Allison/General Motors 10-Speed Transmission Recall: How We Fixed It!

Table of Contents:

• Preface from the Author
• Introduction to the Infamous General Motors 10-Speed Recall (#N242454440)
• How can Transmission Can Cause the Rear Axle to Lock Up?
• What Inside the Transmission is Causing the Problem?
• So How do I Fix It?
• Conclusion

Preface from the Author:

Before we go into detail about this problem and how to fix it forever, we need to offer some preface. 10-Speed General Motors and Allison transmissions are just a small piece of what we design here, but we are so angered by the dishonest way General Motors has managed this recall that we felt that we had to write this and put this information out there 100% for free and in public forum.

We are the company that engineered a fix for this back in mid-2023. We actively receive several calls a day from people who are down all over the country, often little or no support from General Motors. Most of them are not being given loaner vehicles, and some are on the verge of losing their businesses and their homes.

There is a fix, and we want you to know about it because we believe General Motors is actively hiding it from you. Do not let them tell you there’s no fix as you see in the NHTSA filing linked below. It’s simply just not true, which we will prove to you shortly.

Look at this excerpt from the official recall documentation published by the NHTSA where they pledge that they will fix your vehicle for free, but unfortunately there simply isn’t a fix. This a bold-faced lie. We have the remedy, and we have more than enough of them to service the vehicles that are down and General Motors has known this for over a year.

In fact, we can have the parts to fix these vehicles on-site as quickly as overnight shipping with early morning delivery. General Motors simply doesn’t want to pay the bill their engineering malpractice created, and now they’re socializing these costs onto their consumers, and we think you should know about it.

Furthermore, we are aware that some people who are knowingly or unknowingly doing public relations work for General Motors are claiming that this is “barely a problem” and only “effects a few vehicles.” Not only is this unintelligent argument essentially a dismissal of the thousands of people making payments on a vehicle that’s dust-collecting at their local shop or dealership, the facts also prove otherwise.

As of November 2024, 462,000 vehicles are covered under this recall and it appears the recall may be expanded to cover even more. Of course not all of them are experiencing this problem, but all of them contain the parts that cause this problem to take place - a serious concern.

We sincerely hope this helps get you back on the road with peace of mind. If you need absolutely anything, our friendly staff are a phone call away and are trained at length on this specific recall. We’re here to help. We’re assuming that this content will make it back to General Motors, and that’s fine. They knew it was coming. Without further ado, enjoy the publication.

Introduction to the Infamous General Motors 10-Speed Recall (#N242454440):

If you have a 10-Speed General Motors or “Allison” (It’s not an Allison, they paid to license the brand name) transmission, you likely know about the major recall that was issued over the rear axle locking up at high rates of speed; a highly dangerous problem. Can you imagine towing a fifth wheel and the rear axle locking up? You don’t have to, because here’s a video:

Now, according to the all-knowing omniscient engineering geniuses at General Motors, you can still drive the vehicle. Just know that if the vehicle locks up while driving, there may be an increased risk of crash. Does this video look like a safe vehicle to be operating? Would you let a loved one drive this vehicle after witnessing it malfunction like this? We didn’t think so.

We at Next Gen Drivetrain™ have a unique perspective on this problem because we told General Motors about this extreme safety problem for the first time in the beginning of 2024, shortly after the new year. Here’s the crazy part. When we informed them of the problem, and even offered the fix, they usually ignored us, or simply declined to purchase the fix for their customers even at a deflated price.

To make matters worse, we alone have documented hundreds of different vehicles with this problem and it is likely that the vast majority of people with this problem have never contacted us, imputing that it is a massive problem.

To give credit where it is due, some dealerships were willing to let us help them because they didn’t want to be forced to buy back thousands of vehicles. Most of them even paid out of pocket just to help their customers after General Motors denied paying for the fix. When’s the last time you heard of a dealership doing that? But unfortunately, the higher powers of General Motors did not want to hear us or their dealership network out.

Here’s where it gets even worse. We now see General Motors publicly telling people that there’s no mechanical fix. This is a lie, we fixed this over a year ago. We know this because we spoon-fed them this information long before they ever acknowledged the problem. They even told nearly every dealership we were working with that they were unwilling to pay for the repairs using our parts, even when offered a discount to simply help these customers.

They have publicly stated that the best they can do is provide a software update that monitors pressure and puts the vehicle into a “failsafe mode” before the rear axle can lock up. This does not fix the problem, it simply masks the symptom with limp-mode.

Worst of all, the “updated valve body” they claim to be releasing also does not appear to fix the problem. How do we know? We sourced one from an insider and disassembled it, only to find nominal changes that did not directly impact the problem. 

How can the Transmission Cause the Rear Axle to Lock Up?:

With some data logging and mechanical gauges, you can piece together the puzzle relatively easily. Before we explain what causes this problem, we need to explain a bit about how this transmission works.

Like most 10 speed transmissions, this computerized unit does not have any bands, levers, anchors, struts or servos. It’s a strictly clutch-pack based transmission. This isn’t necessarily a problem but it’s relevant to us understanding the cause of the issue.

There are 6 clutch packs in this transmission, two brake clutches and 4 rotary clutches. At any given time, there are 3 clutch packs turned on to enable a continuity of torque through the transmission. 

This means that if at any time there are only 2 clutch packs engaged, the transmission will likely be immobilized/neutralized, and if at any point there are 4 clutch packs engaged, the transmission will try to enter two gear ratios concurrently and create a bind-up condition.

There is a clutch pack in the torque converter as well, but it’s not related to this problem in any way. When we began studying this problem, we realized that the most likely issue was a fourth clutch pack applying at an inappropriate time. 

Like we stated, if at any point a fourth clutch pack engages, the transmission will likely “lock” the output shaft, causing the rear axle to lockup. If the vehicle is in 4WD, it will also lock the front axle. Let’s explore how we figured this out.

What Inside the Transmission is Causing the Problem?:

So what specifically is causing the problem to happen? It cost us hundreds of thousands of dollars in research, design, drafting, data collection, testing and prototyping to fix this problem. Because of this, it frustrated us that General Motors is going so far out of their way to pretend there is no fix for this problem.

It’s even more disturbing when you consider the fact that many people with these trucks are business owners whose lives are financially destroyed by losing access to their vehicle for so long. This is one of the main reasons we’re making this information public.

Worst of all, General Motors has thousands of in-house (and outsourced) engineers. Little ol’ Next Gen Drivetrain™ only has one in-house engineer - the only engineer. How were we able to fix a problem that General Motors with their thousands of engineers could not resolve? Here’s what we discovered and how we figured this out.

We design re-engineered, upgraded 10-Speed Allison/General Motors transmissions and valve bodies that have never had this problem. This means that clearly one of the parts we designed is correcting the issue, and we were determined to figure out what.

Also, we discovered that the Ford 10 Speed (this transmissions fraternal twin) did NOT have this problem. This means that the problem is logically caused by something the General Motors variant has that the Ford variant does not.

Further, we discovered that customers who installed our Project Carbon® General Motors 10-Speed Valve Body Upgrade Kit almost always fixed the problem, and that customers who installed our re-engineered Project Carbon® General Motors 10-Speed Valve Body always fixed the problem.

This means that the problem is clearly caused by a hydro-mechanical difference between a Ford and General Motors valve body. But, we discovered something else that was even more alarming. Are you ready for this?

There are two generations of the 10 speed General Motors transmissions, but only one type of the 10 speed Allison which is most similar to the later generation of the 10 speed General Motors unit. Why is this important?

We have zero recorded events of the first generation of the valve body having this symptom. The first generation of this valve body is almost identical to the Ford 10R80. This helped us narrow it down even further because we now know that the problem is something that was changed between the first generation and second generation 10 speed General Motors transmission.

Also, we know that the problem is a part that is mutual in design between the Allison variation of this transmission and the General Motors variation of the transmission. At this point, there are only so many parts remaining.

Lastly and perhaps most importantly, the problem becomes more likely as the transmission ages, implying it’s caused by a component wearing out or degenerating rather than a spontaneous electronic failure.

So what ultimately was the problem? A combination of crossleaks in the valve body that become worse over time can trigger the transmission to apply a fourth clutch pack erroneously in some of the higher gears, causing a bind-up condition that locks the output shaft of the transmission and subsequently the rear axle.

This is why most customers who installed our Project Carbon DIY valve body upgrade kit fixed the problem, but ALL who installed the valve body fixed the problem. Our Project Carbon Valve Body DIY kit corrects most bore wear, short of extreme scenarios, but our complete valve bodies are machined to perfection and pre-tested, effectuating the 100% fix-rate for the problem.

So How do I Fix It?:

Before we get to this, we need to identify if your transmission has been significantly damaged or not. The strongest and most accurate indicator of this will be fluid complexion. If the fluid looks new or almost new, you can likely perform a valve body upgrade to correct the condition.

If the you wipe the fluid on a white towel and it appears any darker than a red wine, it is contaminated with a large enough amount of clutch material to where this is a meaningful amount of wear inside the transmission.

This does not automatically mean the transmission is “toast” but it does mean that a large amount of wear has taken place. In this scenario, upgrading the transmission is the best option. If you’re unsure how to decipher your fluids color, simply send us a picture and we’ll have an expert review it.

In short, if your fluid looks like the jar on the left, it’s transmission time. Of the fluid looks like the jar on the right, it’s valve body time unless you’d like to perform a transmission upgrade voluntarily.

If it is determined the transmission can be salvaged with a valve body upgrade, there are two options. One is valve body upgrade kit for the General Motors variant and the Allison variant of the transmission. These kits are 100% designed by us, and manufactured in-house using billet steel valves with high-temp O-Rings, the same used elsewhere in the transmission, to correct all major wear points.

They also include a separator plate that molds around the imperfections of the valve body as it heats and billet clips to align the solenoids. Short of extraordinary scenarios, this is usually a long term fix. This kit installs in about 2 hours for an experienced transmission technician beginning to end and closer to 4 hours for your local beer-drinking can-fix-anything suburban dad. Either way, it’s relatively easy.

In more worn out vehicles, or for people who question the integrity of their electronics, a complete valve body offers more benefit. A complete valve body is machined to perfection, and features new electronics/sensors everywhere, truly restoring the vehicle to day 1 operability with all enhanced and redesigned parts.

If the transmission appears compromised from the failure, an internal repair is likely needed. In most cases, an exchange from us is the most beneficial option rational to cost. This is because the price to remanufacture this transmission correctly is very high, do NOT be fooled by cheap “rebuilds” that supposedly fix these issues only to experience the same problems down the road.

Although we do supply some smaller transmission shops with our parts, we do not supply these parts to any other major transmission companies; these parts only exist here. We receive many many core exchanges that were previously “built” at facilities that are using OEM parts and many of them develop the same issue almost immediately. A simple “spring kit” or “updated valve body” is not a fix for this problem.

We know because we tested an economical build that used an updated OEM valve body and discovered that it simply did not fix the problem. TCM Tuning and spring kits did not have any significant impact on the problem either; better or worse. Enjoy a picture of this $6,500 “built” transmission with 3,000 miles on it below.

Conclusion:

Don’t let General Motors or their proxies at the dealership lie to you. We can’t shout this loud enough. There is a fix, and there has been a fix the entire time they knew about this problem and even before. We want to get this information out to as many consumers and technicians as possible so that these vehicles can get back on the road reliably and safely. 

In fact, many dealerships have bought these parts off us at their own expense because they know that if the vehicle is down for an extended period of time, they may be legally required to purchase it back off you. A $100,000 truck is much more costly then a few thousand dollars in parts and wrench time.

If you’ve been effected by this recall/problem and need outside support, Next Gen Drivetrain™ is the only name you need to know. Our staff are trained at length on this recall, and we’re providing support all over the planet.

Our in-house engineering department is here to answer the toughest questions and make sure these vehicles are as reliable as they have the potential to be. Still have questions? Give us a call and let us help!