Champion 720A

Looking for a reverse transmission solenoid for my Champion 720A. The local Volvo dealer says it's obsolete—Champion part number 29749, which became Volvo number 58149. Does anyone know where I might track down this part?

I found a listing for the Volvo Motor Graders Solenoid Valve with NSN 4810-01-322-7579 and part number 58149, model 7324553F1. It's a valve with multiple ports that uses magnetic action from an electric coil to control fluid flow. Thought this might help with your search for the reverse transmission solenoid for your Champion 720A.

Elvaan Equipment Solutions in Canada might have a new or used one if you can't find it elsewhere.

I've done some more digging on the reverse solenoid based on what the manual says, and it's actually checking out fine. I ran an ohm test on it and applied 12 volts as a test - it clicks in properly, so I'm not convinced the solenoid itself is the problem. Here's what's happening with the machine: when I start it up there are no codes and it shifts into forward and reverse with no issues, and all the gears in both directions work fine too. But once the grader warms up and I've been operating it for a while - somewhere between 30 minutes to an hour - it stops shifting into reverse. All the forward gears keep working normally but when I try reverse I just get neutral. Sometimes I can force it into reverse if I'm running at full throttle, but even that stops working after a bit. If I let it cool down for a few hours it'll go into reverse again and then the whole thing repeats. At first I figured the reverse solenoid magnet might be losing strength when it heats up, but I don't think that's what's going on here. I've read about microswitch problems in the shift column causing issues, but those cases were usually when the transmission wouldn't shift into forward or reverse at all, not just reverse after warming up. Any suggestions on what could be causing this would be helpful.

You might want to pressure test the reverse clutch lockup pressure at the solenoid cap to figure out if you've got a low pressure or leak issue, or if it's just a failed clutch pack.

The shaft assembly without a gear on the upper end is what handles your reverse. Mine had work clutches with paper friction material—you could feel the transmission pressurize the clutch servo, but the plates were shot so nothing would engage. I went with the newer bronze ones instead and air tested them on the bench, works great. Installed it today and I'll finish hooking everything up tomorrow. Should be back in service after that. Not a terrible job overall.

Does your machine's transmission reverse slip, or won't it engage at all? Where do you usually buy parts from?

The reverse clutch servo and hydro pack would engage, but the machine wouldn't actually back up in reverse. I bought it that way, and the previous owners had already replaced the pump assembly under the radiator. They figured there might be an internal transmission problem. I took a gamble hoping it was just a clogged strainer or shift control issue. I ordered parts from a gear train supply outfit in Idaho—they had all the clutches I needed in stock. I gave them the Champion numbers and they sent over the updated bronze frictions.

Oil running hot?

Good info, thanks.

Not sure if you're still dealing with this, but I had the exact same problem on mine. I ran it hard for a full day and it cleared up on its own. The fault code was reverse solenoid short circuit, and after about 8 hours of heavy running it stopped throwing the code. My guess is there was moisture trapped inside the solenoid from sitting unused for a few years before I got it.