5 hours later I had it out and reused the original 30 yr old part. I was fortunate that I was able to get it loose by wedging a screwdriver against the flat.

I'm pretty frustrated with CRAP parts these days. Yesterday I had to machine 100 thousands of an inch off of a Karlyn upper control arm inner bushing as it wouldn't even fit in the chassis.

Wow! Pics of the carnage?

Dealer parts for me from now on. This is crap.

Oil cooler hoses made all wrong, upper control arms not fitting in the chassis... Crap parts from Pelican and everyone else.
We spend a lot on parts per month. Not buying parts from these folks again.
My Porsche guys are dealing with the same. Crap parts.

Interesting. I just bought a refurb Bendix brake caliper for my 1981 300SD from Pep Boys. Had to file out one of the two holes for the bolts which hold it to the vehicle. My old bolt would not even go through the doggone hole.

These cars are getting old. Perhaps it's "pattern creep". Like when you cut a bunch of pieces of wood and use the previous cut piece to make your mark.

The problem I have is not knowing where they are made prior to purchase. When I open the box and it smells like a Harbor Freight store I get that sinking feeling the part came from China.
But, it's hit or miss. I purchased one URO brand bushing and it actually said "Made in Germany" on it.

This just happened to me. One side was done and I was looking forward to a faster install for the other. I took the front end apart last fall and got held up by the cold and forgot exactly how it goes back together. I've got all new parts except for tie rod which aren't very old.

So far the screwdriver just lets the nut turn. Of course this happened at the worst place - where the captured nut goes into from the inside and is more difficult to reach.

It looks like a sizable chunk of the wrench would need to come off and I'm hoping to get it apart without going that route. Any other words of wisdom besides staying relaxed until it's figured out?

Hell, that happened to me also when doing the front end on the 560 a while back.

Behr fan clutches are like that now... total garbage. Either stuck locked up or do not lock at all.

Quality parts
 

I also just had this happen during my suspension rebuild. The solution? Air hammer.

I tried a few of the above items, no wrench would fit in there, I tired prying against the square nut, but nothing would budge the initial friction. I ended up grinding a custom bit for the air hammer and had the nut out in less than 30 minutes after hours of trying alternatives.

Take a look at the attached picture with the bit against the nut, you will see that after you get a divot in place, you can use this to hold your bit while you slowly work it off.

:)

Unfortunately, I am working on the least accessible hole - the inside passenger's side. I think a cheap open end wrench with the head trimmed to fit into the stock hole will work without having to modify the body.

Edit: what worked I was working the forward of the 2 guide rod mounting bolts where the larger access hole is toward the center of the car and doesn't have much room. No wrench could be ground down to fit and neither a screw or pliers would get enough of a bite.

I was able to drill a hole in the side of the nut and tap a small drift into the hole. The drift kept the nut from turning and it was easy to unscrew the bolt.

Words of caution: Do not use a drill bit that is too big. There is not much meat on the nut. I started small and went up to ~3/16 I think.

Be careful not to drill into the bolt threads. The threads are 12mm x 1.75 in case you need that info but check with a thread gauge. Interestingly, the bolt is only 11mm while the threads are 12mm.

I reused the old captured nut and added locktite. Hopefully this refurb will out last the car and I won't need to do the job again. Actually, I'd prefer to out last the bushings and be in good enough shape to do the job in another 32 years.

I wasn't fighting rust. A new Lemforder captured nut failed during install. Rust may make the process more difficult.

How about trying a long hex head (about 4 mm or so) wrench slipped in the hole to wedge between the (no longer) captive nut and the channel?

That should "captivate" the nut again, at least temporarily, so you can remove the bolt without the nut spinning.

I don’t think this would work. I tried a spade drill bit that I had which wasn’t in great shape but was still sharp. It didn’t bite. I then tried to use the shaft to jam up in there without success.

I think I’m going to try the drill approach. Try to drill a small hole in the flat, to relieve some stress, and then jam a small punch in there. Otherwise keep drilling it until the nut splits.

Even if the bolt is destroyed, they do sell new ones. And they’ll get lots of antiseize.


Ugh, what a time waster.

Anyone else find some good tricks?

Do you have a stick (arc) welder? If so you may be able to feed that into the hole and apply a tack or two on the nut to secure it to the retainer. The concentrated heat on the nut alone may be helpful as well.

Good luck

Unfortunately not. The hole that is accessible is tiny anyway. It’s maybe 1/4” by 3/4”. I think I’m better off trying to drill it.

There is a video on ************** where he deals with this issue. Might be of use

Kent bragsma

Yeah, I’ve seen Kent’s info.

Splitting the nut is the path I need to take. I drilled into the one side and tried to get it off with a punch. No dice. Would prefer to not destroy the bolt, may need to.

IIRC the guide rod mount service kit comes with a new bolt - I have a couple extras I think if you come up totally short.

So are your mount areas rusty too? Mine were, I got them welded up last year.

http://compu85.net/stuff/mbz/SDL/GuideRodMount.jpg

-J

I had to destroy the nut. Air hammer worked after drilling didn’t.

https://i.imgur.com/4b1oky5l.jpg

Unfortunately the threads aren’t great. So I am in a bit of a pinch. I’m not sure that running a nut or a die over it will help…

https://i.imgur.com/s9ZN55Yl.jpg

https://i.imgur.com/wugaRT4l.jpg

The whole area isn’t rusty. The old ones came out clean. I think the bolts had a bit of crud on the tops and I used a low powered impact to start it… but that broke the captive nut.

So dont use impacts.