Street Performance Transmissions

Dec 2, 2009

The choice of an enthusiast’s car or truck’s transmissions is usually considered more of an investment nature rather than just something for looks or style. No one buys a transmission because it’s candy red or metalflake. When that choice turns to an automatic transmission, what parts make a unit more desirable or a better choice? Or is it the way the unit is built? We talked with several manufacturers of street performance automatic transmissions to get an idea just what they offer that can factor into those choices – for you and your customers

ATI Performance

ATI Performance in, Baltimore, Md. builds street and race transmissions. Jim Beattie answered our question about what determines the quality of a performance transmission. “Well, I guess all of the material put in it and the guys putting it together. We dyno test every unit 100%.”

When it comes to materials, Beattie says, “Materials, believe or not, are extremely important. Hard core race materials are very good for racing. But for the street, they fill the transmissions full of dirt. We tell our street people they have to drive them one of two ways – like they are on the track or on the way to the grocery store.”

He goes on to explain that racing materials are not designed to take the long duration of use. It’s a simple equation when you look at a drag car making 10 passes, for example, in a day. The transmission and its materials go through a heat up and cool down cycle that can preserve the condition and quality of the materials. On the street, there is constant use with no cool down and the materials, already not designed for such sustaining, break down, losing pieces that clog and break the other assemblies of the transmission.

As much as a customer may want to install a racing transmission for his or her planned hard use, it’s not the way to go. So a street machine should use a street machine transmission and not a racing version. Beattie says, “Mainly because the good street materials are clean and do not emit a bunch of metallic garbage. We see so many people use those metallic clutches in street transmissions and street transmissions are totally different.”

ATI uses a simple formula to know what usage determines what transmission. Beattie says, “We classify cars as street cars driving on race track or race cars driven on the street. What distinguishes it is the rear end gear.” Meaning if a car owner is serious about his racing, he will have a taller gear in the car.

When talking specifics, Beattie says, “The GM transmissions have a band in there that locks the direct drum when you put it in second gear and that provides engine braking. However that drum is normally stopped on the up shift by a sprague and set of clutches. That band is very narrow so it doesn’t have any capacity. However, if you would like to use it for braking, keep the throttle on, pull into second and lift or close the throttle.”

According to Beattie, the way a transmission is assembled and adjusted is paramount to performance, too. “Yes, proper clearance and proper band adjustment affect that immensely.”

Speed shops should, according to Beattie, have more of a stake in assisting transmission choices for customers. But it comes down to passing the buck, “They are the middle man and they’re going to take all the heat. So they need to buy from a reputable manufacturer.”

Hughes Performance

Hughes Performance in Phoenix, Az. has drag racing for its main target marketplace. They cover all aspects of diesels, drag, street and truck transmissions. They have an admittedly large motorsports department and pride themselves on not being an automated company.

Tony Kane pegs experience as a big factor of the quality of a performance transmission. “Being in business almost 38 years, we’ve evolved with the market and how the power and torque curves have evolved. With data acquisition and dyno horsepower numbers going up, the quality of the parts has also evolved.”

He cites a typical GM Powerglide transmission of the ’60s as being built for handling 200 horsepower. Nowadays, that same Powerglide – albeit modified – may be asked to handle over 2000 horsepower. It’s certainly not the transmission as much as the plethora of so many aftermarket parts and modern technology.

“The transmissions that we build at Hughes, everything has been changed to enhance the performance and extreme conditions they run in – whether they be street or strip.”

How and what materials are playing a factor? “There’s Kevlar, high static, and for bands, red material and blue materials. Everyone has trade secrets for such as input and output shafts, their own recipe for success for those components.”

Why do some materials work better than others? Kane’s answer reflects the entire industry, “As much as we manufacture, we test. A lot of the durability of a transmission is not in the clutches and bands. They will fail for other reasons. Changes from transmission to transmission; every unit is a little different.”

What about processes used on the parts and even assembly? How do they affect durability and quality? “There are a lot of input shafts on the market. Even though two input shafts may look the same, there’s different metal techniques; the shapes, radius, you could have two input shafts and one will break in 100 passes and another won’t.” And manufacturers judicially guard their secrets like any other trade.

So what should speed shops look for when choosing transmissions? Kane tells us what Hughes watches for, “We look to have experienced help. When the customer explains, they are there to get the right components the first time.” He tells shops, “I would want to go with a reputable company. I wouldn’t just pick a name out of a hat. You wouldn’t do that with a doctor. I would tell the speed shops to look at the history, see tech support, get to know the company that you’re going to be dealing with. Feel comfortable with the company. A company that stands behind the product.”

Transmission Specialties

Transmission Specialties, in Aston, Pa. makes units for street and serious racing. Their Peter Miller easily pinpoints what determines the quality of a performance transmission. “In our case, it is a top notch tranny builder. You need somebody who has been doing high performance transmissions for years. The biggest problem is using a stock transmission builder who puts in high performance parts. Our builder has been doing it for almost 30 years. If a trans is sent back to him, he takes it as a personal affront.”

That same builder is always pushing Miller and Transmission Specialties for better and better components. As such, the company’s return rate is almost nil. Miller goes on with,

“The majority of the parts for our high performance transmissions are made by us. Anything that we think is going have stress from power, we try to make ourselves. We have a full array of CNC machines to make our parts.”

The materials used go hand in hand with what they are building. Miller points out, “We are primary known for high horsepower – over 1000 hp – transmissions. We make a NASA input shaft. The key is to identify the stress points of a transmission and make the parts with the best steel and then heat treat them right.”

To clear up the chicken and the egg of better parts versus better materials, Miller says it comes down to using both. That and attention to detail in parts and how the transmissions are built. “We call it quality north to south. The toughest thing in this industry is to make a trans that will stand up to 2000 horsepower. Then you can make one for 500 hp.”

Shops should get plenty of input from the person that is buying and using the transmission in order to give them what they want and especially need. Miller breaks it down, “One of the keys is to get the info from the racer. Someone who has 300 horsepower is different from someone who has 600 hp.”

Shops can do even better by communicating better with customers, preventing headaches for all involved. Transmission Specialties’ favorite customers are, Miller says, “Someone who is bona-fide and gives us the right info so we don’t ship the wrong trans to the customer.”

Performance Automatic

Harvey Baker of Performance Automatic in Gaithersburg, Md. agrees that it’s all about the parts. “The quality is determined by the type of parts,” says Baker. “We have two final inspections and dyno tests and we use the best of components such as torque converters and kick down cables. We have what we call our Street Smart Packages for street rods and one of their main goals is reliability. And to keep them reliable and keep the longevity in the torque converter, we have to make sure all the components match.”

To keep their product competitive, they are picky about what goes into their units. Baker says, “We use all aftermarket-produced clutches and steels. They are all new. The wearable stuff is all new. The parts from a factory are rated to handle 300 hp at best.” So it makes sense for them to use better parts. And there’s another reason, “We want to use the higher quality parts because we have a minimum of one year warranty. We have six Street Smart Packages that have lifetime warranties.”

But what about manufacturing? What processes affect durability and quality? Baker says, “The processes where you get your durability and reliability is using good quality cores. We hand pick the best cases, all the hard parts. Let’s say out of 10 cores, remembering that we have a warranty, we may have only four that pass our inspection.

You have to look at cracks in the casings, no warps, no leaks, no problems. Of course, all of our builders are very well versed. Once it’s expertly assembled it’s put on a dyno.” But that’s not all at Performance Automatic. Says Baker, “We also have a valve body dyno.”

What advice can speed shops take? Baker says, “We design our transmission to fit many different categories. Direct bolt in is the first, second is the type of vehicle. One example is a street rod with automatic over drive. A 2004R is narrower than a 700 R4.” That helps in fitment of nearby components such as headers, mufflers, brake assemblies and all those pieces that are normally located near the transmission. “And we want to find out what their intended use is for, too”.

So choosing an automatic transmission with your customer can be a complex operation with many different aspects coming into play. Much like the performance automatic transmission itself.

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What About Manual Transmissions?

It’s not all that different when that third pedal comes into play. We gave Stu Hamilton of Richmond Gear the same questions about manual transmissions. On quality, he says. “Mainly the processes that you use to actually manufacture gear sets. As engineers, we make sure the quality of the steel you use to make the gears is the specs you requested. The heat treating portion of the gear sets is very critical to the performance of the gears inside the transmission.”

What about the materials they use? “Basically, we work with mild carbon steels for most performance applications. If there are certain applications where you require more durability, we will modify the specifications of the parts.”

And for why some materials work better than others, Hamilton says, “The surface characteristics of gear sets will determine the wear-ability. Alternate materials can sometimes can give you toughness for a gear set – the ability to take higher torque loads and shock loads.”

In the manufacturing process of components, can different processes affect the durability and quality of parts? “Yes,” says Hamilton. “The tightness of tolerances related to gear characteristics such as the profile of the teeth and the lead of the teeth. And their run-out characteristics all directly affect the load carrying ability of that set.”

Speed shops should look for a good fit when choosing transmissions with and for customers, right? “Yes. They need to get a transmission that suits the needs of the consumer. Will the customer be happy with it? They need to do a little homework.” What should they look for? What specific factors? “Tire size, rear end gear ratio and how they plan on using the vehicle.”