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spridget tranny questions

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Stan Swanson

Freshman Member
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Hello all,

I need some advice on spridget transmissions. I am planning to install the internals from a spridget CR box into an Austin A-30 case. goal is to approximate the modifications of a period Lotus Eleven gear box using the spridget internals. My first question is what sprite box I need to aquire (date, engine size, serial number, or other identifier). I found a reference for determining a CR box by the chassis plate, is there any way to identify a CR box other than this, especially from the case itself? Do I count revs on the input/output shafts (and is there one gear that would be the best indicator of the Close-ratio gear set)? Any cautions on terminal problems with used spridget boxes? What are the gear ratios for a factory CR box. what else do I need to know? Box will be mated to a Coventrty Climax motor with planned 90-100 HP. feel free to e-mail me directly at mhkites@worldnet.att.net
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Stan Swanson:
Hello all,

Do I count revs on the input/output shafts (and is there one gear that would be the best indicator of the Close-ratio gear set)? Any cautions on terminal problems with used spridget boxes? What are the gear ratios for a factory CR box.<hr></blockquote>

Stan, I found references to 3 Sprite gearsets, 2 of which were called close-ratio. The early, non-CR boxes had a 3.63 first gear,2.37 second, and 1.41 third. I think the Lotus CR had about a 2.5 first.

The Mk II and later Sprites had a 3.2 first, 1.91 second, and 1.36 third (Not sure about third but 1.36 is close)

The other Sprite CR box is probably rarer than original Lotus gears & had a 3.0 first.

I'd use first gear as a quick test - count the revs in and out. It appears to me that you'll have a harder time finding a wide-ratio box than a CR one.

Maybe one of the Sprite wizards can tell you how to recognize the boxes, & whether there are better ratio options. I expect all of these would be real "stump pullers" in an Eleven.

(We had an Eleven years ago - #324 - but iirc it had a TC transmission)

Good luck
 
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