Jack71

I just finished a complete rear suspension & differential rebuild on my 74. Boy, that crossmember shot like a cork from an upside-down bottle of campaign :eek: Now I'm moving back the drivetrain towards the tranny and am considering a 700R4. How difficult a job is it to shoe horn this unit into the car & is it a worthwhile effort?

I saw some shifter kits available for this conversion, any experience with these? What are the other gotchas? I'm planning on putting in a 383 torque monster next :D -- first the tranny though.

Thanks in advance...

TedH

The Bow-Tie Overdrives kit makes it easy. It arrives in a crate with all parts and instructions (the custom x-member ships separately via UPS). I installed it myself using 4-5 jacks/jackstands strategically located/maneuvered during installation. I found the hardest part was to keep the torque converter on but once I realized that I had to keep the tail shaft lower than the converter, no more of that problem. I just measured for the shorter driveshaft (shortening mine) and, according to the BTO diagram, will shorten 3".

I expect to connect the lines/filter later this week once I install the driveshaft and hook the differential back up to the spindles and struts.

dennisr

I also used the Bow Tie kit. Very good quality and installation was easy. spoke with their tech's a couple time during setup and they were very helpful. I wouldnt attempt the install without them.

1976C3

Check around here b4 you do. I have sen some comments on here about the longevity of the 700r4 under torquie motors. If I remember correctly, the jist was that if your going more horespower then to beef up your current 350/400, but for those staying reletivly mild and want the gas milage etc then go with the swap.

*shrug*

jamiejamison

If you want a good rear gear for good short times and a car thats still great on the higway, then the 700r4 is for you. The gear ratio of the 700 is great for drag racing. I run 1.69 60 foot times with a ZZ4, 700r4, 3.73 rear, 2800 stall converter. If you want the 700 to last have it built with beefed up parts and use a lockup torque converter, the lockup will keep the heat down on the tranny. 75MPH at 2400 rpm on BFG street legal drag radials 275x60x15. Mine was built by A&S Transmissions in Deerfield Beach, FL. They also provided the special made lockup converter. Go for it, Jamie

Jack71

I just put in a set 3.73 Strange gears as well!

I'm just concerned about the longevity of the 700r4. Sounds like there is a mixed review. Dumb question -- what's the advantage of the lock up torque converter you're referring to & why does it help the trans run so much cooler?

--Jack

TedH

I think the lock-up is a benefit where you have a high-stall converter. If not locking up, then the trans is slipping due to the high stall (never stops slipping) and as a result, the trans heats up. Lock-up reduces/elim's the slip and therefore, you get lower trans operating temps.

One other observation on the 4L60. In this case the trans in my 2001. I find that the lockup will drop rpm 400-500 after 4th gear and that is a major fuel savings when touring. I averaged 30mpg on the highway (I-95, Fl to Virginia) so lock-up saves gas too! :cheers:


[Modified by TedH, 9:35 AM 9/25/2001]

69Roadster

I've looked into this myself thinking about swapping a muncie for one. The reason there are mixed reviews about how they hold up is because it depends on how they are built. A stock one can be broken pretty easily with a 500 hp car. A heavy duty one should withstand that much. If you do an internet search on 700R4 you should see the different kinds for sale. Price varies dramatically with how strong they supposedly are. One thing to notice is that with the high horsepower rated ones a lock up stall isn't an option. Lock up stall = hollow input shaft = weaker transmission.



[Modified by 69Roadster, 2:49 PM 9/25/2001]

80 Proof

I would highly recommend it, especially if you buy the transmission from Bow Tie. Why? They address all the concerns of the potential problems of the 700R4. You will find that Bow Tie does numerous upgrades to the transmission in order to take on the torque and horsepower. Their standared transmission is good for 500 HP, if you have more, they will set you up with a higher RPM stall TC and probably do some additional upgrades to handle whatever your air pump (engine) is putting out.

I love mine, it shifts "champagne glass on the dashboard..smooth". It downshifts when it is supposed to, an' most of all that overdrive gear just can't be beat...it is to say,the very least...SWEET!!!

Call Steve Holmes at Bowtie 760-947-5240, and if you decide to do the swap call me or email me so I can tell you of all the pitfalls I ran into, so you don't have to go through the same thing I did.

Good luck,

Brett Emes
813-671-8466
b.emes@verizon.net

jamiejamison

True the lockup converter uses a input shaft with a hole in it, but so does the non lockup shaft have a hole though it. Use a later year shaft that is thicker, 30 spline instead of the 27. I run a 10 inch lockup converter, special built with reinforced brazed fins, and ballon plate. We get these built with 2800 to 3500 stall. We run one at 575 hp in a Nova. Jamie

Chris69

TedH... Did you have to make any mods to the exhaust system with that BTO crossmember? I'm having problems with mine. The PB pulley bracket hit the driver's side floorboard and doesn't have the proper pulley angle and the exhaust pipes can't be bolted back up since it hits the crossmember. BTO Steve said they just assume that anyone that does this conversion also plans to redo their exhaust system. Wasn't in my plans... We're working now on modifying the original crossmember to try and get that to work and send back the BTO unit. It's a shame, since that crossmember looks trick under there. If you know of any tricks, please let me know before we get too far along with the mod to the old one. Tnx

One other thing... Is there a 'real' benefit to installing the OD lock-out switch?


[Modified by Chris81, 12:11 AM 10/6/2001]

KorbenDallas

Can someone provide a link to bow-tie? Thanks

Chris69

http://www.700r4.com

ZD75blue

http://www.bowtieoverdrives.com/68-81Corvette700R4.htm

Budman68

I'm in the process of this change over. Seems pretty straight forward. The hard part is locating a suitable tranny for the car. I bought a fairly new one the other day thinking it can out of the car as described, but it turned out to be a 83 model. I've got to exchange it now.
Thinks to look for in a rebuildable core.
Date stamps of 7 and greater.
30 splines on the inpute shaft.
A arced casing mark through the cooling lines.
The truck version with the heavier inspection cover.
Good luck.

Jack71

What rear gears are you guys running with your 700R4 now?

I just installed a set of 3.73s and think this may be too much with the lower first gear on the 700R4. The bowtie website states this combo is equivalent to a TH350/400 with 4.56s. That is a lotta first gear.

Racer16k

I've got 4.56 with my 700r4. Lotta fun in town and still gets 18mpg. Wicked in the wet though. Wife thought it was cool, so it can't be all bad.

Red73

74Jack, 3.73s, great off the line, 2200rpm at 70mph.