A855 - 5 Speed

torque rateing has little to do with real life.

my motor is a 300ftlb motor and for its 12 year production life sat in front of a 240Ftlb rated 4 speed (a bit like a ford Srod) which had some minor ratio tweaks, changes to numbers of needle rollers, metallurgy changes during its production life to improve a range of things, mainly torque handling and ratio changes to fit with rear end changes etc....
but it stayed as a 240ftlb rated 4 speed
the ford version with slightly fatter input, shorter output/tail and closer ratios was rated at 280 mine currently has ford-ish/ Aussie R/T ratios in a chrylser case.

its a rateing derived by knowledge of bearings and materials, distance between centres, dimensions and ratios of gears, and running the trans at a specific torque settings against an dyno brake for periods of time then extrapolating. the aim is to provide a rateing for torque handling that makes the car manufacturer confident that if it was physically possible to run the trans at say 300ftlb for the warranty period of the car they wouldn't be getting a warranty claim for busted trans.

id guess the dyno work either starts at a destructive level of torque or they work towards one and them aim to quote a rateing in the middle.
i.e the test version of a specific transmission might have handled 2 or 3 times the rated torque with a detrimental impact on its life expectancy
Lifeexpectancy has to be at a minimum longer than the warranty period of the car so the rateing is chosen to give say 5 years life rather than 5 weeks. thus a trans that isn't run at rated toruqe 100% of the time lasts 10 20 40 years and 200,000 miles

as for transmissions popping out of gear....as mentioned by other posters back in the thread if its a cottage industry transmission, do they have the facilities to do all of the testing that say TREMEC or Aisin do
did they have the finance to enegage with somone to do the testing for them.
or did they rely on "chrylser did all of this for 833" so a thick ally case and hang a 5th gear off the back is all we need to worry about.

id guess tremec probably still have a dyno room filled with machines and instrumntation that Mr Borg and Mr Warner purchased way back... and the modern equivelent slots in when the old gear breaks :)

mounting a complete trans on a lathe running it through the gears and then driving it in a car isn't really good enough. Not saying they did that but it is hinted at earlier :)

i take the attitude that if i'm gonna fit some upgrade to my car i'll focus on a chunk of more modern OEM stuff from brand x its been tested for me a million times by the people who purchased that car.... T5 for example fits with my needs its benfits and short comings are well known. The tremec 3550 was used as a 3650 in mustangs, and was the basis of modern TKO tremecs. The ford dudes tested that early Tremec box to destruction for us. They did not have an a833 in the back catalogue to do the job for 50 years, and ford looked elsewhere.

if you have a popping out of gear 855 i recon Paul Cangialosi at 5speeds.com could fix it. he is a very buiness minded man who has survived on his great reputation and inovative work for years. he also speaks his mind so if he thinks its crap... he'll tell ya. look him up on youtube, check that workman like attitude the skills and the advice.. and he answers the phone and replies to emails, even to some bloke in london called dave. thats rare, US companies studiously ignore me, its like getting blood out of a stone with most but thats another story..


Dave