increasing lift capacity on jd 855

[dfkrug]

That's also a good point , but the 7, 8, and 955 all share the same 70 loader. The pump upgrade should be OK though ??

I thought the 70A loader only came with the 855 and 955, and the 755
used the 60 FEL.

Regardless, DSM points out the pump had a lower flow rate and the
tractor's system relief is set lower than the 955. The higher flow rate
is a benefit even if you stick with the 2050 psi RV setting. No reason
you can't change the RV (under the seat), too.

Since the pump is shaft-driven on the back of the tractor, perhaps one
should consider buying an aftermarket higher displacement pump (about $200)
and adapting it?

 

[JD755]

The 60 loader is used on the 655. The 755 uses the 70 loader and the 855/955 use the 70A. However, to muddy the mix, early 70A loaders for the 855 were called 70, not 70A. The only difference between 70 and 70A loaders is a dimension on the masts to allow for the different wheelbase between 755 and 855/955. The cylinders are identical between the two. Prior to the introduction of the 70 series loaders, these tractors used the 52 series loaders. They did not have an automatic parking stand and were much more cumbersome to install and remove.

 

[dsmau]

Well I had all winter to think about my options and get a little educated about tractor hydraulics and finally made a couple moves.
First, I found a place where I can get a brand new Japan made replacement pump either 7cc/rev as the actual one or 8.8cc/rev if I want to go up to the 955 like GPM for about 150 dollars. It would be a direct bolt on so no other expenses than the pump and lost oil unless something unforeseen happens

Knowing that, I shimmed the relief valve to increase the pressure to 2250-2300 PSI. It was very easy to do. I have not tried it yet as I am still doing other maintenance on the tractor and can't move around. The relief valve is on the flow divider and the part number for the 5 shim pack is AM875169. It costs about 3.00 and all it is 5 pieces of round stainless steel of different thickness. I originally had 2 parts in mine at 2050PSI. I added 2 thick ones from the pack and ended up close to 2300PSI. I did not want to go all the way up to 2500PSI like the 955 because I did not know if my pump could easily do it and my tractor is 20 years old so I do not want to abuse it. The relief is very ease to access under the seat and you do not loose any oil trough that hole making it easy to try different combinations until you like the result. Now I can't wait to try it.

Again, during my long Quebec winter, while reading the 70A operators manual I noticed the statement about it being shipped with a .09 inch needle restrictor on the yellow line which is one of the bucket hoses. I looked up on my tractor and I had a .07 restrictor on that line!! I took it out completely and now of course it moves much faster. I will probably drill it a bit and put it back in but I am wondering why it was smaller than in the manual. I guess people can actually tweak those to personal preference. What else does it impact on the tractor? I just know that it was too slow to do anything with the snow last winter. I ended up using the box blade 95% of the time. It is OK when used with dirt in the summer but with snow, things have to move faster.

I will now test my new setup and if something happens to my pump, I know where to get a new one and I will probably get the 8.8cc/rev model while I am at it.

BTW, the only part different between the 855 and 955 in the SCV/Flow divider is the internal proportional flow divider valve. Since it is dividing flow between Power Steering and SCV, it must be keeping the same flow to the Power Steering on the 955 and allow the remaining to go to the SCV. If I do end up changing my pump, I will probably loose a portion of the increase flow to the power steering but I will live with it. The valve is almost 200 dollars at JD

Sorry for the long post.

 

[kimodc]

Thats some great research! Thanks for sharing it with us too. Where do you find the "needle restrictor" you talk about on your loader? Also, do you mind telling us where to get a pump for $150? That price sounds great.

Thanks
Kim

 

[dsmau]

Thats some great research! Thanks for sharing it with us too. Where do you find the "needle restrictor" you talk about on your loader? Also, do you mind telling us where to get a pump for $150? That price sounds great.

Thanks
Kim

No problem sharing. I am not an expert myself so I like to bounce my ideas around. The restrictors are at the junction between the flexible hoses and the metal lines on the loader. After trying it this weekend, I notice that it does dump much faster but did not see a noticeable improvement on the rollback movement. It will be great for snow in the winter but not when working with dirt unless you want to dump the whole load at once.

The biggest improvement is of course the increase in pressure. I am extremely happy now at 2300PSI. It was just what I needed to be able to lift my full 54inch bucket.