The Stovebolt Site Forums The Shop Area Driveline 3.38:1 ring/pinion upgrade

I'm looking to buy a new ring/pinion set to reduce my final gear ratio for highway cruising. 3.55:1 ratios are pretty common but I found a couple of gear shops that offer 3.38:1 ratio for these 1/2 ton 8.2 dropout rear-ends.

Here is one:
http://www.tomsdifferentials.com/2011catalog/Pages13.pdf

I crunched the numbers for cruising along at 65 mph (typical speed limit in my area), and 3.38 would get my RPMs down to 2650 from 3000+ that I'm currently getting with the stock 3.9:1 gears.

Anyone run 3.38:1 with the ole thriftmaster 235? My bone stock 235 feels like it's strong enough to handle a taller ratio. Any other suggestions that wont break the bank?

I've got a granny 1st gear, so I'm not worried about take offs and I'm not going to be climbing any mountains or towing anything around. Just looking to give my weekend warrior a little better highway manners.

I've considered the T5 upgrade path, but I really like the stomp to start pedal ('55), and the three on the tree is just fine with me. Besides, I've got such an original truck that I'd hate to modify it too much.

the 3.55's fit the AD years, the 3.38's fit the Task Force years ..... which series do you have? either work fine with a 235 if you're not hauling heavy loads .... neither option is cheap compared to finding a good used original 3 speed OD trans

Bill

I've been looking for the 3 speed OD but everything I've seen is overpriced. A gear upgrade is cheap compared to the OD 3 speeds I've seen.

What doe you mean by Task Force vs. AD? I've got a '55 1/2 (second series) 3100 1/2 ton.

Ah... Duh! AD is advanced design. Just figured that out. It is a task force, so I'm assuming I can go with the 3.38 gear upgrade. Right?

the 47-55.1 is the Advance Design series, the 55.2-59 is the Task Force series, which is what you have ... the BW or Saginaw 3 speed OD's can be found for half the cost of a gear change if you look a bit ... check with Patricks for either the gears or the OD

Bill

Thanks. Patrick's is close too. I'll call them to see if they have any ODs in stock.

Why isn't there a 3.38 or lower than 3.55 available for the AD trucks?

the gearsets are different for the open and closed rears - the 3.38 originated at GM in 58 [as well as one other ratio I think] as a response to mileage concerns resulting from fuel price increases in the mid-50's, they've been available in the aftermarket ever since

Bill

@Chenzo, Welcome! Another option is putting a T-5 behind your 235. There is plenty of information here and on other boards on how to do this. Those who have done it seem to love it. THis is just something else to consider, but it is way cheaper than other OD approaches or rear end changes. My 2 cents!

Best wishes,

Les

My 59 is running 3:38 gears. Im running the 235 as well with a granny low. I still take off in second. I only use 1st when I am towning my trailer and its full.

http://carphotos.cardomain.com/ride_images/3/3457/1029/33640514032_large.jpg

Good luck. Got my stuff from patricks