M103 Trailer Shock

[Valence]

Good news!


I got my new shocks that I'm going to use (Monroe P/N 37114), so I ground down the end of the shaft a bit so a nut could make it past, and cleaned up the threads and it looks like there's still enough threads left! No need to cut a size smaller or replace the mount.

I should have tried this way sooner.

Here is the test fit and there's threads showing it's not even tight yet. Because of the (obviously) limited threads, I will use one of those mechanical (all metal) lock nuts.

 

[Valence]

A long with a number of other projects, I picked up the shock mounts from the powder coater, they look great and he did a good job not painting the threads or post! I hope to get to this project later in July/August.

 

[drivebymashing]

Looking forward to see if it helps with bounce. I know the m353 trailer is ridiculously bouncy. I have permanent brain/spine injuries.

 

[Valence]

I've shelved this, relatively straight forward project for too long. After inspecting my trailer, I see that shock mounting holes do not already exist in the frame.

Would someone who has a variant of the M103 frame with these shocks please measure how far the top mount is placed back from the vertical center line of the axle? I can guess from the picture, but I prefer not to.



Edit:
Hah! I guess never mind! I should have taken the upper plate in there when looking. The upper holes *DO* exist, it's the rear mount of M105 cargo bed.



The upper shock mount is threaded on the inside. (The top left hole in the plate in the below picture). It was designed to use the box to frame mounts.


Note: The above two pictures of the upper shock mount are backwards, meaning, what I have pictured here is the left-side upper mount on the right-side of the trailer. Don't make the same mistake I did!

 

[Valence]

I reviewed the original pictures more closely and realized that I messed up. I had placed the left side upper mount on the right side. Of course this means I now have two extra holes on the right side frame. Maybe those will get welded up whenever the trailer gets restored (if ever).

Anyway, when properly installed, it's a nice fit! The shock is pretty close to the axle and well aligned with the upper mount. This is actually pretty easy, straight forward install. As with many things, I've managed to complicate it some though.



As a reminder, the shocks I'm using are Monroe P/N 37114. I opted for a slightly different length than juanprado suggested because I had gotten them at killer clearance prices on eBay.

To align the lower mount to squarely match the upper mount, I used a straight edge to mark on the axle where the interior edge of the frame was, and then measured from there and marked the same distance the upper shock mount protruded from the frame. In short, the inside of the lower shock mount was exactly 15" from the inside of the drum, and the top plate was level with the leaf spring perch, almost touching it, but not quite.



I may have to get new brake lines as some joker in the past tightened the nut on the tee with the flexible brake line and didn't hold it, resulting in twisting and bending of the hard lines. A mark on the axle makes it look like it leaked at one point. I don't know if there is even any fluid in the trailer's master cylinder, something else I'll have to investigate.

 

[tobyS]

I may mount an S-788 shelter on the 105 axle. I'll be removing 4 or 5 of the springs to bring it lower, leaving the overloads in place. That would be a good time to add shocks. Thanks for all the shock info.

 

[Valence]

I may mount an S-788 shelter on the 105 axle. I'll be removing 4 or 5 of the springs to bring it lower, leaving the overloads in place. That would be a good time to add shocks. Thanks for all the shock info.

I'm glad you found some of this thread helpful!


The installation is complete. I actually had to take a sledge hammer to the inside of the left frame rail as the edge was bent down slightly, making it very difficult to get the upper shock mount in place. There is a notch at the bottom of the upper mount for the wire harness, but I still covered the harness with a piece of hose to help prevent any wear through. Also, the all-metal lock nut on the lower left mount worked out very well, even had 2 threads to spare.

I'll have to go measure the clearance to the bottom of the lower mount.



(Yes, the anti-seize kind of got everywhere, but I suppose that's its purpose)