At this point the 48 Hour Camaro is well on its way to completion at the Barret-Jackson auction this week. Throughout the last 2 parts in our series on building the ultimate autocross 4L75E for the 48 Hour Camaro we’ve discussed many of the critical components used to update and upgrade the transmission. The transmission we built for use behind the Lingenfelter LS3 engine has to reliably and repeatedly hold up to the 579hp/487tq the engine creates along with the tortures of autocross, road racing, and general mayhem the car will be subjected to.
In this Part 3 segment we will dive into the “heart” of the transmission to discuss how we blueprint the valve body for maximum performance. It should be noted that this procedure isn’t reserved for just the high end builds. We go through this process on every level of build we do here to ensure that the valve body meets our strict standards of excellence. Finally we will finish the transmission assembly and put it through the paces on our custom built dyno to give it the final pass before we turn it loose. If you haven’t seen the previous articles you can see Part 1 and Part 2 by clicking those links.
Blue Printing the Valve Body
We spend a lot of time on the valve body to ensure that it is outfitted with all of the latest critical updates. The list below details what each of these updates mean for the transmission. Once the updates are applied we then vacuum test each valve for wear to provide zero leaks between the valve and bore. We also pack in Brand New Accumulator Pistons to replace the OE plastic ones that are prone to cracking and loosing pressure.
Performance Spring and Shim kit – The spring and shim kit is a carefully selected group of components that work together to precisely tune line pressure, accumulator pressure and shift calibration. It’s the best way to get an impressive transmission that responds to throttle and increased load with quick, firm shifts.
Actuator Feed Limit (AFL)Valve – The AFL valve is a solenoid feed regulator valve that feeds the EPC solenoid and shift solenoids. The OE AFL valve design has a large reaction area and is highly affected by side loading, which wears the valve body bore. The EPC solenoid oscillates the torque signal and AFL oil, which increases valve action. As the bore wear increases, oil pressure is reduced to the shift solenoids, which causes solenoid and ratio codes. The same AFL oil loss results in lower line pressure. This is a commonly overlooked upgrade since it requires special machining to be done to the valve body.
TCC Regulator & Isolator Valve – Severe wear of the Torque converter clutch (TCC) regulator valve bore, caused by oscillation of the OE valve, allows regulated converter apply pressure to exhaust. This is a primary cause for TCC-related slip and overheated converters. Exhausting apply pressure also diminishes line pressure, which can result in burnt clutches. Excess wear at the isolator valve bore reduces TCC apply pressure. We recondition the bore and install the new TCC regulator and isolator valve kit which then restores normal TCC operation by shoring up the hydraulic integrity of this circuit. This new TCC valve also gives us a 10% higher apply pressure, and the hard coat anodize finish prevents premature wear.
Forward & Reverse Abuse Bore Plug – The bore plug is held loosely in place with a coiled spring pin, allowing the opposing spring and oil pressure forces to stroke it within the bore. This constant oscillation causes the plug to wear and allows PR oil at the low overrun valve and 3-4 clutch oil at the 3-2 downshift valve to exhaust at the abuse valves. This excessive oil loss can result in delayed apply of the low/reverse clutch and a tie-up of the 3-4 clutch and 2-4 band. This upgraded forward and reverse abuse bore plug resolves these problems by use of an increased plug diameter to restore proper valve body clearance and by using a smaller retaining pin hole to reduce plug movement which results in excessive wear. This plug is used in two locations in the valve body: to separate the forward abuse and low overrun valves, and to separate the reverse abuse and 3-2 downshift valves.
Heavy Duty 2-3 Shift Valve – When the GM 4L60-E family of transmissions evolved from the 700-R4, the overrun clutch apply no longer applied in 1st and 2nd when accelerating from a stop in D3 shifter position. This change was made to improve coast down drivability in D3, but had the side effect of reducing the torque capacity of the input section. In order for us to improve input sprag and forward clutch durability we install this heavy duty 2-3 shift valve that applies the overrun clutch in D3 1st, 2nd, & 3rd gears. We feel it is a critical upgrade for all heavy-duty and performance vehicles.
New Solenoids – The valve body solenoids can and do fail over time. They can develop a short in the wiring, the plunger can get stuck, or the return spring can fail. We always replace the solenoids with brand new OE units rather than take our chances that a used solenoid will hold up for as long as we would like it to. This is another area that many budget built transmissions neglect due to the extra expense.
Dyno testing is the last stop before we ship out any of our automatic transmissions. Bowler Performance has been in the business of building transmissions for over 50 years now, and we can tell you without a doubt, that our transmission dyno is one of our most valuable pieces of equipment. The transmission dyno is the best way to re-create a real world scenario to ensure that the transmission we ship to you does everything we promise it will. Most dynos will be powered by an electric motor or gas engine along with a set of gauges and sensors to monitor the pressures and temperatures inside the transmission being tested. The dyno we use here at Bowler Performance is a custom built unit that utilizes a big block Ford engine producing about 550 lbs-ft of torque coupled with an electromagnetic braking system that can replicate an 800 lbs-ft torque load on the transmission.
If there is an issue with any one component in the transmission we will know 99.9% of the time before it ever leaves our shop so that we can save you the time and frustration of removing and replacing that transmission again due to a faulty part. We dyno test transmissions because we care about the product we are building and sending you. Transmission dynos are expensive, and usually your local rebuilder will not have one available. This is not to say that their transmission will fail, but you should be cautious of what their warranty or guarantee is, otherwise you will be the one stuck with the bill to pull it back out, wait for it to get repaired again, and then put it back in.
The transmission dyno allows us to check for proper line pressures, gear and clutch engagement, proper operation of the solenoid valves, and any other specific functions that particular transmission needs to do perfectly. For all the electronically operated transmissions, the dyno also gives us the opportunity to set up, program, and test the controller for proper operation in the project it is being built for. Another key benefit of the dyno is that it exposes any possible leaks that may occur, because a leaky new transmission will definitely ruin your day.
We believe that no matter what level we are building the transmission for it deserves to be checked and tested to the fullest extent. There isn’t a process or procedure that is any less important on a stock type build than it is for a full out race build. When you’re shopping around for a new transmission take the time to ask questions and educate yourself about what the transmission builder is doing for the amount of money being charged.
The 48 Hour Camaro build is currently underway at Barrett-Jackson, but you can still tune in at watch via Facebook and Instagram. Each day the team provides video updates of the progress so you can see details on the products and procedures used to put it all together.
If you’re a fan of watching the Barrett-Jackson auction on TV, tune in on Saturday, January 20th to watch the Bowler Equipped 48 Hour Corvette meet its new owner. Click the photo above for more details.
Even though these last few newsletters have highlighted our automatic transmissions we are also an Elite Tremec Transmission distributor, and we will gladly work with you to configure the ultimate manual transmission package for your project. Contact us today to get started on building your perfect transmission conversion.
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Did you miss part 1 or 2 of our 48 Hour Build blog? Go back and learn more now!