Subframe mount replacement problem
 

83 300D...I have removed a subframe mount. I had to turn the center bolt to the point of destroying the rubber bushing. I removed the remainder of the rubber bushing. I had already removed the metal plate with the center bolt still attached to the remainder of the rubber bushing. Can not seem to remove the bolt from the destroyed bushing, the two are as one.

I am to the point of thinking the best thing to do is purchase a new bracket and bolt. The bolt seems to be frozen to the bushing, the treads were not damaged.

Can you buy the bolt and frame, have not found it at the product forum? Any other suggestions?

Thanks:confused:

I want to accomplish this subframe mount task soon myself. I have the replacement mount kit.

Need more details on what exactly is the problem. Is the big bolt rusted and seized up tight with the subframe mount metal bushing in the center of the rubber block? I think that is the way I interpret the issue.

So, you have the task of getting that loose. Well, I think you need a strong vice to hold the bushing, some penetrating oil, and a propane torch. Start soaking the bolt/bushing interface in penetrating oil - not the whole thing, just some where it needs it down the bolt. Repeat this application for a few days. Then light the torch and heat it up good - clamp it in the vice and try to turn the bolt out of the bushing.

While it may take a few days of application for the penetrating oil to really soak in, you can always try to shortcut this (if time is a factor) by applying the oil over the course of one day and trying the removal later. It all depends on how badly it has seized.

The alternative of course is new bolts and bracket from a dealer. I'm sure they have them or can get them.

Thank you for your post. When I replace my subframe mounts I'm going to coat the big bolt with anti-seize to prevent this from happening, based on what you found.

Ken300D

not to ask a stupid question

but what is a subframe mount. and could it failure result in water leakage into the car.

thanks

bob

Ken's assumptions are all correct.

I have ordered a different kit from a local MB shop that has the center bolt (my kit did not have that center bolt?). I have also ordered a new pair of brackets, one for the right and the other left. I could go through a process of drilling the head off the old bolt but for 15 bucks each what the heck...they are kind of rusty anyway.

This is one of those simple looking processes taking several days, the love we have for this kind of stuff!

Thanks for the feedback!

Bob,

At risk of showing my lack of true knowledge....

Subframe mounts are under car and are major connections between suspension system and body. By all counts, these things get hard or crack over long period of time and impact handling and ride. I read once that if badly worn, they will cause car to "drift" as would bad alignment. I have also read several times that to keep car functioning properly, they need to be re-newed whether you think so or not (on older cars).

I don't believe water in car has anything to do with them as they are bathed regularly where they are located.

I'm going to replace mine (or have them replaced) soon. Project 333B.

Nic
'85 300CD @ 144k miles

Lyle,

I don't know where you got your original replacement bushings, but I got mine for the 108 right here at PartsShop. The bushings came with all new mounting hardware, including center bolts, good thing too as mine had just about worn through 1/4 of the diameter from rubbing on the inner metal cone (see pics in the DIY section).

Misson completed on my subframe bushing project. I had a problem only on the first one I replaced. The second bushing went smoothly. The only difficult thing is getting that center bolt started into the treads. You need to really push that bolt up into the hole and then get the thing started. On the second bushing the bolt was in perfect condition and I was able to reuse it.

And you can tell the difference in the ride, a much firmer feel, not as loose I guess you could say.

By the way I got that pesky bolt off of the old bearing by drilling the head off. I did not buy the new brackets.

For next time. If you remove the center bolt FIRST (19mm.) then the four attachment bolts(13mm.), it will let the center bolt break free of the rubber mount while it's still stable from the attachment bolts. (Usually. Unless, of course, the center bolt has cold welded/corroded to become one with the axle). Once the center bolt is out then remove the attachment bolts and pry that rascal out.