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Topic: 4 speed vs. six speed Allisons (Read 671 times) previous topic - next topic

4 speed vs. six speed Allisons

I know Pierce & I have coaches of the same year, different sizes, but his is 4-speed. When did FT switch over to 6 speed for the 40 footers? Not a big deal on the flats, but, out here in the "Westies",  our "6"  sure works perfect. ^.^d
1993 U-240 "La Villa Grande"..CAT 3116 w/ Pacbrake PRXB...Allison 3060 6-speed..
Previous: 1983 Airstream 310 turbo diesel, 1979 Airstream 280 turbo diesel
                                      Build # 4297
                                      PNW natives
                      Home base:  'Cactus Hug' (Ajo, Arizona)
                        DW Judy & Chet the wonder dog
                        Full-Timers 'Sailing the asphalt sea'

Re: 4 speed vs. six speed Allisons

Reply #1 –
Not sure of all the facts, but when they put the 350 Detroit's in the 4 speed s to handle more power of the 6/92's as far as the hills I have no problems. Besides I don't get in a hurry any more . 8)
Andy & Eileen
MONTROSE COLORADO
1992 U300  40' 6V92 TA
2016 4 Runner
1998 Jeep Grand cherokee

1998 Jeep Grand Cherokee) Build # 4135 Skp# 122921

Re: 4 speed vs. six speed Allisons

Reply #2 –
93 mid year 6 speed was optional on U280
The selected media item is not currently available. Dave Head & Megan Westbrook
Titusville, FL - The Great Outdoors
'98 270 buying this month
Toad is a 2018 F150 XLT

Re: 4 speed vs. six speed Allisons

Reply #3 –
The four speed has a reputation of being bullet proof and the 6V-92TA had too much torque for the 6 speed at the time. I think it was 1995 before Allison fitted a six speed to the U300 that would handle the torque. By that time smog caught up with the Detroit so the '95s had CATs with one or two M11s. Smog also caught up with the CATs shortly there after. The big gain with the six speed is the great first gear ratio and the high gear that would drop our RPMs down on the highway. Our first gear starts are just OK at sea level but without a waste gate turbo, very slow off the line up at high altitudes like Santa Fe. Plus, we have to back up our driveway as first is too tall. Fuel mileage would probably go up a half mpg with the taller ratio. Our mountain home location also brings out the worst in the ratios.

Still, the 746 has done well by us in a little over 100,000 miles. The second, third and fourth gear lockups work great. The Detroit has used 12,609 gallons of diesel for exactly 8.0 mpg, up one tenth from the reading at 62,000 miles so not bad for the short fourth ratio.

While the U280 did have an optional 6 speed in '93, the 8.3 with Banks mods raise the torque beyond the recommended limits. The late 8.3s Cummins today have up to 380 hp as installed in RVs and lots more torque.

Pierce



Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: 4 speed vs. six speed Allisons

Reply #4 –
Quote from: Dave Head –
93 mid year 6 speed was optional on U280

Like good wines, I believe FT made their finest coaches from '93 to '96. I have the paperwork on ours, I don't know how to convert '93 dollars to current, but, I know our coach sold for for $200,000, without bells and whistles, like Zip Dee awnings all around.  ^.^d
1993 U-240 "La Villa Grande"..CAT 3116 w/ Pacbrake PRXB...Allison 3060 6-speed..
Previous: 1983 Airstream 310 turbo diesel, 1979 Airstream 280 turbo diesel
                                      Build # 4297
                                      PNW natives
                      Home base:  'Cactus Hug' (Ajo, Arizona)
                        DW Judy & Chet the wonder dog
                        Full-Timers 'Sailing the asphalt sea'
 

Re: 4 speed vs. six speed Allisons

Reply #5 –
Bob McGrath who owned Encore and was Foretravels top sales guy for many years at Nac when I last talked to him was looking for a 97-99 u320 36 or 40 for his personal use.

I reminded him he had had a 97' 40 on his website he owned.  He said he sold it and after his third pacemaker installed wanted to go rv'ing.

No idea where he ended up or if he found a coach ever.

"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4