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The OCTA and its articles are in a serious need for updates because the fleet info is incomplete particularly because there are shuttle buses used for OCTA ACCESS Service that are not in the fleet. I have lived in Orange County, California for almost my entire life and this is the bus system where I had my first bus rides in 2015! The following details that must be added to the OCTA and its articles are: The OCTA was established in 1991 from the Orange County Transit District OCTA units 8501-8599 are 2014-2015 Glaval Buses built on a Ford F-450 Chassis OCTA units 8601-8700 series are 2017 StarCraft buses built on a Ford F-450 chassis OCTA routes 20, 51, 145, 187, 188, 191, 193, 410, 411, 430, 464, 490, 757, and 758 are discontinued Add OCTA routes 53X, 57X, 64X, 150, Bravo 543, and Bravo 560 OCTA units 8301-8364 were 1999 ElDorado National Aerotech buses built on a Ford F450 chassis. These buses were retired in 2008. OCTA units 6301-6312, 6400s, 6500s, 6600s, 6700s, and 6800s have been retired. OCTA units 6341-6345 OCTA units 5122, 5675, and 7575 have Near Zero ISL-G engines All 2007 New Flyer C40LFRs (5502-5599, 5601-5674, 7501-7528) have Cummins Westport ISL-G engines OCTA C40LFR build dates: 5501: September 2006 5502: March 2007 5505-5508: April 2007 5510-5530, 5540, 7529: May 2007 5536-5539, 5541-5542: June 2007 7501-7528: January 2008 7572: July 2008 7592: May 2008 OCTA XN40 build dates: 5702: January 2015 5753-5761: July 2016 5765-5775: August 2016 5852-5856: January 2017 5858: February 2017 OCTA NABI 40-LFW build dates: 2117: July 2000 2144-2160: August 2000 2201-2215: July 2001 2217-2270: August 2001 2277-2320: September 2001 2323-2372: October 2001 Units 2209, 2214-2215, 2217-2218, 2222, 2228, 2232-2233, 2237, 2243, 2248, 2254-2255, 2263, 2270, 2278, 2280-2281, 2287-2288, 2296, 2311, 2313, 2317, 2324, 2340-2341, 2345, 2349, and 2357 are active. All other 2200s and 2300s are retired. 1100s series Flxible New Looks have Detroit Diesel Allison V730 transmissions OCTA units 6351-6364 have Hanover Monochrome LED signs New Flyer D40LF units 5302, 5306, 5331, 5335, 5342, 5353-5354, 5362, 5376, 5387-5388, 5401, 5403, 5406, 5408-5412, and 5416 are presumed to be active. 1987 OCTD SuperBuses: 7001-7002 (White Motor Company WX42 trucks), 7501-7502 (Capre SuperBus trailers) 1993 OCTA SuperBuses: 7101-7110 (WhiteGMC WX42 trucks), 7601-7610 (SuperBus Trailers) 1997 ElDorado National Aerotech buses built on Ford Econoline chassis: units 8101-8191 1995 New Flyer D40LF units 5208 and 5241 tested two separate experimental OCTA paint schemes in 1999. 5208 had the two-stripe orange and blue 'Millennium Look' livery while 5241 had a mostly blue and white OCTA livery. OCTA unit 6031 was a 2008 ElDorado National E-Z Rider II BRT originally intended to replace the 1997-1998 E-Z Riders, but it was rejected. This bus supposedly had a Cummins Westport ISL G with an Allison Transmission B300R and Transit Sales International is presumed to have this bus on their website.

Since I haven't found any good thread to put this in (as this pretty much applies to any vehicle with an Allison transmission), I'll start this thread here and hope somebody has an answer. Today I came across this document on the web: https://freightlinerads.azureedge.net/ShiftSelector2013.pdf It shows how to use the familiar keypad I've seen on many buses I've been on. In particular, I've noticed the so-called "5th Generation Electronic Controls", which has the high-res, dot-matrix graphical display, looks different from the one I've seen on vehicles in the GTA like GO Transit's latest D4500CTs and Enviro500s (and even retrofitted to its old coaches, such as this one below): https://1drv.ms/i/s!AgqCsfFShZgBidkZJejIlrCELE77CQ As you can see, despite the crappy resolution of my image, the typeface used to display the transmission speed looks different from the one in Allison's PDF document; while the latter shows crude-looking numbers, the ones I've seen use the beautiful-looking Arial font. I believe this could be attributed to one of Allison's OEMs, as quoted in the document: Is this so, and if it is, does anyone have further information about who made the shift selector seen in my image?

I am sure most of you know about the Allison HT740 and HT747 transmissions, but the lower-rung MT644 and MT647 are not quite fondly as remembered. These share some of the same parts, such as torque converters. The MT644 was designed for engines up to 300 hp and 780 lb/ft of torque, whereas the later MT647 ups the input torque rating to 950 lb/ft. But for transit buses, these ratings will be different; for now I know the input hp limit for bus engines is 250. The MT648 was the electronically-controlled equivalent of the MT647. Torque converter ratios are 2.21 (TC495) and 1.92 (TC494). The HT740 was designed for engines up to 425 hp and 1300 lb/ft of torque, but in transit buses those ratings are reduced to 350 hp and 1100 lb/ft. The HT747, with its special three-gear pump for better coolant flow, is used only in transit buses and is rated for engines producing up to 350 hp and 1100 lb/ft. The HT741 and HT748 are the respective electronic equivalents of the HT740 and HT747. Torque converter ratios are 3.04 (TC470), 2.21 (TC495), 2.09 (TC499) and 1.83 (TC496, not available for HT747). I also want to know whether or not any buses that originally came with the MT644 or MT647 were changed to the HT747 or HT748 transmissions for durability reasons shortly after initial delivery or during their mid-life overhaul? So far I know a few buses had swapped out their MT644 or MT647 transmissions for HT747s or HT748s: Timmins Transit (Timmins, ON) 1982 Orion I 01.504 52-54 (54 was later resold to Ajax Transit as 2044) Mississauga Transit (Mississauga, ON) 1983 Orion I 01.504 8401-8404 Mississauga Transit 1984 Orion I 01.506 8405-8416 (8416 was resold to the National Research Council shortly after initial delivery) Mississauga Transit 1985 Orion I 01.508 8501 (replaced 8416) Vaughan Transit (Vaughan, ON) (later York Region Transit) 1987 Orion I 01.502 517-518 (original 6V71N engines were also reportedly changed to 6V92TA MUI's) University Transit Service (Charlottesville, VA) 1983 Orion I 01.506 5139-5239 and 5337 ~Ben

I am wondering if anyone has any application data regarding the Allison automatic transmissions used in our favorite buses of the 1970s, 1980s and early 1990s? Typically, these are the transmissions to be used in city buses: 100-175 hp = AT540, AT545 175-210 hp = MT640, MT(B)643 210-250 hp = MT(B)644, MT(B)647, MT(B)648 175-275 hp = MT(B)654CR, V730, V/VR731(RH) 275 hp or more = HT740, HT(B)741, HT746, HT747, HT(B)748 ~Ben

Has anyone ever determined which torque converter ratio is best for each engine/transmission combo? Example 1: Allison AT545 transmission with TC290 (1.72:1) torque converter behind Cummins B5.9 190 hp (475 lb/ft) engine Example 2: Allison MT643 transmission with TC360 (2.86:1) torque converter behind Cummins B5.9 210 hp (485 lb/ft) engine Example 3: Allison MT644 transmission with TC494 (1.92:1) torque converter behind Detroit Diesel 6V92TA 253 hp (766 lb/ft) engine Axle torque ratings: calculated input torque to axle, determined by: T = maximum gross engine torque (lb/ft) N1 = lowest transmission forward gear ratio N2 = torque converter stall ratio (2.5 or specific value for automatics, or 1 for manuals) Say you have a Detroit Diesel 6V92TA MUI (mechanical unit injection) engine mated to an Allison MT644 automatic transmission, being used in an Orion I transit bus. Allison recommends the transmission not exceed more than 740 lb/ft of input torque from the engine for transit bus applications. Only two TC (torque converter) ratios were produced for the MT644: 1.92 (TC494) and 2.21 (TC495). As the 6V92TA 253 hp engine has 766 lb/ft of torque, the 1.92 TC ratio would be best suited to the transmission. Otherwise, the Allison HT747 transmission (for engines up to 345 hp/1100 lb/ft) is recommended. 766 x 3.58 x 1.92 = 5,265 lb/ft input torque to axle. If anyone knows what the recommended input torque to axle rating is for a Rockwell R143 series rear axle with 4.63 and 4.11 ratios, please try to answer. ~Ben

Is it true that the 1982 and '83 Orion I's--the U.S. versions finished in New York--used the Allison HT747 transmission (rather than the original HT740) behind their DD 6V92TA engines? I'm talking about those buses as run by such agencies as: Pacific Transit System (Raymond, WA) Milford Transit District (Milford, CT) Montachusett Regional Transit Authority (Fitchburg, MA) Yakima Transit (Yakima, WA) SLO (San Luis Obispo) Transit (San Luis Obispo, CA) San Luis Obispo Regional Transit Authority (SLORTA) (San Luis Obispo, CA) GATRA (Taunton, MA) IndyGo (Indianapolis, IN) Waukesha Metro Transit (Waukesha, WI) The 1982 GATRA Orion I's are unique in that they were the only such 35-foot units finished in NY to carry the old model 01.504, since most of these got out with the model 01.506, which continued into part of 1984 (the year both the 01.504 and 01.506 were replaced by the 01.507). Did these three buses, numbered 8217 to 8219, use the Detroit Diesel 6V92TA engine and Allison HT747 transmission? ~Ben

Has anyone here heard of the Allison MT654CR 5-speed close-ratio automatic transmission? I know it seemed most popular outside North America; many articulated buses in those countries used it including the Volvo B58 and B10M. Input power: 300 hp max Input torque: 950 lb/ft max Input speed: 1900-3000 rpm Transmission gear ratios: 1st: 4.17:1 2nd: 2.21:1 3rd: 1.66:1 4th: 1.27:1 5th: 1.0:1 Reverse: 10.76:1 Torque converter ratios: TC430: 3.59:1 (crawl ratio: 14.97:1) TC495: 2.21:1 (crawl ratio: 9.22:1) TC496: 1.83:1 (crawl ratio: 7.63:1) TC497: 2.7:1 (crawl ratio: 11.26:1) Crawl ratio: first gear ratio x torque converter ratio ~Ben

Is it true that the MCI MC5C only listed the Allison MT644 as the automatic transmission (for both the 6V71 and 8V71 Detroit Diesel engines), with the HT740 being a special order option not listed in dealer brochures? I know the MT644 certainly was the only automatic that could fit behind the 8V71 in the MC5C without extra clearance, since the 8V71 is a longer engine due to it having two more cylinders compared to the 6V71. The HT740 automatic transmission was both superior to and longer than the MT644, the "longer" part of the aspect being the reason I see all these posts (on Bus Talk and related websites) about the 8V71/HT740 not being compatible in the MC5C due to the overall length of the powertrain, but I did see posts about the 6V71/HT740 being a good fit for the MC5C. That bit being said, even the 6V92TA/HT740 combo, as used in the MC9 since 1981, could make a good-enough fit in the MC5C. Could anyone please shed some light as to whether or not both the MT644 and HT740 were cataloged in the official MC5C brochures? Thank you, Ben (ClassicBusFan81)