im building a 29 a coupe, 305 sbc bout 260 hp, running a saginaw 3 speed manual out of an 81 el camino v6 car, have a gm 10 bolt with 3.42 gears. rear tire should be somewhere between 29.5 to 31. im thinkin it should be a decent all around setup as there will be alot of highway driving goin on, but i still want a decent bottom end. any opinions are appreciated. i did use the search function, but not finding anything on people with 3 speed setups, mostly auto and 4 and 5 speeds
GM Saginaw transmission ratio identification <!-- The following table has been generated by the Internet ***istant Wizard for Microsoft Excel. You can find this add-in on "http://www.microsoft.com/msoffice/freestuf/m***cel/index.htm" --><!-- ------------------------- --><!-- START OF CONVERTED OUTPUT --><!-- ------------------------- --><TABLE border=1><TBODY><TR vAlign=bottom align=middle><TD># of grooves</TD><TD>1st</TD><TD>2nd</TD><TD>3rd</TD><TD>4th</TD><TD>Notes:</TD></TR><TR vAlign=bottom align=middle><TD>0</TD><TD>2.85</TD><TD>2.02</TD><TD>1.35</TD><TD>1.00</TD><TD></TD></TR><TR vAlign=bottom align=middle><TD>1</TD><TD>2.56</TD><TD>1.81</TD><TD>1.37</TD><TD>1.00</TD><TD>Third gear on cluster has 25 teeth</TD></TR><TR vAlign=bottom align=middle><TD>1</TD><TD>2.56</TD><TD>1.81</TD><TD>1.44</TD><TD>1.00</TD><TD>Third gear on cluster has 21 teeth</TD></TR><TR vAlign=bottom align=middle><TD>2</TD><TD>3.11</TD><TD>2.20</TD><TD>1.47</TD><TD>1.00</TD><TD></TD></TR><TR vAlign=bottom align=middle><TD>3</TD><TD>3.50</TD><TD>2.48</TD><TD>1.65</TD><TD>1.00</TD><TD></TD></TR><TR vAlign=bottom align=middle><TD></TD><TD></TD><TD></TD><TD></TD><TD></TD><TD></TD></TR><TR vAlign=bottom><TD colSpan=6 align=middle>*** The grooves are found on the input shaft. I am sure there are exceptions to this rule.</TD></TR><TR vAlign=bottom align=middle><TD></TD><TD></TD><TD></TD><TD></TD><TD></TD><TD></TD></TR><TR vAlign=bottom align=middle><TD></TD><TD></TD><TD></TD><TD></TD><TD></TD><TD></TD></TR></TBODY></TABLE><!-- ------------------------- --><!-- END OF CONVERTED OUTPUT --><!-- ------------------------- --> Last Update: 7/20/99 Name: Fred Teufert Email: fteufert1@worldnet.att.net<SCRIPT type=text/javascript>_popupControl();</SCRIPT> pdq67
GM Saginaw transmission ratio identification <!-- The following table has been generated by the Internet ***istant Wizard for Microsoft Excel. You can find this add-in on "http://www.microsoft.com/msoffice/freestuf/m***cel/index.htm" --><!-- ------------------------- --><!-- START OF CONVERTED OUTPUT --><!-- ------------------------- --><TABLE border=1><TBODY><TR vAlign=bottom align=middle><TD># of grooves</TD><TD>1st</TD><TD>2nd</TD><TD>3rd</TD><TD>4th</TD><TD>Notes:</TD></TR><TR vAlign=bottom align=middle><TD>0</TD><TD>2.85</TD><TD>2.02</TD><TD>1.35</TD><TD>1.00</TD><TD></TD></TR><TR vAlign=bottom align=middle><TD>1</TD><TD>2.56</TD><TD>1.81</TD><TD>1.37</TD><TD>1.00</TD><TD>Third gear on cluster has 25 teeth</TD></TR><TR vAlign=bottom align=middle><TD>1</TD><TD>2.56</TD><TD>1.81</TD><TD>1.44</TD><TD>1.00</TD><TD>Third gear on cluster has 21 teeth</TD></TR><TR vAlign=bottom align=middle><TD>2</TD><TD>3.11</TD><TD>2.20</TD><TD>1.47</TD><TD>1.00</TD><TD></TD></TR><TR vAlign=bottom align=middle><TD>3</TD><TD>3.50</TD><TD>2.48</TD><TD>1.65</TD><TD>1.00</TD><TD></TD></TR><TR vAlign=bottom align=middle><TD></TD><TD></TD><TD></TD><TD></TD><TD></TD><TD></TD></TR><TR vAlign=bottom><TD colSpan=6 align=middle>*** The grooves are found on the input shaft. I am sure there are exceptions to this rule.</TD></TR><TR vAlign=bottom align=middle><TD></TD><TD></TD><TD></TD><TD></TD><TD></TD><TD></TD></TR><TR vAlign=bottom align=middle><TD></TD><TD></TD><TD></TD><TD></TD><TD></TD><TD></TD></TR></TBODY></TABLE><!-- ------------------------- --><!-- END OF CONVERTED OUTPUT --><!-- ------------------------- --> Last Update: 7/20/99 Name: Fred Teufert Email: fteufert1@worldnet.att.net<SCRIPT type=text/javascript>_popupControl();</SCRIPT> pdq67
Since the 3-speed you have came from a six cyl. car my guess is that it has a 2.85 low gear. With the 305 and 3.42 rear gear you should be fine.
3.42 gear and thirty inch tire is about 3400 rpm at 90 mph, or (more conservatively) about 2270 at 60. Not really long-legged, but certainly in the acceptable range for cruising at modern speeds. Gear spacing will be a little wide compared to a four- or five-speed, but should be ok for most purposes.
That ratio table is for a FOUR speed not the 3 speed you have!! ok, i understand that, but if you look online, there is a chart for saginaw 3 speed transmissions that gives almost the identical information as far as grooves on input and 1st gear ratio.
The Jalopy Journal
