3pt lift cylinder scored- repairable?

[Pete O]

I have my Ford 4100 in a thousand pieces at present, split it 2 ways for both the clutch and the hydraulics. Having almost completely dismantled the hydraulics in the rear axle casing, I've found that the lift cylinder and piston are both badly scored. Too far gone to just hone the cylinder. A replacement cylinder and piston is very expensive to obtain here in Aus. I'm contemplating boring the cylinder oversize but that will leave me with an undersize piston. Does anyone have any knowledge of an economical repair option for this problem?

 

[Alan W.]

If there is just a few deep scores you can braze the scores, grind them down close with a die grinder then hone the cylinder. We use to do this on large expensive cylinders for the coal mines. A bit of a pain to do but it works well if done correctly. Not sure of the type of piston you have. We would just change out the rings or poly packs on the piston after deburring. Never had any callbacks on any we did.

 

[jaxs]

There's simply too much pressure for a slooply fit. If you find someone that will spray weld and turn the piston on the cheap you might come out. Most likely time to replace the cylinder.

 

[Pete O]

I went into a local machine shop that does a lot of tractor work, he suggested boring the cylinder to the next standard hydraulic cylinder size (which would be 85mm) and then putting a sleeve on the piston and cutting the groove to take a standard 85mm hydraulic ram seal. This sounds like a reasonable option. Brazing the scores and honing to keep it at the standard size also sounds like a reasonable option. A new cylinder would cost me around a thousand bucks. That doesn't sound like a reasonable option!

 

[Alan W.]

Thats sounds like a very viable option. Will even increase your lift force by a bit. I am curious how the sleeve will be sealed to the piston. May be more practical to turn a new piston.

 

[Pete O]

Turning a new piston would be more of a challenge than it sounds due to the way the rod seats in the piston; there is a concave, semi-spherical socket in the piston that receives the head of the pushrod which is rounded. The rest of the piston is a simple affair but replicating the rod seat isn't; I'll be doing the machining in my home shop which is very well equipped but I'm not sure I have means to cut the concave seat. The plan is to turn the piston down to accept a sleeve around 6mm thick, shrink-fit the sleeve to the piston along with some loctite bearing retaining compound, and then add some grub screws to secure the sleeve against being pushed along the cylinder by hydraulic pressure.
I'm about to leave the project for a couple of days hunting, will see if we can come up with any other suggestions while I'm away. Even just thinking about it now, I might be able to find a ball-nose endmill with the correct radius for that seat...

 

[Dave M7040]

Turning a new piston would be more of a challenge than it sounds due to the way the rod seats in the piston; there is a concave, semi-spherical socket in the piston that receives the head of the pushrod which is rounded. The rest of the piston is a simple affair but replicating the rod seat isn't; I'll be doing the machining in my home shop which is very well equipped but I'm not sure I have means to cut the concave seat. The plan is to turn the piston down to accept a sleeve around 6mm thick, shrink-fit the sleeve to the piston along with some loctite bearing retaining compound, and then add some grub screws to secure the sleeve against being pushed along the cylinder by hydraulic pressure.
I'm about to leave the project for a couple of days hunting, will see if we can come up with any other suggestions while I'm away. Even just thinking about it now, I might be able to find a ball-nose endmill with the correct radius for that seat...

Could you make the new piston as a solid piece with a recess to accept the old piston inside. Like a pocket. Connecting the old to the new is not an issue as the serious force it would see would be to push the old and the new pistons together. A new piston with its own seals would not have the tendency to slide as would your sleeve idea.

Wish I had machine shop equipment and better yet the knowledge of how to use it.

Any idea why the scoring happened? A filter with a broken element perhaps. The amount of movement and frequency of movement seem very small compared to an engine piston which is going up and down thousands of times per minute.

Dave M7040

 

[Pete O]

I bored the cylinder to a shade under 85mm, left .008' on the I.D. for honing. I spoke to a local engine rebuilder who has the gear to hone it to a fine finish so I'll take it to him next week.
As for the piston, I think that cutting the seat part of the existing piston out and inserting it into a new piston is probably going to be the best option.


The brake & clutch pedal pivot shaft was badly worn where the clutch pedal pivots on it; I ground it down to fresh metal and slathered it with some metallised epoxy; I've set it up in the lathe and left it curing overnight.

 

[CincyFlyer]

That epoxy-coated pivot shaft will wear rather quickly; I'd weld that up, or make a new shaft.

 

[bigdeano]

I built a piston up with brazing rod and machined it to finished size. It was for a 6" cylinder on a hyd press I made. It was a steel piston, don't know what yours is made of.