Marc, Easiest way to calculate the gear ration if you don't have the number of teeth on the ring and pinion to calculate off of is to: 1. Jack the rear end of the car in the air 2. mark a spot of the u-joint with a piece of tape or a marking paint pen 3. rotate the tire one complete revolution while someone counts how many times the marking on the u-joint make a complete revolution. This will be your ration. slightly more than 3 turns will be a 3.15, 3 and one half turns will be a 3.54. Just shy of 4 turns will be a 3.91, just over 4.10 and so on. Nick Alfano Performance 4849-76 st. Kenosha, WI. 53142 262-308-1302 262-942-8271 after 6pm central and weekends Message: 2 Date: Sat, 20 Nov 2010 15:20:25 -0500 From: Marc Montoni <Freedom@xxxxxxxx> To: amc-list@xxxxxxxxxxxxxxxxx Subject: Re: [AMC-list] 68 AMX Tire Q Message-ID: <20101120202758.42AA6984008@xxxxxxxxxxxxxxxxxxxx> Content-Type: text/plain; charset="us-ascii" I said: >> I just bought a 68 AMX. 290 4 speed. The tires are dry rotted and I want to >> get a new set. Stock Magnum 500 style (but painted) wheels. >> >> Anyone care to recommend a modern size that will fit with no issues? Ken Ames <ameskg@xxxxxxxxx> said: >Which differential ratio do you have? When the weather cleared last week, I spent ten minutes looking for a stamped code on the rear axle, but I'll be danged if I can find it. I even scraped off the grime and paint with a razon on those small bosses where I would have expected a stamping. No joy. I would assume it's a 3.15 or 3.54, although as I recall the 3.54 was more likely found on 343/390 cars. I'm more concerned with fit than performance. I don't intend to thrash it on the track (I have a Spirit to do that with, now). In short, I just want it to look good, handle OK, and not have interference issues. Any help? _______________________________________________ AMC-list mailing list AMC-list@xxxxxxxxxxxxxxxxx http://list.amc-list.com/listinfo.cgi/amc-list-amc-list.com