Custom gear production

[Modern Garage]

Barstool discussion.
We were watching yesterday's Superbike race and the comment was made of a rule change allowing non original transmission ratios, which led to my dream of swapping an overdrive ratio in the third gear set on my car's four speed trans allowing me to have overdrive with no visible modification. Anybody care to hazard a wild guess as to the cost to cut and harden custom internal gears for a car or motorcycle?
Joe

 

[engineer2]

Talk to these guys.

AM Gears: tradition and technology | Euroricambi Group

An established brand based in Bologna, focusing on light commercial and 4x4 pick up vehicles, medium and heavy duty Japanese applications and agricultural machinery. Take a look at our full range here.

www.euroricambigroup.com

I think they have done some custom Muncie gear sets.

 

[speed bump]

Couple grand based on the ( bigger) gears I have had done before.

 

[RPH]

Look through this site. New gears require extensive design and production processes.

Home - Forest City Gear

Trusted in the Most Hostile Environments. Trusted in the Most Hostile Environments. Since Our Founding in 1955... we have developed a reputation as a world-class manufacturer of fine and medium pitch custom gears. Our uncompromising commitment to quality, innovation, and service is...

forestcitygear.com

 

[Modern Garage]

Thanks for the replies. A couple of grand for a one-off customer gear pair is about what I would have guessed with no design needed - just copy the original dimensions and change the OD's to another diameter and tooth number then heat treat.
My overdrive idea was just a pipe dream, but we were wondering what kind of investment the race teams were up against to change internal ratios.
Joe

 

[cannuck]

If you were to build an industrial gear meant to take automotive gearing loads, one single reduction pair would be bigger than your entire gearbox. I did a bit of testing for a major gear manufacturer and it let me sneak a few dozen peeks behind the kimono. It is an extremely specialized business. Yes, millions of people can cut gears but maybe a thousand or so on the planet have the skill and experience to produce GOOD automotive custom gearing.

If you want OD, best take a look at a Gear Vendors OD unit. No where near as nice as the Chicago Gear one - but that was dropped about 15 years ago (related to the rather rare dual range Corvette gearbox).

 

[Copymutt]

Check w/ these guys. Ive rebuilt specific ratio Muncies w/ their help. Z series might have an overdrive.

Auto Gear Equipment | Custom gearboxes | Muncie and Tremec Transmissions

Since 1945 AGE has been producing custom gear-boxes and Muncie and Tremec Transmissions for OEM systems and performance vehicles.

www.autogear.net

 

[Red 17]

Ford and Chrysler via NP did this in the late '70s.

Ford had the SROD from the top loader 4 speed: Chrysler and GM use the NP440 from the NP/Chrysler A-833/N833.

The result is a transmission with a weak OD, and a Grand Canyon gap between 2nd and 3rd.

You can find these transmission out there ready to go for RWD and 4x4s for not a lot of money.

To spend the money to make one would be a poor investment. You could have an OD 5er or OD automatic for less, or even a GV for less as indicated above.

 

[Monza Harry]

As @Red17 above points out that transmission is [or was] available. New gear sets for 1st (?), and 2nd are used to re-gear for the purpose of narrowing the gap from 2nd to 4th [direct] and 3rd becomes OD not cheap but looks correct for a purist looking car other than a shifter arm is flipped IIRC. They "were" expensive when introduced, so more modifiers went to the then emerging 5 & 6 OEM transmissions for similar money to the 4 sp. OD trans. Harry
I found a website talking about this gearbox: https://www.corvetteforum.com/forums/c3-tech-performance/1933960-munice-4-speed-overdrive.html but the links aren't working for me!

 

[Modern Garage]

Yes I remember the Ford and Dodge 4sp O/D boxes, that's what got me thinking about this, but my application is a little British car. After a good look at the parts I think it won't be feasible with this trans because of the inner dimensions of the gearbox. The 3rd speed gearset would have to be huge to overcome the primary ratio of input to cluster gear and wouldn't fit inside the box, and the primary reduction can't be changed substantially due to the input bearing size.
Just a daydream/thought experiment.
Joe