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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: blazing816 on January 03, 2013, 10:17:26 am

Title: Help in picking the right Gear Ratio for me.
Post by: blazing816 on January 03, 2013, 10:17:26 am: I am starting to get parts for my frame off build up of a 87 4x4, 31" tires and 700r4 going to put a stock 350 or a bored 350, trying to keep the look original but make it run and drive better then stock. The stock gear ratio is 3.08, which I do not think will be the best for my application. I mostly will be using this in city and highway driving, somethimes pulling an little ATV trailer, but about 2-4 times a year pulling a 23ft 4,200lbs camper. I was thinking that running 3.42 or 3.73, to me it seems like a good medium decent MPG (I know are trucks are great) but still have some towing power. I currently have a truck with 31" TH350 305 and it oringal came with 3.08 (but do not know if there original) and it tows my camper but entering the freeway is not fun, especially if its on a hill. I would just like input and what you think I should be running.

Other question is should I just buy some different 1/2ton or 3/4ton axles with 3.73/3.42 gears, or since I want this truck "brand new" and thinking about rebuilding everything. Should I just buy new ring and pinion gears and replace it all when I have/replace the bearings/seals??
Title: Re: Help in picking the right Gear Ratio for me.
Post by: mehunter1 on January 03, 2013, 11:37:42 am: As for gears I would elect for the 3.73. You will really like the pulling power getting on the freeway with the camper in tow. Personally you could just change them out and it might be easier you doing it, then going out find the right set of axles, then have to clean them up anyway, but others may disagree with me.
Title: Re: Help in picking the right Gear Ratio for me.
Post by: Captkaos on January 03, 2013, 12:22:29 pm: For the use, the stock axles will work fine. I would just buy axle overhaul kits along with a new ring pinion and install it.
3.42 or 3.73 would be fine, if you want more pulling go with the 3.73, and if you think you might go up on tire size the 3.73 will still be good if you go to 33's.
Title: Re: Help in picking the right Gear Ratio for me.
Post by: Engineer on January 03, 2013, 08:17:01 pm: With O/D I'd definitely go 3.73s.

If you were going to tow more I'd recommend 4.10s
Title: Re: Help in picking the right Gear Ratio for me.
Post by: Da67goatman on January 03, 2013, 08:26:41 pm: I'll second that, 3.73 or 4.10s.
Title: Re: Help in picking the right Gear Ratio for me.
Post by: blazing816 on January 04, 2013, 12:56:38 pm: Thanks for the replies....I was leaning towards 3.73 myself, so it sounds like the plan I am going to take.