Shift Kit

To say I can’t keep my fingers off of anything is an understatement. If it has an engine, you can bet that I’ll find some way to modify it. It’s this very reason I refuse to own a car like a COPO Chevelle – as if I could afford one. Cars of that caliber need to be preserved, and I’m not a preservationist. Hence, the reason I own an old Chevy pick-em-up truck.

In the past, my C10 has received upgrades like a Dakota Digital dash and a seat reupholster thanks to the help of Classic Industries. This time, I had the bright idea that I needed to get my hands on the transmission and do something about the factory-appointed shifting qualities. Don’t get me wrong, the transmission works fine, but fine doesn’t cut it. And, since I can’t leave well enough alone, I thought I would install a B&M Shift Improver Kit.

Shift kit

The sealed package of goodness that contains almost all the parts you’ll need. We say almost, because you should probably change the filter while you’re doing this, and one is not supplied.

What’s About To Happen

We’ve all heard of adding a “shift kit” to an automatic transmission, but what is it, and what exactly does it do inside your transmission? In a nutshell, the upgrade simply alters the flow of fluid through the valve body, creating firmer shifts and improved efficiency. If it’s an improvement, why didn’t the factory do it initially? That’s easy. The general public would probably have been returning cars left and right, feeling that they would rather have smooth shifts, not firm. In general, the popular opinion is that shifts need to be smooth. Total performance wasn’t at the forefront of the mind of car builders, but customer comfort was – generally speaking.

Shift Kit

Once the pan is out of the way and you have cleaned up the fluid mess from the driveway and yourself, you can get into the task at hand.

Installing a shift kit is actually pretty straightforward. Depending on the manufacturer, the kit will consist of a steel plate, some springs, and we hope, easy-to-read instructions. Commercially available shift reprogramming kits are often installed primarily so the driver can “chirp” his or her tires when they hit Second gear. Let’s face it, everybody does it. Noise from the tires notwithstanding, installing one of these kits will provide quicker power transfer between gears, albeit at the expense of a smooth, seamless shift – which is a good thing for enthusiasts.

Unfortunately, many enthusiasts either live with their transmission’s smooth shifts, or pay someone to upgrade their transmission. It is understandable that many are to scared to get into the inner workings of an automatic transmission. But, believe it or not, installing a shift kit and reprogramming a valve body only requires a couple of simple hand tools and an afternoon in your garage or driveway. In fact, I did this upgrade in my driveway with the Cheyenne propped up on a couple of jack stands. I will add this: Having the transmission out of the truck or having the truck on a lift would have made the install easier.

Once the filter is out of the way, you can get to the pivot clip holding the detent control valve lever (left) and the S-link (right).

What’s It Going to Do

There are different types of shift kits designed for different tasks, but generally speaking, a performance-oriented shift kit is designed to provide firmer shifts by changing the flow of transmission fluid through the valve body. By “firming up” each shift, a performance gain is actually achieved. Even if it is fractions of a second, the quicker response time of a shift is a performance upgrade.

Shift Kit

If the front servo assembly falls out (arrow) after you remove the valve body bolts, put it back in place and use a little grease to hold it. I even went to a local transmission shop and got a new O-ring for the assembly since it fell out.

In regard to the B&M kit I installed, there was actually a Heavy-Duty or a Street/Strip option to choose from. This means that a decision needed to be made. According to Steve Macias at B&M Racing, “The choice between the two is application dependent. If you are installing our Shift Improver kit in a motorhome, a vehicle that is used for towing, or one that sees a lot of stop and go driving, the Heavy-Duty setup will probably be the best fit. The Heavy-Duty kit will give you firm, positive shifts, but it still delivers shifts that are comfortable enough for daily-driven street vehicles. The Street/Strip setup is generally the way to go if you are installing this kit in a high-performance application. Whether it’s an on or off-road race vehicle or street machine, the Street/Strip setup will provide quicker, even harder shifts than a Heavy Duty install.”

The hole(s) you drill are dependent on whether you are looking for the Heavy-Duty or Street/Strip function. Here you can see the marked location that will be drilled.

He continued, “That said, converter size and stall should also be taken into consideration when choosing between the two. Stock size converters with mild stall speeds will feel the shifts more than say a 10-inch, 3,000 stall converter using feed holes larger than 1/8-inch. Small diameter, higher stall converters will soften the shift feel.”

Installing a shift kit can also help your transmission last longer. This happens by reducing the slippage and shift overlap that is inherently built into a transmission to create those smooth shifts. Installing the B&M kit does require transmission pan removal, separation of the valve body, and the drilling of hole(s) in the valve body separator plate, but this is something you can do at home.

Once I had the plate drilled and filed smooth, I placed a dollop of grease on the check ball and positioned it per the instructions. I could then place the separator gasket/plate assembly against the transmission case.

In short, the valve body is like the nerve center of the automatic transmission. It is a maze of fluid channels and passages that direct the transmission fluid to push various valves that operate the appropriate clutch pack or band servo (Insert confused look now). But, how does drilling a hole or two in a sheet of metal change the transmission’s shift characteristics? “The fluid feed holes regulate the amount of fluid that is supplied to a clutch pack. By increasing the size of a given feed hole, you shorten the apply rate of the corresponding clutch. This gives us the quick, positive shift feel to prevent clutch slip,” Steve said.

…the Street/Strip setup will provide quicker, even harder shifts than a Heavy Duty install. – Steve Macias

What Did I Get Into

With my new-found knowledge, a couple of jack stands, and a vague idea of what I was doing, I jumped in head first. After draining the transmission fluid into the drain pan, onto my driveway, and down my arm, I then removed the filter and filter gasket. Now, before you go any farther, it might be a good idea to take a picture of the valve body so you know the proper placement of the manual linkage, detent spring and roller, S-link (or in some cases, offset link), detent control valve wire and lever, and support plate. All of these pieces need to be put back during reassembly, and in the proper position. Fortunate for me, I knew where everything goes, so I took images solely for the purpose of this tech article (thankfully, you can’t see the smirk on my face as I say that).

With your picture now safely tucked away on your phone, remove the pivot clip holding the detent control valve lever and then remove the lever. Next, take out the eighteen bolts holding the lower half of the valve body and then lower the valve body by pulling straight down and disengaging the manual valve and link from the manual lever (Do not let the manual valve fall out of valve body). The manual valve is what is connected to the S-link.

Shift kit

All it takes is 100 in./lbs. on the valve body bolts.

It’s time to remove the support plate and stock separator plate, gaskets, and four check balls. You will not be reusing the stock separator plate. If you’re like me and doing this on jack stands, when you remove the separator plate, the check balls that are between the plate and case will fall out. That’s no problem, they don’t all get reused anyway. That means you only need to find one or two of them (depending on which version you install) after they roll down the driveway.

Shift kit

The B&M deep pan that I used also came with a new filter and the filter extension.

When it comes time to modify the new separator plate, this is where you need to decide whether your installing the Heavy-Duty or Street/Strip version. If upgrading to the Heavy-Duty function, you will need to reuse two check balls and drill one hole, while the Street/Strip function requires one check ball and drilling two holes. The instructions show you where to drill and reinstall the ball(s).

shift kit

It’s kind of tough to see in this image, but that is the filter extension that came with the deep pan.

Hopefully, We Have No Leftover Parts

Now, install the upper valve body gasket on the case side of the separator plate. You can use a small amount of grease to hold it in place, and then install the lower valve body gasket (identified by the Z-shaped slot) in position on the valve body side of the separator plate. Again, a small amount of grease will hold it in place. I also dabbed a small dollop, glob, or whatever you want to call it to hold the check ball to the gasket/plate assembly while I reinstalled it. A pan bolt can be used to temporarily hold the gasket/plate assembly in place after positioning it.

The stock support plate now gets reinstalled along with the B&M oil transfer plate. The order of the plates must be correct. Install the seven support plate bolts finger tight, and align the rest of the separator plate bolt holes with transmission case bolt holes as well as possible.

shift kit

If you’re installing the Heavy Duty kit, you’ll also need to remove the accumulator cover located on the right side of the transmission case. You’ need to remove the cover, discard the spring behind it, and then reinstall the cover.

Now you can remove the pan bolt that is temporarily holding the gasket/plate assembly, and guide valve body into position. My transmission was equipped with an “S” link, and once it was properly installed per the instructions, I installed all of valve body bolts finger tight. Once they are all “snug”, you can tighten valve body bolts to 100 in./lbs. Tech Tip: If you try to install and tighten one at a time, you will not get them all started. That is why you get them all started and snug before you tighten any. Make sure gear selector inner lever operates freely at this point with positive indexing in each gear.

Shift kit

The spring that is behind the accumulator cover.

After you reference the “before” picture you took and confirm everything is reinstalled the same way it was before you began, you can reinstall the pan. I actually upgraded to a B&M deep pan, to allow extra fluid and even little better cooling capability.

Once the transmission is back together, you need to add transmission fluid. B&M recommends their Trick Shift or Type F fluid. Start by adding five quarts, and then check as you normally would. Top off as needed.

I will admit that installing the B&M kit would have been easier if the transmission was out of the vehicle, but with a few basic hand tools and a drill, you can do this at home in your driveway. The instructions with the kit are easy to read and follow, and tell you exactly what to do and where to do it.

While I didn’t need to upgrade to a deep pan, The addition of a drain plug and added cooling effect of the aluminum and fins afforded the by the upgrade was worth it in my book. You don’t need to install a deep pan with the shift kit, but I wanted to.

This is the first of hopefully many performance upgrades I’ll make to the truck, and since it is my daily, I installed the Heavy Duty option. I have owned many cars with the street/strip option, and I have to admit, while the shifts of the Heavy-Duty version are not as hard hitting as the Street/Strip option I have installed in the past, they are very firm and precise, and in no way harsh enough that it makes the truck any less fun to drive everyday. Now it’s time to figure out what to upgrade next.