New Build Questions

[MileHiGuy]

Hello - Been lurking on the forums for a while but after our history with 7 previous pusher coaches we are ready to try the HDT truck based MH's out and have some questions. We currently have an enclosed car hauler but when retirement gets a little closer a 26-28' stacker will be the plan.

We have toured the major manufactures in Elkhart there are certainly pro's and con's to how the big players build but our preference would be to build a Renegade Classic with 3-slides, Aero front cap with a walk in cab.

Truck wise we are working with an independent Freightliner Dealer. Looking at the Cummins ISX as the Detroit changes how the exhaust is routed causing a loss in one storage box.

I would like input on spec'ing a motor with the Eaton Ultrashift Plus 13 speed versus an Allison 4000 six speed. All my previous coach experience has been with an Allison but have never had a coach with more than 1250'lbs of tq. Gear splits might be a little wide for our 7% 10,000' grades we have here in Colorado.

I am fearful I will be disappointed with the rate of which these autoshifts accelerate from a stop or pulling into traffic where as the Allison are not too horrible - not that city driving is the primary concern.

One nice attributes to the Autoshift is that the motor can be spec'd with 2050'lbs Tq versus 1850 limit for the Allison which could be an asset with the big hills.

Is there an appreciable advantage in mileage with an Autoshift?

As a side note I have looked into options for building a Cascadia Glider with an older version motor but generally these are only built with manuals plus other obstacles.

Thanks for any advice, these certainly are big financial commitments. We have been extensively looking for a used coach (Racing Junk) but finding one set up for sub zero operation with a floor plan we desire has been challenging.

[tgdameron]

I would ask you to consider talking with IWS Motorcoaches as they have proven to us to be the most knowledgeable about Renegade and have extensive experience with sub-zero Classics. They know how to spec them based on your needs. Give them a call to get their take on your needs. 800-376-7114

We purchased our Renegade from them and have not had one regret either with them or the coach itself.

[porky69]

My Haulmark has a Detroit 515HP/1650FT-LB with a 12speed Freedomline Autoshift and it has more than enough power for any hill I have ever encountered on public roads, very rarely falling more than 5mph under the posted speed(the mountains in British Columbia are similar to what you mention) Also more power requires more cooling capacity, which most chassis are limited on, on a long (3+mile hill)the engine fan is screaming to keep it cool. Most highway haulers (80,000lb or more) run lower power levels than this so 1850 or 2050 ratings in a RV are pretty much showing off. Acceleration with the autoshift is on par with the Allison but the exhaust brake is more effective with the autoshift (more gears keeps the rpms closer to optimal performance range)

I can't speak for the Eaton autoshifts but mine skip shifts if it senses the conditions are right, but has the extra gears if you need them.

I have long hauled and heavy hauled with trucks ranging from 300hp to 600hp with Allison 5&6sp, Fuller 9,10,13,15 and 18sp (some with 3 or 4 speed auxiliaries), both autoshift and manual.

If I were to build one from scratch I would go in the 500-550hp/1650ft-lb range with a 13 or 18speed (manual for me personally, but understand why one would want an auto). More than enough power for a 45,000lb RV setup.

[Bob86ZZ4]

Welcome to Truckconversion.net! I think you're going to like a T/C compared to the D/P. Have you looked into Space Craft Custom Built Recreational Vehicles, Fifth Wheel Trailers, Travel Trailers, Semi Trailers, Bunkhouses, Box Conversions, Restroom Trailers, Custom Built RV, custom built rv trailers, Toy house, toy hauler, toter home, toterhome, motor coach ? They are a pretty good builder too, I think.

As far as transmissions. I've heard good things about Volvo and their I-Shift.

[38Chevy454]

I have the ISX (with 450 hp tune) and the Eaton Ultrashift 10 speed. Shifting is pretty quick, but not automatic quick. With no clutch pedal in the cab it really is easy to drive and for the most part the computer picks the right gear and shift points, both up and down. The only time it can get wrong is coasting at lower speeds it will sometimes pick 1 gear lower than optimum. Not really a big deal, it just upshifts real quick. Remember that the bigger the engine (ie ISX 15 liter) it has less rpm range and will work better with additional gears to keep in optimum range. No matter what you will not win any races taking off from dead stop.

I have driven all over CO, major interstates to 2-lane highways in the mountains. Over 11,000 ft passes and towing an open car trailer or four down. I find the power is sufficient, sure more can be better. I especially like the three-stage engine brake for controlling descent after cresting the mountain.

I can't say if mpg is different manual vs slush box. I am geared so 1500 rpm is 70 mph and that becomes a nice cruising speed for me 70-72 is typical. I get about 7 mpg and not sure physics would allow that to be much different with either trans. You have a certain aero drag and weight, and that takes a given amount of fuel.

[MileHiGuy]

Thanks for the feedback. IWS packages some nice coaches generally on the shorter side with a single drive axle. His personal preference is for the Allison for better off the line performance and smoother engine braking.

Decisions decisions!

[bushpilot]

our coach has the Mercedes MBE4000 (aka DD13), 12.8L (tuned to 450hp / 1650 tq) with the ZF/Meritor Smart Shift 12 speed....our coach could be tuned for 500hp (just haven't bothered).

moderately loaded (220 gal of water, 120+ gal of fuel), beer, ice & food....but no toad, our coach tips the scale at 36k lbs.

full to the gills the coach probably doesn't exceed 38k (not including the 4200 lb jeep wrangler sport).

this summer we had no problem pulling the 7%, 6000' + grades around sedona....were typically in the left lane passing some cars (and certainly all the trucks).

our coach isn't gonna win any drag races, but we have never had an issue merging into traffic or getting around "town"....hell i just dropped my buddy off at Houston Intercontinental Airport on sunday (jeep in tow)....no problem dealing with traffic there (either).

I was skeptical about the auto-shifts at 1st but, once you have the pleasure of driving one you'll appreciate the performance and capability (no slipping torque converter)....the auto-shift trans are pretty smart....skip shifts gears as needed, depending on rate of acceleration & load/tow....and it does the same thing on down shifts....i say its one of the coolest features of the coach.