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Discussion Starter · #1 ·
How would one go about figuring out what gear ratios to find for their application in a used Lenco? Trying to save some money by not buying new.
 

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Discussion Starter · #3 ·
If someone can provide one sure, but I don't like to ask someone to just give me the answer. I'm looking to learn what ratios wold work best and how to figure out what ratios to find if I were to change a component of the build.

Build direction:
~3100# (not finished and weighed yet), moly chassis, 638bbf, 10-71, 33x15x15 Hoosier, 4.57's. Looking to use a 5 speed for better highway manners during Drag Week. Unless I can get a comfortable 4th gear ratio.
 

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Discussion Starter · #5 ·
Yes, 5 speed or 4 speed with a clutch.

Maybe I'm using the wrong terminology. When I'm looking at used tranny's for sale, I want to make sure I buy one with the proper gear sets in them so I'm not having to buy them after. Or maybe just one of them. Does that make sense?
 

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I would be happy to help you out. I can help you on here, or over a phone call (or both).

Street Strip / Track Only?
Weight?
Horse Power?
CID?
RPM?
NA/N20/SC/TC?
Suspension Type?
Tire Size/Type?

I don't type as easily as I used to before I went turtle, so bare with me.
 

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Discussion Starter · #8 ·
I would be happy to help you out. I can help you on here, or over a phone call (or both).

Street Strip / Track Only?
Mostly Street with track use. 1/4 mile and 1/8th mile.
Weight?
best estimates for finished weight with me in it is 3100#
Horse Power?
Shooting for 1500 at 12# boost
CID?
460 based 638ci BBF
RPM?
7000 peak
NA/N20/SC/TC?
Roots 10-71 from TBS
Suspension Type?
Full Moly Tube Chassis. 4-link Rear.
Tire Size/Type?
Hoosier Quick Time Pro DOT 33x22.5x15 rears.

I don't type as easily as I used to before I went turtle, so bare with me.
Most of this build drives people crazy. I hear "why?" more times than I can count. And to answer that, because I want to. Plenty of things in the world to waste money on. Why not waste it on something that makes you "little-kid-at-Christmas" happy.
 

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I have a few ratios for sale, let me know what your looking for when you fig your ratios out


-Rich
 

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correction my stamp 1.25



.
.
.I am not looking to change mine yet, in my case it would be more cost effective for me to just to buy another used trans w/ 1.30 or 1.31 stamp
and let a friend have it to go through it , cause I haven`t had enough mentoring yet to do my own.
 

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Are you going to want a 4 speed or 5 speed?

I would say as a "street/strip" application you will want to be a little on the under geared side. If you were looking at this as 100% track... I would start about here.
4.30 rear gear, 2.50 - 2.60 low gear. Now clutch selection will play a roll, as you will need something capable of holding the power and weight, but able to slip or be tuned on the track. I have several customers similar to your application.

So... as far as finding a trans, if your looking for a 4 speed or 5 speed will determine what "gear sets" you want.

How a Lenco works is simple. You simply multiply the gear sets together to get 1st gear,
EXAMPLE:
(Back Case) 1.184
(3rd Case) 1.256
(2nd Case) 1.280
(Front Case) 1.31

1.184 = 1.184 Fourth Gear
1.184 x 1.256 = 1.487 Third Gear
1.184 x 1.256 x 1.28 = 1.903 Second Gear
1.184 x 1.256 x 1.28 x 1.34 = 2.55 First Gear

They are generally marked as %. 1.184% for example.

With the Lenco, you can switch the order of the gear sets and change gear splits.
USING SAME GEAR SETS Changing 2nd gear ratio...

1.256 = 1.256 Fourth
1.256 x 1.184 = 1.487 Third
1.256 x 1.184 x 1.34 = 1.992 Second
1.256 x 1.184 x 1.34 x 1.28 = 2.55 First

I hope this helps...
 

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Discussion Starter · #13 ·
Are you going to want a 4 speed or 5 speed?

I would say as a "street/strip" application you will want to be a little on the under geared side. If you were looking at this as 100% track... I would start about here.
4.30 rear gear, 2.50 - 2.60 low gear. Now clutch selection will play a roll, as you will need something capable of holding the power and weight, but able to slip or be tuned on the track. I have several customers similar to your application.

So... as far as finding a trans, if your looking for a 4 speed or 5 speed will determine what "gear sets" you want.

How a Lenco works is simple. You simply multiply the gear sets together to get 1st gear,
EXAMPLE:
(Back Case) 1.184
(3rd Case) 1.256
(2nd Case) 1.280
(Front Case) 1.31

1.184 = 1.184 Fourth Gear
1.184 x 1.256 = 1.487 Third Gear
1.184 x 1.256 x 1.28 = 1.903 Second Gear
1.184 x 1.256 x 1.28 x 1.34 = 2.55 First Gear

They are generally marked as %. 1.184% for example.

With the Lenco, you can switch the order of the gear sets and change gear splits.
USING SAME GEAR SETS Changing 2nd gear ratio...

1.256 = 1.256 Fourth
1.256 x 1.184 = 1.487 Third
1.256 x 1.184 x 1.34 = 1.992 Second
1.256 x 1.184 x 1.34 x 1.28 = 2.55 First

I hope this helps...
Thank you so much for that detailed explanation. I'm up in the air on whether or not I need a 4 or 5 speed. 4 seems to be enough but I'm wondering if a 5 speed would be beneficial enough during Drag Week to take on the extra expense.

Now just to make sure I understand the anatomy of the trans, the back case is closest to the reverser right? First gear would be the case closest to the engine?

In your opinion, what clutch setup would work best for my application? And with that setup, would you recommend the gear ratios you listed?
 

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Correct, back case is by the reverser... I would want to talk to you about clutch as usage amount and some other things will play into your choice.

I think what I would actually shoot for in a 5 speed would be what is below for a CS1 as the options aren't as open as a CS2 or CS3

1.256
1.256
1.28
1.28

1.256, 1.577, 2.01, 2.584

Splits look a little better.

4 Speed....

1.256
1.37
1.48

1.256, 1.720, 2.546



CS1 Gears 1"
1.25% - Uses 34 tooth planet gears, a 23 tooth sun gear and a 91 tooth ring gear.
1.28% - Uses 32 tooth planet gears, a 25 tooth sun gear and a 89 tooth ring gear.
1.31% - Uses 27 tooth planet gears, a 25 tooth sun gear and a 80 tooth ring gear.
1.34% - Uses 24 tooth planet gears, a 25 tooth sun gear and a 74 tooth ring gear.
1.37% - Uses 26 tooth planet gears, a 31 tooth sun gear and a 83 tooth ring gear.
1.41% - Uses 24 tooth planet gears, a 34 tooth sun gear and a 83 tooth ring gear.
1.44% - Uses 20 tooth planet gears, a 32 tooth sun gear and a 73 tooth ring gear.
1.44% - Uses 22 tooth planet gears, a 35 tooth sun gear and a 79 tooth ring gear.
1.46% - Uses 22 tooth planet gears, a 37 tooth sun gear and a 80 tooth ring gear.
1.48% - Uses 22 tooth planet gears, a 40 tooth sun gear and an 83 tooth ring gear.
1.50% - Uses 17 tooth planet gears, a 34 tooth sun gear and a 68 tooth ring gear.
1.56% - Uses 16 tooth planet gears, a 41 tooth sun gear and a 73 tooth ring gear.
1.68% - Uses 15 tooth planet gears, a 62 tooth sun gear and a 91 tooth ring gear.
 

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Discussion Starter · #15 ·
Correct, back case is by the reverser... I would want to talk to you about clutch as usage amount and some other things will play into your choice.

I think what I would actually shoot for in a 5 speed would be what is below for a CS1 as the options aren't as open as a CS2 or CS3

1.256
1.256
1.28
1.28

1.256, 1.577, 2.01, 2.584

Splits look a little better.

4 Speed....

1.256
1.37
1.48

1.256, 1.720, 2.546



CS1 Gears 1"
1.25% - Uses 34 tooth planet gears, a 23 tooth sun gear and a 91 tooth ring gear.
1.28% - Uses 32 tooth planet gears, a 25 tooth sun gear and a 89 tooth ring gear.
1.31% - Uses 27 tooth planet gears, a 25 tooth sun gear and a 80 tooth ring gear.
1.34% - Uses 24 tooth planet gears, a 25 tooth sun gear and a 74 tooth ring gear.
1.37% - Uses 26 tooth planet gears, a 31 tooth sun gear and a 83 tooth ring gear.
1.41% - Uses 24 tooth planet gears, a 34 tooth sun gear and a 83 tooth ring gear.
1.44% - Uses 20 tooth planet gears, a 32 tooth sun gear and a 73 tooth ring gear.
1.44% - Uses 22 tooth planet gears, a 35 tooth sun gear and a 79 tooth ring gear.
1.46% - Uses 22 tooth planet gears, a 37 tooth sun gear and a 80 tooth ring gear.
1.48% - Uses 22 tooth planet gears, a 40 tooth sun gear and an 83 tooth ring gear.
1.50% - Uses 17 tooth planet gears, a 34 tooth sun gear and a 68 tooth ring gear.
1.56% - Uses 16 tooth planet gears, a 41 tooth sun gear and a 73 tooth ring gear.
1.68% - Uses 15 tooth planet gears, a 62 tooth sun gear and a 91 tooth ring gear.
Where is the Like or Thumbs up button? Thank you for being so detailed in that. I will be getting with you about the clutch situation as the build progresses.

Now for my next noob question. Hutch had brought up earlier in the thread that final drive is 1:1. So, in a 5 speed, once you pull the 4th lever down, the ratio is 1:1. And, based on your example above, with the 3rd lever down and the 4th up (4th gear), the ratIo is 1.256. Am I tracking that right?
 

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Yes... You can actually shift a Lenco out of order also if you want.... hahaha. But once all levers are pulled, your 1:1. If you push a lever back up, you add that ratio back to the equation.

This is the same... but air shifted.... also I shift left to right as opposed right to left. I like to complicate things.

 

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Discussion Starter · #17 ·
Ok I got it down now. These are simple but not every day type trans so hopefully this thread helps somebody new like me in the future.

Thank you again for explaining in such detail.
 

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Great Thread !
I am in the same position. CS-1 4speed going in a 1968 3200 lb backhalf ladder bar Camaro 1000HP BBC.
I have been happy with a T400 so I was thinking keeping the gear ratios as close to that of a T400 for simplicity.
Not sure if fine tuning gear ratios would make a noticeable difference on the street.
At the track I expect mid 8's which is plenty fast for a street car.
 

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Just contact lenco, they are very willing to offer up ratio choices for certain applications. They have helped me immensely. Great people to work with.

Corey
If I was buying new I would. I would like to buy a used trans, i'd rather not waste their time unless I plan on spending some money with them. Sooner or later, I will spend money with Lenco.
 
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