pacuda59
pacuda59
This winter i'm going to have my Slant 6 and auto-trans rebuilt. A friend just told me about a TorqueFlite being parted out of a Duster 340. Does it make sense to use a TorgueFlight with a Slant?
TorqueFlite Question
- Thread starter pacuda59
- Start date
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Both the 904 and 727 transmissions are TorqueFlites, so, just saying it's a torqueflite doesn't narrow it down. It could still be either one.
And regardless, nothing that fit a behind a small block like that 340 will bolt up to your slant 6, they have different bellhousings, which are part of the case.
pacuda59
pacuda59
Thanks!
pacuda59
pacuda59
Are there any options for a slant other than the stock tranny. I'd be nice to have an overdrive for the highway.
None in an automatic that I’m aware of. I’m not really a slant 6 guy though so maybe there’s some kind of conversion out there I’m not aware of.
If you use a slant bell housing you can use an 833OD 4 speed manual where 4th is a .71 or .73 overdrive gear. Here’s some info on the 833OD’s
4 Speed Transmissions transmission
Your other option would be to add a gear vendors overdrive behind the 904.
pacuda59
pacuda59
Thanks again!
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Keep the 904.
If anything, increase the stall speed a couple of hundred rpm.
If you go to a regular manual trans, you will lose the Torque-Multiplication feature of the TC. This will require a bigger rear gear to compensate for, or lots of clutch slippage.
If you go to an overdrive manual trans, the low gear in it is already 16% better, but the engine will still puke when it hits that 1.67 second gear, still having the stock rear gears; again, because of the loss of TM in the TC.
For a stock slanty, the 904 is the best trans for it..... IMO ......
But I'm no fan of the very low stall they put in front of it. I once put a 2800 in front of one of mine, and that was a lot of fun. Except that 2800 was only a 2600 in my slanty combo. Years later, after that car was long gone, that same TC did turn out to be a 2800, behind a stock 318,lol.
The 225 only works in a 67 up chassis because it has a 4 inch arm, making plenty of enough low-rpm torque. The TC just multiplies that on the start line, and then lets the slanty build a bit of rpm before slamming the door, with usually 2.76 gears, or less. So the second thing to do, is increase the TM in the differential. Even 3.23s will wake her up considerably; especially with a 2400 or better TC.
I know that wasn't your question, but it seemed to me, to be, the direction you were going in.
The A833 overdrive does work well with,say 25.5" tires, and
3.91s to get a hiway equivalent of 2.85s, for 65=2450
.....................or with 3.73s to get 2.72s, for 65=2240
.....................or with 3.55s to get 2.59s, for 65=2130
.....................or with 3.23s to get 2.36s, for 65=1940
Accelerating to hiway speed with anything less than 3.55s,will make second gear a bit of a tuff pull, because of the huge .54, 1-2 split.(54%).
With 3.23s say, you might have to rev the slanty to 3600/27 mph in first, to drop into second at 1950. And now you will probably rev that up to 3600 again/51 mph, then shift into direct for the final pull from 2157/51mph to 65 mph@ 2770, then into overdrive to cruise at 1940.
So as you can see, the Rs drop down to 1950 and 2157 between the shifts, and the slanty has to have good torque down there to maintain a reasonable rate of acceleration.
The same happens with any other rear gear and reving to 3600. The only thing that changes is the speed in each gear, and the TM in those gears, making the rate of acceleration better with a higher number rear.
Here it is with 3.73s
Reving first to 3600 again, this is now 23.7mph, instead of 27. The Rs still drop to 1950 in second. And 3600 in second is now 43.8 instead of 51. And shifting into direct still pulls the Rs down to 2157 again, but the final pull is now from 43.8@2157, to 65@3200; so theoretically speaking, the whole run should have a much faster rate of acceleration. And then it drop into overdrive at 65=2240.
BTW
2240 is similar to a rear gear of 2.73, with a 904, at zero-slip.
The ratios stack up like this; first the A833od with 3.73s
11.52-6.23-3.73-2.72 ; and then the 904 with 2.73s
.........6.69-3.96-2.73 ;but it might look like this;
.........7.66-4.16-2.87-2.73 if you factor in the TC TM,say 15% on the start line and 5% the rest of the time, falling to zero-slip at cruise.
Look very very carefully.
The od box gives you a fabulous starter gear, but after that the 904 gives you better ratios, even with a 2.73 rear.Here's one more, with 3.23s and the 904, and again grossed up by 15 and 5%
.........9.1-4.92-3.39-3.23, and 65=2770 at zero-slip
If you add a 2400TC to this and especially if you increase the compression in the slanty, this would be night and day difference in your zero to 60 rate of acceleration.
Another option is the A998/999 with the wide ratios and a tad less gear. Say with 2.94s;again grossed up 15/5
.........9.26-4.48-3.09-2.94, and 65=2522 at zero-slip, compare that to the 904
.........7.66-4.16-2.87-2.73, and 65=2342
That's plus 21% in first, and plus 7.7% in second and plus 7.7% in Drive, with plus 7.7% cruise rpm
.
If anything, increase the stall speed a couple of hundred rpm.
If you go to a regular manual trans, you will lose the Torque-Multiplication feature of the TC. This will require a bigger rear gear to compensate for, or lots of clutch slippage.
If you go to an overdrive manual trans, the low gear in it is already 16% better, but the engine will still puke when it hits that 1.67 second gear, still having the stock rear gears; again, because of the loss of TM in the TC.
For a stock slanty, the 904 is the best trans for it..... IMO ......
But I'm no fan of the very low stall they put in front of it. I once put a 2800 in front of one of mine, and that was a lot of fun. Except that 2800 was only a 2600 in my slanty combo. Years later, after that car was long gone, that same TC did turn out to be a 2800, behind a stock 318,lol.
The 225 only works in a 67 up chassis because it has a 4 inch arm, making plenty of enough low-rpm torque. The TC just multiplies that on the start line, and then lets the slanty build a bit of rpm before slamming the door, with usually 2.76 gears, or less. So the second thing to do, is increase the TM in the differential. Even 3.23s will wake her up considerably; especially with a 2400 or better TC.
I know that wasn't your question, but it seemed to me, to be, the direction you were going in.
The A833 overdrive does work well with,say 25.5" tires, and
3.91s to get a hiway equivalent of 2.85s, for 65=2450
.....................or with 3.73s to get 2.72s, for 65=2240
.....................or with 3.55s to get 2.59s, for 65=2130
.....................or with 3.23s to get 2.36s, for 65=1940
Accelerating to hiway speed with anything less than 3.55s,will make second gear a bit of a tuff pull, because of the huge .54, 1-2 split.(54%).
With 3.23s say, you might have to rev the slanty to 3600/27 mph in first, to drop into second at 1950. And now you will probably rev that up to 3600 again/51 mph, then shift into direct for the final pull from 2157/51mph to 65 mph@ 2770, then into overdrive to cruise at 1940.
So as you can see, the Rs drop down to 1950 and 2157 between the shifts, and the slanty has to have good torque down there to maintain a reasonable rate of acceleration.
The same happens with any other rear gear and reving to 3600. The only thing that changes is the speed in each gear, and the TM in those gears, making the rate of acceleration better with a higher number rear.
Here it is with 3.73s
Reving first to 3600 again, this is now 23.7mph, instead of 27. The Rs still drop to 1950 in second. And 3600 in second is now 43.8 instead of 51. And shifting into direct still pulls the Rs down to 2157 again, but the final pull is now from 43.8@2157, to 65@3200; so theoretically speaking, the whole run should have a much faster rate of acceleration. And then it drop into overdrive at 65=2240.
BTW
2240 is similar to a rear gear of 2.73, with a 904, at zero-slip.
The ratios stack up like this; first the A833od with 3.73s
11.52-6.23-3.73-2.72 ; and then the 904 with 2.73s
.........6.69-3.96-2.73 ;but it might look like this;
.........7.66-4.16-2.87-2.73 if you factor in the TC TM,say 15% on the start line and 5% the rest of the time, falling to zero-slip at cruise.
Look very very carefully.
The od box gives you a fabulous starter gear, but after that the 904 gives you better ratios, even with a 2.73 rear.Here's one more, with 3.23s and the 904, and again grossed up by 15 and 5%
.........9.1-4.92-3.39-3.23, and 65=2770 at zero-slip
If you add a 2400TC to this and especially if you increase the compression in the slanty, this would be night and day difference in your zero to 60 rate of acceleration.
Another option is the A998/999 with the wide ratios and a tad less gear. Say with 2.94s;again grossed up 15/5
.........9.26-4.48-3.09-2.94, and 65=2522 at zero-slip, compare that to the 904
.........7.66-4.16-2.87-2.73, and 65=2342
That's plus 21% in first, and plus 7.7% in second and plus 7.7% in Drive, with plus 7.7% cruise rpm
.
Last edited:
pacuda59
pacuda59
Thanks AJ!
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