HistoryEarly automatic transmissions used simple motor oil as a lubricant, but as the systems became more complicated, producing ever more heat, a specialty lubricant was required. General Motors answered the call first in 1949 with Type A transmission fluid.Type A was followed by ATF offerings from Ford and Chrysler in the ensuing decades.
For a time, these fluids sufficed for most of the automatic transmission market. Today though, mechanics must ensure the ATF they intend to use meets the OEM specs for each vehicle. What makes modern ATF special?Besides defeating oxidation, the best automatic transmission fluid must also be non-foaming and must not deform the seals in the transmission or react with the various metals inside the housing.
It must also allow for the clutch friction surfaces to engage without undue slippage.To achieve these requirements, manufacturers use chemical additives that make each ATF formulation unique. The additive package also includes viscosity modifiers to keep the fluid from thinning at high temperatures and friction modifiers that smooth shifting.Complicating matters further is manufacturers’ requirement that ATF not break down and change properties over the course of 100,000 miles or more. Of course, operating conditions will affect the life of ATF.The cooler operating temperatures offered by synthetic ATFs can make a big difference to component longevity. The best automatic transmission fluids usually claim to improve vehicle fuel mileage, but renewing the fluid will almost always do that.
( are some other ways to improve your miles per gallon.). What is the difference between ATF formulations?There are many different ATF types, and each auto company has its own requirements. Manufacturers do not make ATF, but rather license the names of their specs to petroleum companies. Oil companies are generally free to develop additive packages to meet the requirements.The major American car companies each have their own licensed ATF. General Motors is currently on its Dexron VI specification, while the modern Ford spec is Mercon V.
Chrysler uses ATF+4. The difference between these fluids lies mainly in their friction modifiers.Mercon ATF historically allowed for more component friction at slower speeds, while Dexron’s modifiers allowed for higher friction at higher speeds. There is otherwise little difference between the two, and the best automatic transmission fluids meet the requirements both sets of specifications.European and Asian car companies normally each have their own sets of specs as well, but there is a great deal of overlap in those markets.
However, vehicle owners should never assume an ATF is right for their vehicle. Due diligence may be required, including reviewing manufacturer and oil company literature. Can I use modern ATF in an older transmission?Most modern ATFs, such as Dexron VI and Mercon V, are backward compatible with most older transmissions. There are exceptions, but this backward compatibility holds as a general rule. Early versions of Mercon V had limited backward compatibility, but Ford corrected the problem.Both fluid types can be used to top off a system running any of their earlier versions, and a full drain can be done without the need for a system flush. However, ATFs meeting the older specs cannot be used in transmissions requiring the modern fluids.
Check your vehicle’s manual for the manufacturer’s recommended ATF, and only substitute for a fluid you are positive meets those specs. Valvoline uses Group III paraffinic oil as the base for its MaxLife synthetic ATF.
Its additive package is so refined that is suitable for nearly every modern automatic transmission application — ATF+4 and CVTs excepted. Because it is synthetic, MaxLife has an extended drain interval.Rather than simply being compatible with transmission seals, MaxLife’s additives include an agent that conditions seals to prevent leaks.
It also includes cleaning agents to clean off any deposits from friction-prone components, though its other additives discourage the deposits as well. Castrol uses a Group III base oil for Transmax full synthetic ATF, but most of its other Transmax transmission fluids are mineral-oil based. It is an affordable alternative to pricier synthetics, but offers performance to rival any other ATF.There is a Transmax ATF for nearly every application. Transmax Import Multi-Vehicle, for example, is suitable for most Japanese cars, but it also meets ATF+3, Dexron III and Mercon V specs for older American vehicles. Choosing Transmax may force car owners to do a bit more homework, but the savings may just be worth it. ConclusionThe best automatic transmission fluids are suitable in many vehicles, which tells us as much about the state of modern transmission engineering as it does about the state of modern chemical engineering.
These endeavors are now so high-tech that the fields are homogenized.Picking an ATF for a vehicle is an understandably frustrating task. The high cost of repair makes the decision seem critical, which is why a quality, reputable product like Valvoline MaxLife is so attractive. It uses a long-lasting synthetic base stock to meet many OEM friction requirements, and its use can extend the serviceable life of a transmission.
Alright folks, the engine build is over and running well so it's time to move on to the next step in my IHC adventure, the transmission. Unfortunately the Torqueflite 727 doesn't get much love around here. I don't think there's even an automatic transmission section in the KB!These automatics are my favorite part of these old IH powertrains.
The engine is always fun but there's something about these tranny's I just love. When I first purchased my Scout II, The tranny was leaking from every location with the exception of the dip stick tube. The bands were out of adjustment, the filter was old, and the PO had been driving it around like a manual for quite some time as it was mysteriously shifting from 1st to 3rd at like 5 mph, hmmmm. After opening the hood, the throttle valve rod was just laying across the engine unhooked, go figure. The only good news was that it was leaking so bad the fluid stayed pretty fresh.
So I had to force my self to dive into it right off the bat. I remember being terrified the first time I dropped the pan. Something about seeing the valve body, servo's ect.just scared the hell out of me. Some projects went smooth, some not so much but in the process I've become quite infatuated in these slushboxes and have tried to learn as much as I can about them.The Torqueflite is an extremely durable transmission. It was used in a number of vehicles over the years and is well known at the strip too. They easily drive our low HP engines and only last about 40 years or so in the process.no biggy! These internals are driven completely by hydraulics with the exception of NSS switch.
It's the only electrical component on it. When you get into the inner workings, you just have to respect the folks that originally designed them, or any automatic for that matter.
Absolutely amazing.Just like the engine, this build will be slightly modified. A stock 727 can handle way more HP that our engines could ever produce but there are some inherent weaknesses that I'll tackle as well as a few improvements in areas that I think I'll benefit from. Nothing crazy, but this is isn't your typical IH owner 'what's the cheapest way possible to get this tranny built' rebuild. There being so many of these trannys still on the road today along with the fact that they are popular strip trannys, the aftermarket support is amazing. I walked into my local 'quality' transmission shop here in town and almost everything I needed was on the shelf, performance parts included. Not used to that!!Anyway, I'm currently running a 1972 727 behind the new engine and while it's still running fine, it's old and tired, that's for sure.
I'll be replacing it with a spare 1973 unit that is currently stripped down and waiting for new parts. The advantages of the 73 is that it comes with a part throttle kickdown as well as the improved vent baffle system. These being the two main issues I have with the current unit. I want to be able to kick down into second in more situations during a typical drive without having to floor it. The part throttle kickdown will provide me with that.
Also, the old vent system is prone to leaking which is annoying as well, especially on a cold morning after the converter has drained back. I run it just under the full mark now which seems to help quite a bit but the new baffle should be the real fix.So without further ado, here's what we started with: 304, 727, D20. Isn't it beautiful!This won't be a step by step rebuild as there are a few very really good resources for these units and there's just no need to repeat it all. However, I'll still cover the important items and will be happy to take pics of anything you might need. The extension housing is different than all others so I will go into greater detail on that part.Here's a list of the resources I know of that have and will continue to help me out greatly. 1& 3 are my favorites.1.2.3.Parts list! Here's everything I'll be using with notes and links when I have them.1.
Transtec DKB 2200A rebuild kit. Stock kit w/ Borg Warner clutches and steels.2. Raybestos Pro series solid rear band.3. Red lined solid front band. (some prefer a solid band here for durability, some prefer a flex band for increased contact area on the drum.
Monroe states a solid band is necessary for high pressure applications.4. Not sure how many I'll use here but they provide 15.5. Increased band holding capacity6.: Comes with 2 D ring seals and 2 Teflon seals. The accumulator bore can wear to the point that it requires a sleeve. Mine has not but the 'D' ring provides a less abrasive, more positive seal in the bore.
Very little if any leaking past these rings.7. Better seal for better shift characteristics. HD strut won't flex under increased pressures.8. Provides O ring seal for pistons pin to eliminate cross leak. Also replaces the stock Control Load servo for better shift characteristics. (note: stock control load servo can be modified to act like a non- control load version.)9. Eliminates 3 issues.
The pistons cocking and/or cracking in it's bore. It's also a double seal design and the top seal rides on a fresh surface in the bore for increased sealing.
They term it as a 'Case Saver' (Note: the stock servo can be modified to do that same thing)10.11.12.15. Street stall option +500rpm, link to home page16.17., Stator and input.18. Thanks to a some schooling as well as a slight nudge from fellow BP member's, JVX low Gear kit - 2.74, 2.54, 1:1Parts being replaced due to wear:1. Rear clutch drum: The band surface is damaged and black from heat.
It can be cleaned up on a lathe but I found a very nice used one locally for cheaper.2. Front planetary: I have a couple very loose pinions. I've purchased a rebuilt unit from A&A Transmission. Low gearset has replacement planet.I think that covers it. I'll add to it if I see something I've forgotten. Anyway, As I mentioned, it's already torn down and I've taken quite a few pics already.
I'll will post them up shortly.The only outstanding dilemma I have at this point is the Torque converter. Some of you may have seen my thread over @ IHPA. I'd like to push the stall up a hair considering I pushed the power band up on the engine. I'm trying to figure out how far to go so if you've got an experience with TC on a built SV, I'd love to hear about it.ThanksJason.
I installed a lower gear set in my 73 scout and enjoy the extra kick in pants to get going if you haul heavy loads or to help you crawl slower for trailriding. I believe 2 racing trans shops build them and I believe they are in 2 ratios but I am not sure as the last time I looked was 3 years ago. 2nd gear is also lower in this set therefore I have a bigger cam so the motor can rev up higher and still use it for passing gear. However if I had a stock cam passing gear or 2nd gear wouldn't do much. However Jauringer has a higher reving cam so this my work great for him.I too love this trans. Its tough, if built correctly, I just wish it had an overdrive!!!!Oh wellBrandon. Hey guys thanks for the note on the lower gears.
I've done a little reading them. IIRC, there's two different types.
The modified/welded 999 gears and the billet low gear sets.The Billet set being the correct way to do it, so I've read. They're expensive though. I think ATI carries them for 1200 bones @ 2.77:1 While I would love to do that, it might be a little steep for me. (no pun intended) I'd be more interested @ around the $500 mark, $1200 is just a lot.I've read it equates to roughly a two ratio upgrade in your axles, does that sound about right? (IE: being at 3.73 now, it would respond as 4:28)I agree Brandon, and OD would be great. I notice a lot of Mopar guys like the 727 to 518 swap for just this reason.Jason.
My sets were the ones with the 999 low gear planetaries welded into the modified outer shell (or however they made it). Stock 1st is 2.45:1, lower is 2.77:1, as stated. Because 1st is lower, 2nd is also lowered a bit too (power flow through shared gearing), and there's a slightly larger gap between the 'new' first and second gears.
If the welds are properly done, I don't know why this type set would be considered inferior to the other. I put a lot of miles on that Scout and as far as I knew, the new owner's driven it all over creation, too, with that same set. Sure an plus when towing up to the Scout's rated limit (I did that on occasion, too). I'd have to look around to see if I still had that receipt. I know I paid $400 for the last set, but that was around 2003.In any case, put an auxiliary tranny oil cooler to it, as well as a deep pan.
These thrive on cool fluid and lots of it. I ran a temp gauge and mine was always around 180 degrees. I also ran a 4-row radiator so the first pass of oil exiting the torque convertor dumped quite a bit of heat into it and the extra cooler tidied things up.edit: checking in the IHON site brought up JVX as the vendor. That's who I bought mine from back then.My 0.02. Here are a few tear down pics. There's really not much to it. It all comes out pretty easy.As you can see in the pic above, the tranny was DIRTY!
I plugged any open holes and took a pressure washer too it before I even cracked it open. It cleaned up reasonably well really.
The nice thing is it can be moved around pretty easy. I can pick it up and put it my work bench without breaking my back which is nice.Here's the first look inside. Even dirty fluid keeps the internals pretty dang clean.Close up of the valve body. Low reverse or rear servo is at the top right.
It's responsible for applying the rear band in manual low and reverse. The high pressures created by the reverse circuit is what can crack or cock the piston in it's bore. (as mentioned in the parts list)Kickdown or front band is on the bottom right. It's your second gear band.The black lines across the pan bolt holes indicate the threads are still intact. The ones that weren't got a helicoil insert.With the valve body removed, you can see the accumulator bore and spring in between the above mentioned servos. It cushions the 1-2 shift as well as the rear clutch when shifting from park to a forward gear. This dealys the 1-2 shift so firmer springs, no springs, and sometimes blocker rods are used here to make that shift quicker.This one just has a spring on the outside.
Some have one on the inside too.Here's the inside of the tail housing. (love the RTV I won't use any sealer anywhere on this build. Sealer has it's place and I own a bunch of it but I don't think it's necessary here. There are no areas I've seen that have a hard time sealing.) In the back you can see the rear bearing. The grey plastic protrusion is part of the speedo housing seal. The hole on the front right is where your parking rod from the valve body goes.Here's the other side, the bull gear side that attaches to the transfer case.
There's a double seal here. One that faces the transmission keeping it's fluid out of the transfer case and the other faces the transfer case keeping it's fluid out of the tranny. There's also a breather hole in between the two seals to neutralize pressure.With the ext. Housing removed you can see the rear output shaft. The rear support at the very bottom and the governor housing just above it. The very top splines are for the bull gear.
The slanted splines below it are for a speedo gear. ( if we used one here.)Here's the pump body coming off.Most will use a slide hammer to pull the pump body off the case. However It's not necessary and can easily be removed with a punch and hammer from the backside.Clean, simple, and it takes very little force.Here's the other side of the pump body.
In the center you can see the reaction shaft support is still attached with 6 bolts. A couple things to note here. The brown looking washer around the base of the support is the washer that controls the input shaft endplay. It's recommended to check that endplay before tearing apart the tranny so you have an idea of the where you are.
Mine was.082' which is a little higher than I want so I'll have to tackle that down the road. The next thing to note is inside the support bore. There is a bushing at the very top which will be replaced but below that are two black rings. Those are wear spots from sealing rings riding for 40 years! Those will need to be cleaned up with a break hone.
Last is the later style vent.So after that There's a snap ring to remove but it basically just pulling subassemblies out and keeping everything organized.A large C clamp is helpful to remove the servo pistons.Once you get to the bottom of the case, you'll find the sprag. Notice the crushed springs.To remove the outer race there's a set screw that has to come out first.Then I took a little punch and knocked it from the backside through the rear support bolt holes.Rear support.Now that it's empty, I've got to do some more cleaning on the case and ext housing.All the subassemblies are laid out on my other work bench. I'll tackle one subassembly at a time.
First thing I did was to inspect everything for wear. Next was to install new bushingsthrough out.Jason. My sets were the ones with the 999 low gear planetaries welded into the modified outer shell (or however they made it). Stock 1st is 2.45:1, lower is 2.77:1, as stated. Because 1st is lower, 2nd is also lowered a bit too (power flow through shared gearing), and there's a slightly larger gap between the 'new' first and second gears.
If the welds are properly done, I don't know why this type set would be considered inferior to the other. I put a lot of miles on that Scout and as far as I knew, the new owner's driven it all over creation, too, with that same set. Sure an plus when towing up to the Scout's rated limit (I did that on occasion, too). I'd have to look around to see if I still had that receipt.
I know I paid $400 for the last set, but that was around 2003.In any case, put an auxiliary tranny oil cooler to it, as well as a deep pan. These thrive on cool fluid and lots of it. I ran a temp gauge and mine was always around 180 degrees. I also ran a 4-row radiator so the first pass of oil exiting the torque convertor dumped quite a bit of heat into it and the extra cooler tidied things up.edit: checking in the IHON site brought up JVX as the vendor. That's who I bought mine from back then.My 0.02. It looks like they still have them Mark.
No price in the catalog. I'll call Monday and get some info.TORQUEFLITE GEAR SETSThe proper gear ratio for the horsepower andtorque to weight ratio of your car will improve yourreaction time, sixty foot time, and elapse time (ET).727 - A5182.08 Low Gear Set.
726002.45 Low Gear Set. 726012.74 Low Gear Set. 726022.77 Low Gear Set. Click to expand.Erik,The 'high dollar' Allison 1000 series automatic in my 2006 GMC Duramax diesel also uses tapped threads into the aluminum case. I was very careful setting up the torque wrench when I switched the factory shallow pan to a standard Allison deep pan. At least the main filter is an external spin-on so the only time the pan filter is normally changed is during a rebuild.Thanks to the OP for a very interesting write-up.
It has been decades since I have been inside a 727 transmission.And for those fighting problems with vintage rigs take heart from the issues that modern computers can cause. I have been fighting an intermittent issue for several months with my 2006 Sierra where the engine would sometimes keep running when the ignition was turned off. The four factory service manuals total over a foot thick which gives you an idea of the complexity. Everything is computer controlled via a network and the engine and transmission each have separate controllers with a BCM (body control module) coordinating everything. The high pressure common rail diesel has an additional controller just for the fuel injectors and high pressure pump. Even the power windows are separate nodes on a network controlled by commands processed via the window switches. I finally narrowed the problem down to low voltage being fed to some of the ECM (engine control module) ports with the key in the off position.
This was sufficient to keep the processor alive which caused it to turn on the ECM power relay which then fed normal power to the ECM. The root cause was mouse pee in the under hood bussed electrical/fuse/relay center which established a leakage path between a constant 12 volt feed (known as IGN-0 voltage in GM speak) and the IGN-E bus which then back-fed to the IGN-1 (run/start voltage bus) via the IGN-E bus fuse. A $40 replacement for the corroded bus center was the final cure but I have about 5 hours of troubleshooting time and I hate to think what the dealer cost for troubleshooting this annoying intermittent would have been. It really made me appreciate the simple non-electronic diesel in my Deere 955 utility tractor. I can also vouch for the advantage of the lower 1st/2nd planetary gearset. I purchased the JVX unit with the 2.74 first ratio.
I've been running it since the late '90s. JVX and the transmission rebuilder had no issues with using the gearset in my application. My 727 runs the B&M Shift Improver Kit, Mopar Performance deep steel pan w/ composite pan gasket, and Derale finned cylinder external ATF cooler. On the bolt-in sprag: I inquired about one when this trans was rebuilt. The rebuilder said that a proper (snug) fitting standard sprag should work just fine behind an IH V8.
He inspects the fit of the unit in the case splines before rebuilding. Much like you Jason, up until this time last year I was very intimidated by these slushboxes, but again like you, circumstances kind of forced me to dive into a malfunctioning one that had been 'rebuilt' by a grizzled 'expert', or so it seemed.
I didn't have any money to pay anyone else to fix it, but what I did have in abundance was time. So I rolled up my sleeves and plunged in head first.
You probably remember the thread I started here last year chronicling my exploits because I seem to recall that you chimed in a few times. Long story short, I was able to turn that batch of lemons into lemonade and since then I've successfully serviced several other TF's. During that process, I've also grown quite fond and respectful of these units. My experience in no way qualifies me as an expert, but I know just enough to be dangerous and the learning process continues on almost a daily basis.
While our opinions may differ on what brand of kool-aid to pour down the fill tube, the common ground far outweighs that one aspect. I will be following this thread with great interest as you continue along your merry way. Thank you for your willingness to share and keep up the good work. You are a true Binder patriot and your experiences and observations serve the greater good. Thanks a bunch Scoutboy! Yeah, I didn't mean to come across like I did on that fluid discussion.
That came out like I was indicating you use the wrong fluid when I really didn't mean it that way. I just use something different.Oh, I remember the fun you endured with your 727. I couldn't have guessed that outcome with 600 tries.
It's was a good lesson learned for everybody though. Even the guys that come highly recommended can screw up just as much. Some people like what they do and care about the product they put out, some people just work for Friday. Sometimes it's hard to tell the difference.Erik, thanks for the info. I actually found a few posts of you discussing these low gears in my searches. I have to say, you guys are getting me all riled up about these damn low gears! I look forward to speaking with JVX tomorrow and if there in that range I mentioned earlier, I might just have to pull the trigger.
It's only money right?Also, If I want them that bad and can't spend the cash now, I can just wait. This project didn't require me to put my baby down so it is what it is.Mark back to your original post regarding my comment on the Billet vs welded gears.I think most of it may be because it's all strip related info, which is where most of this low gear info comes from. Guys pushing 600 Hp with punishing burn outs and extreme launches. I'm sure in those situations, the billet units might be the only way to go. However, considering you and Erik having been running/ran these welded pieces for years, I think that's a pretty good indication that the welded pieces are not prone to failure behind our tire shredding SV's.
Plus, you just never know how picky somebody might be when you're reading that type of info. Reminds me of an old post I read here once where a guy basically called another guy a sinner because he had a crescent wrench in his automotive tool box.
'Those are for plumbers, not mechanics!' .We all have different opinions.I'll provide JVX's updated info tomorrow. Hopefully it's good news.I do want to end with one question. I'd like more info on is the low gear 1-2 shift. Mark, you touched on it already. The 1-2 shift gap is already fairly noticeable which I'm hoping to eliminate with a with a slightly higher stall speed Torque Converter.With the low gears creating an even bigger gap, does it fall on it's face a little at the 1-2 shift? Maybe that's a little too strong but how noticeable is it?Thanks guys, I really appreciate the help.Jason.
I don't recall the gear ratios of the set I have but first to second seems tighter or pulls harder than stock 2nd gear ratio does. Now the gap for 2nd to 3rd increases and may add slightly more lag than a stock setup but not that I really notice. The relative high torque at low rpms I believe helps out here. Plus with your higher reving cam you can hold 2nd gear longer if needed before shifting into 3rd if pulling something, driving up a long grade, or just out running the law for fun!!!!! It makes the whole experience of rebuilding a trans more interesting in my humble opinion.Good luck.
All righty, Spent this morning talking low gear sets with a couple folks. I found that the JVX and A&A guys were very helpful. Especially the man @ A&A.
He started quizzing me before I even asked the first question.he didn't seem afraid to turn me away if the application didn't fit the situation. The more I learn the more it sounds like the low revving, high torque IH SV is a pretty dang good candidateHere are the prices/description;JVX low gear set: $515.00 2.74 1st gear 1.54 2nd. They upgraded 999 pieces machined and welded to fit the 727.
The kit includes a sun gear/ w bushings, 4 pinion planet w/ Torrington bearings (sweet!) and the associated annulus w/ Torrington bearings as well. The thrust washer to bearing conversion is probably where most of the expense is. It cost quite a bit just to convert to stock bearing planet'sA&A low gear set: $750. Same as above but Billet. Really not a terrible price over the welded pieces and way less than the ATI racing set I found first. They might be all steel though.Well, the JVX piece hit my range so I pulled the trigger.
He'll have it shipped out today.I really appreciate the help and the referral to JVX. This has certainly made this build more exciting IMO.Ok, next phone call is to TCI etal. I need to talk torque converters.
I've got a thread over @ IHPA that Scoutboys been helping me on. Between that and a few phone calls to these performance companies, I hope to be able to make a good decision here.