696pack
Well-Known Member
Although I have not bought one yet (and will eventually for my 6 pack bee) I have always been an advocate for Passon's 4 speed overdrive rather than the 5 speed or 6 speeds available.
I just don't understand the big facination with the 1 or 2 extra gears.
For those that want more top end, how much can you use? There are few wide open spaces that you can safely drive 150 mph+ and if you get caught these days you can lose your car and go to jail. The areo dynamics of our old cars make it difficult as well.
I suspect that many want an overdrive for the same reasons I do, to reduce engine wear and for an attempt at improving mileage. If you are only looking at one of these then you better figure out how many miles per year you plan to drive your car and do the math as to how many years you are going to have to drive it just to break even on the cost of conversion.
The Passon 4 speed overdrive does not require a different shifter or any other parts to replace your existing trans except for a different clutch disc if you have a 23 spline rather than an 18 spline trans. Unless you are the one driving the car or a passenger watching the tach on the 3rd to 4th shift no one ever suspects you have had a modification to the trans.
With a 5 speed Passon you at least have to buy a new shifter mechanisum and I have not researched it for possible other items needing replacement such as the above mentioned clutch disc for the 4 speed.
With the Tremac conversions we all know there is MUCH more to buy and invasive modifications. These mods may not be a big concern for the pro touring types but I don't want those types of invasive mods to MY car.
Below is an easy comparison of the Passon 4 speed/over drive and the 5 speed. I don't see enough difference to justify the extra gear. I also like the fact that with my car/engine/rear combo (1969 6 pack bee, 523 stroker, 4.56 gears) that with the 4 speed overdrive I will be running throug the 1/4 in 3 gears just like an auto trans and one less possible gear to miss. You will note below that the first 3 gears of the passon 4 speed overdrive are nearly identical to an auto trans 727.
Gearset TireSize RPM Speed Rear End Ratio
Stock 1:1 28“ 3248 65 m.p.h. 4.10 : 1
Passon Performance
Overdrive .80:1 28“ 2580 65 m.p.h. 4.10 : 1
4 speed overdrive gear ratios 5 speed
1st 2.65 : 1 2.66 : 1 2.64 : 1
2nd 1.93 : 1 1.59 : 1 1.92 : 1
3rd 1.39 : 1 1.00 : 1 1.40 : 1
4th 1.00 : 1 .80 : 1 1.00 : 1
5th 0.70 :
Passon 4 speed/overdrive unit
Stock Rear Ratio
(1:1 4th Gear) Adjusted Rear Ratio
with Overdrive
3.23 : 1 2.58 : 1
3.54 : 1 2.83 : 1
3.55 : 1 2.84 : 1
3.91 : 1 3.13 : 1
4.10 : 1 3.28 : 1
4.56 : 1 3.65 : 1
I just don't understand the big facination with the 1 or 2 extra gears.
For those that want more top end, how much can you use? There are few wide open spaces that you can safely drive 150 mph+ and if you get caught these days you can lose your car and go to jail. The areo dynamics of our old cars make it difficult as well.
I suspect that many want an overdrive for the same reasons I do, to reduce engine wear and for an attempt at improving mileage. If you are only looking at one of these then you better figure out how many miles per year you plan to drive your car and do the math as to how many years you are going to have to drive it just to break even on the cost of conversion.
The Passon 4 speed overdrive does not require a different shifter or any other parts to replace your existing trans except for a different clutch disc if you have a 23 spline rather than an 18 spline trans. Unless you are the one driving the car or a passenger watching the tach on the 3rd to 4th shift no one ever suspects you have had a modification to the trans.
With a 5 speed Passon you at least have to buy a new shifter mechanisum and I have not researched it for possible other items needing replacement such as the above mentioned clutch disc for the 4 speed.
With the Tremac conversions we all know there is MUCH more to buy and invasive modifications. These mods may not be a big concern for the pro touring types but I don't want those types of invasive mods to MY car.
Below is an easy comparison of the Passon 4 speed/over drive and the 5 speed. I don't see enough difference to justify the extra gear. I also like the fact that with my car/engine/rear combo (1969 6 pack bee, 523 stroker, 4.56 gears) that with the 4 speed overdrive I will be running throug the 1/4 in 3 gears just like an auto trans and one less possible gear to miss. You will note below that the first 3 gears of the passon 4 speed overdrive are nearly identical to an auto trans 727.
Gearset TireSize RPM Speed Rear End Ratio
Stock 1:1 28“ 3248 65 m.p.h. 4.10 : 1
Passon Performance
Overdrive .80:1 28“ 2580 65 m.p.h. 4.10 : 1
4 speed overdrive gear ratios 5 speed
1st 2.65 : 1 2.66 : 1 2.64 : 1
2nd 1.93 : 1 1.59 : 1 1.92 : 1
3rd 1.39 : 1 1.00 : 1 1.40 : 1
4th 1.00 : 1 .80 : 1 1.00 : 1
5th 0.70 :
Passon 4 speed/overdrive unit
Stock Rear Ratio
(1:1 4th Gear) Adjusted Rear Ratio
with Overdrive
3.23 : 1 2.58 : 1
3.54 : 1 2.83 : 1
3.55 : 1 2.84 : 1
3.91 : 1 3.13 : 1
4.10 : 1 3.28 : 1
4.56 : 1 3.65 : 1