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How to: Project Frankentranny "AKA" A4LD / 4R55E / 5R55E Hybrid Project - A MUST READ!

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On to the intermediate drum and the reverse/high clutch pack.
Here's a view of the front of the A4/4R version:
27133VC-006F.JPG


And here's the front of the 5R version:
27133VC-007F.JPG


You can see that the A4/4R has the bushing in the center where the drum rides on the center support snout, where the 5R version has a steel race for the snout roller bearings.

Another improvement is how thickness of the lugs at the back of the drum has increased (look at the bottom):
27133VC-008F.JPG


Here's a shot of how the thinner lug of the A4 actually deformed the metal of the input shell. The 5R version had no deformation at all as far as I could tell.
27133VC-009F.JPG

Here's another shot of that deformation:
27133MC-018F.JPG


Now to the other side. Here's a pic of the back of the drum with a thrust washer in the A4 (note that the clutch plates are not in place in this pic):
27133VC-010F.JPG


Here's the drum out of the 5R with a Torrington bearing in place of the thrust washer:
27133VC-011F.JPG


Here's a closeup of the channels that carry the steel clutch plates for the reverse/high clutch pack in the A4:
27133VC-014F.JPG


Here's a closeup of the channels that carry the steel clutch plates for the reverse/high clutch pack in the 5R:
27133VC-012F.JPG

Notice that the shape of the channels that carry the steel clutch plates in the drum have been changed with a triangular back so that fluid has an easier time getting out of the clutch pack when it is applied (when fluid needs to get out of the space between the friction plates and the steel plates).

Here's something that I didn't catch on the teardown of the 5R:
27133VC-013F.JPG

That's right, only four friction plates in that clutch pack. If you look up at the drum pictures, you can see that the top of the pack is lower in the 5R than in the A4. I'd like to get at least five, if not six plates in this pack, so I'll update this when I pull the pack apart and find a way of making it happen.

[Update]
I pulled this clutch pack apart for two reasons. The first reason was to see if the piston size had been increased because there were fewer friction plates - the piston was the same. The second was to see how I could get more friction plates in there (at least five).

When I disassembled it, I saw somthing that was hidden before (by the top pressure plate). Here's the components (minus the drum and piston):
27133revhi_clutch.JPG


Here's a closeup of the edges of the steel clutch plates:
27133revhi_steel.JPG

These are different plates than are in the A4, as they have small semicircles removed from the edge of the engagement tabs. This, together with the v-groove in the drum, make for a pretty big pathway for the fluid to get out when the clutch is engaged.

The stock A4 steel plate thickness (0.065"):
27133revhi_steel_replacement.JPG


The stock 5R steel plate thickness (0.081"):
27133revhi_steel_stock.JPG


I found information that shows four thicker (0.081") steel clutch plates for the OHV engine, which means that four friction plates would be normal also. I still want five, so I'm working on some combinations of steel plates to make it work. There isn't enough room at the bottom to take material off the top of the piston, so it has to fit up beneath the groove cut in the drum for the snap ring.

I am going to upgrade the inner snap ring retainer with a full-surround unit (which they used on the overdrive clutch pack, but not on the rev/high clutch pack for some reason). Here's a picture of that part:
27133revhi_retainer.JPG


[Update #2]
I found out that there are two sizes of piston (and corresponding drum) for the reverse/high clutch. The two parts listed are XL2Z-7D044CA for the small piston used on the SOHC, and XL2Z-7D044AA for the larger piston used on the DOHC. The one that came out of this tranny was of the large piston variety (AA). Maybe the ones with large pistons only had four frictions and the small piston variety had five, but this is only speculation.

The other part of this update concerns the way I'm going to get five plates into this clutch pack. I'm going to use the thinner steel plates (.065s instead of the .081s) as well as cutting the retaining plate back around the large snap ring to 0.125" (stock is 0.200"), while still using a 0.065" thick snap ring. There isn't any room to go any further forward on the splines on the forward clutch drum (as shown below), so I'm having to go back on these splines, which means making the clutch plate stack taller by adding to the top instead of adding to the bottom. Getting five plates to work will require some pretty simple machining, but getting six to work would more than quadruple the necessary effort, so I'm going to be OK with just five (only 25% better than stock :D ) . If anybody needs to have me turn down a separator plate for them, PM or e-mail me. I'll update this with pics when it is done. BTW, I think I'm going to end up with 0.075" of metal from the separator plate in the channel (meaning it won't spin around in the snap ring groove).
 



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Hate to interrupt.... but it appears that the intermediate drum would mate to the A4 input shell... do the "guts" (forward drum etc) inside work out that way? In other words could you do an A4 rear end into a 5R intermediate/forward and use the 5R center? (course if you do a 5R OD front end, the 5R center and intermediate and forward, I guess one would have to ask why not finish it off 5R in the back.)... just curious though....
 






Glacier...I have stuck that 5R interemediate drum onto the input shell of the A4, but I'm not positive how the tolerances work out quite yet. The lugs fit perfectly, but length is what might trip that up. After you see the upgrades further back, you might reconsider wanting to leave out the last 25% of the 5R guts. I know that the forward clutch drum has to be used because of the larger intermediate shaft. That doesn't leave many parts until you get to the back of the case. I'm hoping to have the rest of the pictures up tonight, so you won't have to wait long ;) Some of the best is yet to come :eek:

BTW, thanks for telling me how to get the pictures inserted correctly.
 






On with the forward clutch pack...a historical burner of a pack if there ever has been one! Did they make a whole bunch of changes to this piece? Not really, but the one change they did make is a pretty big one in my book.

Remeber the center support and how it had a sleeve on the inside of the snout? Here is the reason for that steel sleeve in the 5R (notice the roller bearings):
27133VC-016F.JPG


Compare that to the old A4 design (the two seals that should be in the two grooves around the snout are missing in this photo):
27133VC-015F.JPG


I did put the thrust washer and bearing in place for these photos, even though they were shown on the last part as well (for those keeping count). For those of you pay REALLY close attention, the holes in the sides of the 5R are slightly larger than the A4 version.

So, where the old design had the entire weight of this pack being supported by the intermediate shaft (which itself wasn't supported very well), the new design uses some bearings...it can't hurt. I did notice that there were some rollers missing, and at first I thought it was damaged, but then I noticed that the spacing was equal (six rollers then a space, six rollers then a space, etc.). I'm guessing that they kept these rollers out so that the fluid to activate the forward clutch could pass through more easily (it makes sense to me).

Here is a pic of where the wear of the six friction plates from the forward/reverse clutch pack from the A4 engage the splines (six arrows):
27133VC-018FB.jpg

There's enough space (at the bottom) where I think you could even get a seventh plate in there.

Now, here's where the wear of the four friction plates from the forward/reverse clutch pack (previous part) from the 5R engage the splines (four arrows and some space at the bottom just begging for more plates):
27133VC-019FB.jpg


So that's pretty much the differences in these pieces. Here's a look at the backs side by side (the A4 version doesn't have its clutch plates in place):
27133VC-022F.JPG
 






So we are now back to the output shaft ring gear and planetaries (and associated bearings).

These are the bearings that go together on the A4 ring gear plate:
27133MC-001F.JPG

The three peices of the bearing fit together to act exactly the same as the bearing used in the 5R (which is three pieces with a crimp so they don't separate.

So here's the 5R's bearings (in front of the ring plate):
27133MC-002F.JPG


The A4 ring gear plate (front):
27133MC-003F.JPG


The 5R ring gear plate (front):
27133MC-004F.JPG


Here they are side by side (front):
27133MC-005F.JPG


Here they are side by side (showing the backs with the Torrington bearings that support the planet carriers in both):
27133MC-006F.JPG


These parts are virtually identical, except the 5R ring gear plate doesn't have material cut out of the plate, but since there is no torque applied to this plate, it is inconsequential.
 






Rear Planet Carriers

These parts are pretty close to the same thing also...no major improvements to be made. A shelf to locate the front bearing was made sharper for more positive location, and the bearing on the back (has the input shell sun gear riding against it) has the race flipped around so that again it is a single three-part bearing unit instead of three parts that make a bearing. :rolleyes:

Here's the front of the A4 unit:
27133MC-007F.JPG


Here's the front of the 5R unit:
27133MC-008F.JPG


The manufacturing process changed in that the A4 unit had the arms bent up, welded, and then ground flush (this leaves alot of residual stresses as well as being slightly more expensive than the updated method):
27133MC-009F.JPG

and
27133MC-011F.JPG

The teeth help keep it located properly while they are welding the part.

Now the 5R unit had its arms heated up to where they were more flexible, bent around to a pin, and then welded. You can see the discoloration from the heat. Grinding is expensive as it requires another step in the manufacturing process. Heating it up before bending it also reduces the amount of residual stresses in the part and help to keep it from cracking/fracturing.
27133MC-010F.JPG

and
27133MC-012F.JPG


These are the shots of the backs of the units (a sun gear on the input drum rides on the inner bearing in the center). Here's the A4's back:
27133MC-013F.JPG


and the 5R's back:
27133MC-014F.JPG
 












I notice something I got some email on once.. the inner most top race.... some were "innies" and some were "outies"....even within the same generation it appears
 






Next piece back is the input shell. This is what was being damaged by the intermediate drum in the A4 because of the thin lugs. There isn't much to these parts, and the only difference I can see is the back of the shell where either a bearing (5R) or a thrust washer (A4) are located. The washer has a wider flat spot at a slightly different height (talking thousandths of an inch difference here).

The front of the shells (A4 on left, 5R on right):
27133MC-016F.JPG


Side view comparison (A4 still on left):
27133MC-017F.JPG


Rear view of the A4 (w/ thrust washer on the back):
27133MC-019F.JPG


Rear view of the 5R shell (w/ Torrington bearing on the back):
27133MC-020F.JPG


Now for a reality check...This is how far we've come in this exploration (without the bellhousings and pumps shown - A4 on the left, 5R on the right):
27133MC-021F.JPG


That's it for at least a few hours....more later. :thumbsup:
 






Great Job Brian.... I was amusing the the errata laying around... calipers etc.... how geekish. <g> This is probably the best thread on here, and certainly a "Most Useful Thread".
 






Very nice detail in your description and photographs, well done.
 






I would've liked to shown lengths and micrometer/caliper readings on everything, but it would take a huge amount of time, I'm not sure how much benefit would be had from it, and because I only have two hands. The way that I've been taking the pictures is by having the flash turned off, holding a light in my left hand, and shooting the picture (as steady as I can so it isn't blurry) with the right hand. I figured that if there is an easy location to make a switch from 5R parts to A4 parts, it would be evident from the design and I could take measurements on that single piece, but so far I've just been trying to document the differences. If needed, I can measure any part because this thing isn't together yet, but it is looking very do-able.

On some bearing races being innies and some outies...I finally figured out the the outies go inside the bore of the mating/adjacent gear, where the innies have the gear sit on top. Sorry to have made a big deal out of it, I was just confused at the time. I know that trying to hit a stack height within 6 thousandths of an inch is tough and I just wanted to make sure I wasn't screwing that up with one out-of-place race. 6 thousanths of an inch in back, and 6 more in front that is, so one one-hundredth of an inch...but that's machines for you (and why the micrometers and calipers are necessary in a project like this).

Thanks for the kudos. I know it takes a bit of their space and bandwidth, but I'm hoping it makes a difference for at least one other person besides myself - if nothing else but an understanding of the differences. That would make it all worthwhile. Alot of people seem know about engines, but there is a severe lacking of understanding when you get to the "magical" piece that goes between the motor and transfer case. I'm hoping to fill in that gap at least a little bit.
 






We are back past the input shell to the low/reverse planetary gear carrier. This part mates up with the low/reverse drum. Here's a shot of the front of the A4's low/rev planetary gear carrier:
27133M-001F.JPG


Here's the same part from the 5R (front):
27133M-002F.JPG


Here's the rear of the A4 unit:
27133M-003F.JPG


And the 5R unit again:
27133M-004F.JPG



There are the same number of pinions (planetary gears), but again they changed they way it was made. Instead of the arms on the back plate being made flat and then bent up, welded and gound flat, they just made a piece that was cast in the proper shape. Dimensional tolerances should be better for the newer part, and the part can be made out of stronger material because it doesn't have to be bent into the right shape. I have a feeling that if you tried to bend an arm of the new basket 90 degrees (like the old part was for making the part) that it would crack, not because it is weaker, but because typically when you use a stronger material, its ductility (bend-ability) decreases.

Another thing that is different is that there are fewer but wider lugs, again without sharp inside corners (presumably for better fluid relief as well as getting rid of stress concentrators). This shows up again on the drum too (where the lugs meet up. The 5R planetary gear carrier is also shorter, which allows something else to occur - the inclusion of a snap ring that was absent on the 4 liter versions of the A4.

The front of the 5R unit also has a raised lip to positively locate a Torrington bearing.

Here's some detail shots of those differences. A4 unit:
27133M-005F.JPG


5R unit:
27133M-006F.JPG


Close up side-by-side front:
27133M-007F.JPG


Close up side-by-side side (front is up):
27133M-009F.JPG


Side-by-side front with the front thrust washer (A4) and bearing (5R) in place (same washer/bearing as was shown on top of (behind) the input shell):
27133M-010F.JPG


A4 unit on top of the input shell:
27133M-011F.JPG


5R unit on top of the input shell:
27133M-012F.JPG


A4 unit w/ rear thrust washer, oil dam, and clip in place (first time to show this washer in this post):
2713314_A4_lowrev_planet.JPG


5R unit w/ rear Torrington bearing, oil dam, and clip in place (again, first time in this post):
2713315_5R_lowrev_planet.JPG


Just as a note, these clips shown in the last two pics go around the output shaft and lock it into place.
 






There is no point in having a sun gear (input shell gear) and planetary gears without having a ring gear, so here it is. The differences are in the plate that carries the ring gear. The 5R unit is set up for bearings on both sides (it has depressions or ridges for positive bearing location and parts serving as bearing races), where the A4 unit is set up for thrust washers on both sides (wide flat spots).

Here's the front of the A4 ring gear and plate:
27133M-015F.JPG


Here's the front of the 5R ring gear and plate:
27133M-016F.JPG


Here's the rear of the A4 ring gear and plate:
27133M-018F.JPG


Here's the rear of the 5R ring gear and plate:
27133M-019F.JPG


Here's a closeup view of the rear of the 5R plate:
27133M-020F.JPG


Here's a side-by-side of the two units (A4 on the left):
27133M-017F.JPG
 






All of those pieces fit together inside a drum called the low/reverse drum. My camera battery died so I'm reserving this space for this drum.
 






Now we are at the rear sprag and race. The rear sprag is what "locks up" the low/reverse drum to keep it from spinning the wrong direction. The thing that opposes the force trying to get the drum to spin in the wrong direction is the rear sprag race, which is a piece of steel pressed into place on the rear aluminum snout of the case (the race is splined and bites into the aluminum). The only way to get the rear race off is to drill some holes (in the right locations) and beat it out from the back. In the A4, there is a thin steel washer behind the race.

Here is a picture looking back into the inside of the A4 case showing the race and the "wave" washer (which is retained by the race):
2713306_4R_race.JPG


Here is the same view of a 5R case:
2713304_5R_race.JPG


Notice there is no wave washer behind the inner sprag race. When I test fit the 5R sprag into the A4 case, I was getting just a little bit of interference, and it was coming from that wave washer. The only way I knew of to get it out was to bang off the race, so that's what I did. So that I could make a direct comparison of the two races, I also drilled the case of the 5R and banged out that race.

For those of you that have done this (for the Sonnax upgrade for example), you know that it isn't that hard to get the race off of the A4 (when it's done right). I did the A4 first, and then went to do the same to the 5R, and let me tell you, it took A LOT of banging to get that race off. The teeth of the Sonnax race are longer and take more force to press on that a stock race. The 5R race had teeth comparable in length to the Sonnax replacement. I sacrificed a hardened steel punch (and then used a larger one) to get that booger off.

Here's some pictures of the A4 race.
Top
27133Z-022F.JPG


Outside diameter measurement:
27133Z-028F.JPG


Height measurement:
27133Z-029F.JPG


Where things ride in the A4:
27133Z-023FB.jpg


Here's a picture of the A4 case without the race and washer (notice one of two holes where I pounded it out):
27133Z-001F.JPG


Here's some pictures of the 5R race.
Top:
27133Z-003F.JPG


Bottom (scarred from beating it out, but smoothed it with a Dremel before reinstall into the A4 case):
27133Z-004F.JPG


Outside diameter measurement:
27133Z-009F.JPG


Height measurement:
27133Z-010F.JPG


Where things ride in the 5R (and soon to be in my Frankentranny):
27133Z-007FB.jpg


They are the same length and same outside diameter (2.700"), but the 5R race definitely has more "bite" to it because of the longer serrations.

Here is a couple pictures of the scarred "wave" washer from behind the A4 race:
27133Z-024F.JPG


27133Z-026F.JPG


Here is a picture of the replacment washer from Sonnax:
27133Z-027F.JPG


What I'm going to have to do is press/beat on the 5R race into the A4 case without a rear washer in place.

[Update]
Well, I got the 5R's race on the A4's case today. Had some issues with the machine shop I was planning on going to, so I did it myself. They didn't want to let me watch, wanted me to set the case on the floor (a soft aluminum case on your concrete floor :thumbdwn: ), wanted $60/hour, etc.. I got out my "high-tech" equipment ;) and got to it:
27133Z-012F.JPG


27133Z-013F.JPG


Do use gloves to hold the case, as the metal can be real sharp in places (not all of that red liquid in the pictures is tranny fluid). Notice the round piece of steel right above the hammers. This is the jig/support that is put into place when the new race is being installed.

When I thought about what I read about how much force it took to press these newer races into place, I realized that I hadn't heard temperature being discussed before. I figured that to make it easier, I would let the case get as cool as it could (in the 40's at night), and warm the race up (200F for an hour in my oven is what I did, but don't go too much higher than that or you run the risk of losing the heat-treatment of the race). That's another good reason for the gloves. I wiggled the race on and rotated it so that the existing case splines were matched up with the race splines, and then put the 4X4 on top and started with the small hammer. It went down most of the way pretty easy, but I was really giving it some decent whacks with the sledge to get it down the last half inch or so.

Here it is, installed flush with the top of the snout (maybe +/-0.0005" from side to side) without a washer behind it:
27133Z-011F.JPG
 






Brain, if you recall, my 12 ton shop press wasn't up to the job of pressing on the sonnax replacement race... just a heads up to save you some possible grief. Also make sure you press it on FLUSH with the snout (to start - that's the stock location and it is critical. Note though that should you find you need some more room within the case, you MIGHT be able to get it by pressing the race on below the snout end!)
 






Rear Sprag

The A4 used a sprag unit that was sandwiched between two brass-clad steel washers shown here:
2713363.JPG


The problem with them is that they would wear through the brass and have steel to steel contact (not good). Sonnax offers a replacement/upgrade to these end caps that are solid.

Here's a pic of the rear sprag (in the low/reverse drum) sandwiched between two of the updated end caps:
2713309_A4_rear_sprag.JPG


In the 5R, they got rid of the washer and end caps and replaced them with bearings. Here's a shot of the 5R rear sprag and bearings:
2713310_5R_rear_sprag.JPG


Here's a closeup shot of the bearings:
27133115_5R_rear_sprag_closeup.jpg

A bearings ride on the front of the rear race, while B bearings ride on the side of the race. In order to have room for these bearings riding around the front sides of the race, the sprag rides further back on the race and there are no bearings behind the sprag.
 






Glacier, I do remember that issue you had with it not sitting flush...three thousanths if I recall correctly. I'm going to get the new race exactly flush with the front of the snout, however big the press has to be. I think that if I try to counter-sink the race on the snout, that I might run into tolerance problems with how the inner back of the sun gear rides on the snout. Those longer teeth really do a good job of holding it on (even front to back, let alone around as the torque from the lockup is applied).
 



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On to the output shaft!
Here they are, side-by side:
2713332B_output_shafts.jpg


A is the front tip and has roller bearings inside the shaft that the snout of the intermediate shaft fit into.
B is where the clip that was shown in the rear planetary carrier gets attached(reverse/high planetary carrier).
C is where the haft runs in the rear output shaft support bushing (A4) or bearing (5R).
D is where the govenor/parking gear (A4) or the output speed sensor/parking gear (5R) are splined on.
E is where the shaft splines into the transfer case (4WD).

Here is a closeup of the front tips with the bearings (location A):
27133MVC-009F.JPG


They are the same.
 






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