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700R4 low pressures?

27K views 136 replies 9 participants last post by  '49 Ford Coupe 
#1 · (Edited)
Hi folks, I am getting ready to go into my 700R4 to do some more mods and correct some errors I made in last winter's build. I did before work pressure tests this morning and got some troubling results. Minimum TV, in P, N, D, 3 @ 1,000rpm, pressure is 90psi which is fine. But then in reverse, pressure @ 1,000 is only 110. In manual 1st and 2nd, pressure @ 1,000 is still just 90 psi. Full TV, pressure in P is 105. N is 110. D is 95. Man 3rd is 100. Man 1st and 2nd is 100. When I raise rpm to 2,000, pressures @ full TV are P & N- 220, R-210, D 190, 3-200, 1&2-210. Gauge is steady(no wiggly needle). In R, D and 3, when I rev the motor with the TV locked full open, pressure jumps to 240 before falling back off to the readings listed above. I wonder if that might be the pressure relief valve opening. I would like that to hold til 300psi if possible.

The unit has a .296 rev boost valve and the .500 TV boost valve with a high rate regulator valve spring. I have dual springs on the line bias valve and a new 10 vane pump. I expected much better readings. My ignorance is that I put the unit together and drove it most of the summer without pressure testing. Won't make that mistake again. To make things worse, the TCC never worked since the build and I know I got it hot. I know that there are probably several things that could cause this kind of behavior. Does anyone have any thoughts? What jumps to the front of your mind? Sealing ring(s)? Damaged pump? Gasket blown? I plan to go into the unit first thing in the morning and have the weekend to get it back together. I have a full gasket set, new sealing rings, and some other goodies to put in it. If I need other parts, I will need to run to Portland tomorrow to get them. Up side is that it is coming winter and I don't drive the car in anything but sunshine. Worst case is I find something wasted that I can't get tomorrow, I put it back together best I can, limp it home and go back in later better prepared. Moral of this story is pressure test before you drive it. Damn!

I am very thankful for any help. Go ahead and chew my butt. I've earned it.
 
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#109 ·
LOL! Good call dogwater. OCD definitely in full swing. I am about ready now to go back into the unit. I got the bushing driver set last night. Good set. Still will need to be careful driving the bushings. Crosley says that it's better to install them with an arbor press so not to compress them too much. Especially if the drivers don't fit real snug. These drivers aren't too bad but probably not as good as the factory service tools. I only have 4 bushings to do so that helps.

I know that I'm probably going further with this then I need to but I really want this unit to be as close to perfect as I can get it. Having the clearances just right and all roller thrust bearings is a step in the right direction. Plus, it's only my time and a little money.
 
#110 ·
I installed the double wide rear sun gear bushing in the extra gear I have on hand. I used the new driver set with the adapter that fit the bushing best and drove it in rather than pressing it. I now know what dogwater was talking about as far as the bushing ending up being tight on the shaft. I have my new reaction shaft to try the sun gear out on for fit. At first the bushing was way too tight on the shaft. I think I probably drove it just a little too far into the gear and maybe deformed it against the machined back stop. Maybe 2 less blows with the hammer would have been good. I ended up having to clean it up with emery cloth and scotch brite to get it to fit well. It's an $8 bushing and I'm thinking of getting another one and trying to install it with the press this time. The fit is really pretty good now but I'm curious to see if I can get it right using the press and not have to mess with sand paper. The service manual doesn't say anything about using emery cloth or lapping compound on a newly installed bushing. I'm sure that I'm over thinking this but I just want to get to where I can do the job right.
 
#111 ·
Looks like no one is really following this thread anymore. Can't really blame folks for dropping it. My OCD is kinda hard to follow. I don't even talk about this project to my friends and family anymore. They just wouldn't understand. At any rate, I ordered the last piece of the puzzle on Monday. The Smart Shell from Sonnax will complete my collection of parts and allow me to delete all thrust washers from the unit in favor of roller thrust bearings. I was going to let the thrust washers behind the sun shell and in front of the reverse input drum go for now but once I decided to swap out the front washer, it only makes sense to do the rear washer along with it. I will also be setting end clearances down to the minimum for improved stability at high speeds.

I realize now how important the geartrain created by the rev input drum and sunshell is to the strength and durability of the trans and how overlooked it is by both the OE and ATSG who don't even mention checking endplay of the rev input drum.

I plan to do this last D&A in the next few weeks, once I have all the parts on hand and can schedule a weekend free. Once it's done, I will again post a parts list with all the mods I've done.
 
#114 ·
I've saved all of this cause I spend hours searching the web for those little tips an tricks for about trans rebuilding. This has almost everything someone would need to build a very strong 700. I'm not up on 200r4's but I think a lot of these applys also. One thing I found not to long ago is the top snap ring that holds down the 3/4 clutches, that same snap ring in a TH350 & a C4 is thinner. Depending on the thickness of the steels & clutches used one might be able to slid in an extra steel & clutch. Another one was using the back half of a 13 vane pump (4l60e) an the front half of a 10 vane, you would have to port match the fliud passages. You'd end up with a 13 vane pump for a 700 r4. It said you get a slight increase in fluid pressure from the pump, I don't think its worth the trouble to do that though. I do have both of those pumps laying around doing nothing an I'm kind of interested if its do able. Once I get do with painting my Camaro I'll look in to it. An yes I check in here a few times a week.
 
#115 ·
Cool. I am happy to think this might all be useful to others. I am set to go next weekend. Got the Smart Shell Friday and mocked up most of the rear gear train stack from spare parts I have on hand. It all rides on Torrington bearings now, very smooth. The selling point of the Smart Shell is that it takes load off the captured bearing in the rear planet. All the real tranny pros Ive talked to said that's not a real issue. However, what the Smart Shell also does is replaces the nylon washer behind the sun shell with a bearing. It not only smooths up the assembly but it moves the support of the shell further out from the center for better stability and strength. I can see where it really beefs up the gear train.
 
#117 ·
Oh oh. That shell in your photo looks an awful lot like the Smart Shell I have sitting in front of me. Does it help that mine doesn't have any balance holes drilled in it?

I was concerned about the strength of the Smart Shell but with the heat treating and all, I thought maybe they had addressed that issue.

How about using the Torrington and the short roller clutch race that come with the Smart Shell, with the Beast Shell I have already? I was planning on test fitting the parts to see if this is possible. Have you tried something like this?
 
#118 ·
Today is the day. I'm already into the unit. I've done the reverse input drum bushing swap and installed the front pump Torrington. It went together perfect. One thing is bugging me though. While Ive got it out, I did a quick wet air test of the input housing clutches. I was suprised to see that when I apply air to the 3-4 clutch, alot of air escapes through a hole in the housing. This hole is in towards the center from the 3-4 check ball capsule. It looks like it must be a lube hole for the reverse input clutches because that's where the oil it bleeds would go. I don't remember if the factory housing had this hole. Does anyone have one handy they could look at for me? I'll tear the housing down if I have to to plug this hole or whatever is needed if this is a problem. The clutches in the housing are all brand new and everything tested good except this weird thing with the 3-4.
 
#119 · (Edited)
Okay, I learned something new. The hole in the input housing that bleeds fluid off of the 3-4 clutch piston is there to provide lube oil to the reverse input clutch and to the Torrington bearing at the front of the input housing. I figured it must be fine since 3rd gear has been engaging great. Especially with the Transgo 2-3 shift kit from Pro Built Automatics. The mods in the kit include deleting the 3rd accumulator to remove the factory cushion from the 3-4 clutch apply. With these mods, the 2-3 shift is instant and tight like flipping a switch. Plus, with the line bias valve blocked and the combination of the .500 Sonnax boost valve and the TCI purple PR spring, I'm getting close to 290psi in 3rd. So, obviously, the lube hole isn't affecting 3-4 apply pressure much. I just wish that the manual would have mentioned this in the air test procedure. They do say that air from the overrun clutch apply will exit through the forward clutch apply, but not that air from the 3-4 apply will blow out though a hole in the housing. Whatever, now I know.

The process this weekend went pretty well. Things started out great. I took Crosley's advice on installing bushings and used many light taps on the driver instead of beating them in. I wasn't able to get the front bushing out of the reverse input drum without damaging the rear bushing so I replaced them both. That went very well. Then, like I had planned, I removed the low reverse clutches and the low reverse roller clutch support and stacked up just the components that support the sun shell and the reverse input drum to check end play of this part of the geartrain. With the pump installed using the old gasket and no o-ring, I had .020 end play. This is more than the .005 claimed by the manufacturer of the bearing, bushing kit but it's still better than the .150 allowed by GM. Once I had verified end clearance on the reverse input and sun shell assembly, I removed them and checked end play of the input housing with the all of its supporting components installed. The Sonnax .015" shims really helped in setting this up. I ended up with about .018 clearance there.

I did end up having to use the Smart Shell as the bearing and race wouldn't work with the Beast shell. If needed later on, I can have some machine work done and find a different bearing to make that set up work. But on Saturday, it wasn't to be.

I did run into one hitch that almost stopped me. I want to warn anyone following this thread who decides to perform these upgrades about the subtle differences between the late style reaction shaft(Torrington) and the early style(thrust washer). On the surface, they look identical but for the machined relief where the Torrington rides. However, the difference comes in where the planet carrier Torrington installs. If I'd had an extra planet carrier on hand I could have test fit the parts before Saturday. I'm sure that a trip or phone call to Standard Bearing in Portland could have solved the whole problem since they have or can get every type size and shape of bearing imaginable. As it was, being stuck with what I had on Saturday, I had to get creative and spent alot of time painstakingly enlarging the inner diameter of the late style bearing to fit the early style carrier. Then several more minutes cleaning the bearing of shavings before I could continue the build. The obvious solution to this whole mess would be to simply switch to a 5 pinion front planet. Then the assembly would have fallen right together. As it is, I ended up with a smooth running assembly with plenty of clearance between the hard parts. It just sucked having to go about it the way I did.

The rest of the job went great. I chose not to replace the other bushings in the unit after carefully checking them for clearance. They all checked out fine. I replaced the 2-4 band since I had damaged the one I started with last winter. It's a $40 part and not a big deal. I also added just a bit of clearance at the 2-4 servo pin, up to .100", as it looked like in the few miles that i put on the unit since I was last in there, the band may have been running just a little tight.

I rewired my TCC controls so that I will have lock up in 4th when the switch(the factory fog light switch) on the dash is turned on. Through my earlier testing, I determined that the ACCEL DFI ECM activates the TCC relay with 12v applied to the TCC input signal circuit. That works well with the factory TCC brake switch. A simple wire connection made it all work.

At the back end of Saturday's work, I have a fully rollerized 700R4. I now have TCC controls that should work fine for me. The issues I came away with include no 4th gear. I probably left a check ball out or it could just be the Dr Tranny's Assembly Goo I used to stick the check balls in place during assembly. It's alot thicker than vasoline and it may just need more time to dissolve. I also still have too much MTV pressure causing the 1-2 shift to come too late. So, I'll need to drop the pan and change spring shims again. I think I'll just try running no shim and see how that works. I'm still runing 120psi line pressure at idle in gear. While I'm in there, unless 4th gear starts working on the way to the shop next weekend, I'll drop the VB and make sure I didn't leave a check ball out.

As far as pictures go, sorry guys. I thought about taking pictures but then I get so focused on the job, I don't want to stop for pictures. Just selfish that way I guess.
 
#120 ·
Glad to hear that your getting there. I know what that is like to only make little steps, one at a time. When warm weather hits, i'm going into my 200 4r again for a little twieking and i'll be good to go also. I should just leave it alone, but its there and i just can't help myself. I think you'll feel the same way also because you did it yourself.
 
#121 ·
Thanks dwwl. I spoke with the tech guys at Greater Dimensions Engineering about the end play result with their kit not being what they stated. They said that it's because of the Smart Shell and the low/rev race that goes with it being cut too short overcompensating for the Torrington. That makes sense to me and was kind of what I was thinking. The end play could be reduced by simply going to a thicker bearing or adding a .015 shim. They agreed though that .020 is very good. Much better than the OE spec. I'm wishing now that I'd brought the car to work today. Not much going on and I could have dug into the trans to fix 4th gear and my MTV pressure. Oh well, a week away from it won't kill me.

In the middle of writing this post, Dana from Pro Built called to check on me since I called him for help on Saturday. He seconded what Crosley said about the lube hole in the input housing. He also said I probably screwed something up that I don't have 4th now. I am double checking the separator plate gaskets and I can't see anywhere they don't match. I swapped out the Transgo gaskets in the unit for Transtech from the paper rubber kit. I'll drive the car back to the shop next weekend and if I don't have 4th by the time I get here, I'll drop the pan and see what I did wrong.
 
#122 ·
Well.....I Thought I'd seize the opportunity to take car of the trans today, since it was so slow yesterday. Weather man calls for snow on Saturday and I want to get done ahead of that. Turns out I've done 3 cars and over 8 hours work already today before 2pm. Better yet, it's been trying to snow all day. I may still get the chance to dig into the car today but then I may end up having to leave it here at the shop if it decides to snow for real. That's winter in the Willamette Valley for you. It'll probably be 65 and sunny by next week.

In the time since I started this post, I got the opportunity and dropped the VB on the trans. Guess what's not there? The 4th accumulator check ball. Dammit! I knew I missed that one. I was going to grab it and I got distracted. Oh well. Good news is the trans fluid is perfect. In the 35 miles since Saturday's work, and that includes one hairy smoke show as I tested the 1-2 shift point. Not a spec of friction material or metal. Has to be a good sign right? Now... maybe I'll get to see if the TCC works. Finally.
 
#123 ·
An't, not proper english, an't it fun. The more i work on these tranny, the more i want to learn them. Well, atleast the 200 4r. I'm sure you think the same of the 700 r4. I've copied every thing i could find about them, and have a folder three inches thick. I also have a old dresser full of old good parts as well as some new parts, not counting a ready second tranny. Make a record of what you did to it, that way you'll never wonder down the road what and how you modified it.
 
#125 ·
Thank you Crosley, and of course you are correct. I still have no 4th gear. What is somewhat telling is that I do have TCC lockup, which means that I am getting 4th gear signal to the pressure switch. I don't know if I had lockup before I installed the check ball because I didn't try turning on the dash switch to see, but last night I had it. I had doubts about the check ball myself from reviewing the hydraulic schematics since this check ball doesn't do much, especially with the Transgo mods deleting the 4th accumulator function.

Something I noticed last night with the TCC locked was a pulsation, like the 4th servo was cycling on and off. While doing the roller mods on Saturday, I thought I saw where the 2-4 band might have been set a little tight so I removed one shim in front of the 4th servo. I run the Sonnax dual piston 4th servo which isn't very forgiving of too much freeplay. I'm wondering now if I may have set the clearance too large and now the 4th servo is over extending and passing oil.

Maybe you recall how I suffered the consequences once before of making wholesale changes. Ending up having to undo what I had done so that I could see what change was causing my problem.

What sucks is this is a 3rd gen F body with a tiny little trans tunnel and the tall fat super hold servo will not clear the body to come out without unbolting and lowering the trans quite a bit. Not such a big deal, just irritating how I did this to myself again. Making wholesale changes and ending up having to undo them one at a time. I did double check band clearance but I was probably too generous. The superhold only calls for .075-.125 and I bet that .150 is way too much. I am running the Superior 2nd servo with the Sonnax 4th which is unorthodox but it was working fine until Saturday. Should have left it the hell alone.

I think at this point, I'm going to take a few weeks off from this project. Let it sit safe and warm in the garage while I regroup and collect my thoughts. This 4th servo takes lip seals which will certainly be rolled and possibly cut from over extending and being pushed back in by the return spring. It's best that I have a new set on hand before I go back into it.

Positive points are that my TCC is now working. First time in probably 14 years. I also removed the shim from the TV spring and now my shift points are back where I wanted them. "Small steps Sparky" BTW, trans fluid is getting pricey and I've been going through alot of it. :spank:
 
#127 ·
After more research, I'm really questioning if the 4th servo could be moving far enough to pass fluid. Even with the dual pistons, it appears that the servo can probably move quite a bit before a piston ring goes past the housing. I also see that the Sonnax 4th servo uses teflon rings and not lip seals. It was the superior servo that used a lip seal. A quick air test will verify whether the servo is okay or not. I'm puzzled as to what else would cause that weird pulsation. I did remove a pressure switch that I had installed in the TCC signal port trying to make the TCC work in more than 4th gear and replaced the switch with a hex plug. I'm wondering if that plug may be too deep and blocking a passage but would that affect 4th?

From the hydraulic schematics, it appears that enough pressure on the 2nd servo circuit could prevent the 3-4 relay valve from moving and thus prevent 4th from engaging.

The changes I made to the hydraulics of the trans were removing the TCC pressure switch and installing the hex plug, removing one .052" shim from the 4th servo, replacing the Transgo gaskets with Transtech gaskets(I have triple checked to be sure that the Transtech gaskets don't block any passages), installing a drilled 4th accumulator piston with spring to support the separator plate against the heavy 2nd accum spring, removing the shim from the TV spring. What have I done wrong?
 
#128 ·
Well I think you went just a little over board with the 700. Me being me I still don't fully under stand how an auto works or I just don't see everything working together in my mind. So that being said I didn't get to crazy with modding things, even though I did a few. On an engine I understand everything so I feel comfortable in doing mods, I can see in my head what's going on, on a auto trans I'm not their yet. I think you need to revert to the K.I.S.S. syndrome. I don't think plugging the tcc port or installing a 4th accumulator piston had anything to do with loosing 4th. The others I don't know. I was concerned about your pressures being that high an using the aluminum pistons. I'd check all of them for cracks, I think you should be using the steel pistons.The only other thing is check the valve body gaskets for V on valve body, C on case. Like I said before just get it working right, shifting right an just drive it. Like my old man used to tell me "Are you fixing it or are you f--king with it" That always used to piss me off but I understand more better now.
 
#129 ·
Lol. Yeah dogwater, I think you got me there. I actually feel pretty good about how everything has come together on the unit. Yes, I definitely went overboard on it, but that's kinda how I roll. Lol. I'm very sure that no 4th is something simple. All other gears are solid and the shifts are super tight. The roller components took most endplay out of the geartrain so shifts are even better than before. Since 3rd is very strong, I know everything in the input housing is solid. I know what you mean about the steel pistons but my aluminum peices seem to be good for now. I'm pretty sure that it's probably just the servo. I've had this happen on other units I've put together. I'll take care of it in few weeks.
 
#130 · (Edited)
OH YEAH!!! Got it set up right today and it seems perfect so far. I must have gotten distracted when I was assembling the 4th servo a few weeks ago. The Sonnax 4th servo comes with two shims. One automatically goes in. The other one is for setting up band clearance. I put the thing together with no shim at all. What I thought was band clearance was just the servo housing bottoming out in the case. The air test kinda said it all. The air just blew out the exhaust hole as fast as it went in. Even though the trans tunnel on the 3rd gen F body is tight, I was able to sneak the servo out and back in by just moving the trans around a little and didn't have to completely R&I it. It turns out, the servo I got had already been updated to the D ring piston seals instead of telfon rings and the seals were fine. The post repair air test went quite differently with perfect function of the servo. I did go ahead and R&I and completely clean the 3-4 valve train as well just to be sure.

On the TV valve train, I reinstalled the .050" shim I had tried before along with the Transgo .035" shim that goes with the 2-3 kit. The .035 shim goes under the end of the TV valve blocker that comes with the Transgo kit. The .050 shim that I made up goes around the blocker and adds tension to the spring without affecting total plunger travel. I made up the .050 shim after I decided that the .100 shim I had tried earlier was too much. I also swapped the 1-2 shift valve spring for one 33% softer. The softer spring corrected the issue of a late 1-2 shift. So far the 1-2 shift timing seems perfect. The 3-4 shift seems to be right where it was before the mods. I won't know exactly where full throttle 1-2 and 2-3 shifts are until I can get the car out on some long stretch of back road. The car shifts from 2nd to 3rd at 80mph and even if it shifts from 1st to 2nd at 5,500, there will be noise and tire smoke and I've already driven past two police cars today, so it doesn't feel like a good idea right now. If shifts end up too high, I'll have options on how to correct it. The TV valve train is easy to swap without even dropping the VB. I could also just change governor springs. We'll see how it goes.

Base line pressure now in 3 and D is 120psi cold, 105 hot and rises quickly with throttle. Max line seems to be 280-285 in 1st and 2nd, and 275 in 3rd. I know that higher pressures cause increased heat but I have beefed up the cooling system with 3/8" cooler lines and dual coolers and I have done the Transgo PR valve mod for increased cooler flow, so I hope it will be okay. I know that today after tooling around town, a cruise on the highway and one tire smoke session, the fluid was just warm when I removed the pressure gauge. The former fog light switch turned torque converter control switch works perfectly. In 4th gear, I can turn the converter clutch on and off with the flip of a switch. I love it.

This has been a long saga and I hope that those who have followed my progress or who read this thread later can benefit from my experience. What I have created here, with alot of help from some real pros, is a 700R4 reinvented. There are still ideas in my head for future upgrades, likely sometime around the implant of the new motor. Among them are billet forward and 3-4 clutch pistons. The billet forward piston is available from Sonnax. The 3-4 I will have custom machined because I don't like the idea of a stamped steel piston at 300psi. With the new motor will also come a higher stall converter and the largest boost valves from TCI. Other than those few things, this trans is pretty much bullet proof. There is no off the shelf performance 700R4 offered anywhere that is built like this one. You could have one built if you can find a builder who will actually take the time and effort to go to all of this work. I know of one guy, our man Crosley, but he would probably need a good chunk of change to do it. Crosley would do these mods because he's the one I got the ideas from.

I will write a complete run down of the process I've gone through on this beast of a transmission, detailing all of the mods and parts used, why I did them and how they worked out. I will also point out my mistakes and how to avoid them. It will be somewhat of a novel as this job became quite involved. Most likely I'll get to that Monday morning before the shop opens. For now, I'm off to wash the car and enjoy it some more. OH YEAH!!!
 
#132 ·
After a little more road time this weekend, I finally came into the shop this morning and put all of my transmission misc parts and literature away for good I think this time. This trans is everything I want it to be and I am ready at last to just drive it and enjoy it. As with anything men build, there are certainly things that could be changed. The 1-2 spring I installed could be 10% stiffer perhaps, the car at light throttle wants to start out in 2nd gear unless I manual shift it. Of course with the 3,500 stall converter and high line pressure, it won't hurt a thing to let it take off in 2nd at light throttle. Any kind of throttle pressure at all kicks it down to 1st. This just one of those things that I'll notice as I drive it but it's not enough to really worry over. This trans shifts so perfectly, and if I want a higher shift point I can just hold it in manual 1st or any other gear using the B&M shifter. I also am now keenly aware of the sensation of driving a built, small cube SBC with a locked TCC. I don't think I'll be using the lock up anywhere but on the freeway at 65+. The next motor with a few more cubes might not mind so much, we'll see. Again, the thing here is that I can control when the TCC is allowed and when it's not so, no problem.

The main thing is that if I do decide on the next fluid and filter service to change things a little, the only disassembly needed will be dropping the VB itself. Everything else is where it will stay.

Now as promised, the list of mods along with the why and how of each one.

Starting at the front of the unit:

The torque converter is a 3,500, 9.5"(254mm) stall Edge brand with lockup.
I went with Edge because it was slightly less money than Vigilante. Both of these brands were offered by Pro Built Automatics and I worked alot with Dana on this unit. If he sells it, it's a trustworthy part. When ordering the TC, I was asked a list of questions from the peak torque RPM of the motor to my driving style. The Edge TC was custom curved to fit my answers. The result is excellent. There are many fine makers of TCs out there today. I will say here that Edge is one you can trust.

Next is the oil pump. Fluid pressure in these transmissions is critical to the performance and longevity of the unit. The more power you put to the unit, the more pressure it needs to hold the clutches from slipping. Watching various rebuild videos, I saw many who were rebuilding their own pumps. None that I saw were having the pump case remachined. When you have the pump apart, you will see how the rotor creates a wear ring in the case. The basic rule here is that if you can catch a finger nail in this ring, replace the pump. I figure, why even take the chance. A rebuilt pump runs about $125-160. Considering the cost of rebuilding a transmission, this is pocket change. I found a local rebuilder at Oregon Torque Converter who does an excellent job on these pumps, including setting clearance, another critical part of the job.

Next is the input housing. Of all of the rebuilds I looked through, everyone uses the stock factory housing. There are versions offered with hardened shafts and reinforcement rings. The issue I have with the factory housing is the 3-4 clutch pack. GM designed this unit with the 3-4 clutch at the very rear of the housing, retained by a snap ring. The stock housing, with the snap ring groove, provides a limited space for this clutch. HP 3-4 clutch sets add frictions in order to increase holding capacity. Even the factory, on the 4L56E, stepped up to 7 frictions from a maximum of 6 in prior versions. With the limited space provided by the design of the housing, the only way to increase friction count is to go with thinner plates. The first thing most kits do is reduce thickness of the apply and backing plates and the snap ring that holds it all together. When this clutch is applied, there is nothing supporting it from the back. Just the snap ring and backing plate. Thin frictions and steel plates flex under high apply pressure and this flexation can't help but reduce holding power of the clutch. No wonder we see so much failure of this clutch pack. That's why, even though no one else seems to use it, I went with the Sonnax Smart Tech input housing. This is a $500 part and I had to really talk myself into spending the money on this one part, with so much else the unit needed. This one part makes the rebuild very expensive. It also cures absolutely the weakness of the 3-4 clutch. When installed with the shorter 3-4 apply ring(stamped #7) and the tallest input ring gear, the Smart Tech provides an additional .200 of 3-4 clutch capacity. The apply plate that comes with the housing is made from super hard billet steel and does not flex. The housing has no snap ring groove and the backing plate is held on with 15 screws and is also made from super hard billet. This one part transforms the 3-4 clutch. It allows the use of very high apply pressure and with the Transgo 2-3 shift kit produces a rock solid instant 2-3 shift. I don't expect others to go out and drop the cash on this part. But, I have to say it's worth every penny.

I'll continue this write up in another thread.
 
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