Rpm for a 93 cummins powered Winnebago Adventurer

The gps groundspeed cross checks with the speedometer so unfortunatly that isn't the issue.... Actually starting to worry me a bit, was really hoping it was normal or something obvious...

Here's my issue. The 5.9 Cummins (1993)was governed at 2700 RPM so your RPM reading at 2500 RPM is 63 MPH. According to your post RPM and speed, you couldn't go much faster, doesn't make sence, unless your top speed is about 65 MPH. Either the tach or the speedometer appears to be reading incorrectly.

Your speedometer could be off. Click link for your manual: http://www.allisontransmission.com/servlet/DownloadFile?Dir=publications/pubs&FileToGet=OM1334EN.pdf

and here is the specs: http://www.messb.com.my/allison_at_545.html

Thanks so much for the reply's. bsinmich is correct i believe it is a 4 speed transmission. I took it for a drive today and at 60 mph it was sitting around 2300 rpm. I really can't tell if it is working that hard because it is actually pretty quiet to drive. Data plat says it is an AT 545

If you want a better answer give us more info. My 5.9 with Allison MD 3060 turns about 1900 rpms at 60 mph in 5th gear it does not shift into 6th until near 65. There is a shift sensor located on the throttle cable that connects to the tranny if this linage is broke or comes loose it will not let it shift properly until it reaches max prm and then will let it shift. Try WOT until you hit the red line usually around 2800 prm's and see if it goes into the next upshift. In the meantime give more details and maybe we can give an accurate answer.

I think they were still making a 4 speed transmission in the early 90s with all mechanical controls. They were a lot less expensive to install.

I second that something is wrong.

Check your transmission control. For some reason, you could be locked down into third. You should have a five speed (or maybe even a six speed) transmission, probably an Allison 3000 series.

If I had to take a wild guess, it could be a failed relay in the Allison control box. This is a black box about 5 inches square and probably located in your electrical bay. Take the cover off. You'll find about 6 or 8 relays. I've replaced all of mine as a preventive measure. The relays are very common and should be available from any auto parts store. I bought a box of 24 on the internet since my coach uses a LOT of this style of relay. They just pull out and plug in.

What does it sound like? What i'am saying is, you should hear that motor really working hard at that RPM. I have the 5.9 cummins 98, with the 3.55 gearing, and traveling at 70 MPH, i'am only at about 2000 RPM. And at that speed and RPM, the motor is not laboring at all. Your ears should be a good indication as to the motor's work load.

Something is wrong. Your 5.9 should be red lining at 2500. Going down the road at 60-65 MPH RPMs should be around 1600 +or- depending on tranny, tire size, etc.