mo.woodie Posted January 21, 2014 Report Share Posted January 21, 2014 Hi, I've got a l20b mated to a BW35 auto and a diff ratio of 2.8:1 with 205 65r 15 tyres in a 62 Commer van which was in the car when i got it, I'm still restoring the van but have some questions regarding this set up. 1/ Would anyone know if this set up would work. 2/ Is there a 4 speed auto to fit the l20b to give it longer legs when cruising 3/ i'm thinking 2.8;1 is not right for this set up maybe 4.2:1 ? Any help would be gratefull Quote Link to comment
MikeRL411 Posted January 21, 2014 Report Share Posted January 21, 2014 Whitch Borg Warner transmission? The British "Letchworth" if I haven't screwed up the spelling, or the US Muncie Indiana unit? They are different! Quote Link to comment
RTB Posted January 21, 2014 Report Share Posted January 21, 2014 Wouldn't a higher diff ratio give less cruising ability. Higher ratio means better acceleration. But higher RPM on the highway. Quote Link to comment
mo.woodie Posted January 21, 2014 Author Report Share Posted January 21, 2014 how can u tell which box it is, british or us? Quote Link to comment
MikeRL411 Posted January 21, 2014 Report Share Posted January 21, 2014 how can u tell which box it is, british or us? Quick check without crawling under the car or dismantling anything is to look at the carb plate. If you have a cable hooked to the throttle shaft and disappearing into the transmission, it's a mechanical downshift British Borg Warner. If not, then it's a vacuum shift American Muncie Indiana transmission. The purist will crawl under the car, degrease and copy down the info from the ID plate on the transmission housing. Given your location and the autos listed, I would bet on the British unit. It was used all over Europe. Quote Link to comment
mo.woodie Posted January 21, 2014 Author Report Share Posted January 21, 2014 yes it is the British one Quote Link to comment
ggzilla Posted January 21, 2014 Report Share Posted January 21, 2014 Its a BW35 Yes it will work, but with very slow acceleration because tall tires and high gearing. Changing to 4-speed would have almost the same cruising capability- which is very high geared already. The L20B is comfortable cruising at 3500 rpm, so it don't need longer legs. 4.1 will give a tremendous boost to acceleration. Quote Link to comment
mo.woodie Posted January 22, 2014 Author Report Share Posted January 22, 2014 So if i change to a 4.2:1 diff ratio would it benefit me to also change to the 4 speed auto? Quote Link to comment
ggzilla Posted January 22, 2014 Report Share Posted January 22, 2014 Benefit everything except your pocketbook. Quote Link to comment
mo.woodie Posted January 22, 2014 Author Report Share Posted January 22, 2014 Thanks mate for your input i can get a humber hawk diff with the correct ratio and PCD to suit my commer and front disc conversion as well, Now only have to find the 4 speed auto.. Cheers Quote Link to comment
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