David Vizard said:
It seems to me that the real performance issue here is getting a gearbox to take the crushing torque output possible with a turbo. I have to admit my knowledge of current transmission tech is weak at best. What are the best possible choices for a tranny if I was to build a Turbo mini?? Some help please guys.
hi david ,
transmission wise ,heres what i have found at 248.7 bhp on a a plus box ...,some of it a bit contrary to popular opinion .
running through the drive train from the bottom up ,
the diff pin welds itself to the planet gears ,then rotates and digests the roll pin ,then the whole assembly rotates in the diff carrier...this all needs to be replaced with a 4 pin diff ,i use the one from min-its .
or you can go to the expense of a quaife atb ,or a plate type from trannex or mini spares etc .
the helical gearbox strips the teeth from 3rd gear and the 1st motion gear ,and leaves you with a box of teeth in the bottom and 4 stripped gears ,note this is on falken treaded tyres ,not grippy yok's.
solution ,i fitted the trannex clubman set ,straight cut ,with a 2.58 1st gear .first is a bit high for a 3.1:diff , but bearable .
now drop gears , i think i am the only one in the over 200 bhp elite lol using a helical gearset still , this has been fine and caused no problems ,this is quite contrary to accepted opinion ,generally from those who have no experience of running this sort of power.
here they are after a few years of abuse
well the normal thing to do used to be to run a grey cover or double grey ,and replace the thrust bearings every now and again due to the heavy loads put on the crank..
i then designed and built a twin spring verto clutch ,this is now used by most of the top bhp mini's,and seems to have solved the thrusts problem ,you may have read of them under the name 'rts' clutch ,egotistically standing for 'robert twin spring '(embarrised icon here! )
some have made thier own ,and some have asked me to make them ,both the fastest rd mini (12.5s 120 mph 1/4 mile nic rizzardini) and the most powerfull a series(16v,310 bhp john kimmens)...run my own bespoke clutches .so i think they are a proven solution .
lastly ,the bearing in the primary gear ,i run the floating bush ,and this HAS got well hot in the gear ,showing a sublte pinkish tinge and a few stripes ... i would say this is handling a fair bit more than its design spec !
generally 3rd gear is the gear that breaks ,i think i may have been a little easier on my box than those running relly grippy yokohamas ,and lsd diffs, i run a best of 2.32 60 ft and .767 g in 2nd gear on 23 lbs of boost ,they car is still wheelspinning at 70 mph on a grippy avon park track ,as data logged .
those with lsd 's etc can run anywhere from 1.95 to 2.2 60 fts ,which knocks a fair bit more off the overall time .