What does your tach say?

fun time · 03-18-2006, 12:46 PM

Curious: At 63mph my tach reads 2200rpm. 1999 Adventurer w/275 Cummins. This seems high? What are you taching at this speed? I am beginning to think either the speedo or tach is off.

fun time · 03-18-2006, 12:46 PM

Curious: At 63mph my tach reads 2200rpm. 1999 Adventurer w/275 Cummins. This seems high? What are you taching at this speed? I am beginning to think either the speedo or tach is off.

John_Canfield · 03-18-2006, 12:55 PM

I think we run about 1750-1800 rpm at 63-65 mph but my drive train is totally different from yours (Cummins ISL and Allison 3000.)

BigTrace · 03-18-2006, 03:25 PM

Ditto with John C. I all depends on the engine and trans your running. 2200 maybe perfectly normal for your combination.

Art D · 03-18-2006, 05:09 PM

Seems high to me. That's almost identical to my Sightseer 30B with 8.1L Workhorse.

AFChap · 03-18-2006, 05:39 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">think either the speedo or tach is off. </div></BLOCKQUOTE>
How long have you had the rig? ...does that match with it's history?

It sounds a little high maybe, but definitely depends on your drive train, gearing, etc. Could be rather than speedo or tach being off, that the tranny is not shifting into the highest gear, or is slipping. The only way to really tell is to talk to a Cummins expert who can analyze your engine/transmission/rear end combo and tell you what the cruising rpm should be.

DonavonP · 03-18-2006, 07:24 PM

Fun Time, I think you might be able to figure it out with THIS axel ratio converter.

I believe you have an Allison 3000 transmission and that your 6th gear has a ratio of 0.65:1
Your 5th gear has a ratio of 0.75:1 - do you feel it shift into all the gears.

My 1997 230 Cummins would hit 6th gear at 50 mph. I believe the rpm was about 1800 rpm @ 50mph but can't remember for sure.

fun time · 03-19-2006, 02:20 PM

Thanks all for your replies. You guys always ask the right questions. No question it is shifting through all gears and here is the amazing part....I average 12mpg without a toad driving 60-63mph...I am not kidding! I have checked on numerous long trips. That is why I am beginning to think it is within the speedo or tach. Anyone else out there have the same unit and same year?

J. Henderson · 03-21-2006, 12:23 PM

I have the Itasca equivalent of your Adventurer. Our transmissions are not electronic four speeds. Your tach readings and fuel miliage are similar to mine.

rebelsbeach · 03-21-2006, 01:00 PM

J. Henderson, Welcome to the forum and thanks for your post!

fun time · 03-22-2006, 04:35 PM

J.Henderson: Thanks for the reply. Just an FYI for both of us and any others with similar coaches. I spoke with Freightline today concerning this matter and here was there reply:
The top RPM for our coaches is 2400RPM. There are settings on the back of instrument panel (Tach) of which I was told to check. He said to write down those settings and give him a call back. He will then verify whether they are correct or not. This was the first place he said to start. He said he has seen this problem before on ones that have the "full all in one clusters". Short of taking it to someone who can determine the realRPMs that is the best he could do. He really suspects the problem is the guage. I told him I have had mine up to 2800RPM and still going. He said that is very unlikely. As always he was very helpful and knowledgeable.

kenbt · 03-23-2006, 11:35 AM

On my 2005 c-7 350 cat I am running 1800 at 63 mph