Building it better! AOD

Dirtyd0g

Registered User
This transmission should be familiar to many of the people around here. It is a Lentech Strip Terminator with electronic od delete and transbrake. It will take me a few days to show everything, some of it I am waiting for parts on that should be in tomorrow.
The direct drum that was in this transmission was a cast iron drum that was twisted, That is a new one on me usually the cast iron drums will rip the splines out instead of twisting, the stamped steel drums hold larger frictions and are not prone to spline damage, they are however prone to twisting. In the past coupel years I have done several things to improve the drum. The most effective being flame hardening the center section. This is done by gently heating the center tower and then quenching it in used diesel motor oil. We use that because the carbon in the oil helps to carbonize the metal and increase it's rockwell hardness.
The first picture is of the cast drum, The arrows point at problems with these drums, if you look at the top you can also tell that it is hammered. That is because I had to take a BFH and knock it out because it was twisted and swelled so it no longer fit inside the planet like it should.
A= spline wear, these are about half gone, in this area you can also see where I had to beat it out.
B= drum twisting, that hole was supposed to be round
C= spline wear, not a huge issue but a sign of wear.

The second picture is one I took of the flame hardenening process.

More to come
Alan
 

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The lentech converter wasn't a bad unit, but I am certain I build a better unit(without the rediculous price tag either)
To not confuse the thread I will do the pictures a couple per post.
For starters the front cover of the lentech (built by TCS of canada) is a nissan OEM frotn cover with a heavy guage plate added to it and 4 pads welded on to make the correct bolt pattern, Really it isn't a bad setup, for a lesser vehicle it woudl do the job just fine, This transmission is getting a much stronger billet front cover that has to be used with the inptu shaft I use. The input shaft and converter must be properly matched. Using the setup I am using is virtually bulletproof. The shaft is 300m with a 31 spline input to the converter. The spline pattern of the shaft I use is very deep for strength. Shown below is a comparison of the lentech shaft that shows how much spline they had driving and the new shaft that gets nearly full spline engagement. Shown in green is the new shaft and how deep it's splines drive, shown in red is the lentech shaft and how deep it's splines drive. Also note the shaft I used is slightly smaller however it is made with 300m non twist steel. The lentech shaft is stock aod diameter and made of 4340 steel
The picture of the covers. The lentech is on the left with arrows pointing to it's features
A= small diameter bushing, not really a bad thing this is functional for use with a stock shaft transmission so it must use the stock bushing diameter.
B= Welded together balloon plate, again not a bad thing but the billet housing I use is considerably better.
C= Welded on small pads for bolt pattern with 3/8 fine thread threads. Again not really bad, but not sufficient for this kind of torque
On the right The cover I use
A= Large bushing with lubrication grooves, this is my own custom modifications, a really nice setup.
B= billet front cover with 7/16 fine thread bolts for ultimate strength.
 

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Are you going to make any changes to move the shift points higher when just left in Drive? Changes to the governor? This is some interesting reading

Ken
 
Are you going to make any changes to move the shift points higher when just left in Drive? Changes to the governor? This is some interesting reading

Ken

Ken,

This transmission has a full manual valve body and doesn't up or downshift, unless you move the shift lever.

David
 
Are you going to make any changes to move the shift points higher when just left in Drive? Changes to the governor? This is some interesting reading

Ken

Its the combination of the valve body used and the govenor used that controls the shift points in full auto. On my car with the SilverFox VB, my shift points at WOT in all gears is at 5500 with the stock SC govenor. The valvebody has an adjustment in it that I can lower/raise my shift points about 400 rpm's either way. Outside of that range you'll need to change to a different govenor.

When I'm racing I manually shift at 6200, but normal driving at WOT I like the 5500 shift.

Fraser
 
The valvebody is going to be cleaned inspected and reused. I don't feel that the problem is valvebody related at all, planetary failure combined with forward clutch welding together seems to be the big issues. For the most part this transmission was completely stock with just a set of alto red frictions. Rather than give it all away now I prefer to break it down piece by piece.
Alan
 
The valvebody is going to be cleaned inspected and reused. I don't feel that the problem is valvebody related at all, planetary failure combined with forward clutch welding together seems to be the big issues. For the most part this transmission was completely stock with just a set of alto red frictions. Rather than give it all away now I prefer to break it down piece by piece.
Alan

Alan,

I'm enjoying the piece by piece break down, and not just because it's my transmission ;)

David
 
Some of these parts you will have to see in person to appreciate, pictures just don't show the stuff. I do have your chunk of forward here that I found completely humorous. Good luck trying to seperate them. I got the top one off and it left a hole in the friction with a spot weld looking part on the steel.
Alan
 
The valvebody has an adjustment in it that I can lower/raise my shift points about 400 rpm's either way. Outside of that range you'll need to change to a different govenor.

When I'm racing I manually shift at 6200, but normal driving at WOT I like the 5500 shift.

Fraser

I talked to Lentech and he said something about shimming springs in the valve body(Its a lentech valve body) Also did some searching for a diffrent govenor. For bracket racing it would be nice to just leave it in drive and just click off close run after run. Other than that I have to get my shift light working so I can manually shift it. Can you explaing how the valve body is adjusted?

Ken
 
I talked to Lentech and he said something about shimming springs in the valve body(Its a lentech valve body) Also did some searching for a diffrent govenor. For bracket racing it would be nice to just leave it in drive and just click off close run after run. Other than that I have to get my shift light working so I can manually shift it. Can you explaing how the valve body is adjusted?

Ken

Its a feature that Dan (SilverFox) adds to his valve bodies, which requires dropping the pan and turning a screw in or out depending on what you want.

He calls it the WOT system and you can read it here.

Fraser
 
im not too fond of mechanical transmissions, once you go electric you'll never look at a mechanical trans the same ever again

and for the price you can't beat it
 
The converters have some very distinct differences, compared to stock both are great units, however I really feel the unit I build is better than any. Here are a few more reasons why.
The first picture is a comparison of the pump side of the converters.
Picture A points to the balloon plate used by TCS on the lentech converter, Not a bad balloon plate however not good enough in my opinion. I offer a unit with a similar setup rated to a max of 500hp, the double balloon plate increases the rating up to 1000hp, the plate I am using on this unit is unlimited (see 2nd picture).
Picture B points to the balloon plate as it will appear once welded to the pump.
The 2nd picture shows the very thick precision made balloon plate I am using.
The third picture shows the inside of the lentech converter pump, note it is all furnace brazed which is considerably better than most manufacturers.
The 4th picture is the inside of the pump I am using, the arrow points to the lubrication channels made into the balloon plate, these guarantee that the bearing is never going to starve for oil.
 

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Next we have the turbine assembly, this is the part that drives the transmission. I already mentioned the spline depth differences of the input shaft, if you look at the comparison between the 2 turbines you will see there is considerably more spline depth on the unit I am building.
The first picture shows a comparison of the 2 turbines. The lentech unit is furnace brazed as it should be. The unit I built has a few advantages. The arrows point to the features that make the unit I am building a better unit.
A= Lubrication groove and hole located in the center so that it does not hurt converter efficiency and allows for lubrication to the rear bearing.
B= Tig silicon bronze welded on inside, also welded on opposite side. The lentech unit is only welded on one side and is mig welded, which tends to distort and weaken the base metal.
C= silicon bronze tig welded outer part of blade
D= silicon bronze tig welded inner part of blade, welding these 2 points prevents the blade from rolling up which is the #1 cause of internal failure on high horsepower converter blades. Welding these gives this converter and unlimited torque/hp rating.
The second picture is the front side of the turbines, The arrows point to.
A= silicon bronze welded turbine hub for ultimate strength without metal fatigue.
B= Damper eliminator, this is required to use stock input shafts and limits spline engagement for the purpose of allowing both shafts.
C= Mig welded turbine hub
picture 3 is the most important part of the converter On the left is the TCS/Lentech stator on the right is a very expensive 22 element sonnax stator.
The advantage to the lentech is cost, all they needed to make that work was a race that had the correct spline, everything else came in the nissan core they built it from. The Sonnax unit on the right is rated for up to 1000ftlb of torque and is the best known stator setup. Anything with over that amount of torque must be spragless to survive.
arrows
A= Standard roller clutch, still not a bad unit, rated for about 600ftlb of torque
B=Steel stator cap used with sonnax stator, this cap is on both sides.
C=22 element sprag assembly, the strongest setup known to the industry.
D= triple wound snap ring to guarantee this unit stays together.
 

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One of the major component changes on an aod at this power level is the output shaft and it's sealing rings. Pictured below first is the stock shaft, next is the scarf cut sealing rings on it. The last picture is a 93 markVIII output shaft with solid one piece teflon sealing rings. These prevent leakage to improve direct clutch pressure. The direct clutch is generally the weakest clutch in this transmission so anything that can be done to improve it is a good thing.
Alan
 

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The first picture here is the direct clutch assembly with all of it's components.
A= high energy dynax frictions, the best frictions for this clutch available. Also the steels are the thicker .080 units from a 4r75
B= Direct drum, this is an upgraded unit I flame hardened in earlier pictures. Here it is with new seals installed, the piston, spring retainer and the new bushing pressed in.
C=direct hub
D= machined pressure plate to allow more frictions without a weak steel for a top plate.
E= 4r70w style bearing spacer with stepped groove to prevent the snap ring from falling out. The stock one was flat.
F= snap ring
G= new bearing
The next picture is the bearings that go on the other side of this drum. The open one is stock, the sealed one is the new design unit, some modifications for clearance are required for this to fit.
The last picture is the accumulator piston, the unit we will be using has 4 seals compared to the stock one which only had 2
Alan
 

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The pump bushing in this unit had already been upgraded to a taller unit from lentech. It however was in poor shape and not my choice of materials. I prefer to use babbit bushings however the bronze is acceptable.
The first picture is the pump with the bushing in it.
The second picture is a comparison from a stock short height bronze bushing to the taller babbit bushing I prefer.
The third picture is the gearset we are replacing due to damage of the previous one, unfortunately their are not any upgrades to this unit. I did however press bronze bushings in all of the parts of it to replace the factory aluminum bushings.
The last picture is pressing the bushing into the sun gear.
Alan
 

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I messed up the last batch of pictures trying to resize them, I will see if any can be salvaged, shouldn't have deleted the originals and it is all finished now.
The specs for the rest were
Forward drum= stamped steel stacked with 6 raybestos stage 1 high energy frictions and a 5.4 wave plate.
Reverse drum, late 4r75 with hardened tips and mechanical diode. Spiral snap ring installed and the drum was stacked with 4 raybestos stage 1 high energy frictions and wrapped with a 2 inch high energy carbon band.
The B overdrive servo found in the unit was replaced with a sonnax A+ servo, using the cushion springs to soften the shift because of the fixed line pressure. Anyone interested in reading about that can read the instructions on the part at sonnax.com in the transmission section under ford aod.
The extension housing was replaced with a 4r70w to use the larger bushing which is also new. The driveshaft yoke was replaced with a matching 4r70w yoke. The driveshaft loop went really well I will get pictures of it in the morning.
Alan
 
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