Retrofitting new hydraulics

Might not be too expensive to use say 4x8 cylinders or whatever to match the bore of the old ones vs more common and probably cheaper 3x8's. If it saves changing the pump you would probably come out ahead.

[quote="Deas Plant."]Hi, Dave-o.
If it is as original, that will be a low pressure/high volume system, which likely means that you have a low pressure/high volume pump fitted as well. This would not be the best type of pump to work with new high pressure/low volume rams as it would be hard put to deliver enough pressure to operate the newer high pressure rams with their smaller bore sizes which need the higher pressures to achieve the same power as the older rams.

It would definitely be possible to fit a later style higher pressure/lower volume pump to match newer rams if needed, just an extra cost.

Just my 0.02.[/quote]

I thought that might be the case. I really need to measure the pump pressure before making a call. Luckily, the range of cylinders available is extensive.

Dont know what the pump costs, but a 4" bore x 12" stroke is about $557 vs $445 per side for a 3.5" bore. Not exactly cheap, but substantially cheaper than having the old ones rebuilt.

Hi, Dave-o.
If you can get the same bore and stroke in new cylinders, I think that would be the way to go. By all means, check the output pressure and flow of the pump to see if it really is up to the job. If it comes pretty close to original specs, I can't see any reason why newer cylinders with the original bore and stroke wouldn't work to give you about the same performance that the original set-up gave.

But what would I know? I'm just a 'pore, dumb bulldozer operator'.

Just my 0.02.

As Deas said I would stick with changing the cylinders like for like.

If you go smaller and try to increase the pressure you have to consider other factors such as;
Valving - a lot of the older valving will not handle modern hydraulic pressures.
Hoses - hoses have most likely been replaced so they may not be underrated but they would still need to be checked.
Pipe and Fittings - some fittings used on the older machines are not up to the modern pressures. For example the La Plante Choate blade on my D6 uses barrel unions which handle the measly 850psi of the system but would not handle modern hydraulic pressures.

What is wrong with the cylinders? For an old D4 like that I would simply put a new set of seals in it and hone out the bore. If the chrome is worn/rusted off the rods then it is a simple job to replace the rods. It looks like the rod seals are v-pack seals or chevron seals that are simple to adjust. If the piston seals are steel rings then they can be replaced with new ones or replaced with v-pack seals. A little machining may be necessary.

I have just replaced the rods, rod seals and piston seals and honed the bores on the cylinders for my 944 and they are four times the size of the ones on a D4. Total cost $1500 for the five cylinders (including power steering cylinder).
I also replaced the seals and rods on my D6 5R about six months ago and the total cost was $800 but again they are much larger cylinders.

Regards

Phil

[quote="PhilC"]As Deas said I would stick with changing the cylinders like for like.

If you go smaller and try to increase the pressure you have to consider other factors such as;
Valving - a lot of the older valving will not handle modern hydraulic pressures.
Hoses - hoses have most likely been replaced so they may not be underrated but they would still need to be checked.
Pipe and Fittings - some fittings used on the older machines are not up to the modern pressures. For example the La Plante Choate blade on my D6 uses barrel unions which handle the measly 850psi of the system but would not handle modern hydraulic pressures.

What is wrong with the cylinders? For an old D4 like that I would simply put a new set of seals in it and hone out the bore. If the chrome is worn/rusted off the rods then it is a simple job to replace the rods. It looks like the rod seals are v-pack seals or chevron seals that are simple to adjust. If the piston seals are steel rings then they can be replaced with new ones or replaced with v-pack seals. A little machining may be necessary.

I have just replaced the rods, rod seals and piston seals and honed the bores on the cylinders for my 944 and they are four times the size of the ones on a D4. Total cost $1500 for the five cylinders (including power steering cylinder).
I also replaced the seals and rods on my D6 5R about six months ago and the total cost was $800 but again they are much larger cylinders.

Regards

Phil[/quote]


Thanks Phil

The fly in the ointment (so far) with replacing like for like is the clevis ends. The largest I can turn up so far is 1"1/2 and the current ones are 2". So there's that.
Pulled one apart tonight and the bore is certainly far from mint. A little rust damage and general wear and tear. Going to run an bore hone through it and see how it comes up.

If you dont mind, who did your work?

[quote="Dave-o"]
If you dont mind, who did your work?[/quote]

Me. I did it all😊

[quote="PhilC"]As Deas said I would stick with changing the cylinders like for like.

If you go smaller and try to increase the pressure you have to consider other factors such as;
Valving - a lot of the older valving will not handle modern hydraulic pressures.
Hoses - hoses have most likely been replaced so they may not be underrated but they would still need to be checked.
Pipe and Fittings - some fittings used on the older machines are not up to the modern pressures. For example the La Plante Choate blade on my D6 uses barrel unions which handle the measly 850psi of the system but would not handle modern hydraulic pressures.

What is wrong with the cylinders? For an old D4 like that I would simply put a new set of seals in it and hone out the bore. If the chrome is worn/rusted off the rods then it is a simple job to replace the rods. It looks like the rod seals are v-pack seals or chevron seals that are simple to adjust. If the piston seals are steel rings then they can be replaced with new ones or replaced with v-pack seals. A little machining may be necessary.

I have just replaced the rods, rod seals and piston seals and honed the bores on the cylinders for my 944 and they are four times the size of the ones on a D4. Total cost $1500 for the five cylinders (including power steering cylinder).
I also replaced the seals and rods on my D6 5R about six months ago and the total cost was $800 but again they are much larger cylinders.

Regards

Phil[/quote]


Thanks Phil

The fly in the ointment (so far) with replacing like for like is the clevis ends. The largest I can turn up so far is 1"1/2 and the current ones are 2". So there's that.
Pulled one apart tonight and the bore is certainly far from mint. A little rust damage and general wear and tear. Going to run an bore hone through it and see how it comes up.

If you dont mind, who did your work?

[quote="Dave-o"]Thanks Phil

The fly in the ointment (so far) with replacing like for like is the clevis ends. The largest I can turn up so far is 1"1/2 and the current ones are 2". So there's that.
Pulled one apart tonight and the bore is certainly far from mint. A little rust damage and general wear and tear. Going to run an bore hone through it and see how it comes up.
[/quote]

Just had a look at your pictures again. If the bore does not hone up reasonably well it should be fairly simple to fabricate new barrels.