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Thread: Straight cut gears?

  1. #1
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    Straight cut gears?

    Has anyone put straight cut gears in an a555? Looking for my Consulier race car.
    I am a left foot braker and don't want to totally destroy the gears.
    With good rev- matching it shifts without the clutch pretty well. The warmer the tranny fluid gets , the more difficult to find the sweet spot.

    How tough are these gear boxes? How well do they hold up like this?
    And any other ideas ?

  2. #2
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Straight cut gears?

    I'm sure someone has. I know there are a couple straight cut 525s out there. The stock gearboxes won't like the clutchless shifts and will go through syncrhos, and fork pads pretty quickly if I had to guess. Over the years guys have taken off every other dog tooth on their gear sets to make crash boxes which will shift pretty easily without the clutch from what I've read. That may be something to look into.

  3. #3
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    Re: Straight cut gears?

    Thanks for the info so they just machined off the teeth? Synchros left stock?
    I have a couple tranny's that are in pieces as well as a couple which are NOS, so it sounds like a project to try.

    With the teeth modified in that way, does it create less strain on the parts? Or just help to get smoother shifts?

  4. #4
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Straight cut gears?

    This thread should answer all of your questions about this process along with a few you didn't know you had yet.

    http://www.turbo-mopar.com/forums/sh...Mods-Crash-Box

  5. #5
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    Re: Straight cut gears?

    if you're getting this involved I have a suggestion

    where the forks inside the trans bolt to the rods that move the fork back N fourth

    those little fork to rod bolts are a huge liability

    why?

    bolt with thread , threads into fork
    tip on end of bolt fits into hole in rod

    shift hard .. a lot

    tip breaks off end of bolt and drops out bottom of hole in rod

    tip then goes plink plunk all the way across the top of the gear sets

    until it gets to the ring gear and pinion...where it DOES go through

    then your case splits at the front secondary shaft bearing...end of race

    finding other little bolts and threading both the fork and rod would prevent this possibility

    better to have to drill out the little broken off part of bolt then waste the trans

    lol I managed to STILL drive THAT for 3-4 days afterwards

  6. #6
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    Re: Straight cut gears?

    There's been pictures floating around of a straight cut gear set that is believed to have come from a Team Shelby car. I *think* that set was for the A520/555, however, it was a close ratio set from what I remember. No other good information about it that I remember seeing out there.

    As for left foot braking, you don't downshift to the gear before the point where you need to apply throttle?

  7. #7
    Supporting Member Turbo Mopar Contributor zin's Avatar
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    Re: Straight cut gears?

    Quote Originally Posted by Dr. Johny Dodge View Post
    ...tip then goes plink plunk all the way across the top of the gear sets

    until it gets to the ring gear and pinion...where it DOES go through
    I know the old autos used to have the ATF and R&P separated so that the R&P could run regular diff lube, seems like a good idea in this case as it would eliminated the shrapnel in the R&P should something let loose in the trans, as well as allow the use of "proper" gear lube... (this would require welding things closed and a separate fill/drain plugs, etc. so not for the faint of heart for sure!)

    Mike
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  8. #8
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Straight cut gears?

    Quote Originally Posted by Reaper1 View Post
    There's been pictures floating around of a straight cut gear set that is believed to have come from a Team Shelby car. I *think* that set was for the A520/555, however, it was a close ratio set from what I remember. No other good information about it that I remember seeing out there.

    As for left foot braking, you don't downshift to the gear before the point where you need to apply throttle?
    I'm fairly certain the Team Shelby units were 525s.

  9. #9
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    Re: Straight cut gears?

    Quote Originally Posted by zin View Post
    I know the old autos used to have the ATF and R&P separated so that the R&P could run regular diff lube, seems like a good idea in this case as it would eliminated the shrapnel in the R&P should something let loose in the trans, as well as allow the use of "proper" gear lube... (this would require welding things closed and a separate fill/drain plugs, etc. so not for the faint of heart for sure!)

    Mike
    thinking a nice little sheet metal shield / deflector might not be hard to make .. if one could figure out a way to fasten it in the trans safely .. maybe use the secondary shaft bearing retainer bolts ??

    if anyone has pics , a link or can give some decent description of this manual trans with oil pump I'd like to hear or see about it

    I came to the conclusion years ago that not only do you have to watch for things getting hot .. you have to watch for them cooling back down afterwards as they may not do so at a rate all the parts are happy with

    case in point being my first 525 that locked up solid at 30 mph
    about 1 mile and 2 min after it had just made a downhill run at about 130 .. for about 1/2 mile

    - not knowing at the time .. ha ha , no oil

    I should add
    I rebuilt that trans .. tight , so tight the car idled slow for the first couple of min
    after that it was indestructible in a 200 hp car
    I had it for 6 more years until I traded it to a buddy who had long worn out his welcome with repeated transmission swaps
    afterwards I didn't have to fix his anymore so that 7-8 years I know of
    -new bearings, spider gears for turbo trans, diff pin and turbo 1-2 fork , new pads and 5-30
    I used a split pin from a dodge dart steering box coupler for the dif pin
    trans was 305 carb car
    I didn't check a single clearance I just let it idle and set it's self up

    and it survived the 6 motors that all lost rod bearings in front of it
    (yeah one a year ) so obviously I was beating things to hell

    trans always made the ride back lol - rest of the car , not so much

    and not to brag but rather put a much needed point on the ol' 525's score board
    that was the first transmission I ever took apart and put back together so I wasn't doing anything "special"

    it's the internal slop that allows parts to crash into each other and break.. thus any well used old trans is a failure waiting to happen
    Last edited by Dr. Johny Dodge; 05-02-2019 at 03:12 AM.

  10. #10
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    Re: Straight cut gears?

    I have thought about trying to separate the gearset from the diff, but because the pinion gear is in the gearcase and part of the output shaft, there's no way that I can see to completely divorce the FD from the gearset. The 2 will *always* share fluid.

  11. #11
    Supporting Member Turbo Mopar Contributor GLHS60's Avatar
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    Re: Straight cut gears?

    Best to run the thickest lube possible about a pint overfull rather then trying to seperate them.

    Thanks'
    Randy


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