Diesel Tuning PFinder

Built vs Stock Transmission

A stock transmission is often the limiting factor when considering horsepower upgrades. Built transmissions generally included upgraded internal clutches, a modified valve body, and an aftermarket torque converter. These upgrades allow your transmission to handle more torque and harness that power to the ground.

Are you Demanding a lot from your truck?

Deciding to build your Allison transmission before it fails is an appealing option. No one wants to be left stranded on the side of the road or stuck in LIMP mode. If you are planning to increase your power output and really work your truck hard, a built transmission is likely a required upgrade for you.

Is 400HP too much for a stock transmission?

It’s not the horsepower, it’s the all the torque you make at low RPMs with a diesel that really can cause problems. The 5 Speed Allison 1000 generally gets weak and starts to fail around 700-800 ft.lbs. of torque. Where the 6 Speed version can generally handle up to 900 ft.lbs before clutches start to slip.

Slipping Clutches

Inside your automatic transmission is a system of clutch packs and steels that engage and disengage to create different gear ratios. The hydraulic pressure that is applied to the clutches can be raised through either tuning or a shift kit. Raising that pressure, or just abuse over time, can result in wear and tear on the actual clutch material. A properly built transmission should always include some sort of upgraded clutches to ensure longevity and reliability.

Limp Mode

If you have ever had a P0700 code, or been stuck in 3rd gear with an Allison 1000 you know the horrible feeling that accompanies Limp Mode. This is a protection mode that your transmission goes into when it detects potentially massive issues. Often, limp mode can be temporarily cleared by cycling the key on and off 3 times. However, it’s root cause may be something like slipping clutches which cause an incorrect gear ratio. 


Have More Questions? We've Got Answers.

Call Us weekdays from 8am til 6pm. We’re happy to answer all your questions and explain transmission tuning.