Thinking about putting a 700R4 in place of origional tranny. I know the overdrive will help me on the top end but what about on the low end. I heard it will have a lower low gear. Is this right? Also has anyone done this to give me any do's or don'ts?

 

Yes, the 700R4 has a lower 1st gear than TH350's and TH400's:

700R4: 1st= 3.06 2nd= 1.63 3rd= 1.00 4th= .70
(also same for 4L60E trannies)

TH350: 1st= 2.52 2nd= 1.52 3rd= 1.00

TH400: 1st= 2.48 2nd= 1.48 3rd= 1.00

The only problem you may encounter using a 700R4 is choosing a torque converter. Depending on where you get the transmission from, it may come with a converter that is a "lock-up" converter, that is controlled (I believe) by the vehicle's computer. You may have to run a non-lockup converter, or somehow have the lockup wired up so that it is functional (or not??), but I'm afraid that's beyond what I do and don't know. What I do know is that, in my experience (others may have better experience) the 700R4 is not as "strong" as an old Turbo-Hydramatic transmission - case in point: my dad's '89 Chev pick-up has already seen 3 transmissions - the original, and 2 rebuilds - all of which have blown way sooner than what I would expect a good TH350/400 to last. HOWEVER, I'm not saying that with a little money, a more "bullet-proof" 700R4 can't be built, but a stock one can't handle the same abuse as an older transmission IMO. Anyway, I hope that helps you out a little, and don't let me scare you out of this project - I actually considered it for my old '81 Z28.

BTW: I got the tranny ratios from this month's issue of Chevy High Performance magazine.

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1996 Sunfire coupe - 2.2L, M5 - performance mods?? Needs too many to list!!

1981 Z28 - sold Aug. 2000 - why? I don't know!
- 383 stroker, TH350 trans., 3.42 posi
Pics

 

700's made before 88 have problems (weak sprags, front seal blowout syndrome), 88 up are better. 700 uses same yoke as th350, powerglide, saginaw, early muncie, but is a longer transmission, so driveshaft will need shortening. Tranny mount holes are about the same distance as th400's from the engine, so you can use a 400 crossmember if you elongate the holes.

Adjustment of the TV cable is critical. There are special brackets available for use with carbs.

The 3.06 first gear blows. I have a 700 in my 89 Formula 350 and first gear is hard to use cause it just smokes the tires. Driving in the rain is bad, especially around corners. The rear end tries to come around even if I'm light on the throttle. The rpm drop from first to second is huge. So when I take off going around a turn I have to be light on the throttle, causng tranny to shift into 2nd early and the engine just goes blahhh. My 71 with a 400 sbc and th350 is much easier to balance between thrust and smoke.

Only advantage to 700 is the overdrive, but it is a huge one for the daily driver (formula).

 

I urge you to read up on the swap at www.bowtieoverdrives.com . I personally think that you will love a 700r4 in an earlier car. If you are worried about the 1st to 2nd shift you could look at a TH2004r, but I recommend the 700r4.

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69 Camaro Z28 "clone" 327 AT
DAYTONA YELLOW WITH BLACK Z28 STRIPES
327 - "461" camel back heads. TRW,Edelbrock,Ultradyne,Hooker
TPI 700r4 automatic transmission

 

I have a 700 in my 81, so far I love it.

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81Z:zz4 350, w/700r4(4L60)
3.42's, t-tops,open and sealed cowl. 81Z

R.I.P. 99Z: M6, t-tops, 3.42's,
lid, borla.

 

The Buick GN's have been running the 200R4 beefed up for years. I think it's the same length as the T350 so you wouldn't need to shorten the driveshaft. The 700R4 can be built to handle up to 700hp, above that the TH400 is your only choice.

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Jeff H - 69 Z28 Hugger Orange, GM crossram, GM fiberglass cowl induction hood, factory TI setup & factory installed JL8 4 wheel disc brakes - original #'s matching and documented, being restored), 87 Toyota 4Runner SR5 Turbo

 

if your considering a 2004r, then level10 is the place to go. check out the fast turbo buicks for hipo parts for that.
the 700's and 200's can both be made to handle all the power you can probably throw at them, but be alot more exp. than the old 350's and 400's. thats the only thing the 350 has over the 700's.
I have a carb. in my Iroc, and 700r4. I have the special bracket to use when mating a 700r4 w/a holley carb and my 2-3 shifts are still not right. (it shifts at too high a mph into 3, even at light throttle)(in fact, only at light throttle cause when I get on it, it feels perfect) the best solution for that is a manual valvebody from TCI. summit sells them for around $270 and it would replace a shift kit and the cable mounts/brackets cause it doesnt use the tv cable at all. wish I had known about them before cause I would have def. done that and saved lots of money and time.
things I have that I didnt need to buy:]
1)tv cable $35
2)cable mount $20
3)cable bracket for use w/holley $25
4)b&m gov. calibration kit $55
5)shift kit $90

the first gear ratio is def. better. its the same as raising the rearend ratio numerically exc. you dont lose cruise speed on the freeway.
chris


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1985 Iroc Z, (parting out, email for parts)

1986 Iroc Z
355, ported camel hump heads,750 holley, 700r4, 10.5 compr., forged flat tops, solidcam .501I .510E, 4gen rear w/3:73 posi, girdle, and disc's, Edel. torker II, shift kit, 3500 stal, hedmann LT. headers, 4 gen seats, man. strg., lt1 starter, alum. w/p, msd 6al, coil, dist., mallory wires. mid 13's for now. lots to play w/still

1995 z28,SS Hood, Iroc style spoiler, tints and black outs, 700r4,2400 act. stall speed,B&M hammer shifter, 17" budnick trilogy III wheels, 275/40 ZR17, 160 stat, man. cooling fan sw., homemaid CAI,1LE elbow, hypertech airfoil, t.b.bypass,!cat, flowmaster, !maf screen, relocated batt., 1LE front l.c.a.s', poly trans and torq.arm bushings, MSD 6AL, custom program, p&p maf, accel coil, and under drive pulley

mods that i have, just not on car yet:
msd wires, edelbrock mid. headers, edelbrock rpm catback

[This message has been edited by IrocSS85 (edited June 29, 2002).]