The length is different and the output splines will not match either.
It is not a bolt in. It is stil easier and better to use a 700R4. Find
cause of problem because the 700R4 is not a bad tranny. If you are
have problems with a 700R4 is is because of how you are using it
(gearing and usage) and cooling it, not because it is defective
design. Unless you resolve these issue the problem with return even
with a THM 350. Also as some lese stated, the wil be a performace drp
with a THM 350 because first gear is about 22% taller than 700R4's.
Second gear is about 7% taller too.
If they are so strong, why does ever auto wrecker sell one or 2 every other
week ?.. A normal driving non mudding truck shouldn't go through trannies
steady.. 3 people I know whether it be Blazer or full size hate the 700R4
and all the shops even say they are junk... UNLESS you wanna pay $4000 and
get a properly built one. I bought this truck with this POS tranny and I
refuse to use one in my car OR truck.. You may have had good luck but this
tranny is well noted and has a %50-%50 gernade rate.. I'll stick with old
school.. Thanx for the info about the splines.. I'll get my shafts made for
it.. I know of an 88 with a modded th400 ...should be a drop in.. cheers.
I had a new 83 Chev 1/2 ton with the 700R4.....compared to every other
tranny I had experience with, it was godawful in terms of smoothness,
driveability and durability. Someone on this group said a while back that GM
did a major redesign on the 700R4 in the mid to late 80's which made it more
durable and driveable.....which was just peachy for the suckers like me and
thousands of others who were stuck with the first 5 years worth of garbage.
Died after four years of light, non-off road, non-trailering use. Back in
'87, they wanted some obscene amount to rebuild it. I replaced it with a
TH350 with a lockup converter, switched the driveshaft, and that truck went
another 10 years and 200,000 miles without a hitch. It was an easy switch. I
was told the TH400 was doable but more of a pain to. This was on an '83 mind
you, so FWIW.
The 700R4 was troublesome from 81 thru 84 (easily spotted by 27 spline
input shafts) For some strange reason, GM decided to bypass the
cooling of fluid in upper gears when it came out. My guess is they
figured that with converter locked there would be not much heat and it
would save a little power/MPG by not pumping the fluid to cooler. They
fixed this a few years later and by 85 they redisgn a lot in tranny
based on in service failures and the 30 spline unit have these
revisions. Also as stated earlier, ANY 700R4 can easily be upgraded to
the latest revision on rebuild so you can make a solid 700R4 even out
of a 81 version. THey started with the THM 350 and modified it and the
gear ratios and added a OD to it too and it took a few years to get
all the bugs out of it. GM is not alone in have problems with new
tranny designs and the 700R4 was a major shift in tranny design and
application. When they converter the THM 400 to the 4L80 they
basically left gear case intack and retained existing gear ratios and
added a OD section to it with some electronic controls as well and
since GM had some track experiance with the 700R4 by then and basic
tranny was not altered much other than as earlier stated the 4L80 was
not trouble prone from start. Nothing wrong with 85 on 700R4's and
they were last tweaked a minor amount on shift quality in 87 and left
unchanged until the 4L60 came out around 92. The 4L60 and 700R4 share
internal parts with only the valve bodies being different (700R4
manual/hyd and 4L60 is electronicaly controlled) Proper used and cared
for the 700R4 is one of the better trannies GM built and its effective
gear ratio range from first to OD of 4.37 to 1 is superior to the THM
400's 2.48 or THM 350's 2.52 range as it allows for the usage of even
deeper axle ratios for even more power yet lower cruising RPM too.
(you can run a 4.56 with a 700R4 and have a noticably lower cruisng
RPM than a THM 350 or 400 with a 3.73 and a LOT more power in the
lower gears too. The mistake is to use a 700R4 AND tall gearing.
I want to add one more thing. There is two kinds of 700R4 cases out
there and the ones meant for 4x4 have a case that is about 30 to 40%
stronger to handle counter torque from Tcase bolted to it in HD
servvice. You could find them both ways though in standard and HD
cases in a 4x4's. The really easy way to tell them apart is that the
HD case has a casted bolt on lower torque conveter cover while the
standard case has a stamped metal one.
Most 700R4 that I have seen toast is because they are in older 4x4's
with big tires and stock gearing which play heck on tranny. There is a
mindset with some that you do not need to install taller deeper axle
gears and the tranny does a slow burn. ALso some try to tow with 700R4
in OD which is not good either. The tranny has a .7 OD so even with
stock tires and a GU6/3.42 axle ratio the tranny will tend to unlock a
lot in OD and ride converter for a while before downshifting from
fourth to third. At 65 MPH with this combo you are turning about 1800
RPM in forth/OD. When converter unlocks because of load on it the
coverter is slipping and building heat to try to make the extra 30%
more torque just to cruise and it does a slow burn. Throw in oversized
tires and it is even worse. Realistically you want at least a 3.73
(GT4) with stock tires in a big 4x4 and better yet a GT5/4.10 which
which you would have about a ideal match for power and cruise with a
700R4 in a big 4x4. If you are running a lift and big tires figure on
a 4.56 or 4.88 or even more depending on tires size becuase there is
no perfect axle ratio for all apps as it depends on tires sizes. You
do not have to mud to toast a tranny with tall gears and big tires.
People think it does not matter and blame tranny not what they are
doing with it. Go ahead, go back in time with a older tranny and only
three gears and more limited performance potenail due to redcued gear
ratio options or take the time to rethink this and study your axle
ratios and maybe regear them and/or add a aux tranny cooler because
stock cooler does not cut it sometimes and heat from tall gears and
big tires cause tranny to run on converter stall a lot is the 700R4's
number one enemy with maybe shift kits being its second biggest enemy.
Actaully the 700R4 kinda keeps the myth alive about deeper gears are
not needed with bigger tires in that it has a much deeper first gear
and starts a tall combo better than a THM 350 or 400. Many still
believe that the taller the axle ratios the better the MPG in a big
truck (they think that a 3.43 or 3.73 is great with big tires and that
even a 4.10 is all the gerar you need with any tire size) but the
problem is that it still takes the same HP to move the load and the
taller the axle ratio the harder the tranny and engine has to work to
make the needed power. There is one knuckle head around these news
groups that has tall gears and big tires on a 4x4 and cannot use 5th
gear on his 5 speed and goes so far as to say that is just fine or
normal whithout even thinking that there is power lost in the
remaining four gears as well. (They figure that is what low rang it
for even though that is not what it was designed for)
had a 700 in my 87 K5 with a 6" lift and 35's regeared to 4.56 and never had
any problems at all. just gotta know how to drive it. sure if your mudding
or rock crawling the 350 would be a "better" choice. but for a DD i'd stick
with the 700. or if you want drop an atlas in the damn thing.
"SnoMan" < email@example.com> wrote in message
I would still say 700R4 is better for off road because of 22% deeper
first gear which is a BIG plus moreso off road than on it. I image
that your 4.56's played fairly well with your setup.
I run coolers the size of my AC condensor.. temperature has never been a
problem.. I just get abused crap ... you never know what condition your
tranny is in unless you owned it...used 700R4's is like holding gernades.
This is not a good thing, you can over cool oil and a big cooler over
cooling actual restrict cooling flow because cooler thicker fluid is
harder to pump. Even a bbig cooler is not going to save you if you
have the wrong axle gears for what you are doing.
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