Ingredients For Building a Bullet Proof 4L80E Transmission

Posted by on Friday, February 22nd, 2013

The 4L80E transmission is General Motors heavy duty 4 speed, overdrive automatic transmission. It can be found in some of the biggest and baddest vehicles they make and in many large motor homes.  It has also found a place in the heart of hot rodders looking for a transmission that can take the power their high horse power motors make.  Because these transmissions tend to live very hard lives, anything you can do to make them stronger is a good idea. Let’s take a look at some of the parts you would need to make a bullet proof 4L80E.



Input shaft – You want to look for a hardened shaft, preferably one made from 300M steel. It should be precision ground. A good racing input shaft will also have a resized diameter for more strength.

Bands and clutches – You will want to use high performance bands and clutch discs, such as those made of Kevlar.

Valve body modifications – Depending on what you plan to do with the transmission, there are a couple of different paths to take. If you plan on building this transmission for an all-out race car you can go with a trans-brake. Trans-brakes are not recommended for street use because they shift very violently. If you plan to using the transmission in a street car or towing vehicle than I recommend you go with a high quality shift improver kit. A shift kit can be used to change the timing of when the bands and clutches apply. This will cut down on both heat and excessive wear.

internal view of 4L80E


Planetary gear set – You will want to purchase a 6 pinion rear and a 5 pinion front planetary gear set.  You will also want them to be machined from a piece of billet instead of ones that were cast. Cast pieces are not nearly as strong as billet pieces. Companies such as TCI transmissions carry these specialty parts.

Forward Clutch Hub – Because the original forward clutch hub is made from a casting, you want to replace it with one made from CNC billet 4140 steel.

Torque converter – While not technically part of the transmission, it is still worth talking about. Don’t build a bullet proof transmission without upgrading the torque converter too, or it may all be a waste of time.  If the converter fails, it will likely destroy the transmission, too.  You want a transmission that has furnace brazed fins, a billet stator, anti-balloon plates, hardened and ground drive tube and heavy duty, fully welded mounting lugs.

4L80E planetary gear set

Source: Gmhightechperformance,com

There are other items that can be upgraded within the 4L80E but these are the majority of them. Don’t forget that when you order your re-manufactured 4L80E transmission, you can request that they include all these upgrades and more!

A transmission will not last forever, regardless of how well you take care of it. If a decision has to be made to replace the transmission, I highly recommend you consider a re-manufactured transmission as your first choice. They differ from a rebuilt transmission in the fact that they are as good as a new transmission at a greatly reduced price and often include modifications and upgrades that make them much more durable. A re-manufactured transmission also comes with a much better warranty: three years compared to 90 days for a rebuilt transmission.

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