A999 in a 70 Duster

[coyote42]

Alright my transmission Gurus I have a question. My 70 Duster original 318 num match motor and trans is a mess, broken bolts and such. I have a 90 318 I rebuilt with reground roller cam and the A999 that was attached to it. My question is being a lock up converter, can I just drive it with the Lockup switch disconnected or do I have to add a 12v supply to it to dissengage it. I do eventually want to activate the lock up if possible.(any tips on how to do that with a switch?) It has 3:55 8 1/4 SG and 14x10in Cragar tires. The car will be a daily driver Rat Rod.
Thanks, Kyle

 

[moparmat2000]

If I am correct, it will just run like a regular 3 speed with lockup not hooked up. You can hook the lockup up with simple wiring and a toggle switch to engage it. It's worth a 200rpm drop on the freeway.

 

[Cuprum-74]

Alright my transmission Gurus I have a question. My 70 Duster original 318 num match motor and trans is a mess, broken bolts and such. I have a 90 318 I rebuilt with reground roller cam and the A999 that was attached to it. My question is being a lock up converter, can I just drive it with the Lockup switch disconnected or do I have to add a 12v supply to it to dissengage it. The car will be a daily driver Rat Rod.
Thanks, Kyle

Ok this is a couple months old, but here goes:

I have a build that is very similar to yours. My goal is high performance daily driver.
I have a 1991 roller 360 with 10.2 compression with Lunati voodoo roller cam, a tuned Street Demon 750.
I have an A999 as well, but with the Lock-up totally removed. I was able to use Turbo action Cheetah stage 2 valve body and Hughes non-LU TQ converter.
(use at least 2500 stall!) I made the mistake and used a 2000 stall.
my rear gears is 3.21.

Yes there is a way to "shut-off " the lock-up or better yet do a mod similar that @TrailBeast utilized. Especially with those 3.55 gears.

Couple of points:
3.55 gears with the A999 is still a very good all-around "fun" gear around town but will take some of the highway ability.
I'm sure your aware of the A999's 1 & 2 gear ratio vs. 727 and regular 904's. So with your combo your first gear take-off is equivalent to having a 727 with 3.96 rear gears.
With my 3.21 rear my first gear take-off is slightly higher vs. 727 with 3.55 rear. But I can cruise at 72 mph at 3000 rpm.
With your gears: (and I say this because I've had personal experience with using the same gears as you before)
With 26 inch rear tires at 70 mph my rpm's jumped to almost 3400 (something like 3370-3380 to be exact)
With 27 inch tires and 3.55 that would be a better match.
(I'm still thinking of going back to 3.55 gears Since I'm now going to 17 in rims with 255/50R17 rear tires which are 27 inches tall)

With the lock-up you're going to drop about 200+ rpms at highway cruise.

There are pros and cons to our setups:

My setup (LU totally removed/converted non-LU)
+ Cheaper Torque Converters
+ Likely stronger.
+ Less worry about electronics gadgets and such.

Keeping LU:
+ The trans runs cooler, especially at freeway speeds.
+ Flexibility in using a little higher (numerically) gear numbers.
+ You will gain slightly more mileage.

For example:
On my drive to Louiseville CO (from Ogden UT area) 500+ mile one way.
I usually get a best of around 17.5 mpg, but ranges can also average from 15.4 to 16.8 depending on crosswinds (Wyoming for you)
* That's maintaining 70-72 mph keeping it at 3000 rpm and under
* I did get almost about 18.2 mpg one time doing mainly 60-65 mph in the backroads (around 2500-2700 rpm) Sunny, clear 85 degree day with a modest 25mph tailwind.
* My best educated guess is you can gain anywhere between 3-5% increase in mileage (not factoring wind, temp, incline etc.) by keeping that lock-up function - Granted my math is nowhere as elaborate as @AJ/FormS
* With an OD trannys like A500/42RH/46RH, that's a total game changer, expect about a 25-30% increase in mileage on hwy. due to their .69 OD gear.

 

[coyote42]

Ok this is a couple months old, but here goes:

I have a build that is very similar to yours. My goal is high performance daily driver.
I have a 1991 roller 360 with 10.2 compression with Lunati voodoo roller cam, a tuned Street Demon 750.
I have an A999 as well, but with the Lock-up totally removed. I was able to use Turbo action Cheetah stage 2 valve body and Hughes non-LU TQ converter.
(use at least 2500 stall!) I made the mistake and used a 2000 stall.
my rear gears is 3.21.

Yes there is a way to "shut-off " the lock-up or better yet do a mod similar that @TrailBeast utilized. Especially with those 3.55 gears.

Couple of points:
3.55 gears with the A999 is still a very good all-around "fun" gear around town but will take some of the highway ability.
I'm sure your aware of the A999's 1 & 2 gear ratio vs. 727 and regular 904's. So with your combo your first gear take-off is equivalent to having a 727 with 3.96 rear gears.
With my 3.21 rear my first gear take-off is slightly higher vs. 727 with 3.55 rear. But I can cruise at 72 mph at 3000 rpm.
With your gears: (and I say this because I've had personal experience with using the same gears as you before)
With 26 inch rear tires at 70 mph my rpm's jumped to almost 3400 (something like 3370-3380 to be exact)
With 27 inch tires and 3.55 that would be a better match.
(I'm still thinking of going back to 3.55 gears Since I'm now going to 17 in rims with 255/50R17 rear tires which are 27 inches tall)

With the lock-up you're going to drop about 200+ rpms at highway cruise.

There are pros and cons to our setups:

My setup (LU totally removed/converted non-LU)
+ Cheaper Torque Converters
+ Likely stronger.
+ Less worry about electronics gadgets and such.

Keeping LU:
+ The trans runs cooler, especially at freeway speeds.
+ Flexibility in using a little higher (numerically) gear numbers.
+ You will gain slightly more mileage.

For example:
On my drive to Louiseville CO (from Ogden UT area) 500+ mile one way.
I usually get a best of around 17.5 mpg, but ranges can also average from 15.4 to 16.8 depending on crosswinds (Wyoming for you)
* That's maintaining 70-72 mph keeping it at 3000 rpm and under
* I did get almost about 18.2 mpg one time doing mainly 60-65 mph in the backroads (around 2500-2700 rpm) Sunny, clear 85 degree day with a modest 25mph tailwind.
* My best educated guess is you can gain anywhere between 3-5% increase in mileage (not factoring wind, temp, incline etc.) by keeping that lock-up function - Granted my math is nowhere as elaborate as @AJ/FormS
* With an OD trannys like A500/42RH/46RH, that's a total game changer, expect about a 25-30% increase in mileage on hwy. due to their .69 OD gear.

Thank you for the info. Yes I was aware of the gear ratio with 25in tires it came with. I have a set of 3:21s in a box and a plethora of 15in tire sizes up to a 275/60 (28in) if I want to take any long trips. I want the trans to operate as normal and make the lock up work. My 67 Barracuda will have the cheeta man vlv body and our Challenger has a slap stick, so plenty of shifting fun to be had. The Duster is a slightly trick 318 to just get in and go. I will come up with a nice switch in the dash and relay set up for the lock up converter.

 

[AJ/FormS]

the ratios are
2.45-1.45-1.00 for the 904. and
2.74-1.54-1.00 for the A999
With 3.21s your take off ratios are;
3.21x245=7.86/A904, and
3.21x2.74=8.80/A999, which being 12% better, or about the same as one rear gear, which average about 10%.
This allows you to run 2.94s with the A999 for a take off 8.06, still 2% better than the 3.21/A904, but the rpm at hiway speed with the 2.94s is reduced to 91.6%. So that's a win/win . But on level ground,the loc-up feature, will only get you maybe a 5% reduction in rpm to maybe 6% max, unless your engine is gutless, or your TC is slipping . 6% of 3000 is 180rpm, so @Cuprum-74 s results are totally plausible. Generally, whatever percentage rpm reduction you get, it is worth about half that in mpgs; so again @Cuprum-74 s estimates are right-on.
There is a penalty for all this, namely;
In second gear the ratios are
1.45(A904)x3.21=4.65, and
1.54(A999)x2.94=4.53, now a 3% loss for the A999/2.94s, not a deal-breaker, and almost meaningless around town..
But;
The rpm drop between first and second gears is increased from .59 to .56 so with the A999 you will have to rev the engine slightly higher for the trans to drop into second at the same rpm. At 3000 this is ~150 rpm. at 5000, it is ~250rpm, again, almost meaningless around town.
IIRC the A999 TCs will wipe that right out at the bottom.

 

[coyote42]

the ratios are
2.45-1.45-1.00 for the 904. and
2.74-1.54-1.00 for the A999
With 3.21s your take off ratios are;
3.21x245=7.86/A904, and
3.21x2.74=8.80/A999, which being 12% better, or about the same as one rear gear, which average about 10%.
This allows you to run 2.94s with the A999 for a take off 8.06, still 2% better than the 3.21/A904, but the rpm at hiway speed with the 2.94s is reduced to 91.6%. So that's a win/win . But on level ground,the loc-up feature, will only get you maybe a 5% reduction in rpm to maybe 6% max, unless your engine is gutless, or your TC is slipping . 6% of 3000 is 180rpm, so @Cuprum-74 s results are totally plausible. Generally, whatever percentage rpm reduction you get, it is worth about half that in mpgs; so again @Cuprum-74 s estimates are right-on.
There is a penalty for all this, namely;
In second gear the ratios are
1.45(A904)x3.21=4.65, and
1.54(A999)x2.94=4.53, now a 3% loss for the A999/2.94s, not a deal-breaker, and almost meaningless around town..
But;
The rpm drop between first and second gears is increased from .59 to .56 so with the A999 you will have to rev the engine slightly higher for the trans to drop into second at the same rpm. At 3000 this is ~150 rpm. at 5000, it is ~250rpm, again, almost meaningless around town.
IIRC the A999 TCs will wipe that right out at the bottom.

Thanks AJ, I did not know the 999 had a different 1 and 2 gear ratio. Car came with a 3:55 sg 8 1/4. I have a 3:21 in a box. I’m going to run what it has and see how it is. Then change it if needed. Sounds like it will put you back in the seat in 1st gear as it is and not be too bad with 3:21 plus better highway rpm. I built my 318 with some extras to it so it should run well. All my cars have Been 727, 8 3/4 combos.

 

[AJ/FormS]

8.25 housings are cheap and plentiful, plus 3.55s are desirable. It might be good to purchase a second assembly and swap your 3.21s into it?

 

[coyote42]

8.25 housings are cheap and plentiful, plus 3.55s are desirable. It might be good to purchase a second assembly and swap your 3.21s into it?

Got ya, I have a handful of centers and ratios for 8 3/4 to swap but 8 1/4 not as easy.