Short story, John Deere 70 Skid Steer makes nasty grinding noise in forward or reverse. Long story: I do a lot of educational projects with my son and daughter. Current one, we converted a late 1970's skid steer to electric. Project is going decently, and finally got it to the point where we can drive it. Before starting the entire conversion, i welded a bolt to the hydraulic input shaft, and we used a Milwaukee drill to power the skid steer to test hydraulics (no point in doing the project of hydraulics were shot) It in fact worked quite well within the limitation of the drill. Fast forward a month, we have the nice powerful electric motor installed, and doing a basic test. Boom goes up and down and bucket tilts absolutely no problems. A few cylinder leaks not not too bad, can live with that. Problem became forward and reverse. Worked fine while the wheels were off and it was up on wood blocks, full power either direction. Put wheels on and tried driving. it will move fine a foot or two in either direction, then extreme grinding. I liken it to driving a old manual transmission vehicle with no synchromesh and just grinding the gears. I have a owners service manual for it, and from what i could gather online, possibly the chains needed tensioning. As such, I did so. They were a bit lose. So that "should" be good now. Still, the problem persists. I don't believe it's the pump, as no issue with the boom and bucket, it doesn't grind until i start driving it. As our projects are on a budget, hoping it's not an expensive fix. I'm at my limits for hydraulics, next point for me would be parts swapping, if I can even find them, unless someone who knows what they are doing can advise me and or repair. Thank you for your time! Here is a video of the problem. Yes I know I'm wearing sandals. https://youtu.be/hFQNqW5R7ho THANK YOU!!!
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Sandals = Chinese safety boots over here 
I think the sound you hear is because the park brake is on? are the steering levers fighting you moving them forward and backwards? if so, i'd bet the brake is on causing this.
Hoefully it's that simple.
I think the sound you hear is because the park brake is on? are the steering levers fighting you moving them forward and backwards? if so, i'd bet the brake is on causing this.
Hoefully it's that simple.
Andddd i just kept watching the video and saw that if you go slow it allows you to drive further, so it's not the brake, but when under load.Sandals = Chinese safety boots over here
I think the sound you hear is because the park brake is on? are the steering levers fighting you moving them forward and backwards? if so, i'd bet the brake is on causing this.
Hoefully it's that simple.
What speed are you spinning the pump at? i'm wondering if it could be too slow and not getting enough charge pressure and the pump is starving for oil....
Unfortunately the Parking Brake no longer exists. Had to go very low budget on this build, a old farmer that was retiring (85 years old) took interest in our project. He had JD Tractors to tinker with, but said he'd never get to this skid steer (Gas engine that was in it was shot). The skid steer was a step above free. He had it 6 years, and it sat at the owner before him's farm for a couple years before that, as a barn blew down on top of it and they couldn't get it out. For RPM, I'm not sure at the exact moment. I am running the electric motor at 12v, didn't go up yet as I wanted to test it at lower power to prevent possibly breaking something before I can hit the kill switch. I will be grabbing 2 more batteries from my dad this weekend. using repurposed old starting batteries for the time being. Will get deep cycles once it's all set and running right. I have a Tach on order from Amazon. I can try it at 24 then 36v next week, each increases the rpm proportionally. I have it up on blocks right now again. Trying my best to narrow it down. I "WAS" thinking it could be the drive motors. However, I think now it might be the pump??? Or at least problem ending up in the pump??? Up on blocks, I can run fill speed forward or reverse with no problem. HOWEVER, if I press the brake while it is running, so it applies a drag to the drive motors, then it starts chattering up and making the grinding. When I release the brake then it quiets down. I can't get any chatter when operating the boom or bucket. Even with a couple hundred LBS in the bucket. Here is a video link to my current findings. At least if it IS the pump, it's easier to get to for me than the motors. Might be easier to find a replacement as well if it can't be rebuilt. https://youtu.be/Wfl4HerEvsYSandals = Chinese safety boots over here
I think the sound you hear is because the park brake is on? are the steering levers fighting you moving them forward and backwards? if so, i'd bet the brake is on causing this.
Hoefully it's that simple.
Sorry for the post formatting. All paragraphs and spaces between and what not for some reason disappears after I hit post :-(
