Replace loader lift/tilt cylinders with larger ones ?

[Arky217]

I have a Kubota L4200 with the Kubota 680 loader.
The lift and tilt cylinders are leaking.
They all are 24" long with a 2" bore.
The best price that I've found for rebuilding the cylinders
is $100 each.

I was looking at the Northern Tools catalog and noticed that
I can get new 2" bore x 24" length cylinders for $160 each.

Also, I noticed that they have 2.5" bore x 24" cylinders for the same price.

I don't know if the cylinder ends and fittings are the same,
but if they are, do you think that the 2.5" cylinders
would over stress the loader too much ?

 

[BravoXray]

Well, going from a 2" to a 2.5" cylinder increases the piston area from 3.14sq in to 7.06sq in, so assuming a 2,000 psi system, that would increase the extension force from 6,283# to 14, 137", over double the amount the original cylinder would exert.
If both had the same size rod, say 1", the retraction forces would go from 4,712# to 12,566#, over 2 1/2 times as much.

I would bet that kind of increase would bend or break something pretty quickly.

 

[RickB]

Cycle times will be much slower.

 

[jthibodeau89]

Well, going from a 2" to a 2.5" cylinder increases the piston area from 3.14sq in to 7.06sq in

I get 4.9sq in for a 2.5 diameter piston. So 9800lb lift. And the rod will likely be 1.5 diameter, or perhaps 1.375 diameter. So about 6300lbs down force.

The rods on my JD430 loader are damaged, and i am considering a similar swap. When selecting a suitable cylinder, you also need to consider the end pin type, diameter, and width, stroke, and also the port orientation and type. You may need new hoses to suit the port locations and hose end clocking.

Seal kits are inexpensive and generally a simple DIY repair if the rods are in good condition.

Rod replacement is also an option if the cylinder bore is in hood shape.

Finding a cylinder that meets all the requirements can be a challenge. Be aware that an off the shelf generic cylinder may require some modifications to get it to fit your application. In my case the cyl base end will require additional width, the rod end will need to be narrowed, and the hoses replaced due to phasing of the hose ends would be 90° instead of the current 0°.

 

[the old grind]

To compare extension force of a cylinder we don't deduct rod diameter from the calculation.

I've never seen a FEL that didn't raise by extending a cylinder, or one that couldn't raise high enough to tip a tractor over with an OEM FEL.

How much more counterweight would be needed if doubling lift capacity? What's the load capacity of the front tires?

 

[ptsg]

How much more counterweight would be needed if doubling lift capacity? What's the load capacity of the front tires?

And the most important: what's the load capacity of the front axle? This is something overlooked a lot mostly because I don't think that manufacturers put this info on US market tractors.

Tractors on the European market have this info displayed on the serial number tag. Will list Max permissible load on front and rear axles.

 

[Henro]

I paid the same $100 to have my loader curl cylinders rebuilt due to leaking seals after 18 years.

My advice would be to just rebuild your existing cylinders. Simple, exact and easy.

Retrofitting with something that will likely cause damage and future grief is not the way I would go. Now if you had a damaged cylinder that could not be repaired, buying aftermarket might be a reasonable approach, especially after you price OEM cylinders (mine were like $650 plus each)

But it sounds like your cylinders just need new seals like mine did. Happy camper here...

 

[Zebrafive]

I paid the same $100 to have my loader curl cylinders rebuilt due to leaking seals after 18 years.

My advice would be to just rebuild your existing cylinders. Simple, exact and easy.

Retrofitting with something that will likely cause damage and future grief is not the way I would go. Now if you had a damaged cylinder that could not be repaired, buying aftermarket might be a reasonable approach, especially after you price OEM cylinders (mine were like $650 plus each)

But it sounds like your cylinders just need new seals like mine did. Happy camper here...

^^^^^This^^^^^ :thumbsup:

 

[Kernopelli]

I agree with simply rebuilding the existing cylinders. Also, I have often used Baum Hydraulics' calculators, they take any guess work out of the equation and are super fast and easy to use. https://www.baumhydraulics.com/Home/Page/speccalculators#

 

[Richard]

I have a Kubota L4200 with the Kubota 680 loader.
The lift and tilt cylinders are leaking.
They all are 24" long with a 2" bore.
The best price that I've found for rebuilding the cylinders
is $100 each.

Obviously I don't know you and your background. Having walked this walk....(and being willing to blindly jump into a mechanical project with NO clue what's going on)

I decided to try to rebuild my dipper cylinder on my JCB backhoe. I don't know the diameter but I'm guessing 2 1/2" and it was 107.478% about all I could man handle to carry the darn thing!

These aren't rocket science. Take it off, figure out how to take it apart... you have little to lose if you're willing to buy a new one. I'd take one apart and give it a whirl....the seals have to be available somewhere (if I can find them on ebay for my 1987 machine, they'd have to be available for something more main stream??)

I've since redone my stabilizer cylinders.

I might add... years ago, when I first did my dipper cylinder, I took it to a dealer. They charged me $1,000 to do it and I about passed out on the spot. I STILL (stupidly) paid to have my loader (raising) cylinders redone AND the trunnion (swing) cylinders for the backhoe. When the Dipper cylinder needed it again (after maybe 15 years) my spine stiffened and told myself there was NO way I was going to pay that again unless I had to..... so I dug into it and I think it cost me (forget) maybe $100 in parts.

Heck, when I did my stabilizers, the pins were freezing them on the machine so I was unable to remove the cylinder..... so I did them in place.