L35/BT900 Boom Cylinder and Bushing Work

[Nicksacco]

Hello All-

Having bad bushings on the backhoe boom makes the backhoe more difficult to control.
Additionally, a leaking cylinder makes a mess!

Here is a pictorial with some explanations if anyone is considering this work.
I found the job rather easy compared to some of the nightmares I encountered while restoring this old babe.
Here's how I did it:

First I ordered the following parts from Messicks:

Then I separated the Boom from the Tractor using a lift (you can also use a jack). The boom could easily roll as required for reassembly.

I removed the old bushings (top) and the Collar (bottom - goes between the bushings) gouging carefully with a plasma torch - then whacked them out.

I cleaned up the hole and pressed in the new Bushings and Collar using a 1" All-Thread and 2 wrenches.

After rebuilding the Boom Cylinder, I installed it back into the Boom. The cylinder is installed "upside down" in the boom - meaning that the hose attachment points are facing the ground in the boom.

Note that the piston is in two pieces with an Oring surrounded by the seal at the middle.
The first section of the piston has an interference fit to the rod (the hole is slightly tapered) so it required a press to remove and replace.
I also replaced the bushing at the gland end of the cylinder using a press.

And Yes, there is a small Oring that fits between the front and rear sections of the piston in the indentation (not shown).

Joining the Tractor and Boom is easier with some help to assist in alignment and positioning of the large pin.
HINT: Mark the ends of the pin somehow so you know where the holes are that allow a bolt to pass though.

Hopefully if anyone out there is lamenting over this Boom bush replacement, my adventure will ease your mind!

 

[L35]

That is interesting. I don’t recall my piston being 2 pieces. IIRC there was a note in the parts catalog for a split in the serial numbers. I imagine I have one of the lower serial numbers and you have the upper, and there were model year changes with the machines.

Yours is much easier, getting that fibrous square cut oring over the piston to seat in the groove was stressful, always a fear of tearing it. I heat them up in warm oil and it makes them a little easier to work over then into the groove.

 

[PoTreeBoy]

That is interesting. I don’t recall my piston being 2 pieces. IIRC there was a note in the parts catalog for a split in the serial numbers. I imagine I have one of the lower serial numbers and you have the upper, and there were model year changes with the machines.

Yours is much easier, getting that fibrous square cut oring over the piston to seat in the groove was stressful, always a fear of tearing it. I heat them up in warm oil and it makes them a little easier to work over then into the groove.

He had me wondering. I know I had my cylinder out to replace the hoses, and I thought by then I knew to repack the cylinder while I was there. But I knew I hadn't done a 2-piece piston. According to the parts diagrams, there are two types, must be a serial number break. I think I have a later build tractor.

 

[Nicksacco]

Good Points, guys.
I should've mentioned that there are 2 boom cylinders based upon S/N.
That's S/N of the Backhoe - not the cylinders themselves.
There are 2 cylinder types for Swing, Dipper, Stabilizer, and Bucket as well.

Here are the Boom cylinders:

 

[Runs With Scissors]

Nice write up.

Thanks for posting.