riverracer au

getting everything ready for a th400 to 700r4 swap in my '72
sorted out the x-member mount, will use a reversed/cut down bolt on mount off a th350 x-member.
will use a b&m controller for the lock up.
new cooler lines, a corvette yoke and "TV Made Ez system" from BTO.

question time
will the 700r4 torque convertor bolt to my existing th400 flex plate?
what are recommended "transgo" products to install, ie:shift kit, servo etc?
as i wish to keep my existing tailshaft in storage, (crazy i know), what other years will be suitable to source and cut to fit?

oil cooler, i'm already using a separate external cooler mounted up the front behind the center grill on the rails
http://www.summitracing.com/int/part...3612/overview/ it's 10.25" wide and 6-3/8" tall, or should i go to a taller one?
http://www.summitracing.com/int/part...3613/overview/ or http://www.summitracing.com/int/part...3614/overview/
do people still plumb it thru the radiator tank as well?

riverracer au

125 views and not 1 reply... i must ask stupid questions

'75

People will get all nutty about trans coolers, my opinion is that if you're not road racing or pulling a trailer, the one in the radiator will be fine, especially using a lock up torque converter. However I've not seen one get hurt by too large a cooler, unless it was in cold weather.

doorgunner

I've been in the garage/scaring myself installing a hoist for my hardtop! I also am planning a TH400 to 700R4 swap soon. It sounds like you're ahead of me in the planning dept. I don't have the knowledge to answer your questions.....Sorry.....but we do have the same basic set-ups/add-on fluid cooler (which could be connected to the radiator fluid tank for winter usage)

My 700R4 is currently being used in my '34 350SBC street truck, and needs to be rebuilt before being installed in the Vette. I'll use a shortened drive shaft with the original 700R4/tailshaft/housing.

I'll subscribe to this thread/if I find any info, I'll post it here....in the meantime I'll post my swap pics in my build thread.

terrys6t8roadster

My 69 flexplate had both sets of holes, I installed a 200r4 using original flexplate. Originally a th400. You could remove bottom bell cover [tin shield] and check if there is a second set of holes. T

doorgunner

Thanks for the needed info......."We don't need no stinking new flex-plate!"

with a metal-scribe, a variable speed drill, and a permanent marker, there will ALWAYS be a 2nd set of holes for Riverracer and for my swap!

NOTE: Riverracer....make sure the B&M controller has the vacuum-electric switch (it prevents the 700R4 from exploding when accelerating hard)

hugie82

I'm not sure what you mean by keeping you tail shaft in storage but the trans cooler is a good idea. Most trans builders won't gaurantee their trans unless you have a cooler installed. I mounted a long skinny cooler along the front spoiler,/valance .
The shift kits are nice but in our little corvettes, the shift kit can be harsh especially when we sit on the rear wheel.

riverracer au

as mine is fairly original, i'm keeping everything i take off, for the next guy/just in-case.
so rather than cut up my original tailshaft, i'll purchase another to shorten.
that's why i was wondering what other years will be a starting point, mine is a "3921675".
we don't have many corvette wreckers downunder, so i may have to ebay from the US, meaning $$$ for shipping.

the B&M controller doesn't come with a vacuum switch, but it was on my research list to add one.

looking at a some photo's of my engine rebuild, it looks like my flex plate has both sets of holes.

this is where i mounted my oil cooler, plenty of room to go larger/higher if needed.

doorgunner

Thanks for letting "ride along" on your thread...maybe we can get our cars going.....and like the other member said---be careful about shift kits---if they are too harsh, they will do more harm than good. If you have cold winters, you could route the cooler lines in series through the radiator fluid tank. By "tailshaft".....are you referring to the output shaft inside the transmission?

riverracer au

it's what we call downunder the long shaft that goes from the gearbox to the differential, with the uni's on it's ends.
what do you guys call it then?

'75

We call that the drive shaft.

doorgunner

I can understand how Aussies see them as tailshafts.....attaches to the "tail of the transmission".

Our repair manuals classify them as driveshafts.

We call the transmission output shaft a "tailshaft" because it spends it's time in the "tailshaft housing".

(Makes you wonder why we don't call our cars "Garagers")

Frank_Nesta

If you want to replace the drive shaft. It looks like any GM drive shaft can be used as long as the yoke dimensions match what you have. Then shorten it to the length you need. If my memory serves me right it is 3 inches shorter. So have fun at your local wrecking yard looking for a compatable drive shaft.

doorgunner

Frank.....good idea about using a salvage yard GM driveshaft......

ALSO......I did an nternet seach on TH400 A/T.....it seems there were a FEW of them manufactured with a "long" tailshaft housing---which means that the "new" driveshaft would not have to be shortened 3 inches----according to the articles.

riverracer au

looking at the "adjustable vacuum switch" on fleabay

what pressure setting is everyone using? 1-6" or 6-22"

doorgunner

A quality switch costs around $35 U.S. (I bought a cheaper switch first, but it didn't adjust smoothly). My new better switch adjusts much better and is adjustable anywhere from 2 to 22...install the switch under the dash where it can be easily pulled out and tucked back under to make adjustments easier to do without getting under the hood.... ..

once you test-drive your car after the installation, you adjust the screw in or out about 1/2 turn after each test-drive to change the lock-up point on the torque converter to your satisfaction. (I did a lot of reading about the 700R4, and the main reason they break is because people either don't install a vacuum switch or they don't adjust it so that it works correctly). My 700R4 locks up best at 8 to 10"...yours may react differently.

The simplest wiring method is: 12 volts from the fuse panel WITH THE KEY ON...to an OFF/ON switch located in an easy to reach spot inside the car...then from the other terminal on the ON/OFF switch to one terminal on the vacuum switch (you want to wire the switch so that the 12 volts is temporarily turned OFF by the switch when the accelerator is pressed down moderately/which "turns off" the lock-up convertor until cruising speed is reach/then the switch automatically engages the lock-up converter)....then connect a wire to the other terminal on the switch and run the wire to the 12 volt input terminal on the case-connector of the 700R4. Then run a ground wire from the ground-terminal on the case-connector to a clean location on the frame.

(If the car shudders/stalls when the brakes are applied, the 12 volt wire can be run from the OFF/ON switch to an aftermarket switch installed on the brake upper-pedal.....then run the wire from the other terminal of the aftermarket brake switch to the case-connector 12 volt input terminal......my car stalled only one time when I had to stop suddenly/I put the shifter in Neutral/restarted the car and continued driving, so I never installed the additional brake switch that stops 12 volt flow to the 700R4 when braking hard).

If the 12 volt supply wire gets hot, a relay can be added in right before the wire goes to the transmission case-connector.

riverracer au

has anybody done this extension end swap?

from http://www.superchevy.com/how-to/609...swapping-tech/

The 700-R4/4L60 (top) and the TH-400 can be interchanged using a tailshaft
from a ’80-’82 Caprice or SS Impala to relocate the transmission mount.

and a bit more info bout halfway down the page http://www.rowand.net/Shop/Tech/Auto...issionSwap.htm

have found a couple on fleabay.

thought it might be easier than making / modifying a T350 mount

riverracer au

also, anybody know the correct speedo gears to use?

i'm using 235/60R15 tyres (26.1 tall) 3.08 rear in the t700 box

i have looked at 3 "speedo calculators" and i get different answers with each.

i want to order the other parts from BTO soon, and thought i'd get the gears as well

doorgunner

I'm assuming that the matching OUTPUT/TAILSHAFT of the "new" extension housing would also be needed. This seems like the way to go if moving the crossmember would be a hassle. (I only needed to move the crossmember on my street truck transmission swap and shorten the driveshaft.

I'm having the same problem choosing speedo gears...I think I will buy the "middle choice" and try it....then I can go to a larger or smaller gear from there if necessary.

'75

This may help with some of the measurements.