giannid

Yesterday I took a look in the center console where the fuses and relays are all at. There was a few air switches in there and the wires were all labeled and none of them were for the stop switch. Called the dealer and asked the parts guy where the stop switch was at. He told me they were all down by the actually pedal. I tilted up the cab and they were all on a valve underneath the pedal. He mentioned there were 4 of them and they were all the same switches, just for different functions. I was hoping to find a loose wire or something rubbed through down there. All the switches look good with no corrosion or anything on them. The wires all look good also. I didn't check each switch yet with a meter to see if they were working correctly. I'm thinking if it's not actually one of the switches that's bad, I may be better off just running new wires to one of the switches to a new relay in the dash and bypass the entire stop system. If it's a rubbed through wire, I don't think there's any easy way to find it. Plus I may do more damage to the existing wiring of the vehicle. Thoughts?

So these air switches have a wire coming off of them which activates the relay for the brake lights? How many air switches are there and what else are they used for? Looks like I need to go find where they are.

I didn't look above the pedals. I don't think there's anything there. The relays/fuses are all in that huge center console that's all accessible by removing a plates from the passengers side.

So I've got a Mack MR tractor that I'm turning into a dump truck. Working some of the bugs out of it and today I noticed the brake lights are intermittently working. This truck has the brake lights and turn signals separate. When I step on the brake, they flicker. Sometimes they work, sometimes they don't. I can hear the relay clicking. I've got a generic fuse/relay diagram and there's a couple of relays that mention stop. Looks like many of them are the same and I switched them around with other relays and still no luck. I put a test light on the terminal/post marked stop and the test light acts just like the brake light. I'm pretty mechanically inclined and trying to figure out what it is. I'm thinking it may be the actual switch that's activated by air pressure when you hit the brake pedal. Have no idea where it's at though. Any other ideas?

So I've got a Mack MR tractor that I'm turning into a dump truck. Working some of the bugs out of it and today I noticed the brake lights are intermittently working. This truck has the brake lights and turn signals separate. When I step on the brake, they flicker. Sometimes they work, sometimes they don't. I can hear the relay clicking. I've got a generic fuse/relay diagram and there's a couple of relays that mention stop. Looks like many of them are the same and I switched them around with other relays and still no luck. I put a test light on the terminal/post marked stop and the test light acts just like the brake light. I'm pretty mechanically inclined and trying to figure out what it is. I'm thinking it may be the actual switch that's activated by air pressure when you hit the brake pedal. Have no idea where it's at though. Any other ideas?

yep 12k

Truck is from Miami so not much rust. LOL. Road trip JoJo? Lol

I would attempt if and have a heated shop with air tools and a compressor. Just have never done it before and it's not like there's a book or something I can get to show me exactly how to do it. My luck I'll get stuck and have to tow it somewhere to get finished.

So there's a possibility the beam is bad and needs to be replaced? That would be just my luck. The drivers side is pretty bad. There's no telling how long they ran the truck without the auto greaser working. I can't imagine replacing the beam is going to be cheap.

After doing some research online, I'm pretty sure it's a Mack front end. Actually found a couple of complete used axles on online dating back to 1997, so they've been using that axle awhile. I imagine you still have to take the brakes and backing plate to do the the job. Never done it before. How long to these usually take to do at a shop?

Nope. Here's some pics. Had to scrape the grease and crud off of it to see what it looks like. Spent the better part of the day getting rid of the auto greaser, lines and putting regular grease fittings in everywhere. The auto greaser wires were cut so my guess is they just disconnected and not lubed anything at PM time. King pins are definitely wore out. Jacked it up and pried on it with a bar. Seems like the tie rods/drag link are good. You familiar with this front end? I'm hoping aftermarket parts are available as everything at the dealer is stupid money. Doubt I'm going to do the job myself as it seems like it's a big job and never done them before. Probably requires some special tools. Any idea what this will cost? Going to call around tomorrow.

I just purchased a decommissioned USPS single axle tractor. The king pins are wiped out and wonder what they will cost to get done. The USPS specced these trucks with an automatic greasing system that looks like it hasn't worked in years. Never done king pins before and not sure I want to tackle the job myself.

So I'm looking at an ex refuge truck to convert to a dump truck. The truck is a MR688 and it has a camelback suspension. Not really familiar with this type os suspension but know it can be pretty expensive to rebuild. Anyone know what to look out for in this suspension. Dealer says they have a towmotor they can pick the rear up. I'm sure it'd be a lot easier to see if the suspension was wore out while driving it loaded. Just looking for some pointers.

What's your friend have for sale? I'd be more interested in a MR with the E7. Those were the best before the emissions crap arrived.

I'm pretty sure it's a 4000 from what I can tell. I'm going to have to verify what it is so I can make sure I can get the gear put in it for the PTO. I though they were all 6 speeds. Not sure what you mean by locked out. These were road tractors so I'm sure if they had a sixth gear, they would want to utilize it for fuel mileage. I'm curious how to find out if it's a five speed and the procedure for modifying and unlocking the extra gear if it needs it.

Radiator doesn't have a hole in it and the transmission isn't the Allison RDS style with the PTO gear. My upfitter says it's going to be about $4000 to have the trans removed, new PTO gear installed and new housing for the PTO to be bolted to. The guy selling the trucks has the radiator with the hole in it and pumps to mount to the crank pulley if I want them in used parts. I figured I'd go with the tranny conversion option. The trucks are priced good enough where I can put that $4 k into them and still worthwhile. The trucks came from Florida so very clean rust wise. They seem like they need some paint and cleaning up though. Doesn't seem like the USPS keeps their equipment primp.

So I'm looking to build a single axle automatic dump truck. It's been challenging to find experienced drivers for my small construction company. I've got a trustworthy guy that wants to get his CDL and I think a single axle automatic dump truck would be great to start him on. A local guy has a few decommissioned USPS 2007 MR688 tractors that I'm thinking about converting to a small dump truck. These trucks are equipped with the AI-350 and Allison Auto transmission. I already talked to my upfitter about putting a dump body on one and the price is something I could handle. This would be my oldest dump truck on the road and think that might be a good thing as I understand they have minimal emissions systems. So what's the opinion on this truck with this engine and transmission model? Tried a search on the forum but it seems like there's some sort of glitch.

Tomm, I'm looking at buying one of these ex USPS trucks myself. I'm going to send you a message.