AOD question

hytorksc

Registered User
would an AOD's overdrive band hold up to nearly WOT at high triple digit speeds? with the stock 3.27's my SC will pull hard past 120mph in 3rd, but i'm wondering if i change the rears to 3.73's can i rely on the OD band to take it the rest of the way to 150mph, assuming i've built up the SC and transmission enough to do this. 3.73's will carry 3rd gear (locking) up to 112 mph at 5,300 rpm, but that's it. this is not for drag strip, just optimizing for street performance.

thanks-
 
May you can look into the kevlar OD band, I use one, and haven't had problems, but I don't drive my SC that fast on the street.... usually :eek:
 
sizemoremk said:
May you can look into the kevlar OD band, I use one, and haven't had problems, but I don't drive my SC that fast on the street.... usually :eek:
it's really not my intention to drive that fast, i just want to be capable and ready.
i just want to know if i go with 3.73's will i be giving up too much high speed cruise ability? i'm concerned that shifting up from 3rd to OD at WOT is impossible due to the AOD's TV cable setup unless there's a kit out there that allows the OD band to shift at WOT. i know the OD band is the weak link. Maybe i can design/configure a device that shifts and locks in the OD manually (not that i will be accelerating past 120 mph in 3rd alot).
any more advice, opinions anyone?
 
sizemoremk said:
May you can look into the kevlar OD band, I use one, and haven't had problems, but I don't drive my SC that fast on the street.... usually :eek:

sizemoremk,

i notice in your sig you have the aod wide ratio kit. how do you like it? does your car get off the line much harder, and is traction a problem?

thanks-
 
hytorksc said:
sizemoremk,

i notice in your sig you have the aod wide ratio kit. how do you like it? does your car get off the line much harder, and is traction a problem?

thanks-

It definately feels like it launches a better, and it is easier to get the tires a squalin, but I wouldn't call it a traction problem. At worst, it will squal em going into second on a sharp turn and moderatley heavy throttle.

I still don't know if it was a good idea for 1/4 times, as the 2-3 jump is a bit of a letdown... So much that my little brother said it even looks like I slowed down going into the 3rd at the track. But at that time my only real mods were exhaust and this tranny, not even an OD pulley... (had a malfunctioning N2O kit, so it was no good at that time)

In the wie ratio kit, 1 and 2 are both shorter, and 3 is the same as regualr AODand 4th is a little shorter also, look around at baumann controls for more info, they helped me with the whole deal. I probably began to annoy them with questions, but they had great service throughout the deal.

The baumann shift kit offer "full-throttle OD capability" but I'm not sure exactly what that means, but I didn't make that particular mod with their kit yet, as I planned to wait until some more mods are done, and decide what I want to set the shiftpoints at, I'll probably do the OD mod then. I can give you some more specifics on exactly what the OD mod does when I get to the house. Hope I can find the book again...

I've kinda shifted goals, I was just wanting a little more pep last year, and now I have moved up to wanting to eventually run mid 12s. The wide ratio mod was more for some seat of the pants improvement, so depending on your goals it may or may not be a good idea???

I think it would be more popular if it was really a good idea, but I like it myself either way... From the math its suppose to be like running 4.10s in first gear, but back close to normal at cruise.

I am curious though, if I would be able to get down the 1/8 in 2nd gear if it is fast enough??? We only have an 1/8 here, so I gotta go a good ways to get a 1/4 slip...


Check out baumann...
http://www.becontrols.com/
 
sizemoremk said:
It definately feels like it launches a better, and it is easier to get the tires a squalin, but I wouldn't call it a traction problem. At worst, it will squal em going into second on a sharp turn and moderatley heavy throttle.

I still don't know if it was a good idea for 1/4 times, as the 2-3 jump is a bit of a letdown... So much that my little brother said it even looks like I slowed down going into the 3rd at the track. But at that time my only real mods were exhaust and this tranny, not even an OD pulley... (had a malfunctioning N2O kit, so it was no good at that time)

In the wie ratio kit, 1 and 2 are both shorter, and 3 is the same as regualr AODand 4th is a little shorter also, look around at baumann controls for more info, they helped me with the whole deal. I probably began to annoy them with questions, but they had great service throughout the deal.

The baumann shift kit offer "full-throttle OD capability" but I'm not sure exactly what that means, but I didn't make that particular mod with their kit yet, as I planned to wait until some more mods are done, and decide what I want to set the shiftpoints at, I'll probably do the OD mod then. I can give you some more specifics on exactly what the OD mod does when I get to the house. Hope I can find the book again...

I've kinda shifted goals, I was just wanting a little more pep last year, and now I have moved up to wanting to eventually run mid 12s. The wide ratio mod was more for some seat of the pants improvement, so depending on your goals it may or may not be a good idea???

I think it would be more popular if it was really a good idea, but I like it myself either way... From the math its suppose to be like running 4.10s in first gear, but back close to normal at cruise.

I am curious though, if I would be able to get down the 1/8 in 2nd gear if it is fast enough??? We only have an 1/8 here, so I gotta go a good ways to get a 1/4 slip...


Check out baumann...
http://www.becontrols.com/

thanks for the info-

i think the wide ratio was mean't for you to also raise your WOT shift point above 5,000 rpms... probably more like 5,500 rpms to take advantage of the 2-3 shift.

that baumann kit sounds like i could go with 4.10's if i can negotiate use of the OD band more.
 
With the wide ratio you may want to consider 3.55's instead of the 3.73's. I've heard that the 3.73's with the wide ratio is too steep in 1st...and people have difficulty keeping traction on launch.

Also, I've got a Trans-go high rev shift kit that can shift to OD at WOT. It's not as great as it seems. It shifts too soon into OD and slows you down. I keep it in D until I'm ready to shift into OD, then move the gear selector forward. That method works great. As of now I don't have too much power. Once you reach a certain power level (don't know what it is yet on the street, but dyno is about 250 rwhp) the tranny will shift into OD regardless of where you have the gear selector is at. It is great for mildly modified SCs though.
 
hytorksc said:
thanks for the info-

i think the wide ratio was mean't for you to also raise your WOT shift point above 5,000 rpms... probably more like 5,500 rpms to take advantage of the 2-3 shift.

that baumann kit sounds like i could go with 4.10's if i can negotiate use of the OD band more.

:confused:

I believe the wide ration kit means the gears are a wider ration apart...

It has nothing to do with shift points....

But now that you mention it, the wide ration kit does require a low speed governor to shift close to the stock shiftpoints. With the baumann shift kit, it will let you raise the shiftpoints , however if you raise 1-2 shift point, you will also raise the 2-3 shiftpoint.

I.e. they must be changed together, as in if you want 200 more RPM between 2-3, you will also have to go 200 more between 1-2....

When I am happy with my setup, and get it all tuned, I will make 1 trip to the dyno to see where I should set my shiftpoints...
 
007_SuperCoupe said:
With the wide ratio you may want to consider 3.55's instead of the 3.73's. I've heard that the 3.73's with the wide ratio is too steep in 1st...and people have difficulty keeping traction on launch.

Also, I've got a Trans-go high rev shift kit that can shift to OD at WOT. It's not as great as it seems. It shifts too soon into OD and slows you down. I keep it in D until I'm ready to shift into OD, then move the gear selector forward. That method works great. As of now I don't have too much power. Once you reach a certain power level (don't know what it is yet on the street, but dyno is about 250 rwhp) the tranny will shift into OD regardless of where you have the gear selector is at. It is great for mildly modified SCs though.


I agree, I would like to go 3.55s, but I kinda hate going from 3.27 to 355...

But if I decide I need that one more 10-20th of a second, I may just do it....

As for 4.10s, they should work pretty good with some slicks, but of course, won't be much good on the street...
 
sizemoremk said:
:confused:

I believe the wide ration kit means the gears are a wider ration apart...

It has nothing to do with shift points....

But now that you mention it, the wide ration kit does require a low speed governor to shift close to the stock shiftpoints. With the baumann shift kit, it will let you raise the shiftpoints , however if you raise 1-2 shift point, you will also raise the 2-3 shiftpoint.

I.e. they must be changed together, as in if you want 200 more RPM between 2-3, you will also have to go 200 more between 1-2....

When I am happy with my setup, and get it all tuned, I will make 1 trip to the dyno to see where I should set my shiftpoints...

The wide ratio actually changes 1st and 2nd gears to a steeper gear...don't have the ratios infront of me, but it is a completely different gearset in the tranny.
 
007_SuperCoupe said:
The wide ratio actually changes 1st and 2nd gears to a steeper gear...don't have the ratios infront of me, but it is a completely different gearset in the tranny.
Additionally, if you have the wide-ratio kit, it's nearly impossible to setup the 1-2 shift and the 2-3 shift to shift at the same RPMS....usually the 1-2 shift occurs about 200-300 rpm higher than the 2-3 shift.

FWIW, Art Carr and Lentech both don't allow full-throttle upshifts into OD, nor do they allow full-throttle accelleration in OD (each downshifts into 3rd) because the OD band is the weakest link of the AOD transmission.
 
i think the main idea behind getting the wide ratio in the case of the sc is to enable the AOD to have nearly the same torque multiplication at the rear wheels as the 5spd. everyone knows who has an aod sc that you can't get off the line as fast as the stick cars (stock vs stock) and this is why-

gear ratios-

aod normal= 2.40 (1st gear) x 3.27 (rear) = 7.848 final, plus factor in a little tc slippage. this is more like 2nd gear ratio in a 5spd sc (6.333 final).

5spd = 3.75 (1st gear) x 2.73 (rear) = 10.237 final<more leverage than an aod.

now compare the aod wide ratio with the 5spd;

5spd = 3.75 (1st gear) x 2.73 (rear) = 10.237 final

aod wide = 2.84 (1st gear) x 3.27 (rear) = 9.286 final, plus tc slippage will give you about the same leverage as the 5spd.

2nd gear works the same way i think.

IMO, the higher gear ratios require more power to be developed at higher rpms from the motor to match the higher shift points, which is not easy to do in an AOD SC. i don't think the aod is flexible enough to allow setting this up easily.
 
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Are you suing the early or late 5 spd gear ratios?

Another thing to consider is the RPM drop as soon as you shift. The rpm drop when shifting into 3rd is much greater with the wide-ratio gearset. If you aren't at the drag strip, this isn't a big deal. But while racing, it brings you into 3rd gear (highest load on the engine) at a lower rpm than stock-ratio....below your peak torque.

Don't get me wrong, I was originally planning on the wide-ratio kit years ago, but after knowing someone that had one and has now gone back to the standard ratio gearset, I will be keeping the standard ratio.

Hopefully Todd Jelle will read this and explain it a little better, as he is the guy that "used" to have a wide ratio gearset.
 
Kurt K said:
Are you suing the early or late 5 spd gear ratios?

Another thing to consider is the RPM drop as soon as you shift. The rpm drop when shifting into 3rd is much greater with the wide-ratio gearset. If you aren't at the drag strip, this isn't a big deal. But while racing, it brings you into 3rd gear (highest load on the engine) at a lower rpm than stock-ratio....below your peak torque.

Don't get me wrong, I was originally planning on the wide-ratio kit years ago, but after knowing someone that had one and has now gone back to the standard ratio gearset, I will be keeping the standard ratio.

Hopefully Todd Jelle will read this and explain it a little better, as he is the guy that "used" to have a wide ratio gearset.

that's why i'm saying (or trying to say) that it requires winding the motor up much higher in 2nd gear before shifting, which means more power (enough power) has to be developed up high to reap any advantage from this. the powerband of the sc has to be expanded. if you shift higher on the 2-3, the drop won't be too low for the engine to recover because it will be well in it's power band. as you know the aod does not lend itself to intricate adjustments in this way from a shifting point of view. and i was referring to the 5spd gear set on the 89-93 cars. what i'm talking about is just paper theory, but what happens on the track is reality, and may be different. i think i would like the wide ratio set because i don't race my car, i'd just like to have the feeling of getting a short 60ft time, and utilize some of the best advantages of a drag car applied to the street. two different setups. that's also why i wanted to see if i could use the OD band more for the high speed stuff, and make the car almost unbeatable off the line with a wide ratio/rear gear combo. i would even add a mild torque converter, and i bet this AOD would be more fun than a 5spd.
 
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This is a LENTECH quote from there manual.speaking of any 2'' OD band.
And the stock AOD has a 1.500'' width OD band.

Overdrive however is always limited to 400ft/lbs in any AOD.

Randy
 
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yesterday i called baumann engineering discussing the aod overdrive band properties- they said to install the 2" band (don't we already have this?), and they can configure the valve body to hold WOT on OD. the problem is that OD can only hold but so much power, and the stock aod limit on the input shaft would be around 400 ft lbs at the crank which is the snapping point. that's ok with me- i know i don't have the money to build a "king of the hill" supercar sc like D. Dalke and some others here. would be nice to have 450+rwhp, but i think 300+rwhp is enough for me which i'm thinking this power level is in the safe range of an aod as far as torque goes.
 
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Randy N Connie said:
The stock SC bird with AOD has a 1 1/2'' OD Band.


Yes, it certainly is, that is the other advantage to the wide ratio set, the 2" OD band. Though you can get the 2" band W/O the wide ratio kit...

Buamann also told me that the kevlar OD band has more overall holding force, and less wear; BUT it didn't "grab" as fast, so it slightly slips during 3-4 shifts, increasing the temps slightly. This is why I added the external tranny cooler, and more recently purhcased a deeper and finned B&M pan...

TCI will sell you the OD band directly by the way.

Just FYI...
 
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