Results 1 to 15 of 15

Thread: New billet low/reverse drum

  1. #1
    Garrett booster
    Join Date
    Jan 2013
    Location
    zanesville
    Posts
    186

    New billet low/reverse drum

    Here's our first prototype of the aluminum low/reverse drum with upgraded 12 roller sprag. The factory sprag only has 8 rollers, this prevents the high gear drum from flying apart.



  2. #2

    Re: New billet low/reverse drum

    What transmissions does it fit? Are you planning on selling any?

  3. #3
    Garrett booster
    Join Date
    Jan 2013
    Location
    zanesville
    Posts
    186

    Re: New billet low/reverse drum

    These are going to be for the 3 speed auto.

  4. #4
    turbo addict
    Join Date
    Jan 2006
    Location
    Hazelwood, MO
    Posts
    6,566

    Re: New billet low/reverse drum

    I can't remember right now...is the sprag used in all forward gears or only in 1st while in the "D" position on the stock automatic valve body?

    As I understand it the sprag is a known weak point. I am also pretty sure that there is a way to hydraulically accomplish 1st gear without using the sprag. Besides adding to things that need to move to engage 2nd gear, is there any benefit to doing it that way and if so, why not just bypass the sprag all together and just make it as light as possible?

  5. #5
    Garrett booster
    Join Date
    Jan 2013
    Location
    zanesville
    Posts
    186

    Re: New billet low/reverse drum

    The sprag is only against the one-way in 1st, it spins I'm second. Your thinking low band apply, I'm currently working on a valve body using the newer cores. It will be reverse pattern, low band apply, 1-2-3-n, and ability to regulate reverse line pressure separate.

    But you cannot get around the sprag, low band will help prevent the drum from flying apart but the sprag still slips tearing the race up and eventually sends the high gear drum flying. The only way to fix it is to add rollers.

  6. #6
    turbo addict
    Join Date
    Jan 2006
    Location
    Hazelwood, MO
    Posts
    6,566

    Re: New billet low/reverse drum

    Ah...ok. It's been a while since I really looked at it, so thanks.

  7. #7
    Garrett booster
    Join Date
    Jan 2013
    Location
    zanesville
    Posts
    186

    Re: New billet low/reverse drum

    Next part I'm working on is the forward drum out of aluminum. It will be splined to use 904 clutches for high gear drum which have a lot more surface area and will be more readily available.

  8. #8
    turbo addict
    Join Date
    Jan 2006
    Location
    Hazelwood, MO
    Posts
    6,566

    Re: New billet low/reverse drum

    I know these are race only type parts, so the transmissions get torn down for inspection "regularly". I am wondering how you are attacking any issues that might arise from the clutch spline teeth wearing away at the drum splines?

  9. #9
    Garrett booster
    Join Date
    Jan 2013
    Location
    zanesville
    Posts
    186

    Re: New billet low/reverse drum

    I will use 7075 which is about the strongest you can go. It's what everyone uses and they see little to no wear. Now for the forward drum I'll probably have it hard anodized.

  10. #10
    Visit www.boostbutton.com... Turbo Mopar Contributor ShelGame's Avatar
    Join Date
    Dec 2005
    Location
    Whitmore Lake, Michigan, Unite
    Posts
    9,918

    Re: New billet low/reverse drum

    2nd the question about - are these going to be for sale?
    https://db.tt/SV7ONZpQ
    Rob Lloyd
    '89 Daytona C/S

    2.5 T1 Auto
    13.24 @ 100.5mph
    NHRA #3728 AF/S

    boostbutton.com
    tuning wiki

  11. #11
    Supporting Member II Turbo Mopar Contributor A.J.'s Avatar
    Join Date
    Feb 2006
    Location
    Mesa, AZ
    Posts
    2,427

    Re: New billet low/reverse drum

    Quote Originally Posted by boots View Post
    Here's our first prototype of the aluminum low/reverse drum with upgraded 12 roller sprag. The factory sprag only has 8 rollers, this prevents the high gear drum from flying apart.
    I've had a bunch of auto 3 speeds apart and have never seen a problem with the rear drum. Under what conditions does the rear drum come apart or at what horsepower level is yours needed at?

  12. #12
    Garrett booster
    Join Date
    Jan 2013
    Location
    zanesville
    Posts
    186

    Re: New billet low/reverse drum

    I will offer people a chance to get in on the batch once I get more of the details worked out. Still working on final price and quantity, I just didn't want to break any rules since I'm not a paying vendor.

    The the drum itself does not wear, the rollers slip on the race and chews it up. Once they slip it sends the high gear drum 2-3x engine speed and the drum flies apart. Ill post pic of my trans after the drum exploded. Now if the car isn't leaving hard or stalling high then maybe you won't need it. I just wasn't chancing ever again, I don't want to be hit with drum chunks.

  13. #13
    Moderator Turbo Mopar Staff Vigo's Avatar
    Join Date
    Feb 2006
    Location
    San Antonio,TX
    Posts
    10,798

    Re: New billet low/reverse drum

    I guess if the sprag slips the drum is spinning the same speed it would in 1st gear which is ~2.6x engine speed. It would feel like a slipping condition but with such a strong motor it would go from sprag slipping to drum exploding so fast you might not be able to let out quick enough.

    Dont push the red button.You hear me?

  14. #14
    Garrett booster
    Join Date
    Jan 2013
    Location
    zanesville
    Posts
    186

    Re: New billet low/reverse drum

    I couldn't tell that the sprag was failing, I was foot braking the car and let off the brake and a loud bang happened. Here's the aftermath.


  15. #15
    turbo addict
    Join Date
    Jan 2006
    Location
    Hazelwood, MO
    Posts
    6,566

    Re: New billet low/reverse drum

    Quote Originally Posted by boots View Post
    I couldn't tell that the sprag was failing, I was foot braking the car and let off the brake and a loud bang happened. Here's the aftermath.

    YUMMY!! Stir that stick for another 10 minutes and you'll have a tasty treat! LOL

Similar Threads

  1. Transmission 2 billet low/reverse servo pistons.
    By turbovanmanČ in forum Parts For Sale
    Replies: 0
    Last Post: 11-05-2014, 02:25 PM
  2. Drum nooob here.. what do I need?
    By Rrider in forum Suspension, Brakes, Wheels, Traction
    Replies: 13
    Last Post: 12-13-2012, 01:31 PM
  3. Drum Brakes 101?
    By RoadWarrior222 in forum Suspension, Brakes, Wheels, Traction
    Replies: 4
    Last Post: 08-17-2010, 06:08 PM
  4. 413 Billet Reverse Servo?
    By stage3 in forum Transmission
    Replies: 6
    Last Post: 07-23-2010, 05:09 PM
  5. Aluminum drum?
    By ShelGame in forum Transmission
    Replies: 12
    Last Post: 03-21-2007, 12:42 AM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •