Posted on: May 19, 2025

If you’ve been in the trucking game long enough, you learn to recognize the moment when things start to go sideways—not because a warning light comes on, but because something just feels… wrong. It’s not diagnostic. It’s not dramatic. It’s that subtle shift in how the truck moves, like the road is trying to whisper, “Hey, bud, something’s about to get expensive.”

Mine started with a thud. Not a polite, subtle thud either. This was the kind of sound that makes you instinctively lift off the throttle and say a quiet prayer. I was backing up when it hit—literally. The truck jerked violently, then re-engaged like nothing had happened. EXCEPT for the fact that from that moment forward, reverse was never the same. Anytime I was attached to a load, and started backing up, it would jerk. Then it started doing it when I wasn’t loaded. Eventually, it got to the point where I could barely ease it into reverse without having the issue present itself.

Naturally, the first thing I did when the issue started, was hook up my laptop and pull the codes: P1071-96 and P1057-21. If you’re fluent in Mack / Volvo speak, you already know what that means. If not: the first one pointed to a split engagement system internal failure, and the second was the main shaft speed sensor. Now the “-21” suffix means the sensor itself is just fine, but the issue is with what it’s seeing. It’s like saying, “The camera works, but the picture is messed up.” Not a good sign.

After a little research, I came to the conclusion that I was likely dealing with a failed spigot bearing inside of the transmission. When that bearing fails on these transmissions, the input shaft loses its preload and starts wobbling. On a normal transmission, you might get away with that for a bit. On an MDrive or I-Shift? Not a chance! These things have zero tolerance for shaft play, and if something’s not lined up perfectly, the system throws a fit. Apparently, reverse is where it throws the biggest one. Through my research, I was able to find a service bulletin put out by Volvo regarding this exact issue, codes and all.

I ran this theory by my local mechanic, who did his own research and came to the same conclusion as I did. Failed spigot bearing. After we talked about what that meant for a while, he was upfront with me and told me that his shop didn’t really work on these transmissions. He said that one of his other customers had a very similar issue, and they wound up just having to take it to the Mack dealer. If you know me, you know it’ll be a cold day in Hell before a dealer touches my truck! So, that kind of left me in a pickle as far as finding someone to do the work.

Before I made any big decisions, I decided that dropping the fluid was probably a good idea. It had been 200,000 miles since I last changed the transmission oil, but what I found wasn’t shocking: some fine metal in the filter, a little shimmer in the oil. Nothing chunky, nothing catastrophic, but just enough to back up the theory that something was wearing where it shouldn’t be. Yes, I know 200,000 miles is a lot of miles, but we’re talking about a big truck transmission. The service interval is 500,000 miles for the MDrive.

Now that I had a working diagnosis, but no one nearby willing or able to fix it… I did what any desperate, slightly bitter trucker does… I turned to Facebook, and believe it or not, it paid off. That’s how I found HD Truck Repair and Parts in Jackson, Georgia. Darryl, the shop foreman, called me back and, within the first 60 seconds, made it clear that he knew exactly what I was dealing with. No hesitation. No long hold while he “checked with a technician.” He just knew.

For some context, I bought this truck in December of 2020 for $30,000. At the time, it was a good deal—clean, reliable, and well-maintained. The MDrive was the only thing I didn’t love. I would’ve preferred a manual, but those are unicorns now. Still, the truck had been solid for all of these years. Honestly it’s been the most reliable truck I’ve ever driven. Until this…

I dropped the truck off on a Monday afternoon, and by Tuesday morning, Darryl had already sent me a video showing the input shaft dancing around like it was auditioning for a talent show. The spigot bearing was toast, the clutch actuator was wrecked, and there was no point in doing a halfway job. I told them to just fix it all.

Fix it they did, and by Thursday morning, it was ready to be picked up. The truck got everything: a reman transmission, new clutch, new actuator, updated electronics, and everything in between. While they had it open, they also spotted an oil leak at the timing cover and resealed that too. I figured if I was going broke, I might as well do it all at once.

But there was one small problem – I didn’t exactly have a ride to go pick it up. That’s where the Savannah Port Truckers group came through. Huge shoutout to Kat C. for giving me a ride up to Jackson. Yes, I literally hitched a ride with a complete stranger, and honestly, it ended up being the best part of the whole ordeal. We had a great trip and a solid conversation. I’m glad to have made a new friend.

The final bill? $16,000 flat after I added in the timing cover reseal.

Yeah, that one hurt! That’s not a repair – you’re practically buying the truck again. Which made me stop and really consider: do I just cut my losses? I even looked at a 2020 Mack and got very close to handing over a check for it, but I backed out at the last minute. Something just didn’t feel right. I mean, I know the truck I own. I know what’s been done to it. I know what hasn’t. I know the sound it makes when it’s running perfect and the sound it makes when something’s off. That 2020 might look better on paper, but I’d be starting from zero with it, and zero is a risky place to live when your livelihood depends on keeping the wheels turning.

So I stuck with the devil I knew.

And now? No jerks. No leaks. No codes. Just smooth shifting and a bit more peace of mind – though not much peace left in the bank account!

That’s trucking though. One week you’re cruising along thinking you might finally be ahead, and the next, you’re on a first name basis with a shop foreman who knows your truck better than your dentist knows your teeth.

Would I do it again? Apparently, yes. Because I already did.

SPECIAL THANKS AGAIN to Kat C. from the Savannah Port Truckers group for giving me a ride up to Jackson to pick my truck up. You really saved me from a big logistics headache.

Got your own transmission horror story? Drop it in the comments. We’ll cry together, and maybe laugh about it in five or six years—once the financial trauma fades.