Jimmy's Custom Speed Shop
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Current Transmission Designs

Over The Road Guys

Over The Road Guys

Over The Road Guys

Things are changing. Going to start offering RTLO18918B transmissions with treated main shaft, treated input shaft and the option of billet input. Through lots of testing, I'm very confident in what's now available for this crowd. Use the online contact link, at the bottom of this page, to get more info.

B & C Class

Over The Road Guys

Over The Road Guys

This unit has a lot going on. No slave valve or need to range while racing. You'll have 2 options for racing loaded and bobtail. Bobtail is easy, options are endless. Loaded you have 2 options for a top gear. Depending on rear gear and RPM range you can have a top gear of either 1.80 or 2.46 vs ranging the fuller to catch a 1.94 gear (5th)

Why The Oil Lines?

Why The Oil Lines?

Why The Oil Lines?

4 reasons for the lines:

  1. Filtered oil = Longer Life
  2. Bearings in this unit are tight - Pressured oil keeps things happy 
  3. High RPM creates heat. Pumped oil keeps it in check
  4. These transmissions are run with minimal oil in them. Oil circulation is needed. Less oil means less drag

A Class

Why The Oil Lines?

Why The Oil Lines?

Working on a main shaft. Stay tuned, we're close to having it ready. Once it's ready, those who have contacted me will be notified.

Frequently Asked Questions

Please reach out if you cannot find an answer to your question. If you don't understand or even disagree with, the answers to any of these questions, please reach out to me.

Let's use the factory Eaton 18 speed as our example. 1st to 2nd shift is a 30% drop. Say you shift at 3,000 RPM. That's an 900 RPM drop. If the tires don't break loose, what's taking that drop? Something has to twist / snap. I've talked with guys who claim they can shift without letting up. I then watched them destroy their driveline. Be honest with yourself, it's your wallet. A simple burp of the throttle will save you a ton of head ache. 


There's a LOT of different techniques. Long story short, the harder the part, the easier it shatters. With all the questions on this one subject, I've started to look into it much further. Stay tuned with some new ideas. Some already in use and working very well.


Started with 4 options, I've narrowed it down to 1. It works very well. 


This is always a tough one to answer. A transmission is a torque multiplier. How you do it, is what determines the longevity of it. Think of a mountain bike. There's 3 gears up front with 4+ at the rear. Bigger the gear up front the harder it is to pedal, compared to using the smaller gear. You can select several combinations to achieve a certain speed with a certain amount of pressure applied to the pedals. Same thought process is what makes this transmission survive. 


 Air compresses. The more room you give it, the longer it takes to compress. The way the race unit works, there's no need to range anyway. So why have extra stuff?


The first race transmission shifted just like any other transmission. After watching, it became obvious that everyone (racing loaded) was finishing in 5th gear (high side). That requires ranging, which takes time. Why not eliminate it and run a rear gear that doesn't stress the driveline? 


Use the clutch! Maintain RPM with your clutch. The sooner you get moving and off the clutch, the better. That doesn't mean side step it. It means learn your truck. Learn what gear you can launch in without destroying the clutch. Try to be an over achiever and you'll be buying a driveshaft at a minimum.


Once moving, get off the clutch and STAY OFF IT. (Been seeing a LOT of damage from guys who stab the clutch to shift.) Keep slight pressure on the shifter. Burp the throttle (do not mouse trap it). That slight pressure is all you need. If it takes more, you've got something going on that shouldn't.


Try this and let me know your results & thoughts. Feedback is welcome.


Have been working very hard on this! There's several designs currently being tested. The latest does have a very slight rake. There's been enough positive feedback, that we're going to start making these available for others to use. 


These are what I've seen and what guys are saying. Whatever you use, REMEMBER to slip the clutch, not just dump it.

C Class: 2 disc has been proven to last. Some are going to a 3 disc.

B Class: 4 Disc Atlas

A Class: 5 Disc Atlas


Units come with:

  • Iron clutch (bell) housing. Aluminum for non-race applications
  • New yoke will be installed, of your choosing
  • Reverse switch
  • After dyno oil is drained, 50w AMSOIL is put in.
  • You will re-use your pedal shafts. Too many different styles for me to keep track of.

After you get your transmission, there's on going service.

  • Any questions you may have - phone call away.
  • We will be at several events throughout the year. And will gladly help / answer questions. We have traveled to watch / help customers, when they go out for the first time. 
  • At seasons end, get your transmission back to us for inspection. If needed, we can address any issues. Better to find them during winter, than mid-season.
  • Ratio changes are limited, but possible. Want to try something different? Can do that. We will go over options. And a timeline.


Contact Us

Driveline questions? Let me know and I'll see what I can do for you.

Jimmy's Custom Speed Shop

Hours

Monday - Friday: 7am - 5pm

Saturday: By Appointment

Sunday: Closed

CONTACT SPEED SHOP

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