Monthly Archives: August 2011

TV cable adjustment 700R4 overview

Now, a 700R4 even when i was starting out seemed intimidating and we would all chose a 400 or 350 over one cause you simply did not want to deal with the added cost of the build and the damn throttle cable. with the high price of fuel and the availability of these trannys these days, they are now the go-to choice for street applications when you are going to retro fit an different driveline into an old car or custom street rod. to be honest, it is a lot easier than you think these days.

The overall goal no matter what when adjusting the cable is to simply adjust the cable to fully seat the throttle valve fully shut at wide open throttle. stock cables are adjusted by depressing the button at the end of the cable that mounts behind the carburetor/throttle body. you  back seat the stock cable  to the rear of the car to take up slack: to the front to create slack….much in the same way you would adjust a parking brake cable. if you are using  a universal cable , you pull the cable tight and clamp the cable in place @ WOT. whatever it takes, you want full open at wide open throttle with the right geometry to the throttle shaft centerline.

if you are retro-fitting a 700R4 to an older chassis, it is a lot easier to use the proper brackets either stock or aftermarket for both the carb throttle linkage and the cable end hardware. when using the right brackets, adjustment is as simple as openning the throttle to wide open throttle and adjusting the cable to seat the valve(pull it all the way out). holley and edelbrock both make brackets for the 700R4 throttle cable. it isn’t worth dicking around with making your own linkage unless there is no alternative, and there usually is.

if you want to be adventurous(cheap shit) and want to modify the carburetor linkage without using an aftermarket kit, it can be done. from what i can gather, you are basically going to  measure 1 3/32″ off the centerline of the throttle shaft to get the right action on the throttle cable you have to get 30 to 35% of travel must be behind the vertical centerline of the throttle shaft. this is about 1/2″ to the rear of the throttle centerline at idle/low speed usually.

the other 65-70% must be to the front of the centerline of the throttle shaft, or about 1″ from the centerline of the throttle at wide open throttle….or WOT. this is to ramp up oil pressure faster off idle. if  you don’t get the throttle action lop-sided, there will be a constant pressure rise which results in trans clutches burning out…….and you wreck your tranny basically.

DO NOT ADJUST THE CABLE TO MAKE IT SHIFT HARDER. DAMAGE WILL RESULT. use a shift kit or modify the governor to change your tranny shift characteristics. so if anyone has told you to either do that or leave it unhooked…..they are full of shit.

700R4/4L60/4L60E Input and Forward Drum Service

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well since the input and reverse drums of this family of transmissions overlap and are very similar for nearly 20 years, i didn’t see the point in dividing up the articles. as you have probably seen this picture before, but this is the input/reverse drum assembly out of a 4L60e, but is identical for the most part to any of the other trannys. this is pretty much how it comes out of the tranny. you can also see the 2-4 band in the picture.

 

 

rev drum

the job of the reverse drum in this transmission is primarily to be a holding member for 2nd and fourth gear to create planetary action. the 2/4 band basically locks against the outside of the drum in an identical fashion to a low 1/reverse band in a th400. the sheet metal teeth on the outside of the drum engage your sungear shell. to the inside of the drum is your reverse clutch pack. it is typically a 4 disc clutch and can be serviced pretty much like any other clutch pack out of a th350 or th400.  basically the 2/4 band is dissengaged , the clutch packs of the input drum are dissengaged, and the front of the input input drum drives the reverse drum to give reverse.

the outside of the drum is known for excessive wear and if damaged should be replaced during a rebuild. it will wear just like steels in a clutch pack….primarily during the 2nd gear shift. if it is minor wear you should take some emery cloth and at least scuff the surfaced up so the new 2/4 band gets worn in correctly for proper shifting. overall pretty simple but not to be overlooked.

theinput input drum assembly is next. outside of the low 1 holding clutch to the rear(same as a th350), and the reverse drum clutch, this houses everything else pretty much. in a nutshell it seems complicated as hell, but it really isn’t that bad. most of the pistons sit to the rear and all the clutches sit to the front….and there is really only one spring you need to compress to get everything out. pictured here is what the drum looks like as it comes out. you can see the cast sprag to the front that engages the reverse clutch pack. check this quick for gouging and wear. at the base of the input shaft is your sealing rings. now they used several sealing rings over the years. it is pretty much an industry standard that whatever it did have: put the one piece teflon sealing rings back on it during rebuild. and yes it does require some special tooling.

youS3700040 pretty much flip the thing over and drop out the clutch packs. first thing is you remove the outer snap ring, 3/4  pressure plate, clutch pack,  and apply plate(yes there is a pressure plate on both ends). this is your 3/4 clutch pack assembly and can have up to 6 discs/steels. you may also have return springs that fit in 4 spots to the outside of the clutch pack between the drum and pack. these are return springs. some builders leave these out to make the shift quicker and better clutch apply…..sometimes they were never in there to begin with. if they are there, i recommend putting em back in unless there has been a shift kit installed of some kind. the outer pressure plate thickness can also vary so if it is damaged, make sure you get the right thickness to insure proper clutch pack clearance. these are known as a problem area and they make specialty cluch set ups for these like the Raybestos Z-pack to remedy failure in extreme applications. depends on what your application is for during rebuild.

once that is out of the way, S3700039the next one down is the forward clutch. pictured here is a second snap ring….which sits below the 3/4 apply plate. once this is removed pretty much everything else will fall out as far as clutch packs so don’t panic. this is where if you have never done it, you remove the ring….slam it on the bench….and panic when all sorts a shit come out. this is what a diagram in an atsg manual is VERY helpful. 

anyways out comes the snap ring, forward clutch pressure plate(which is also variable thickness) and  forward clutch pack with bottom wavy steel come out with the forward sprag assembly usually. there is at least 4 clutches and steels the sprag assembly should be set aside for later inspection.  below the forward clutch is your overrun clutch set up. the backing plate for the overrun clutch is also your apply plate for the forward clutch…..so if you can take note on how it came out so you don’t get frustrated during re-assembly. the overrun clutch is only 2 small discs and two steels.

at this point, you are down to removing your pistonsS3700037. this is the only real spring pack you need to remove. as you can see here, i made up a small tool with a few bolts and a piece of flat steel, then chucked it into my lathe and used the drill chuck as a compressor. there is a tool for doing this….i’m just a cheap shit and this cost me 20 minutes of time.  now, when compressing the spring pack here only compress it like an 1/8″ or less! there isn’t a lot of free travel under the spring clip here so just push it enough to relieve tension on the clip…then wrestle the clip off. i believe the reason for the lack of compression space was to keep the material as thick as possible in that area of the drum. the area of the drum below the retaining clip is a fail point and there is even aftermarket sleeves offered by sonnax to beef up this area for heavy applications and big power.

once the clip is out, you pretty much can pull out your pistons. S3700036the first set out is the overrun clutch piston(center), the forward piston(middle: holds the overrun piston), and forward piston housing. this picture by the way if how i put em back into the drum as an assembly….they may come out individually.  below the forward piston housing is another return  spring, the tin apply ring(looks like a cheap piece a shit with long fingers) and the 3/4 apply piston. now….you’re empty and you can clean, inspect, and rebuild. now, depending on the year and model, your input drum may have aluminum pistons with seals, molded seals that are made into the piston(require piston replacement), or a mix and match of both styles of pistons. most people prefer the molded pistons for the 3/4 apply piston, however  i think it really depends on the year and the application…..and your budget.

here is a photoS3700031 of the 3/4 piston to the right- apply ring, and forward piston housing.

 

 

 

 

 

here S3700029is a picture of how the piston assembly is layed out from right to left, right being the bottom and left being the top. you can buy all this as an assembly from your parts suppliers if you have chronic damage of want to use modern pistons in an older 700R4

 

 

 

 

 

hereS3700025 is the forward clutch sprag assembly.  this can be a fail point and should at the very least be popped apart to check for cracks and what condition it is in. a double cage 29 element sprag is preferred for these and some of the early trannys had a weaker sprag. enough years have gone by though that if it has been rebuilt, someone probably already revamped it. it basically is a one-way lug type sprag that locks in gears 1-3 and overruns in overdrive….basically driving the entire transmission. so if there is a problem, you don’t check it….you’ll be in deep shit. the two disc overrun clutch meshes with the smaller side of this assembly and when locks gives you engine bracking, otherwise the clutch will overrun allowing you to coast. 

re-assemblyS3700027 is not that bad after you do it once. first, install the 3/4 piston. i use a feeler gauge but some kits come with an installation tool….and there are specialty install tools as well. once in, put on your apply ring and spring, then what i do is assemble the rest of the pistons as pictured earlier and install them as an assembly. then re-install your springs. the first clutch pack in is your overrun clutch pictured here. i am pointing to the seal here that MUST be replaced. this seals the center of the input drum to the output shaft. don’t forget to put it in. i usually put it in first before any clutches. it’s splined on the outside and is hard to miss in the rebuild kit. also when putting the apply plate for the forward clutch on this, make sure you put it in right. the rest of the input drum is pretty much stack and go. like any other tranny, you should soak your clutches. on these trannys i prefer to always replace your steels with your clutches it’s money well spent!

GM 4L60E Teardown Pt. 2

now for the second part of this tear down, we are basically going to break the transmission down into it’s major components the rest of the way. in a nutshell you then rebuild and go through each component separately then re-assemble.

S3700002after the valve body has been separated as described in part one, next i go to the 2-4 servo cover. this applies the band on the reverse drum to give you a holding member for 2nd gear and 4th gear. it is held in by a spring clip and is stubborn as hell. the atsg manual gives you this as a starting point….and the youtube video’s give you the impression that it falls out. well, it is corroded and is a bitch to get out. soak it in wd-40 and tap it into the tranny to get the pressure off the clip. you then either pop out the clip…..or like i had to do….chisel the rotten rusted thing out of the case and try not to bust the case. once the clip is out you are suppose to use a pair of pliers and simply pull the cover out….snip off an remove the o-ring on the outer cover-and the whole works falls out. in reality if it is siezed in the housing like mine was, you put air pressure on the back side of it via the ports under the valve body while coaxing it with a rubber mallet. this is why i prefer removing this after you pull off the valve body, just in case you have a nasty core to deal with.

 

next, ifS3700004 you have not already done so, remove the tail housing. i recommend that you pull the tail housing WITH the speedometer still installed if you can. they are prone to breaking if you try to pull em out from the outside. after removal you can use light pressure from the inside and pop the speedometer out of the tail housing from the inside. you can also see what i call an oil shield in this picture. unlike a th350, the tailshaft comes out to the rear of the case so this does not need to be removed.

 

Now, for pump removal. there is no tapped holes on the front pump for a slide hammer toS3700012 be installed as you would do in an older gm or chrysler transmission. so basically after you remove your pump bolts you can use a specialty tool to pull the front pump out using the stator shaft……or like many gm transmissions you stick a large screwdriver behind the pump through and openning of the valve body side and pop the front pump out by prying against the reverse drum. here again there is no picture of me doing it cause there is youtube video’s and atsg manuals to go by in this instance: a demonstration is a bit more appropriate if you have never done it.

 

S3700011

after you have the pump removed, your clutch packs can now come out. the front 2-4 band can be removed first. it may not seem like it but the band can be coaxed out first with a large screwdriver. if the locating pin has not yet come out of been removed already, it can be popped out from the backside of the pin to help in band removal. after the band is out, the reverse and input drum assemblies can be removed in one glob. also in the picture you can see the the front planetary sun gear as well. this can also be removed at this time and set aside. the input and reverse drums can be separated after removal as they are serviced separately:it is pictured assembled as this is how it looks comming out.

 

next it is time to remove the retaining clip holding in the rest of the front planetary, the output shaft, and sun gear shell assembly.S3700010 i have it removed from the case. it is a pain to get to, but it is basically removed similar to how a th350 tranny comes apart. the exception being that the output shaft will usually fall out once the clip is removed: so make sure you are prepared for that. do not worry about damaging the clip removing it as you should replace this clip….and it usually comes in a good rebuild kit here you see the fron planetary set with clip laying on top and output shaft. the sun gear is removed as well and simply pulls out of the case

 

now, to S3700014be honest the rest of this tranny is damn near identical to a th350. here now you are down to the center support containing your rear sprag, rear planetary gearset, and you low 1/reverse clutch pack. this is basically a th350 set of but it has tighter tolerances than the th350. so it makes removal and installation a bit more of a pain in the ass. nothing to be alarmed about though.

 

at this point your 4L60E should be apart on the bench. each component should be checked over, rebuilt, and appropriate parts replaced at this point.  the case, the gearset and center support, front pump, input drum clutch assy, reverse drum/band/servo assy, and the valve body should be looked at as if they are separate units. approaching a build like this will make comprehending and servicing your transmission a lot easier. it can be overwhelming( if not intimidating) if you try to look at it as if you are doing everything at once.

re-assy is fairly easy once everything has been serviced. if you have done automatic trannys before, it is rather simply. if not, use an ATSG manual and you will be fine as long as you have a bit of patience.

GM 4L60E Transmission Teardown pt. 1

i am going to begin disassembly of my 4L60E.  many of the same internal parts of this line of transmission apply to the 700R4 with the exception of the valve body components. so i am going to deal with the removal and inspection of these separate. first off the biggest difference is that we have an aluminum valve body instead of cast iron like the older trannys. so use caution when handling it as the edges are like a knife if you get careless!

 

S3700015So the ATSG book said to start with the 2-4 servo cover here-the book i got from summit racing said to start with the tail housing. personally to save you a headache start with the valve body. after busting some components trying to follow the atsg manual, i would say start by removing the oil pan, filter, and wiring harness.i didn’t get a picture of it complete with the wiring harness but here it is after the harness is removed to give you an idea.

 

 

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when removing the wiring harness, the solenoid right above the torque converter clutch solenoid must be removed. i believe this is the 3-2 solenoid to the front of the valve body. it is simply held in by a spring  clip just above the solenoid….and will fly off across the shop. these solenoids were pulse motors early on and later were a more simple on/off style solenoid.

 

 

 hereS3700006 we have removed the torque converter clutch solenoid, or rather TCC. this MUST be removed prior to pulling the pump out otherwise you will break the damn thing off. as you can see that’s what i did cause i was following the wrong manual. it is wired in one piece to the harness and comes off with it rather than just a connector like everything else. these are prone to cracking causing converter failure. you can check these with air pressure if you are careful, but if you have an older one and are unsure- spend some money.

 

hereS3700009 i have removed the pulse width modulator (PWM)solenoid so you can get a good viel of the connector going through the case. there is a special tool to remove the connector via pressing the fingers on the top of the case and pushing it through the bottom. you can also use a buddy with small screwdrivers while wiggling it- or a large socket. the prongs will break if you just yank it out. you can leave the pwm in and remove the valve body first to remove this connector a lot easier.

 

NowS3700045 at this point you can turn either turn you attention to everything else and remove the valve body last, or remove the valve body and stuff now and set it aside for later service and inspection. i am going to go the route of getting the valve body the rest of the way off. next out after the harness remove the pressure switch manifold and set it aside. you can also see it’s location in the first picture above. i would also remove the selector tension spring at this point as well just to make life easier later on.

 

nextS3700073 remove you valve body bolts and your valve body assembly. there are check balls located on both sides of the transmission  separator plate and can vary with the years, so have the tranny inverted and pull the valve body straight off. usually the check balls will remain in place…if not be stuck in the mid plate.  remove your check balls. the 1-2 accumulator is in the upper left hand corner holding everything in still as well as the plate to the rear.

 

 

hereS3700071 is when you can take note of your valve body gaskets and what mid plate you have. the mid plate is stamped with a letter designation and the orientation of the gaskets is also marked. if you are investigating a failure this is a place to stop and take notes to see if someone else didn’t screw it up at some point during a prior build….or you need a different mid plate. my fingers are pointed to a “V” and a “C” as the gaskets are marked.

 

 

 you can then removeS3700049 the 1-2 accumulator, rear coverS3700052 plate, and mid plate/gaskets. the bottom half of the 1-2 accumulator is below the mid plate and can also be removed. the pin  at the center of the piston pulls from the case. these accumulator pistons can be a high wear item so inspect them closely before re-installation. note the locations of the rest of your check balls at this time as well. here i am pointing to an encapsulated check ball to the rear of the case. this is suppose to stay in place but can fall out due to wear. this needs to also be checked out before re-assembly. also note the check ball near my thumb in the case that is loose. this one is easy to overlook during re-assembly so take note not to forget.

 

last thing inS3700051 this part of the tranny is the 2-4 band anchor pin. now depending on where you started this may just fall out of it may have to be pushed out after you remove the front pump and/or the 2-4 servo.  at this point you can also remove your selector shaft and parking lever engagements. you can now turn your attention to the rest of the tranny for disassembly.                                                             

 

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GM 4L60E Transmission

well in this second section i will be going through some of the background of the 4L60E transmissions. somewhere between 1992 and 1993 the 700R4 became a computer controlled tranny and was/is redesignated the 4L60E/4L65E. It did not have a governor or throttle valve cable(TV cable) as the earlier models did. the 4L60E uses electrically fired solenoids for shift and what is call a pulse width modulator(PWM valve) in place of  where a governor and modulator valve would be on an older tranny. this is also referred to as a force motor by some people. The on- board computer then dictates shift points,  TCC operation, and overall function of the valve body. most of the mainline internal components are similar(if not interchangeable) with the 700R4. the main difference between the two is the valve body on the 4L65E is made of aluminum instead of cast iron and is fully computer controlled.

The 4L60E also received upgrades throughout the years as well. the 93-94 models had their own valve body set up/1995 was unique unto itself/and the 96 and later models also were different yet. in 1998 them made the housing a 2 piece design with a removable bell housing.

one thing with this line of transmissions over a th350 or good old th400, there were A LOT of different kits and what not. just looking through my book there are 3 different rebuild  kits for the older 700R4 and 3 or 4 different kits for the 4L60E, so getting the right kit for the right tranny and application is somewhat critical. you must also correct things on these trannys that aren’t even defective because they are common fail points. as a rule a thum- the older the tranny the more updates you are going to need. 

S3700001So, i got  this bastard 95 vintage core in on trade. unless i plan on sticking it into another 95 conversion van from connecticut that died out here…..it was a heavy metal band on tour by the way……….it was more cost effective to play with the older 700R4 and put this in the core archive for future use.  These things are all over the place….and i get probably 4 calls a month during the winter of these trannys going out in GM trucks moving snow.  i bet you pass at least 5 of em going to work everyday on the highway in operation. there are shift kits available and like the 4L80, there is performance software out on the market to adjust your shift firmness and timing via the laptop computer or aftermarket programmable module that plugs into your OBD diagnostic connector. i haven’t dealt with these systems first hand yet.

Rochester Carburetor Number Decoding

Did you ever wonder what in the hell the numbers on your carburetor meant? when it comes to Rochester carburetors, In this day and age it is damn near impossible to take a carburetor into your local part’s store and find a clerk that can even recognize a carburetor let alone try and find you a rebuild kit! so in a nutshell you need to know what your carb came from to begin with so you have an idea not only to determine what carburetor kit to get ,but what it may have been calibrated for. Remember when chosing a carb…yeah you can always drill/swap out some jets but with these older rochesters, the passages-air bleeds-main jet-cfm rating-etc are hard set for certain size engines.SO, unless you know for a fact where the carb came from always check the number to see what you are dealing with.

Example: # 7028219
DG 1938

On most Rochesters you can find these numbers covered in shit on the main body. on the q-jets it can be found near the rear corner face of the main body secondaries going up the side of it. on a 2G carb it is on the side of the float bowl. you can sometimes be lucky enough to get one with a tag on it still but that is somewhat rare…..and the numbers are usually covered in corrosion and shit and by mistake-you scrub the numbers off trying to read them. rebuilders may or may not tag the core after the build.

 

7028219

Prefix code. “70” will appear on all late ’60’s Rochester Carburetors.
76 and later will start with “170”
2 – Decade produced.
702 – 1960’s
703 – 1060’s with A.I.R.
704 – 1970-1975
1705 – 1976-1979
1708 – 1980’s

7028219

Year produced.
8 = 1968
If the number was 7045219 then
5 = 1975
7028219 Model
0 – Monojet (1 bbl) Federal standards
1 – Two jet (2 bbl) Federal standards
2 – Quadrajet (4 bbl) Federal standards
3 – Monojet (1 bbl) California standards
4 – Two jet (2 bbl) California standards
5 – Quadrajet (4 bbl) California standards
6 – VariJet (2 bbl) Fed
7028219 – Division.
0, 1, and 2 all indicate Chevrolet.
4 – Buick
5 – Olds
6,7 – Pontiac
7028219 – Transmission most cases
Even numbers – Automatic Transmission
Odd numbers – Manual Transmission
DG Production Code.
1938 Rochester produced carburetor Date Code
193 = 193 rd Day of the year
1938 8 = Year 1968
Other
A8 o MM Carter Produced carburetor Date Codes
A= Jan
B= Feb
C= March
etc….
A8 o MM 8 = year 1968
MM Production Code.