I have a 96 Chevy Suburban 4WD that has over 200k miles. At about 90K the
transmission went out and was fixed under warranty. At about 180k the
transmission went out again and was rebuilt. Reverse recently came out of
the vehicle and the transmission again needs work. The vehicle otherwise is
in great shape inside and out including the engine. I have been told there
were two different transmissions for this vehicle. The one i have apparently
has given trouble from the start. If i have the current transmission rebuilt
should i expect it to go out again in about 90k miles? Of the two that came
in this vehicle is one better, more longer lasting than the other? If so how
do I go about getting the right transmission? Any help or advice would be
One transmission came in 1/2 ton versions (4L60E), the other in 3/4 ton
versions (4L80E). It's not like there were two different versions for a
K1500 Suburban. The 4L80E is rated for greater power/torque input and
towing. I've owned a new 94 K1500 (4L60E) Suburban that the planetaries for
1st and OD went out (apparently a relatively common issue when trouble
happens)on at about 120,000miles. Did a rebuild on the original at the GM
dealer and it was flawless and still going strong with the second owner who
tows with it and is now at 230,000 miles with no issues. Who is doing the
rebuilds and what exactly are they doing when they do it? There are rebuilds
and there are rebuilds.
The 4L60 is a electronically controlled version of the 700R4 which was
kinda based off of the THM 350 design with different gear ratios and
the 4L80 is basically a THM 400 (same gear ratios) with OD added to
it. One of the weaknesses of a 700R4/4L60 is heat. I have a 89 V1500
4x4 burb that has a factory HD towing package and came with a aux
external engine oil cooler and a HD cooler for tranny in radiator but
not a aux exteranl one. I installed a small aux exteranl one shortly
after I bought it and it has been trouble free to this day after more
than 180K miles and over a dozen cross country trips. It has also had
tranny fluid and filter changes about every 25K or two years which
ever comes first. Typically, these unit tend to fail sooner in big
heavy vehicle with big tires of tall gears which places more strain on
tranny in the form of most time spent on torque converter stall (which
makes a lot of heat) and more frequent down shifts too. Sone burbs can
come with a 3.42 (GU6) which causes tranny to labor more, run warmer
and down shift a lot. Do install a aux tranny cooler in series with
factor tank cooler (route it through tank then aux cooler) as it is
cheap insurance. No need to get carried away on the size of it though.
Tranny went out on my 90 Blazer, had a local guy rebuilt it, with a 1
Tranny goes out like 1 yr and a week later. Tranny guy did a complete
free! This time he used a different case. He told me that some cases
will go "bad".
Not sure how or why a case goes bad, but the new rebuild has been
for several years, and I tow a boat everywhere I go.
Really, on a working truck, 90K aint that bad for a tranny rebuild.
Ive been through
several trannies over the years. Im hard on my trucks....and trannies
forever. Just get it rebuilt and go. Talk to your trans expert about
the case and see
what he knows...
Also, if you do any towing on a OD tranny, use D, this will lengthen
the life expectancy.
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