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Best gear ratio when installing 700r4 transmission

42K views 6 replies 6 participants last post by  70 nova  
#1 ·
What is the best rear gear ratio when installing a 700r4 transmission in a '36 Chevy Street Rod for best gas mileage and overall performance?

[ August 04, 2002: Message edited by: agordon ]</p>
 
#2 ·
Ok, I'm not a chevy guy but I'm assuming the 700R4 is an overdrive trans. With overdrive I would go around 3.50 for a good performer that will still handle your highways well (gas mileage). The higher you go (3.73) the more she'll launch but you'll start to sacrifice fuel economy on highways. What type of driving you'll be doing is really the most important thing to consider!! I'm running 3.70's in my stang with a C4 trans (no OD), great for cruising around town but horrible on the interstates. But most of my driving is strickly local cruising so I set her up for that.
 
#3 ·
Hi! I would start by weighting the car. Then check out some of the late models that have your engine trans combo in them to sell how they do. Find out what gear ratio is in the one that feels good to you. Check out crane's gear ratio chart to help get a feel for what will work. Remember to keep the cruise down around 1500 of less in OD to get better mileage. Hope this is of value to you

[ August 04, 2002: Message edited by: Partsman ]</p>
 
#4 ·
This is my opinion, and, as with certain parts of the anatomy, everyone has their own. Given a rear tire diameter of about 30" give or take and inch, the 3:42 ratio GM rear will work outstanding with the 700R4. It will give you the best of both worlds, off the low end pretty good, and not be too high rpm in the cruising range. This can all be altered drastically by tire size, which will change final drive ratio, which is directly related to cruising rpm. Get the picture? Just keep in mind the "other" variables that come into play when selecting the final gear ratio and with an OD tranny. PACO ;)
 
#6 ·
Bowtie overdrives has a calculator in their useful tool area you can use to figure rpms etc. <a href="http://www.700r4.com" target="_blank">www.700r4.com</a> I believe. I have 3.70's with a 26" diameter tire, this puts me at 2500 rpms at 70mph. The bottom end is still fun to romp around with. :D

[ August 04, 2002: Message edited by: 53vicky ]</p>