What is the criteria for using a 3 speed automatic as opposed to a 2 speed auto?

Is there certain combinations that a 2 speed (powerglide) would work better?

Help me decide which to use in my 87 Camaro drag car.

And I have not decided on which engine it will have, SBC or BBC.

 

No opinions or comments? Is this the place to talk racing? If I'm in the wrong place please tell me, I'll move.

 

well the powerglide would be better in something like a big block......you need a lot of torque to make those run decent.....but a 3 spd would work with either small and big block and parts are easier to come by.

 

A glide can be made to work with a SBC but you need some deep gearing in the diff for better torque multiplication off the line to make up for the lack of torque the engine will produce. Launching with a glide is like launching in second gear with a TH350/400. 60' times will suffer but may also be a good thing if track prep is poor since you won't spin off the line as much.

There are advantages and disadvantages to both.

3 speed:
Heavier and uses a bit more HP to turn the internals
One extra shift required
Intermediate sprag prone to failures
Deeper first gear for better launches
One extra gear to keep the engine in the powerband longer
More expensive performance parts

2 speed:
Very lightweight and uses very little HP
Only one shift required and can be modified to operate as a high gear only
Very few modifications required to make one race ready
1.76 or 1.82 OEM first gears. 1.76 is stronger and other ratios are available in aftermarket
Inexpensive performance parts compared to 3 speed parts
Slower 60' times due to shallow first gear ratio
Hard to find in junk yards since the last one offered in a production car was in 1973.

I've had a glide in my race car for quite a few years and won't go back to a 3 speed. It's simple and easy to work on. Since the majority of us bracket race, consistency is the goal. With only one shift, you only get one chance to screw up. With the extra gear of a 3 speed, you'll probably run quicker but speed means nothing in a bracket race.

I use a 1.76 glide behind my 540 BBC. With 4.86 gears in the diff and 32" tall tires, I can still yank the front wheels and carry them for about 20 feet. I launch a 4500 rpm off a transbrake with a 6000 stall converter, shift at 7400 around the 330' mark and go through the traps at 7400.

 

Just the feedback I'm looking for, thanks!

Stephen 87, any idea how much hp/tq a stock PG case will handle?

I have a stock PG under my bench, wondering if it would be cost effective to buy all the necessary parts to make it live, or would I be better off buying a beefed PG from someone like Coan?

 

Stephen, You're car has for sure has te power to launch it well (and it should with that bb), not to mention some deep gears, and turn enough rpm to run those gears.....but what about a more mild build??? just for information for overdriv (I prefer 6 gears, but I road race, lol)
overdriv...what kind of power are you looking to make??? what are your intentions with the car???

 

The car will be drag only, no street.
I want it to run reliable and safe, my two prime objectives.

I have a budget of around $7000-8000 for the engine, carb to pan. I want the most power for the least amount of cash with the two prime objectives in mind.

 

Basic upgrades to a glide are turbo spline input shaft. Steel center clutch hub to replace the weak cast hub. Dual ring servo piston.

All the other changes or modifications are more for convenience such as updated shifter linkage, deep sump pan to add rigidity to the case and it uses a less restrictive filter, better pump and stator support, etc. You can go from mild to wild with a powerglide. I could spend $5000 just on a completely new aftermarket transmission but it would be far more than what I would need. I'd love a set of 1.80 straight cut gears but they're over $1000.

For what you're doing, the simple upgrades should be enough. The first thing you need to do is learn about the glide you currently have. There are many different versions produced over the production run and they're not all the same. Having a glide doesn't mean you have one that's worth using. I have a spare under one of my benches that probably could have been rebuilt and used but I've been stripping it down for spare parts.

To learn all about glides, pick up this book. It shows you how to identify and rebuild them plus what needs to be done to modify them for different types of racing.

http://www.amazon.com/Powerglide-Tra.../dp/1557883556

An alternative to building your own is to buy a performance transmission already built to suit your specific application. You don't need a high end version capable of withstanding 2500 HP. A basic bracket racing version will do fine.

Mine is surviving with the basic upgrades. My input shaft isn't even the top of the line version. It's only the 300M and not the Vasco. I have the steel clutch center and dual ring servo. The transmission has been modified to use a transbrake and I use one from TCI. I ran a chrome pan until a few weeks ago when I finally installed a cast deep pan. My direct hub only had 5 clutches in it and I just finished upgrading it to 7 thinner clutches. The old ones still looked fine but those high gear burnouts put a lot of abuse on the direct clutches. I can't even remember how many clutches are in the low gear hub. I also use a Kevlar band. Because of the times I run, I need to run transmission and flexplate shields. Other than all that, it's still a basic OEM style powerglide. It's still surviving but could also fail at any time. GM never realized how much power this simple transmission could take. They were installed mainly behind inline 6 and small V8's but a few found their way behind bigger engines such as Pontiacs.

 

Stephen, thanks a lot for the input. I have built one PG in the past for a local racer, but it was in a Vega with a SBC 377 on alcohol. He brought me the parts and I put it together not thinking much about it then. He made over 300 runs with it before it failed. I don't know what happened to it.

I have the book you mentioned, but need to round it up.

Where is a good place to buy strong aftermarket PG parts?

Thanks for the help.

 

go with a glide, IMO.
stay away from a 1.82 gearset, they are the weaker.
if going stock, look for a 1.76, or go with an aftermarket set of planets.

 

power glides are what you want for drag racing, only takes 15hp to run it, but in stock form they will die with some decent hp put to them, deff upgrade the internals