Differences in auto gearboxes

[Adam]

Ok, Iv'e got a turbo 350 gearbox, I've also heard of turbo 400's and even 700. Whats the diff? Are the numbers the amout of horsepower they can handle?

Adam

[77CVT]

Is this what you're after?
TH350
1st – 2.52
2nd – 1.52
3rd – 1.00
Rev – 1.93

TH400
1st – 2.48
2nd – 1.48
3rd – 1.00
Rev – 2.00

TH700-R4
1st – 3.06
2nd – 1.62
3rd – 1.00
4th – 0.70
Rev – 2.29

Here’s a link for g’box ratio’s. http://www.2quicknovas.com/tranny.html

The TH400 superseded the TH350.  It is a stronger box but not as well geared as the TH350.  The TH700 is the overdrive box that is used in a lot of our cars (Commodores) and has a stump puller 1st gear.  A good mod for a Corvette!

[rebel]

Note also that some '80 'vettes and Camaro's with the 350c (mx3) auto's, can experience a momentary delay in drive resulting from loss of front pump prime. GM corrected this from production runs of Feb '81.

[Brutus]

Originally posted by 77CVT
 The TH700 is the overdrive box that is used in a lot of our cars (Commodores) and has a stump puller 1st gear.  A good mod for a Corvette!

Either this or the 200R is planned for mine when the engine comes out. That low first gear plus the 3.7s I just installed should make for some interesting takes offs to say the least.:22

[77CVT]

Brutus

Are you getting one over from the States or can the 200R be sourced locally?  If you're getting one from the states, wouldn't it be cheaper to use one out of a VN Commodore?

[revvedup]

any clues about locating a t/700 that ll fit into my 75 coupe 327  would be great ,ive read some horror stories about fitting them , im up to it , but im out the the middle of nowhere so i need all the bits  .

[87Z51]

T700 first gear is sh#t unless you have a truck , run out of revs too fast.
Advantage of T700 is the overdrive 4th ; can run lower diff gears for accel  (which makes 1st gear worse) and still get great economy cruising.

revvedup
You want to replace the T350 with a T700R?
Your stock driveshaft is 3' to long but the yoke will fit.
The trans mount  pad will have to be moved back 2"
If you want TC lockup function you will need to get a switched 12V supply to the tranny.
Need to modify throttle linkage at carb to take TV cable from trans that controls shift points.
No vac modulator like T350.
Other than that it will bolt up.Have not seen one in a C3 so unaware of clearance isuses.

As stated in parts for sale , get a VN/VP V8 trans as a rebuildible core.Has correct mounting pad and from memory cable drive speedo .
A C4 T700 is a expensive option that requires more work.However you can put all the Vette goodies(servos) in a std case .How much Hp you making?
T700s are very fickle ,especially where big torque is involved.
Worth paying the money upfront for the good parts (input shaft  / sunshell , most common parts that break ) if you are going to drive it hard.
The VN/VP ones are the most popular for conversions  because they are pre-electronic so prices are relatively high v late elec T700.
In Sydney rebuild cores go $400 + , as pulled still working trans up to $900 but all high mileage so best to buy the cheapest and get it recoed to your specs.
Have pics if needed

[TIPPA]

WOW... sounds like you know what you are talking about! I'd agree that a T700 is the way to go in a C3. A few club members are running this combo. I owned a VN HSV with one. At 100,000kms reverse started slipping so had it rebuilt. Extra clutches, kevlar (?) band, corvette servo piston, shift kit etc with 2,800 dominator lock up converter and trans cooler. Only lasted a month till it blew itself to pieces (said "line pressure" was too great in it). Second attempt with same mods and trouble-free trans that i was so impressed with i'll be fitting one to my vette too. A mate has one behind a 430hp SS and with similar mods hasn't given any dramas at all.
Heard they can handle up to 400hp when std (less than T400 of course and similar to T350?) but they can handle more with mods...
And overdrive is a GOOD thing...

[77CVT]

TH700 1st gear = good burnouts!  :evil

[Brutus]

I've got one sitting here that was supposedly built to hab]ndle a very high HP drag car. Don't have a converter yet but it's scheduled for the 77........one day.;ay

[87Z51]

As stated t700s are very fickle.
P plater with VN SS thrashes crap out of car ; no probs.Mum and Dad on sunday drive and it sh#ts itself.What kills them is torque more so than Hp.
The only way of getting any certainty is to replace the weak points;ie the input shaft drum and the sunshell.
The steel input shaft is pressed into the alum drum.Hi torque and it blows the splines out of the drum.
Sun gear shell is a piece of pressed metal that fractures around the spline.
The ultimate inputshaft / drum is A$850 ,one with a reinforced drum only is A$350.
Reinforced sunshell with torrington bearing instead of stock plastic washer and modified  clutch is A$350.Upgraded only is A$110.
Sydney prices.
The  two super duty parts are rated to 600Hp and 600ft/lb
A fully rebuilt T700(as in everything new , not just worn parts replaced )runs about $2500.For another $1200 , you can have a trans that will be indestructible .
Build it once and forget about it.

[77CVT]

....Build it once and forget about it.

......if budget allows.

Brutus - you still haven't put that thing in yet??????  

[RHD.68.l89]

The TH400 superseded the TH350.  It is a stronger box but not as well geared as the TH350.  

Bah Bow!
The T400 box came out in the mid 60's for Buick/Caddies/Ponts and Chev got it in 68. It replaced the powerslide. In the early 70's a smaller,more efficient box (T350) started replacing the T400 in lighter vehicles. The T700 and later electronic version, 4L60E is a 4 sp version of the T350 and there is also a 4 speed electronic version of the T400, the 4L80E, mainly used in Suburbans etc.
C6s have a beefed up 4L60E designated the 4L65E but the motor has revised programming to limit the amount of torque applied;37

I have a 68 Bonneville coupe with the 400CI/T400 and 2.41 diff. It amazes most people how well it gets off the line;39