Downside to 4 speed vs six?

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Downside to 4 speed vs six?

January 08, 2011, 11:17:00 am

Howdy all,

My wife Retababes and I are seriously shopping foretravel coaches. We'll be going semi-full-time, splitting time between traveling and our place in Tx. We're moving up from a Bigfoot 10.5 foot camper so all of the coaches we've looked at seem palatial in comparison. Our travels tend to be pretty rural, location wise, so the non airbag suspension actually has some advantages.

I'm finding some good deals on U-225 coaches with the little 6B cummins, an engine I'm very familiar with. The thing that has me offput a bit is the 4 speed tranny. I've heard it tends to shift a bit hard, which is understandable and ok compared to the 6 speed. Will there be a fuel penalty to the four speed? How about mountain driving (we go to Ak yearly from Tx), will these coaches pull a good grade with 250 HP? Will they do it in 3'rd gear and if so, any idea of the speed while in torque curve?

The next choice would probably be a 270 in later 1990's, lots more $ of course, and more "stuff" to keep up with though the diesel genset would be a big plus. Never in the equation is a slide, we don't need it. The newer body style is appealing and I can fix anything on any of these coaches (enjoy it) from fiberglass to electronics.

We buy and hold, our vehicles are sold when the wheels fall off. Whatever we get we will keep for a long time. It's probably wise to consider fuel mileage as da juice won't get any cheaper down the road. While my primary question concerns the 4 speed, I'd be really interested in hearing owners perspectives regarding the 225 vs. newer Foretravel.

Thanks for your help, Chuck Pearson

Re: Downside to 4 speed vs six?

Reply #1 – January 08, 2011, 11:35:31 am

Biggest difference between the 4 and 6 speed transmission (other than two more gears) is that the 6 speed locks it torque converter in 2,3,4,5 and 6th gears. That aids in MPG, but at least as importantly, allows the use of a strong exhaust/engine brake. It is the strong engine braking that sways many to the 6 speed.

Many of the Allison 4 speeds only locked their torque converter in 4th gear. Check with Allison on the transmission in any you are considering.

Both transmissions are completely reliable.

BTW, the Allison 6 speeds started appearing in Foretravels in 1993-- our 1993 U240 has one.

Brett

Re: Downside to 4 speed vs six?

Reply #2 – January 08, 2011, 11:41:15 am

Brett,

Ah. Good point and very important imho. Thanks.

Chuck

Re: Downside to 4 speed vs six?

Reply #3 – January 08, 2011, 05:00:40 pm

Quote

Brett Wolf's Quote: "Many of the Allison 4 speeds only locked their torque converter in 4th gear. Check with Allison on the transmission in any you are considering."

Chuck,
The U-280, in '92, has the Allison 4speed MT-647, which is mated to the mechanical Cummins C8.3, 300 hp engine. The MT-647 locks in 3rd and 4th, which helps some in exhaust braking, but not a lot. The new exhaust brake by PAC, the PRXB is supposed to be the most effective exhaust brake for the 4 speed transmissions.
You might be able to take a CAT-powered 250 hp up steep grades in 3rd gear, but the 5.9 Cummins will get up the mountains, but just slowly.

I wouldn't rule out the air bag suspension of the 280's and the 300's. They can handle just about any "rural" roads as long as there is road clearance. As far as mileage, the Allison 4 speed with the C8.3 gives us routinely 9.2-9.5 mpg at 65 mph. If I slow down to 62, we get close to 10.0. On two tankfulls of 600+ miles this past fall we averaged 10.2 mpg, but for the entire 3500 mile trip it was 9.25 with cruise set at 65-66.

Re: Downside to 4 speed vs six?

Reply #4 – January 08, 2011, 06:47:08 pm

My '94 U225 has the MT-643. I think 3rd and 4th lock up.
Input speed: 2,200-4,000 rpm
Max input power: 250 hp (186 kW) (general purpose); 210 hp (157 kW) (transit/shuttle bus)
Max input torque: 640 lb/ft (868 N-m) (general purpose); 590 lb/ft (800 N-m) (transit/shuttle bus)
Torque converter ratios: TC-380 (1.86:1), TC-370 (2.43:1) and TC-350 (3.09:1).
I think she is rated to pull 73,000 lbs.

It is very slow off the line, but once you get the B5.9 wound up she pulls very nicely. Am running the Allison Transynd in mine. Getting a solid 10 mpg +.

Re: Downside to 4 speed vs six?

Reply #5 – January 08, 2011, 07:31:22 pm

Our SOB 37' DP had the B5.9 215hp engine and a six-speed transmission. The 23,000# coach got 9.5 mpg with no towed vehicle. Power was acceptable.

Our current FT 36' DP has C8.3 325hp and a six-speed transmission with retarder. The 28,000# gets 7.2 mpg with a 4180# vehicle in tow. Engine performance feels about the same. Each coach is provisioned with about 10 hp/1000# of vehicle weight. The exhaust brake in the SOB was OK, but the transmission retarder on the FT is GREAT!

We bought the 1997 SOB for about $25K. We quickly found that we liked the DP, but wanted better quality. The 1997 FT was about $50K. For us, the difference in quality has been well worth the additional bucks. Get the FT that fits your budget. It will almost certainly be a better coach than SOB at the same price.

Re: Downside to 4 speed vs six?

Reply #6 – January 08, 2011, 08:59:52 pm

I had a 4 speed in my 93 C8.3 U280 and thought I wanted a 6 speed. With the rear diff gear ratio change, there is really little difference. No difference in top end. Sure, a 6 speed will shift more to torque curve and be moderately better for in town driving. For me, 'in town' is just something to get 'out of'.
James Triana said - the 4 speeds are bulletproof and anyone can fix them. I know and over the counter rebuild of an MT647 is under 2 grand. A 3060/4060 TCU is $1600-2000.00.
I routinely got 9.5 mpg in my 36 foot U280, and after the banks kit the mpg went up (as long as I kept my foot out of it).

When my 4060 downshifts sometimes I think I'm gonna lose a kidney...

Re: Downside to 4 speed vs six?

Reply #7 – January 09, 2011, 09:01:12 am

My '93 u300, 6V92 has the HT746 4 speed. I was shown that it did lock up after shift into 2nd.
VMS shows a 8.6 MPG average since new (45856 miles).
Recent trip took me thru some pretty steep and long grades north west USA .Tanny did just great, mostly in 3rd gear, rpm's 1500 to 1700.

Re: Downside to 4 speed vs six?

Reply #8 – January 09, 2011, 01:52:54 pm

Yes, there are several different Allison 4 speed transmissions with different features. Clearly, the one uses with a Detroit Diesel 6V92 will be different than the 4 speed used with the Cummins B engine.

That is why I recommend calling Allison when you know the series you have/are looking at to determine its features.

Important feature to me is: In what gears does the torque converter lock up? Important for any form of engine braking.

Brett

Re: Downside to 4 speed vs six?

Reply #9 – January 09, 2011, 02:22:57 pm

The biggest downside is the constant hunting between third and fourth on long grades. I just punch in third and back off the throttle. A six speed would cure that and would be really great if the rear end ratio were numerically slightly lower. Our U300 turns too many RPM at freeway speeds and the fuel mileage suffers a bit. The Jake brake does a great job and I much prefer it over the transmission retarder because of the maintenance issues and overhaul costs.
When accelerating, the four speed seems to shift as if it had five speeds. It locks up part way through second gear and there is a noticeable "shift" at that lockup point. When counting, it seems like a five speed.

The four speed gets the job done well, has an excellent reliability record and won't break the bank if repairs are needed.

Having said all this, I really hate automatics and wish Foretravels were available with six speed manual transmissions like buses.

Did I really need to say that?

Pierce & Gaylie
93' U300/36

Re: Downside to 4 speed vs six?

Reply #10 – January 10, 2011, 12:33:22 am

Quote from: Pierce & Gaylie Stewart – January 09, 2011, 02:22:57 pm

I really hate automatics and wish Foretravels were available with six speed manual transmissions like buses.

Did I really need to say that?

Pierce & Gaylie
93' U300/36

Please, a 13 speed Roadranger! Splitting the gears when climbing a grade is so nice. But being real, a 6 speed manual would be just about right for my 24,000 lbs.

Re: Downside to 4 speed vs six?

Reply #11 – January 10, 2011, 06:30:57 am

Quote from: Pierce & Gaylie Stewart – January 09, 2011, 02:22:57 pm

The biggest downside is the constant hunting between third and fourth on long grades. I just punch in third and back off the throttle. A six speed would cure that and would be really great if the rear end ratio were numerically slightly lower. Our U300 turns too many RPM at freeway speeds and the fuel mileage suffers a bit. The Jake brake does a great job and I much prefer it over the transmission retarder because of the maintenance issues and overhaul costs.
When accelerating, the four speed seems to shift as if it had five speeds. It locks up part way through second gear and there is a noticeable "shift" at that lockup point. When counting, it seems like a five speed.

Pierce & Gaylie
93' U300/36

I agree with you completely, however I am sure that the four (4) speed is used to help keep the engine RPM's up, as that is where the Detroit engine develops the most torque..... lugging a two cycles engine will cause damage to the crankshaft and rods... It would be nice to have that extra gear when running on flat Interstate highways for fuel economy.

Re: Downside to 4 speed vs six?

Reply #12 – January 10, 2011, 01:02:44 pm

There is no down side to the 4 speed Allison, it is an older model, that does not mean it is no good, it is a great transmission.

The 1989 U300, 40' that I am familiar with had the 4 speed Allison with retarder and had the 3.08 rear gearing. Despite all the opinions, it works great, runs well, pulls hills fine and was never a problem in any way. The only weak link with that setup is the radiator across the back of coach. As long as the radiator is clean it cools just fine, my objection is that it is impossible to get to engine through the rear door, only down under the bed or up on either side from under neath. I am too old and fat to enjoy that procedure.
For sure the 6V-92 DDA DDEC 300 hp engine will not run with the bigger engines, nor will the 5.9, 8.3, ISB, ISC ISL Cummins nor the Cats used by Foretravel
Small but important point is to use straight weight 40 diesel oil. That does not mean 15w40 Rotella.
That setup will run many hundred thousands of miles as long as you do the proper servicing.
Relax and Enjoy

Re: Downside to 4 speed vs six?

Reply #13 – January 13, 2011, 05:54:17 pm

I am curious about your comment "Our travels tend to be pretty rural, location wise, so the non airbag suspension actually has some advantages."
What advantages???

Regarding coach selection, there are a lot of features on Foretravel coaches and some change from year to year, so it takes careful study to determine exactly what coach has what and how you prioritize it.
I suggest that you compile a list of all the features on all models in a spreadsheet and then determine which ones have the best value for you.
We got most of everything we wanted in our 96 U270 but we missed "dual pane windows" which for full timing would have been an asset.
Air Disc Brakes are a plus.
Allison Retarder is a great plus
Propane tank size varies. Mine is 80 gallon, most aren't.
We have the C8.3 mechanical (last one I think) so anybody can fix it and no electronics.
Have Allison six speed, would take a seven or eight if I could get it.
Mostly the U270 is utilitarian and a plain Jane without a lot of frills. Also not much electronics to fail and everything is basic.
Our interior is Oak I guess. The ones I see in walnut and other dark woods require more lighting and would make me feel like I was living in a cave.
There are check lists you can use to inspect any coach you look at and I suggest that you use one. Too easy to miss things without it.
Good luck.
Regards,

Re: Downside to 4 speed vs six?

Reply #14 – January 13, 2011, 06:23:48 pm

I don't think this is too cave like... I call it DEN-Zen...
Walnut and ginger-oak.

Re: Downside to 4 speed vs six?

Reply #15 – January 13, 2011, 06:30:12 pm

Quote from: Jon Twork – January 13, 2011, 05:54:17 pm

I am curious about your comment "Our travels tend to be pretty rural, location wise, so the non airbag suspension actually has some advantages."
What advantages???

Regarding coach selection, there are a lot of features on Foretravel coaches and some change from year to year, so it takes careful study to determine exactly what coach has what and how you prioritize it.
I suggest that you compile a list of all the features on all models in a spreadsheet and then determine which ones have the best value for you.
We got most of everything we wanted in our 96 U270 but we missed "dual pane windows" which for full timing would have been an asset.
Air Disc Brakes are a plus.
Allison Retarder is a great plus
Propane tank size varies. Mine is 80 gallon, most aren't.
We have the C8.3 mechanical (last one I think) so anybody can fix it and no electronics.
Have Allison six speed, would take a seven or eight if I could get it.
Mostly the U270 is utilitarian and a plain Jane without a lot of frills. Also not much electronics to fail and everything is basic.
Our interior is Oak I guess. The ones I see in walnut and other dark woods require more lighting and would make me feel like I was living in a cave.
There are check lists you can use to inspect any coach you look at and I suggest that you use one. Too easy to miss things without it.
Good luck.
Regards,

Jon,
My 97 U270 & Neal Pillsbury's 98 U270 have the Cummins C.8.3 but with the mechanical 325 HP vs your 300 HP. And yes, we have the Oak paneling & cabinetry which is easy to work with & find pieces to match if repairs are needed (I've used Red Oak with success...no stain, just polyurethane. And, starting in 97 (I think) dual pane windows were standard? not sure, if standard, but I have these in the coach. Joy stick retarder also. Ducted A/C as well.

Re: Downside to 4 speed vs six?

Reply #16 – January 13, 2011, 10:43:19 pm

Quote from: Dave Head – January 13, 2011, 06:23:48 pm

I don't think this is too cave like... I call it DEN-Zen...
Walnut and ginger-oak.

And those side lamps, with the walnut those are so.... luxury sailing vessel stateroom.

-M

Re: Downside to 4 speed vs six?

Reply #17 – January 13, 2011, 11:33:20 pm

Our 1997 U295 has walnut, C8.3 325, Allison 6 speed w/retarder but no joy stick, double pane windows, 42 gallon propane, propane furnaces, and "bus" doors on the bays. Joy stick is an easy addition ($500+-, cheaper if you do it yourself) which is very nice in the mountains.

Barry's lists at FORETRAVEL Motorhomes service and Repair Information are a super resource for comparing models.

Re: Downside to 4 speed vs six?

Reply #18 – January 16, 2011, 01:00:24 am

I'd like to thank everyone who took the time to post these great responses. Enough positive comments on both the four and the six speeds to make me feel confident that either will do the job well. I truly appreciate you guys sharing the benefits of your hard earned experience. At this point I will purchase the coach that is a good deal and that speaks to me. One thing I am sure of, though, is that it will say Foretravel on it.

I find myself in Springdale Ar., dealing with a beloved family member who has, unexpectedly, entered hospice. My wife and I are staying with her to the end which will, hopefully, be blessedly soon. I can't begin to tell you how much this experience reinforces our decision to chuck it all and hit the road to adventure. We are plotting our circuitous path back home to S. Tx. via various Foretravel coaches for sale. Hopefully one of them will be the one but if not we'll keep on searchin. This forum, and the like minded folks who appreciate quality hardware populating it have been a happy link to sanity through this ordeal.

I hope it's a six speed.

Regards, Chuck

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Downside to 4 speed vs six?

January 08, 2011, 11:17:00 am

Re: Downside to 4 speed vs six?

Reply #1 – January 08, 2011, 11:35:31 am

Re: Downside to 4 speed vs six?

Reply #2 – January 08, 2011, 11:41:15 am

Re: Downside to 4 speed vs six?

Reply #3 – January 08, 2011, 05:00:40 pm

Re: Downside to 4 speed vs six?

Reply #4 – January 08, 2011, 06:47:08 pm

Re: Downside to 4 speed vs six?

Reply #5 – January 08, 2011, 07:31:22 pm

Re: Downside to 4 speed vs six?

Reply #6 – January 08, 2011, 08:59:52 pm

Re: Downside to 4 speed vs six?

Reply #7 – January 09, 2011, 09:01:12 am

Re: Downside to 4 speed vs six?

Reply #8 – January 09, 2011, 01:52:54 pm

Re: Downside to 4 speed vs six?

Reply #9 – January 09, 2011, 02:22:57 pm

Re: Downside to 4 speed vs six?

Reply #10 – January 10, 2011, 12:33:22 am

Re: Downside to 4 speed vs six?

Reply #11 – January 10, 2011, 06:30:57 am

Re: Downside to 4 speed vs six?

Reply #12 – January 10, 2011, 01:02:44 pm

Re: Downside to 4 speed vs six?

Reply #13 – January 13, 2011, 05:54:17 pm

Re: Downside to 4 speed vs six?

Reply #14 – January 13, 2011, 06:23:48 pm

Re: Downside to 4 speed vs six?

Reply #15 – January 13, 2011, 06:30:12 pm

Re: Downside to 4 speed vs six?

Reply #16 – January 13, 2011, 10:43:19 pm

Re: Downside to 4 speed vs six?

Reply #17 – January 13, 2011, 11:33:20 pm

Re: Downside to 4 speed vs six?

Reply #18 – January 16, 2011, 01:00:24 am

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