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Discussion Starter #1 (Edited)
"PERFORMANCE" Ratio Gearbox

For sale is an Alfa PERFORMANCE gear set gearbox.

Ratios are: 3.57, 2.15, 1.36, 1.00, 0.85 suitable mainly for race cars, but can also be used on the street. This gearbox is made using 3rd and 4th gears from a 4 speed gearbox into a 5 speed gearbox. Great choice when you mainly use 3-4-5. It is a very good mix for most tracks.

This gearbox is sold used and as is. In good operating condition. It is shipped with out bell housing or mount.

Price is $2,000. Plus shipping.
 

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Richard Jemison
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Close ratio?

Ratios are: 3.57, 2.15, 1.36, 1.00, 0.85 suitable mainly for race cars, but can also be used on the street. This gearbox is made using 3rd and 4th gears from a 4 speed gearbox into a 5 speed gearbox. Great choice when you mainly use 3-4-5. It is a very good mix for most tracks.
Elisio, how is this a CR box? Stock gear ratios are 3.3, 1.99, 1.36, 1.0, .79 or .85 (if a jr version) ?

When you use 4 speed gears in a 5 speed trans it requires welding the layshaft extension from a 5 speed to the 4 speed layshaft. Or you could cut bore and weld the 4 speed gears to a stripped off 5 speed layshaft, but then you still would not have those ratios you list??.
 

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Discussion Starter #7
Richard,

This is taking an 3rd and 4th gears out of an old 4 speed transmission into a 5 speed transmission.

If not a close ratio, what description should I use?
 

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Richard Jemison
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Close Ratio

Well, it`s actually a wider ratio than a stock box, because you used the 4th gear and input shaft from a 4 speed that has a lower "ratio" between those 2 gears driving the layshaft speed. As a result all of the gear ratios became lower and farther apart other than 5th where the lower layshaft ratio created a .85 gear from the .79 gear.
Only 4th gear stays the same (1 to 1) since the layshaft ratio has no bearing on that output as 4th gear only locks up the mainshaft.

Had you used 3rd from a 4 speed and stripped off 2nd & 1st and welded the bored out 1st/2nd from the 4 speed and used a late 5 speed input shaft and 4th on the layshaft you would create a "close ratio" box. Ratios 3.0/1.85/1.25/1.0 and whatever 5th you might choose to use.
 

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More of a performance street or club event transmission with the ratio's indicated. That does not make it any less useful for many applications.
There exists a chart on the BB, both Richard and I have copies, and Richard has his own variations of the pure racing CR Alfa transmission ratio's. They are somewhat closer together to allow the operator to keep the engine firmly centered in it's Hp/torque band.
 

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Discussion Starter #10
By popular request, I have changed the subject. Back to school I go.

Thanks for the valuable input.
 
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