A442F Transmission Mods (1 Viewer)

[obe12]

Per Wholesale Transmission tech article they cover broad strokes on what your are paying for to rebuild an A442F and do some mods to it.

The cost is prohibited to send them my transmission and attempting to understand how they accomplish their product.

1. Oil pump gears and housing checked.
I flat sanded mine in the machinist block to get the pump gears within specs.

2. Their valve body Nomad “purchased it”

3. Extra clutch disc in 2nd gear brake
I think I have it figured out, my 5 steels are .095 thick
There are .078 available x 6 plus .085 x 6 friction discs.
And .195 thick pressure plate. With the original stack my height is 1.090 thick

Remove 5 steels at .095 then add 6 x .078 plates back in place
Plus 1 x .085

1.161 minis 1.095equals

Around .094 thousands needs to be taken out

The bottom of the 1st steel plate is around .060 above the snap ring holding in the spring retainer.

Leaves .034 has to be removed from the pressure plate or a touch more to give free clearance.

That leaves piston free play at .073 unless it needs more

4. Direct clutch , steels are 5 x .097 and 5 x .0834 and pressure plate .203 is 1.103 measured stack

Replaced with 6 x .071 steels, 6 x .0834 and pressure plate .203 is 1.1294 minus 1.103 is .0264 thousands off pressure plate to have .076 free travel in piston or add more clearance if needed by removing more from .203 pressure plate

5. Torque converter mod, found local performance converter place that is doing my converter, tig the vanes inside, exchanging better internal parts / lockup.

6. Throttle pressure device to work from manifold pressure to increase pull on throttle cable based on Manifoild pressure instead of throttle position.

This is my plan to up grade and update my current A442F behind my new forged lower end turbo intercooled 1FZ. Hopefully pushing 425-500 Target rear wheel HP. If trans can hold it.

Ok, I am all ears

 

[obe12]

Trevor at Wholesale Transmission got back to me via email. Just what they do to modify the clutch’s 2nd gear brake and Rear
Clutch “direct” clutch packs.

Per Trevor, there are .095 and .071 thick steels in the 2nd gear brake, and the friction plates from Low Reverse are thinner too.
The available piston to cir clip “aka snap ring” for the spring retainer to push the piston back when not under pressure that main piston if needed to machine can’t be lower then that. Approximately.040 thousands. The rest have to taken up by the steels and fiber friction discs. After swapping out thinner .071 steels and 6 .083 fibers and stacked it up, the clearance fell within the book limits .075 measured clearance and book specs .0732- .0811 . Again without machining anything yet.


The Rear brake aka direct 3rd gear, that has approximately.083 friction discs and either thick or .071 thin steels too.

By substituting the thick to thinner on direct , it stacked up leaving .034 thousands clearance. Oem Book calls for more but I want to confirm this with Trevor before machining anything.
Book calls .079-.0866 and that’s fairly wide.


I am reaching back out to Trevor to confirm what I have discovered and follow their advise.

By machining the pistons now I can remove some thinner steels and replace with thicker ones if prudent.

So that where I am at today.

Thanks

Tex

 

[obe12]

Trevor says tight is ok, .7mm in the
Rear clutch “aka direc”t and 1.0 mm in the 2nd brake and
Can take .070 thou off the direct piston and up to .040 is safe to not interfer with the cir clip of the return springs on the 2nd brake piston.


And engineer guy mentioned this

quote
“On last thing...Clutch Apply Behavior (for Nomad VB + Turbo Build):

Clearance Effect
0.035" (tight) Very fast apply, possible drag, heat buildup under load
0.050" Fast apply, clean engagement, ideal
0.060–0.065" Smooth apply, safe for hot/high-load builds
>0.070" Lag on apply, risk of flare/delay”

This would leave me in between Whoesale and The Yota Manual.

Maybe this is the safe zone… to go with. Target 50-55 thousand clearance. I can set it to what ever I want by machining the pistons and swapping thicker steels for thinner steels too combination at ll the above.


Tex

 

[bug616]

Thanks for posting this. Really useful info.

 

[obe12]

Trevor says tight is ok, .7mm in the
Rear clutch “aka direc”t and 1.0 mm in the 2nd brake and
Can take .070 thou off the direct piston and up to .040 is safe to not interfer with the cir clip of the return springs on the 2nd brake piston.


And engineer guy mentioned this

quote
“On last thing...Clutch Apply Behavior (for Nomad VB + Turbo Build):

Clearance Effect
0.035" (tight) Very fast apply, possible drag, heat buildup under load
0.050" Fast apply, clean engagement, ideal
0.060–0.065" Smooth apply, safe for hot/high-load builds
>0.070" Lag on apply, risk of flare/delay”

This would leave me in between Whoesale and The Yota Manual.

Maybe this is the safe zone… to go with. Target 50-55 thousand clearance. I can set it to what ever I want by machining the pistons and swapping thicker steels for thinner steels too combination at ll the above.


Tex

I slept on this and chatted with another guy that stacked 6 disc in his build. He found 380 Rear Wheel HP or greater 2nd to 3rd shift , 3 would slip engaging. We chatted about what clearance he used, what was in the Toyota manual. Aka Direct rear clutch is .079 min and going by the engineer point of view could cause flares anything above .070.

suppose we take .079 max and .0275 min “.7mm “ and split the middle … that .0535 kinda where the guy said fast, clean engagement , ideal.
So I think in shoot for .050-0.053 on the direct
2nd gear brake .039 “1.0 mm” to .0732 is .056 in the middle

It’s a chance to see if it works. That’s the reasoning I am applying to this.

I looked up other multi disc direct drums and clutch clearances in Toyotas .. none I found has 6 discs.. the forward uses a cushion plate and when measuring piston stroke that cushion plate has to be collapsed and that will have more travel. So not a good comparison.

The guy with the flaring 3rd gear shift , he spoke of you off of the gas pedal to allow the shift it would hold. That’s ideally means it’s flaring between shifts. So tighter clutch pack should help that. Ala less than.070 … so trial and error here. Planning synthetic Mobile 1 trans fluid. Start with synthetic for the heat for Dextron IV III II not the LV version, larger cooler and hopefully take away heat.

That all I have and my thinking.

I will cut the pistons to allow two thicker plates to intermix with the thins for better heat dissipation and set clearance as described. Time will tell if I chose wisely or not.

 

[obe12]

I slept on this and chatted with another guy that stacked 6 disc in his build. He found 380 Rear Wheel HP or greater 2nd to 3rd shift , 3 would slip engaging. We chatted about what clearance he used, what was in the Toyota manual. Aka Direct rear clutch is .079 min and going by the engineer point of view could cause flares anything above .070.

suppose we take .079 max and .0275 min “.7mm “ and split the middle … that .0535 kinda where the guy said fast, clean engagement , ideal.
So I think in shoot for .050-0.053 on the direct
2nd gear brake .039 “1.0 mm” to .0732 is .056 in the middle

It’s a chance to see if it works. That’s the reasoning I am applying to this.

I looked up other multi disc direct drums and clutch clearances in Toyotas .. none I found has 6 discs.. the forward uses a cushion plate and when measuring piston stroke that cushion plate has to be collapsed and that will have more travel. So not a good comparison.

The guy with the flaring 3rd gear shift , he spoke of you off of the gas pedal to allow the shift it would hold. That’s ideally means it’s flaring between shifts. So tighter clutch pack should help that. Ala less than.070 … so trial and error here. Planning synthetic Mobile 1 trans fluid. Start with synthetic for the heat for Dextron IV III II not the LV version, larger cooler and hopefully take away heat.

That all I have and my thinking.

I will cut the pistons to allow two thicker plates to intermix with the thins for better heat dissipation and set clearance as described. Time will tell if I chose wisely or not.

I measured the Rear Clutch “aka” Direct clutch piston with the pack having .034 thousands clearance, change out two thicker plates to alternate the stack, checked the piston in the lathe and it was .675 thick and removed .065 from it. After all said and done final clearance fail .057 with air pressurizing and using a dial indicator. Missed my .053 ish target but got close enough.

The stack, .071, d , 085, d .071 d ,071, d , 085, d ,.071 d and pressure plate. Alternating thicker steels in to help dissipate heat.


The 2nd brake piston is too large for me to chuck up. Swapped bottom steel .071 to a thicker steel to close up the .075 clearance to .059 is what it ended up with higher air pressure can get .061 in the dial indicator. Tried another fiber this time from .072 thin to .085 and yes closed it up to much. So took it switched it back.

So 2nd no machining, swapped to 1st reverse clutches x6 new,
.071 steels x5 one pressure plate and one thick steel on the bottom. To make up a pack and have .059-.061 clearance based on air pressure applied.


The best I could do myself without larger lathe.

Tex

 

[Kernal]

Could you post up photos of it all laid out on a bench before it's put together, then maybe successive photos
showing it all going back together?? I don't recall anyone (on this forum) rebuilding/modifying an ATM to this level of detail so it would be useful for future searches.

Great work.

 

[obe12]

Could you post up photos of it all laid out on a bench before it's put together, then maybe successive photos
showing it all going back together?? I don't recall anyone (on this forum) rebuilding/modifying an ATM to this level of detail so it would be useful for future searches.

Great work.

The rear low / reverse and one way clutch is installed with the tail section on. The intermediate “2nd brake clutch modified”

Not 3 orings and metal sleeves

 

[obe12]

Thrust washer jelly applied to stick it on the drum
Clutched stacked and aligned with forward clutch hub before installing , aids forward unit set in .

Alignment or 3 orings to case hole and use jelly lube to not cut the orings sliding 2nd clutch support into case.

 

[obe12]

Yeah 3 bond the bolt to retain the clutch support in case and torque them.
Rear clutch / aka direct clutch is next and it sets into the 2nd clutch pack discs and splines into the center shaft through the 2nd gear support.

Next flat race on direct hub, and jelly the bearing on the forward clutch and hub to stab into the direct / rear clutch not the flat needle bearing. And lube inside the center of the forward shaft because there is a sealing ring in the shaft in the transmission

Set forward in

 

[obe12]

Jelly on flat race to bottom of OD support case , bearing should be in the forward drum on shaft sticking up in trans

Insert this 3 orings and jelly in place

Use two bolts 8 mm 1.25 to lower support in trans aligning the 3 holes in the case , and once close I drop in a pump bolt to help maintain alignment and gently push into position.

 

[obe12]

Spiral gear is next, needle bearings ride directly against this gear and a flat part goes on OD support

I jelly the race and bearing on the OD support and then Stab the gear

 

[obe12]

Not this spiral gear has a split sealing ring and can’t be over lapsed , ends need to nut together

 

[obe12]

Now the OD planet goes next it has a bearing on the bottom

I pic it off and jelly it to the spiral gear

Then lower the OD planet by its input shaft and have to twist and reset until planet gear mesh to spiral gear

 

[obe12]

Stack of brake clutches , leaving these out helps get the planet back in.
Thicker plate rounded edge out and snap ring in case

 

[obe12]

Now it’s time for the pump, there is a flat race again I jelly to the pump and line the bushings in the pump where Input shaft comes through, lay gasket in position , and not the 3 holes on each side the mat are together my alignment with the pump as I lower it to the case and again use a bolt to help guide once bolt reaches the case

 

[obe12]

by the manual I install the bolts and snug them up and verify input shaft has end play and can turn !

Once that’s confirmed one by one I remove apply 3c
Bond and reinstall and torque 8 ish pounds and move cross side and do that one , and so on cross crossing

Then final torque 16 ft pounds and it feels like the bolts are going to strip , so and steady wins the race alternating criss crossing

Oh yes final thinner oring around pump and case , thicker is pump groove.

Hope this helps

Tex

 

[Kernal]

That's great work with attention to detail, looks like you've done this a few times before

Previously I watched a (sped-up jerky) video of an A442 reassembly (no narration) and it appears they put it together fairly dry,
any thoughts?

 

[obe12]

Well you can do them dry, however book calls for soaking clutch s 15 mins min before installing. I soak them 2 hrs …
And assemble. Pump again book says use trans fluid to lube gears in it …

I kinda go hey once the engine starts no dry components that can be ran until hydraulic fluid pressure comes up. Converter will take a lot at 1st, Then pressurize the shaft. This lubes the needle bearings. Clutches have to slip in neutral and don’t want to scorch them.

Yeah I have done a few over the years. It’s been 25 years since I have an auto scattered tho . Last where 3 A340H trans for Toyota mini truck, 4runner…. Mine and a friends in Houston.
He wants me to come do his Landcruiser 200 6 speed … it’s needs some help.

 

[Kernal]

Do you pour a quart or so of ATF into the Torque Convertor before installing
or like to add an inline filter after a rebuild?