Community Forums

deasnealy · 06-03-2013, 07:38 AM

We just crossed a western mountain pass in New Mexico and my rig would slow down to 45 mph to pull the grade. This is my first motor home and we purchased the pusher so we would not have this problem. We are not pulling a toad yet and I believe it should perform better. We had a 3yr full service performed on the rig at Freightliner and they replaced a transmission pad that corrected the problem of the rig not showing econ mode. New filters fluids etc.

I also had an odd thing just start popping up. I had to manually downshift the transmission after it slowed to 35 mph without shifting out 5th gear. I believe I have a Cummins 340 and Allison 2500 transmission.

I am going to contact Tiffin, but assume they will send me to an Allison shop to check out the transmission. I was wondering if anyone else had a similar problem with the RED or is it possibly underpowered?

2010 Allegro RED with 10k miles.

Steve Ownby · 06-03-2013, 07:53 AM

If you slowed to 35 mph under wide open throttle and your Allison did not shift then yes there is a problem. Your Cummins ISB depends on keeping the rpms up close to the peak hp rpm for best climbing. The ISB has a good hp rating for its size but is a little lacking in the torque dept. If you get your shifting problem fixed and keep your rpms up I think you will be happy with the performance.

Maladjusted · 06-03-2013, 08:23 AM

What was the grade and how long?

My SportsCoach with the same powertrain (32k lbs with toad) will slow to 45 mph on the steepest grade around here (64 W Ashton).

Triker56 · 06-03-2013, 09:05 AM

In the hills keep it out of econ mode.
On long uphill pulls, manual downshift and keep RPM's at least around 2,100 to 2,3000 using less then wide open throttle pedal. It will run cooler then WOT will.

Don't worry about the speed. It will get to the top using much less fuel then those who are passing you.

phredsee · 07-01-2013, 08:26 PM

If it makes you feel any better, we just climbed the Raton, NM pass doing 32 MPH but we have the gas machine. Kept pace with the diesel trucks and didn't worry too much about the speed. Your tranny does sound like it needs a look see and maybe that will solve the problem.

If you're looking for more power, you might investigate companies that advertise and sponsor this forum, like Brazel's, Redlands RV and Hendersen's Line-Up that provide power upgrades for both gas and diesels.

Prior to the Tiffin MH we currently have now, we had an 04 Winnebago Vectra, 350HP CAT and started out like an old city bus and took forever to gain speed. Hills were worse. Bought the performance package was quite amazed. Examples of our dyno tests were 350HP to 410HP, torque from around 860 ft lbs. to close to 1060 ft lbs., if I remember correctly. They can tell you what past tests have been with specific motor homes.

Have absolutely no connections with any of these vendors other than purchasing various modifications from them and will continue to do so if needed in the future.

BTW, the Tiffin RED is a great little machine, IMHO!

nctox · 07-02-2013, 06:51 AM

I have the 2012 RED 34 and drive frequently in the NC mountains where 6% to 8% grades are common. Slowing to 45 is what I expect on these grades. If I have good highway speed before starting the climb, then I can keep my speed up longer than if starting from a slower speed, but eventually the speed will deteriorate to 40-45.
From reading on other forums, even the larger Cummins (8.3 & 8.9) will slow to about 45 on the steepest grades, since they are in the heavier coaches.
I would call Freightliner (800-385-4357) or Allison (800-524-2303) about your transmission. They can tell you if there is a problem.

Tim,,,

deasnealy · 07-04-2013, 12:49 PM

Thanks for the input. I did make to Allison. They hooked up to computer and ran diagnostics. No issues recorded except the changed the exhaust gear to 3 from 2 and that has helped. Not sure why but after they ran diagnostics my entire rig is running better. I am not sure if there was a software update or what, but I am happy with it now.

Now I have to figure out why my bedroom slide is tracking off center and sometimes stopping during operation. Any chance you know how to access the motors on the bed side slide?

jfran304 · 07-04-2013, 12:58 PM

Quote:

Originally Posted by deasnealy

Thanks for the input. I did make to Allison. They hooked up to computer and ran diagnostics. No issues recorded except the changed the exhaust gear to 3 from 2 and that has helped. Not sure why but after they ran diagnostics my entire rig is running better. I am not sure if there was a software update or what, but I am happy with it now.

Now I have to figure out why my bedroom slide is tracking off center and sometimes stopping during operation. Any chance you know how to access the motors on the bed side slide?

On our 2006 35TSA access to the slide motor is gained by lifting the bed.

Jon

EngineerMike · 07-04-2013, 01:20 PM

Deas- I have a "425hp" ISL, and routinely take steep hills at 45, mine is pulling 31k for the coach & 4.5k additional lbs for the toad. You can't expect to move this many tons of stuff as though you are piloting a BMW. Fuel mileage suffers greatly trying to do so. Truthfully, you add maybe 20 minutes to a long day of driving not being able to hold 55-60 up steep hills. Enjoy the scenery.
IIWMIwouldn't try to amp up the ISB in your platform. Its close to maxed out w/out starting to overstress stuff. Larger diesels attached to an Allison are different in that those blocks come in builds that are higher output, while yours is about as high as the ISB goes. Certainly you could push the envelope, but...

ernieh · 07-04-2013, 03:15 PM

Quote:

Originally Posted by EngineerMike

Deas- I have a "425hp" ISL, and routinely take steep hills at 45, mine is pulling 31k for the coach & 4.5k additional lbs for the toad. You can't expect to move this many tons of stuff as though you are piloting a BMW. Fuel mileage suffers greatly trying to do so. Truthfully, you add maybe 20 minutes to a long day of driving not being able to hold 55-60 up steep hills. Enjoy the scenery.
IIWMIwouldn't try to amp up the ISB in your platform. Its close to maxed out w/out starting to overstress stuff. Larger diesels attached to an Allison are different in that those blocks come in builds that are higher output, while yours is about as high as the ISB goes. Certainly you could push the envelope, but...

I don't see where the OP is thinking about "amping up" his coach, but you are correct. While there may be higher output ISB's, he is pretty much limited by his MH2500 transmission torque rating.