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Re: [oletrucks] 700R4 LOCKUP TORQUE CONVERTER?

To: oletrucks@autox.team.net
Subject: Re: [oletrucks] 700R4 LOCKUP TORQUE CONVERTER?
From: MarkNoakes@aol.com
Date: Fri, 28 Jul 2000 00:16:52 EDT
As far as my Subs go, I'm going to use a 3speed +OD in the Chevy and a 
Hydramatic in the GMC, but I've been following this thread with interest; I'd 
kindof like to put an L98/700R4 in my 86 pickup if I keep it as that's the 
combination that I've got in my 86 vette and it does me well including moving 
big tires (quickly) including SCCA racing.  While it is getting tired 
mileage-wise and probably should be rebuilt now, my 700R4 has the lockup 
torque converter, which comes on at about 42-43 mph.  The car has the base 
diff (an unbelievable 2.59 ratio) but because of the gearing in the 700R4 and 
the TC lockup, it will do 0-60 in about 6.5 secs and still get 27 mpg on the 
interstate at 75mph (not a light car either) while rolling at about 1850rmp.  
I've always heard that these transmissions are somewhat fragile and though 
SCCA BSP limitations don't let me crank the hp up too far (or modify the 
trans other than the torque converter), I run it hard enough racing to 
destroy heavy duty U-joints, but the trans has held up well. . .so far.

Even so, I understand that the winning combination for Solo2 is to have the 
Art Carr high stall torque converter, and I'll probably go that route on next 
rebuild as well as swap to a 3.07 rear, but for a streetable truck, I would 
think a stock/near stock 700R4 would do most people well.  Sure not the last 
word, but it works well in the Corvette, a heavy high performance car with a 
large (but admittedly low profile) tire patch.

Mark Noakes
Knoxville, TN
58/56 Chevy Suburban
59 GMC Suburban
66 Corvair Monza
86 Chevy Siverado 
86 Corvette convertible, SCCA Solo2 BSP #32

In a message dated 07/27/2000 9:25:43 PM, kvdurand@mail.esc4.com writes:

<< On my 700, I wired it to go into lockup as soon as it goes into 4th. I also
ran a wire straight out that will lock it in 2, 3, or 4 when power is
applied. Both of these go to a switch on the dash.  The connector has 4
pins, so it can be rigged many ways. The $100 lockup kits are not worth it.
The B&M (even more expensive) kit locks the convertor at speeds over 43 mph.
This is not necessarily the best way. The Painless and TCI kits lock it up
in 4th. Both kits give good diagrams and options for locking in other gears,
locking manually, etc. The lockup convertor was for mileage, and really
can't stand much abuse. The tranny's 4th gear is also not designed for
abuse. 4th gear, especially on stock units without pump passages enlarged,
starve the rear planets for lube when locked up. One purpose of the throttle
valve is to kick the tranny out of 4th at high speeds. The Corvette 3-4
shift valve and the B&M counterpart risk really screwing up a tranny by
keeping it locked in 4th at high speeds. The 700 is a great tranny, but
shoudn't be abused. Use 4th for mileage, and 3rd for fun.  As has been
stated before, the TV cable has to be hooked up right, or the tranny is
toast. Also, the comment about a 400 with overdrive is not quite correct.
The 400 is much stronger than any 700. The 4L80E shares 3/4 of its parts
with the 400. The 4L60 (aka. TH700-R4) and 4L60E are not so fortunate.
Anybody that can afford the 4L80, have fun. I wish I had those resources.
Complete, it will run about $2500, but it is indestructible. It is also a
computer controlled trans. >>

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