GM built hundreds of variations of the same trans for
differing applications. This is why it is important to obtain an identical
or more heavily built unit, if you will be reusing stock components.
Two speed automatics were
very common from the start in the early 1950s through the early 1970s.
GM, Ford, and Chrysler all had their variants. At the time of the
early Hydramatic when other companies were trying to catch up, it
was thought that a two speed automatic with torque converter was a
superior design compared to the four speed with fluid coupling design
of the Hydramatic. A torque converter does torque multiplication just
like a gearset does. A fluid coupling is strictly a pass-thru device.
Eventually everyone caught on that two speeds were not enough, some quicker
than others. Chrysler replaced the two speed Powerflite from 1953/54?
with the three speed Torqueflite from 1956. Others took longer. At the
bitter end, two speed automatics were seen only at the low end of the market
(early Vega, amongst others).
If you note, the engine torque rating for the TH-200-4R and the TH-700-R4 is very
close in stock form. Considering the weight advantage, the gear ratio
preference, deeper overdrive, and the fact that the TH-700-R4 only comes in
Chevy bolt pattern, the TH-200-4R is preferable for most BOPC street applications
when built properly.
Here are some comparisons of ratings:
|--------Maximum-------|
Engine Gearbox Gross Torque Overall
Transmission Weight Torque Torque Veh. Wt. Conv. Dia. Length
Model (lbs.) (lb/ft) (lb/ft) (lbs) (inches) (inches)
Rear Wheel Drive:
TH-180C (3L30) 130/140 258 440 7716 9.6/10.24 26.29/28.11
TH-200-4R 157 330 550 6000 11.73 28.26
TH-300 (Jetaway)
TH-350
TH-400 (3L80) 190 440 885 12000 12.20 29.30/34.48
TH-700-R4 (4L60) 167/184 350 650 8600 9.6/11.73 29.77/30.64
4L30-E 168/177 258 440 7716 9.6/10.24 28.54/31.57
4L60-E 160/176 350 612 8600 9.6/11.73 29.77/30.64
4L80-E 260 440 885 15000 12.20 31.93/33.02
Front Wheel Drive:
TH-125C (3T40) 161 200 416 5100 9.64
TH-440-T4 (4T60) 195 235 369 5181 9.64
4T60-E 203 280 390 6400 9.64
4T65-E 214 285 400 6400 9.64/10.16
4T80-E 295 305 461 6800 10.43
Here are some common tranmission gear ratios:
Transmission
Model First Second Third Fourth Reverse
Rear Wheel Drive:
TH-180C (3L30) 2.400 1.479 1.000 --- 2.000
TH-200-4R 2.741 1.568 1.000 0.674 2.067
TH-300 (Jetaway)
TH-350 2.52 1.52 1.00 ---
TH-400 (3L80) 2.482 1.482 1.000 --- 2.077
TH-700-R4 (4L60) 3.059 1.625 1.000 0.696 2.294
4L30-E 2.400 1.479 1.000 0.723 2.000
4L30-E Optional 2.860 1.620 1.000 0.723 2.000
4L60-E 3.059 1.625 1.000 0.696 2.294
4L80-E 2.482 1.482 1.000 0.750 2.077
Front Wheel Drive:
TH-125C (3T40) 2.840 1.600 1.000 --- 2.067
TH-440-T4 (4T60) 2.921 1.568 1.000 0.705 2.385
4T60-E 2.921 1.568 1.000 0.705 2.385
4T65-E 2.921 1.568 1.000 0.705 2.385
4T80-E 2.960 1.626 1.000 0.681 2.130
The difference between the transmissions is most likely the
number of internal clutch plates. The main differences between models of
the TH-4L60-E are: 1) different case, bellhousing, and extension
configurations, 2) varying amounts of friction plates vs. steel plates
in various clutch packs, 3) two different torque converter diameters.
[ Thanks to Steve Ochs, Paul Elosge for this information ]
Powerglide
The Powerglide transmission has less parasitic loss.
Durability
It should NOT be used in a vehicle weighing more than about 3000 lbs. It's not
strong enough, even with heavy duty (read expen$ive) parts.
Kickdown
Permutations
[ Thanks to Steve Ochs, Jack Wendel, Jim Chermack, others for this information ]
Jetaway
I have a sneaky suspicion that that old Jetaway will always be a leaker.
I replaced the pan gasket, the filler tube seal, and
the tailshaft gasket, and checked all of the servo points for leaks - it
still leaked. The front seal to the torque converter wasn't leaking either.
Just a shady guess here, but does yours leak from the front passenger side
corner?
Durability
Electrical Connections
Kickdown
The 2-speed automatics from 67 to 69 found in Cutlasses downshift
electrically. The kickdown switch is mounted on the firewall. It's
mechanically connected to the throttle linkage, and has a couple
of wires going down to the side of the tranny.
Permutations
TH-350
The TH-350 will handle in exccess of 550 lb ft of torque if built
right. I have used one behind a brutal 455 for 5 years with NO failure of
any part. It would spin the tires for 30 feet going into second and chirp
them hard going into third. Keep the fluid changes to 12,000 miles, and put
an auxilary cooler on it. As a note it takes 14-18 less horsepower to turn the
TH-350 compared to a TH-400. So you are freeing up some horsepower. It also has a
slightly lower first gear.
The 350 was the transmission of choice for drag racing up to about the
late '70s as it was easy to build up strong. The TH-350 was the tranny
of choice for drag racing because it has less internal mass and weighs
less initially. But, for the same reasons, it is not as strong. The
TH-400 and TH-350 use the same converter.
Durability
The weakest point of the TH-350 is the sprag and
the output shaft. If you really want to put some power to it you must
replace these. Install a good shift kit to keep the slippage and heat out of
the tranny.
Electrical Connections
The TH-350 has no electrical connections. The only 'wire' connection on a
TH-350 is for the back-up lights. The TH-350 uses a downshift/T.V. cable.
Kickdown
During full throttle conditions a kickdown cable provides downshifts for passing
as well as higher rpm shift points for max acceleration. The TH-350 kickdown
cable accomplishes this, with everything being mechanically actuated through the cable.
Permutations
There is a difference between the
6 cylinder version and the 8 cylinder version of the TH-350. The 8
cylinder version uses more clutch plates for greater clutch capacity
whereas the 6 cylinder version uses a thicker clutch piston to make up
for the smaller number of clutch plates. Also, GM built special
versions for the Corvette and police cars; heaviest built of any
of the TH-350.
The THM 350B is the long tailshaft 350.
The TH-350C is a
lockup version of the TH-350, and the electrical connection on the
TH-350C is for the TCC clutch, not the backup lights.
Backup light switch is either on the column or shifter assembly.
TH-325 (FWD).
[ Thanks to John Pajak for this information ]
[ Thanks to Steve Ochs, Jack Wendel, Jim Chermack, others for this information ]
TH-375
Durability
A longshaft TH-375 is like a longshaft TH-400, but it
uses the smaller diameter yoke from the TH-350. The only difference is the
output shaft and the tailshaft housing. The TH-375 has the guts of a TH-400
with the output shaft of a TH-350. It was used in full size cars, and it
effectively shortened the drive shaft. The GM AutoTrans book lists the
TH-375 as being the Heavy Duty version of the TH-350. The TH-375
is also often swapped into big cars as a direct replacement for dead
longshaft TH-350s.
Kickdown
Same as TH-350.
Permutations
[ Thanks to John Pajak, Stephen Hoover for this information ]
TH-400
Durability
Kickdown
The electrical connection on the TH-400 is for the downshift solenoid. Unlike
other GM transmissions, the TH-400 does not use a downshift/T.V. cable.
The kickdown switch (located at the gas pedal inside the car on a 68)
sends 12 volts to a connector on the side of a TH-400 case during full
throttle conditions. This then energizes a solenoid inside the trans
providing downshifts for passing as well as higher rpm shift points for max
acceleration.
Length
Actually, there were 3 lengths of TH400 tail shafts.
Permutations
TH-425 (FWD).
[ Thanks to John Pajak, Mike Rothe for this information ]
TH-425
Well, it's my understanding that the TH-425 was basically a TH-400 severed
aft of the torque converter. A chain drive was mounted to the truncated transmission
and the remainder of the transmission and differential mounted below for FWD
applications. There's a good picture of one at http://www.hughes.net/~gcifu/eldosaurpark/pwrtrn.html.
If GM followed form on the TH-325, it should be a TH-350 simularly altered
for front-wheel-drive use. TH-425, used from '66-'78.
Durability
Electrical Connections
Kickdown
Permutations
[ Thanks to Patrick Flowers for this information ]
TH-325
Kickdown
Durability
Seeing that the
TH-325 was used in conjunction with Olds 350's and Cadillac 368's (the
RWD models used the TH-400), it probably has a capacity similar to a
TH-350. It's really a downsized version of the TH-425, used from
'66-'78; does anyone know how much physically larger (if at all) this
earlier version is?
Permutations
The TH-325-4L, a 4 speed version of the TH-325.
[ Thanks to Kevin Wong for this information ]
TH-200
A light three speed transmission that is the same length as a TH-350.
Durability
If the original trans is a TH-200 then it is probably not worth rebuilding.
A used TH-350 will cost less than a rebuild for a TH-200, and will probably
last longer.
Kickdown
Permutations
TH-200-4R.
TH-200-4R
All of the TH-200-4R's should have lockup torque converters so this isn't
an issue when at speed.
Durability
What probably kills the original TH-200-4R tranny is shift quality. The stock
pump and pump pressure is too low for hard shifts. Note: the 1986 and prior
TH-200-4Rs shifted fairly hard in stock form. The 1987 units were recalibrated and have a soft 1-2 shift at WOT. Also, the stator support is not strong enough for hard shifts.
The big killer is not the 1-2 shift, but the 2-3 shift. A real hard 2-3
shift at full throttle will break some internals in the tranny. The goal is a
firm, quick shift but not a rapid, hard neck breaking shift. I modified my
TH-200-4R for a quicker 1-2 shift. It now shifts quick and firm (will chirp both rear tires) but it is not a harsh shift. Note that high performance rebuilt TH-200-4Rs have hardened stator supports and other features to eliminate this problem.
A lot of replacement transmissions get trashed by dirt and debris in the system.
What most people miss when the transmission is rebuilt, or convertor replaced, is
the transmission cooler in the radiator, or an auxiliary cooler. If those are not
flushed THOROUGHLY, the debris from the previous transmission
failure will destroy the next transmission in short order. The majority of the warranty repeat failures we see are caused by re-using a converter or improperly flushing the
cooler. This is witnessed by a failure rate in dealer replaced
transmission of 3 times the rate of factory installed tranmissions. The failure rate
is the same for both factory new transmissions and factory rebuilt
transmissions.
A rebuilt TH-200-4R with the race hardened parts and a clean system, should more
than handle anything that you could do to the 307 including nitrous.
Electrical Connections
A late model TH-200-4R has 3 wires: 2 are used for the TCC solenoid, and the other
is to signal the computer when 4th gear is engaged. The transmission
will function without the wires connected. However, running the TCC
disengaged on a TCC equipped transmission will lead to more
transmission heat buildup, hence reduced economy and longevity. This
is probably more of a concern on an overdrive tranny like the TH-200-4R,
where there is actually a built-in overtemp switch which closes when the
fluid reaches 260F, and forces the torque converter to lock-up during 4th
gear operation. The lockup feature requires at most 2 wires. If the
3rd is for reverse light operation, you'd have to find an appropriate gear
selector switch for the steering column to wire this in, if going from a
3-wire to a 2-wire hookup.
Kickdown
Overdrive & Lockup Activation
The overdrive in a 200-4R is activated by the valve body in the trans if it
is an 1988 or older. The torque converter lockup is activated by computer.
You could either ignore it and suffer in gas mileage or activate the lockup
via a switched 12 volt source. There is also a kit availible that will
lockup the converter automatically using some type of pressure sensor in the
valvebody. If the car was originally availible with the overdrive then the
means for automatic lockup by the car's computer may already be there.
Ignoring the lockup may cause exessive heat buildup due to the torque
converter slippage and lead to premature transmission failure.
The ECU is normally used to lock up the convertor in 4th gear electronically.
You can do a little re-wiring and replace the pressure switch in the transmission
(from normally-closed to normally-opened) to make the converter lock up. Details
are on the WWW page http://devserve.cebaf.gov/~bowling/jag2chevy.html
A switch is installed internally in the 4th gear oil line. Only, and always,
in 4th does it lock. One can wire a defeat switch on the dash, plus a vacuum-operated switch for unlock at WOT. The parts for this application are now common, and are even sold through Summit.
Permutations
[ Thanks to Bob Valentine, Kevin Wong, Greg Pruett for this information ]
TH-250
Durability
Kickdown
Permutations
[ Thanks to for this information ]
TH-700-4R
The 4L60 is also known as the TH-700-R4. A great bang for the buck
trans. A 3:1 1st gear gives good acceleration. The performance
disadvantage is the large spacing between gears. I also hear that
under high torque situations overdrive is the first gear to go -
clutches can't handle the stress. There are also different versions of
the valve body, some don't allow overdrive to engage if you have full
throttle. I believe only the Corvette valve body will allow OD and
full throttle. But heck, $1200 for a B&M version of this trans is an
absolute bargain, especially compared to others. You will need a new torque
converter and they can be expensive - but you will still come in under
what the 5-speed would cost you.
Durability
The TH-4L60-E (TH-700-R4) was improved again in 1996. Shift quality
and durability was enhanced. But the real choice for heavy duty
racing is the TH-4L80-E or the TH-400.
Kickdown
Overdrive & Lockup Activation
Permutations
The TH-700-R4 is now known as the TH-4L60-E. The TH-4T60-E is a FWD tranny.
The TH-4T65-E is new for 1996 for the Hi-Po applications
(Grand Prix GTP, Riviera S/C, Monte Carlo Z-34, etc).
[ Thanks to Steve Ochs for this information ]
4L80
The 4L80 is an
electronically controlled trans. This means a computer of some sort
must be used to control not only shift points, but shift harshness. If
you are rolling your own computer you can really do some cool stuff.
The trick is to use the diesel computer and have someone reprogram it.
HotRod or CarCraft showed a Buick GN with an aftermarket computer
controlling the trans. Pretty slick, simply by reprogramming the trans
using a laptop compuer, the trans could go from race to street.
Durability
Kickdown
Overdrive & Lockup Activation
Permutations
[ Thanks to for this information ]
Early Hydramatics
The four speed Hydramatic was considerably different from more modern
automatics. it had NO torque converter! I had two fluid couplings
(from mid-1950s on), one of which was used for shifting purposes.
It filled and drained to effect one of the shifts, along with
regular plate clutches for other shifts. The shift involving the fluid
coupling was very soft and slow.
There were a lot of very interesting automatics in the 1950s, the
Triple Turbine Dynaflow probably being the most unusual. It did no
shifting whatsoever for normal driving, at least not in the normal
sense. It had a multiple element torque converter (triple turbine),
where each turbine was connected through a separate concentric shaft
to a different gearset. During driving, as speeds and loads changed,
the fluid flow through the torque converter would hit the different
turbines in different proportions. So you never really shifted...
you might have 60% of the torque delivered through third and 40% through
second, with the proportion through third increasing as speed increased.
Obviously this was a very smooth transmission, but the car was slow
and the fuel economy was poor compared to more normal automatics.
For the 1950's, Cadillac and Oldsmobile used the Hydramatic (4 speeds).
Buick used the Dynaflow (3 speeds). Chevrolet used the Powerglide (2-speeds).
I am not sure what Pontiac used, but it was one of the above (I think
the Hydramatic).
Chevrolet also used a Buick Dynaflow at one point for their higher
performance engine (for the 348 only (precursor of the 409)).
The Hydramatic used fluid coupling(s), while everything else used
torque converters.
There were several variants of the Hydramatic and Dynaflow over the
years. The early Hydramatic didn't have the second fluid coupling.
The early Dynaflow didn't have three turbines, and I believe did
actually shift through clutches for at least one of the shifts.
The Triple Turbine Dynaflow is nothing like the recent CVATs.
Those CVATs are based on two variable diameter pulleys with a belt
between them. The technology was originally developed by a Dutch
auto manufacturer by the name of DAF (since acquired by Volvo). The
1960s version had a rubber belt in tension between the pulleys. This
kind of worked for the car had something like 25 HP. The recent CVTs
use a steel belt in compression. This works pretty well with a higher
power engine, like 100+ HP.
The Dynaflow was a good automatic for the time, no one cared to much
about fuel economy back then. It wouldn't be good today. There also
was a performance penalty, but you could get around that with a bigger
engine. Only problem was Buicks competitors kept using bigger engines
too. There was a great horsepower race going on at the time.
The current steel belt CVT is supposed to be both good for performance
and fuel economy. The driving characteristics are supposed to be a bit
weird, at least compared to normal cars. The engine is somewhat constant
speed, where when you initially accelerate, the rpms go up and then
stay there pegged as the CVT slowly varies the ratio.
'S' did stand for Super, and this terminology was used at least since
1952. My 1952 Oldsmobile sales brochure has a discussion of Drive and
Super, like it was a new feature for 1952. Back then it was the four
speed Hydramatic, which went up to 1963-64 or so. This was replaced
by the Turbo-Hydramatic, a three speed with torque converter.
Note that Super and Second may have different connotations. I seem
to remember Super may have limited the transmission to first and second,
with a different shift point between them than if left in Drive.
There were other automatics (Ford?) where the selections were D-2-1,
and 2 did mean second much more literally. Another set of selections were
D-L2-L1, which might have meant the same as D-S-L. The current
Chrysler Auto-Stick is another transmission where the gears are much
more directly controlled while in that mode... 1-2-3-4 I believe can be
selected more or less directly, as long as speed and rpm are not completely
out of range.
Oldsmobile started using the S range in '52. They changed the name of the
tranny that year to Hydra-Matic Super Drive. Hence the S stands for Super
Range. The quadrant read N-Dr-S-Lo-R. No P. Park was actually reverse
with the engine shut off. Shutting the engine off threw out the parking
pawl. Surprisingly, the '52 sales book doesn't tell you what S does, just
that it was to be used when you want super performance. The owner's manual
doesn't tell you much either. I gave my shop manual to the guy who bought my
'52 Ninety Eight, but I think it said in there that S kept the transmission
in third up to something like 55 or 60 mph, then allowed it to shift into
fourth. Lo was actually first and second, not just first. Dr, naturally
allowed the trans to shift through all 4 ranges. From a standing start,
these cars can go about 3 feet and they shift to second. Then there's a long
pause until the shift to third. Then just that quick they go into fourth.
Super was evidently used to prevent the premature fourth gear upshift when
climbing hills and on powerful starts.
All of the first Hydra-Matics were 4 speeds from 1939 through the middle
'50s. Dual range meant that you had several drive ranges on the shift
quadrant & could lock in certain shifting patterns such as 2nd gear
start for snow & ice or locking the car in 3rd for decending hills.
Durability
Kickdown
Permutations
1956 and later Hydramatic transmissions are different than the earlier ones.
They have dual fluid couplings. 1955 and earlier Hydramatics have only one,
which means that from a performance perspective you can get firmer shifts
out of the 1955 and earlier transmissions than the later ones. This happens
because the secondary fluid coupling on 1956 and later transmissions
is an integral part of the transmisssion, and can't be removed for the
transmission to work.
According to my shop manual, from sometime before 1954 and until
1955, you got what they call a Dual Range Hydramatic. In 1956, the Dual
Coupling Four Speed Hydramatic was introduced, and was available until
1960. During this time it was produced in two different versions - one
made from 1956 to 1959, the second had a run from 1959 through 1960,
although the differences look minimal. In 1961, the book lists a Three
Speed Hydramatic being
introduced, with a scaled down version used in the early F-85. I'm pretty
sure it's unrelated to the TH-350, and I think it was used until 1963 or
1964, whenever the slim jim was introduced.
[ Thanks to Paul Elosge, Bill Culp for this information ]
Switch Pitch (TH-400 and Jetaway)
The TH-400 switch pitch
torque converter DOES NOT provide overdrive. It does provide two
different stall speeds in the torque converter, and this might be
considered to be an extra gear. The transmission itself is still a
3-speed with ratios of 2.48, 1.48, and 1.00 to 1.
The dual pitch converter has a normal stall speed of about 1800 RPM,
and it multiplies torque just like any other converter when in the
normal mode. In the high stall speed mode, the converter stalls at
about 2800 RPM but it DOES NOT multiply torque. If you have a large
displacement engine with a lot of low RPM torque, this works well. If
you have a smaller engine, or an engine with a very long cam which
doesn't start to make much torque below 3000 RPM then you will probably
be disappointed with the dual pitch converter. In any event, the dual
pitch converter will not provide overdrive.
Durability
Same as the regular TH-400 or Jetaway, depending on what you have.
Electrical Connections
Same as the regular TH-400 or Jetaway, depending on what you have.
Kickdown
Same as the regular TH-400 or Jetaway, depending on what you have.
Length
Same as the regular TH-400 or Jetaway, depending on what you have.
[ Thanks to Steve Ochs, J2RKT@aol.com, Bob Hale for this informatiton ]