What will a better converter do for me (AOD)

Dirtyd0g

Registered User
To show the differences in what stock converters are and what makes an aftermarket converter better.
Attached are pictures
The first shows the worst problem on AOD converters, ballooning. THey all do it, nothing will stop it, To some extent if you keep stock input shaft setup this will happen again with enough power. See the crank bolt marks in the front cover. Extreme cases have leaked from the pressure, The only way to fix this problem is a billet front cover. Using the stock shafts that front cover is limited to about 450 ft-lb and 6500 rpms. The stock shafts don't last well above that anyway.
 

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The lockup damper has been redesigned multiple times. The first design was complete trash and became obsolete around 1986. I do not have a picture of this as they are hard to find anymore.
The second design is pictured here, it wasn't really bad they rarely break, but the thrust spacer that locks into the tabs on it are known to break those tabs off (thrust spacer picture not available it is a brass spacer with tabs). While this isn't destructive to the transmission if the parts get into the wrong places they can do severe damage.
The pump is another huge issue of these converters as none of them were ever furnace brazed. That chingy changy sound when you get on and off the throttle is this fins lifting up and moving around. Furnace brazing can and will fix this. In the pictures I put all of the fins back in the spot they go it, in the next one I gently lifted up so that you can see the over 1/4 inch of movement. When these fins lift up the converter is terribly inefficient. This will cause poor performance and fuel economy.
 

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These aod converters really don't have much in them. The last piece is the stator. Notice that the caps on this unit are made of phenolic (plastic) this actually is good stuff from a normal operation stand point. Under low load with clean fluid this setup will last forever. Once overheated the slightest bit it becomes very brittle. It is also prone to attracting debris into it's surface which makes it become abrasive. This can be fully fixed with an aluminum cap and a bearing.
 

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Now you have seen the inside of the stock converter with the exception of the turbine, On these stock converters the turbine is bypassed in 3rd and 4th gears so they really hold up better than most. They have hollow rivets which get loose after about 60,000 miles and the turbine hub is powdered metal. Not great however rarely a problem.
Performance converters are a whole new world. Smaller diameter, higher stall and torque multiplication, lighter weight, and when done properly much stronger parts.
These pumps can be built a variety of different ways. I usually build them in 2 fashions, single balloon plate or double. Generally the single flanged hub balloon plate is sufficient. Attached are pictures of the single balloon plate not yet welded in, The single plate welded in and the double plate installed. I also added a picture of the inside of the pump showing the inside of the flange and the brazed fins. Built like this, these can handle virtually anything you can throw at them.
 

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I posted this post a while back which basically says the same things about the stock converter and what can be done to improve it.
http://www.sccoa.com/forums/showthread.php?t=93089

The turbine of these 9.5 inch converters is fairly simple. I prefe rto furnace braze all the fins, in some extreme power applications it is also useful to tig weld the tips of them. The hardened splines in these units is probably overkill with the size of the outer shaft, but certainly helps the inner shaft on non direct drive application. The other thread explains the differences in parts here, they are the same parts used in either converter.
Picture of turbine is first below showing the furnace brazed fins, unfortunately I did not get the other side which shows how thick the turbine hub is.
Last picture is the stator, there are 4 known stator part numbers with different fin angles. The version shown is rated for 450ft-lb of torque before it must be modified from a roller clutch to a 22 element setup. In the one case here I have actually eliminated the sprag for use in a turbo 1/8th mile car. Eliminating the sprag is much cheaper than using an expensive 22 element setup and at some point the only way to make one survive. 90% of people here will do just fine on a standard roller clutch.

Feel free to ask any questions.
Alan
 

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very good read for me. was wondering what the group buy one will do. maybe I should get one.
 
Excellent write up alan. A couple of questions. Explain the diffrences of the locking and nonlocking TQ converters. Not just that one continues to multiply torque going down the track but how and why they work. Can a nonlocking converter be used on a stock transmission? Is the stall going to be diffrent on a tq converter installed behind a 450 lb tq engine and a 350 lb tq engine. The savings in rotating weight over a stock converter. I read a thread on here a long time ago where a guy claimed about 50+ HP going from a stock converter to a light weight 9.5 Is there a diffrence in weight between the 9.5 converters out there. What would you project the reduction in 1/4 mile ET would be going from a stock converter to one of the 9.5 converters with a 2800 stall be, given a hypothetical existing 1/4 ET of 13 seconds. Just curious. I know Im already stoked about getting a 9.5 converter

Ken
 
very good read for me. was wondering what the group buy one will do. maybe I should get one.

and me.
I was convinced a couple months ago that I needed a better one, but I can't afford it yet:mad:
Your converters are the cure for the aod affliction!
 
Ballooning is caused by the centrifugal force of rpms and the internal pressure.
A torque converter cannot increase torque of the engine it can multiply torque and better converters multiply more. Direct drive creates a weak link in these transmissions. The smaller converters are also much lighter making them more efficient.
Alan
 
Alan,
What is the weight of the 9.5" with ballooning plates?

My TCI Streetfighter 10" with ballooning plates weighed nearly the same as the stock replacement converter that I pulled out (which was balloned also) when I did my engine swap before the shootout, both are lockup units.
 
I pulled the Lentech nonlocking converter out this morning. It is one inch smaller in diameter than a stock converter and has an advertised stall of 2200. I weighed it with fluid inside and it weighs 35 lbs. I am curious what the 9.5 weighs with fluid


Ken
 
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