Tires Project 1070 R4 conversion success! Pics included! :)

[Radius118]

So I managed to get it all figured out and I figured I would document my findings here for anyone else who wants to put R4 tires and wheels on their 1070.

The 1070 had 2 choices for tires. Turf and R1. R4 tires were never an option from JD for this machine. Mine came with R1. It turns out the 990 is basically the same mechanically as the 1070, and the 4005 is for all intents and purposes almost exactly the same as the 990 but with a different model designation. I also found out the 970, 1070, 990 and 4005 all use the same front axle assembly. It's possible the 870 may also use the same assembly but I was not able to verify that.

Further investigation revealed that the rear of the machine uses a standard 8 on 8 bolt pattern and 6" center bore. One gotcha concerns the front axle. The wheels for these axles use a metric bolt pattern - 150mm (5.906") bolt pattern with a 90mm (3.564") center bore. Additionally, the R4 wheels use a 26.924mm (1.060") offset. So the front wheels must come from a metric axle (JD/Yanmar, Kubota, etc) while the rear wheels can come from anything as long as they have the industry standard 8 on 8 bolt pattern and have the correct width and diameter. 2 piece wheels offer more track width options than single piece wheels of course.

So now that I had all of that information, I decided that since the donor wheels were likely to come from a 990 or a 4005, and since the front axles were the same, this means the rear rolling gearing would the same or very close to the 1070. Plus, since the 990 and 4005 were both available from JD with R4 tires, I decided to use the JD specified R4 tire sizes for my 1070. This would be a 10x16.5 front and 17.5Lx24 rear.

I did the math on the published circumference of the original R1 front and rear tires to get a rolling ratio of .599. Now that I had a number to work from I could start looking at R4 tires in the sizes I needed. Working all the numbers on the various (affordable) options I came across, I went with a set of take off rear wheels with brand new Titan 17.5Lx24 tires and a set of barely used (likely take off) front wheels from a 4005 with brand new Deestone D304 skid steer 10x16.5 10 ply front tires. Using the published specs for these tires, I end up with a rolling ratio of .623. This is a difference of approximately 3.9% Perhaps a little on the high side, but still within the 5% tolerance allowed for.

So I ordered up the set and got them yesterday. Stuck them on the tractor and went for a little cruise in 4wd. No binding and no tearing up of my turf. Looks like mission accomplished!

Someone can comment, but I think the front tires are mounted backwards on the rims. However, I have heard that doing that will save significant wear on the front tires. So I will probably run it like that for now to see how it goes. If I need more traction I suppose I can dismount them and swap them around. Turning the front wheels the other way doesn't really seem to work as it puts the offset the wrong way.

Yes, I have a new front hood piece for it.

Next is to fill the rear tires with WW fluid. I want to use Rim Guard, but I think it's just too expen$ive. Although unless I can get WW in bulk for substantially less than buying it by the gallon jug, it's not *that* much more and I may end up going that route.

Next up on this machine is to fix the bucket, then start on the process of adding the necessary hydraulics so I can put a grapple on the front end and build a Top 'n Tilt.

Michael

 

[beenthere]

Looks good. Thanks for the detail and the detective work.
And yes, for forward traction, the fronts are not right (IMO).
But for traction in reverse, they are fine.
All depends on when and where you are when traction is needed.

 

[pmsmechanic]

If you switch the front rims side for side the offset and the tread will be correct.

 

[Zebrafive]

Looks good. Thanks for the detail and the detective work.
And yes, for forward traction, the fronts are not right (IMO).
But for traction in reverse, they are fine.
All depends on when and where you are when traction is needed.

I Agree with above post.
I have heard of mounting the fronts backwards for repetitive loader work and better traction backing out of a pile. I had not heard it will decrease wear.

If you switch the front rims side for side the offset and the tread will be correct.

I was thinking the exact same thing, just swap side to side. You beat me to the post :drink:

 

[Radius118]

Thanks for the replies..

I swapped the rims/tires from side to side and went out and got my machine really dirty working in some mud and clay. The tires worked great!

Thanks,
Michael

 

[robpm]

Looks really nice Michael. Reminds me of my 990. I am glad it is working out for you.

 

[Deleted member 216442]

Be advised that your 8b backhoe should have a retrofit kit installed that prevents the curl cylinder from buckling under certain circumstances - like when you hook a stump and lift, it will relieve the curl pressure. I bent my cylinder twice and on the second visit the JD dealer mentioned this issue. For some reason, my backhoe was not in their ownership database although I bought it all new from that dealer.

 

[Radius118]

Be advised that your 8b backhoe should have a retrofit kit installed that prevents the curl cylinder from buckling under certain circumstances - like when you hook a stump and lift, it will relieve the curl pressure. I bent my cylinder twice and on the second visit the JD dealer mentioned this issue. For some reason, my backhoe was not in their ownership database although I bought it all new from that dealer.

Thanks for the heads up on that. Is this some type of mechanical retrofit or hydraulic? How can I tell if it's installed?

The tractor serial number shows that it was produced in '98 - the last year for these. The original owner told me that the tractor and backhoe attachment were all purchased together, so I would assume the backhoe is newer rather than older. Perhaps it already came with the change?

Thanks,
Michael

 

[Deleted member 216442]

I got the parts and installed the kit myself. It was a valve body or parts that replaced the curl control bank of the hydraulic valve control parts when you remove the sheet metal under the hoe control levers. I think it is just a relief valve added, basically, in one direction (uncurling). I think there was a metal tag that hung on one of the hose outlets or something that might be useful in identifying it; I'd recommend contacting the dealer to see if it came already fixed or was ever retrofit. When the issue occurred, the big curl cylinder bent into the dipstick arm and bent the arm and the cylinder. First time it happened I thought I might have backed into something and bent the cylinder. Second time I knew for sure I had not done that. Both times I was digging stumps out and had hooked a tooth and was lifting, not curling in. I was upset they wouldn't pay for either fix. If you don't get anywhere with the dealer I could take some time and look at my paperwork and remove the sheet metal of the controls and see what shows, maybe send you some copies and/or pictures. Mine was purchased new by me in 96, and the dealer had failed to enter the hoe in their database. All the other stuff I purchased was in there, including tractor, loader, mower deck. Another way to tell, although it risks damage, is to hook something, with a tooth, then lift and see if the curl will open up. It should to prevent damage. Before the fix it would not uncurl when lifting.