Electronic Transmission Control

[Doug Dayson]

Hi All...

The stock HD (Vette/Trans Am/Z-28/Formula etc) 700R4/4L60/4L60E is rated at
375 ft/lbs...lesser standard duty 700's (S-10 etc) at 325 ft/lbs...

Note that the mid 1988 and later 700R4...4L60...and 4L60E's are essentially
identical with the exception of the E's electronic controls...

The aftermarket can add "beef" to the 700 family to approximately 450 ft/lbs
(TCI/B+M)...475ft/lbs (Premier Performance/Toy Shop)...and 500ft/lbs is
claimed by Art Carr...

Not sure about the stock 2004R's torque rating except that "stock" it's
somewhat less than the "stock" 700 family...remembering that "stock" T-Types
and GN's aren't that quick...now a aftermarket 2004R can be built to be 
similar in torque capability to a aftermarket 700...and the fast GN's etc chew
them up regularly...

I've run a aftermarket (Toy Shop in LA, CA) 700R4 in my 71 Vette with a "warm"
400hp...455ft/lbs...406ci for seven years and counting...it's ran a best of
12.87/112 mph on street tires...many passes and no trans problems...however a
friend's 89 Vette equipped with a 535ft/lb Lingenfelter Super Ram'd stroker
can't keep a 700R4 in one piece for long with Drag Radials...he's thinking
4L80E (if it'll fit?)...

The wide ratio 700 can be a advantage in a street car (good off the line and
easy cruise)...and a disadvantage in a race car (rpm recovery too low)...but
keep in mind that the 2004R is actually a wide ratio box as well (compared to
the standard TH-350 and TH-400's) though it's ratio spread isn't as wide as
the 700's...I'd venture that the same car (with optimized rear gear) should be
a tenth or two quicker with the 2004R...

Ratio comparison...

700R4/4L60/4L60E ratio's...3.06...1.62...1.00...0.70

2004R ratio's...2.75...1.57...1.00...0.67

4L80E ratio's...2.48...1.48...1.00...0.75

TH-400 ratio's...2.48...1.48...1.00

TH-350 ratio's...2.52...1.52...1.00

The 4L80E is perhaps the best bet from a racer's or towing standpoint as it's
got the closest ratio spread and it's torque capacity is the highest...but
it's physically longer and slightly larger in diameter than it's cousin the
TH-400...and it weighs 100 lbs more than the others excepting the TH-400...and
it's parasitic drain is about 50HP more than the others...

Also of note concerning the 4L80E's...I've heard that their sprags are weak
compared to a TH-400's...fortunately the TH-400 sprags will retrofit...

As far as living behind a 300HP 350ci...either member of the 700 family or the
2004R would be the best bet...

Regards...

Doug



MysticZ wrote:
> 
> Swayze wrote:
> >
> > this is not an answer, but another question.
> > which of the later OD  GM trans should I look for,needing only TCC  and
> > 300HP+ survivability in a street driven car; 700R4,200??,4L60?,4L80? (BOP)
> > my trans knowledge is from the twospeed TC powerglide days.
> 
> My 4L60E isn't complaining about 350 horsepower or 400 foot pounds. It's
> not the horsepower that trashes a tranny, it's the torque. But with 300
> HP, you shouldn't have a problem with a 700R4 or 4L60E. The -80E weighs
> a ton and the rest have no overdrive, so I'd stick with the 700R4/4L60E.
----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org