a few have been really interested in how i am making the th425 work in a reversed rotation set-up work. so here it is :
i have made the "chain drive" into a "gear drive". by adding the 2 gears it makes the tranny run backwards. by running two different size gears, it changes the gear ratio for the better. depending on which gears i use i can get around 3.50 for a final drive. i still have a little more work to do on it, but that pretty much how it works. no, i am not selling this yet. there will have to be some deals made with some vendors and machine shops to make it affordable. as well as some major testing. i will not sell this until it has been proven to work, so that may be a while. it will be a direct bolt on and can be done in less than 1 hour. more to come later.
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10:59 PM
PFF
System Bot
Jul 15th, 2003
Gordo Member
Posts: 2981 From: East Guilford, NY, USA Registered: Mar 2002
There is no problem with running the transmission backwards(pump,etc.)?
since the pump still runs off the engine, it still pumps the same direction. the other gear (drive) gear is what runs backwards. all the gears and bands, ect, are all bidirectional, so they can go either direction with out any problems. the only problem could be is, if you ran some really different size gears (1 real big-1 real small) the could be some pressure & heating issues, but it would have to be really extreme. the only real issue is that the gears are noisy. kinda like gear drives on a sbc, but it sounds kinda cool. i am working on trying to get the noise down a little. more later!!
only way to cut down gear noise is by using a different tooth shape like a nice double hearingbone ( for a V ) or hypoid types of gearsets that maintain a constant mesh - is like the normal drive gears in a manual transmission vs the reverse gear - reverse is a straight tooth and noisy - the rest are quiet..
BTW Cardealer, that's an ingeneous method you came up with, very good.
While your working out your gear selections, how about a tidbit reguarding the above photo?
It looks like you fabricated a mounting plate that bolts up to the existing trans face, which then holds the two roller gears in place.
How about it?
Have you had a chance to look into this application working with the thm325 yet?
just as you described, mounting plate to 4 pre-existing holes in the trans. as of now there is no gear(s) that can be combined to get any real better gear ratio. i am working out a deal with a vendor for a 3.70 final drive, should be happening in the next couple of weeks. but it has nothing to do with the reversed rotation gear set. i havnt had time to research the th325 yet, but i really wouldnt feel comfortable about doing anything with that trans as it is week already. thanks for the complement, its nice to hear things like that. it makes me feel like not quite as big as idiot as i really am!
