Doug,
While I'm not in any way defending the 700-R4, getting only about 53000
miles out of each rebuild would indicate another problem.
I would start looking for other causes MYSELF. The first thing you
should do is put on an aftermarket fluid cooler bypassing the one in the
radiator, not in series with it.
You should also check the ENTIRE length of the oil cooler lines for
kinks or dents. I have seen cases where road debris has hit a cooler
line and squashed it enough to reduce flow.
If you have been rebuilding the same transmission perhaps you should get
a different 700-R4 from a junkyard and have it rebuilt, or buy an RV
model from B&M. Sometimes an individual unit has an internal problem
(such as a bad case casting) that no amount of rebuilding can fix.
A short story to illustrate: I had a customer with a 1 ton chevy box
truck that he kept very overloaded. It had a TH400 in it that went bad.
I replaced it and blew out the cooler lines. 1 month later he was back
again with a failed TH400. I replaced it and added an external cooler in
series with the one in the radiator. 2 months later he was back with
another failed transmission. I suggested he look for a heavier duty
truck and I proceeded to replace the transmission again. I knew that
something was not quite right because we were dealing with a TH400, they
just don't burn up like that. I really dug into it that time and noticed
that when I blew out the cooler lines the oil shot out, but didn't spray
out like most did. I checked and found that the cooler in the radiator
was PARTIALLY restricted. It flowed enough I didn't notice it the first
two times but it kept the tramsmission running too hot with that load.
John
"49-50-54-57-79-95" Chevy 3800 Panel
Doug Sims wrote:
>
> O.K. Here's my 2 cents worth on the tranmission issue..
>
> My wife drives a '90 GMC, 350 TBI with 700R-4 transmission. The truck is a
>beauty
> and only has one problem. The 700R-4 is a piece of junk. She is on her 4th
> rebuild in the last 5 years. The truck never tows anything and according to
>the
> tranny guy is susceptible to extended highway driving. It has been upgraded
>with
> the hardened planetary and all of the stuff that is supposed to make them
>great,
> but it still will not even stand up to highway driving. The shop that
>rebuilds it
> told me the first time that this is one of GM's problem children. He warns
>about
> any truck use of the 700R-4. We've only got about 214,000 miles on this truck
>but
> if I can't get a transmission in it that will last I'm going to get rid of it.
> I checked into the 4L80-E since it is supposed to be the next best thing to
>the
> TH-400. Best price I've gotten on it yet is $3500.00 complete, (computer,
> harness, everything needed to swap it over). This price goes up to $3700.00
>for a
> carburated engine due to necessary sensors that must be added to control it.
>It
> is rated for 700+ft/lbs torque and over 24,000 GVW tow capacity. The 700R-4
>and
> the 4L60-E are rated at 450 ft/lbs torque (at best, depending on the
> bulletproofing) and less that 12,000 GVW tow capacity.
>
> Passnb4U@aol.com wrote:
>
> > In a message dated 4/18/99 11:08:14 AM Pacific Daylight Time, lakek@oit.edu
> > writes:
> >
> > <<
> > Sorry guys, Mr. Cummins and Mr. Adrian have gently corrected me. The 4L80E
> > is the tranny that is based on the old TH-400. The 4L60E is the 700R-4,
> > and is a newer design that is not as heavy duty as the 4L80E. It sounds
> > like the 4L80E is the 3/4 and 1-ton tranny. Now I get to go back and tell
> > my friend at the local "auto recyclers" that he was wrong. So how much
> > stronger is the 4L80E than the equivalent 4L60E/700R-4? What are these two
> > transmissions rated at for torque/hp? My 88 1/2-ton has the 700R-4, and I
> > have done a lot of towing with it. My 86 Blazer (full-size) also has this
> > same tranny. I have had really great luck with both of them. Is this a
> > fluke or is the 86 and up 700R-4 that much better? Thanks again for
> > correcting me, it only hurts a little =^).
> >
> > Kevin Lake
> > 56 GMC Suburban/napco >>
> >
> > Just one more minor thing, the 4L60 is the same as the 700R4, the 4L60E
>was
> > the electronically controlled version.
> > There were some significant changes to the 86/87 up version of the 700R4,
> > of which I don't recall, but just a note, a pre-86/87 700 can be rebuilt
>with
> > the newer stlye parts.
> > I think '90 through '92 the 4L60 was used, after that the 4L60E.
> >
> > Mike
> > oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
>
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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