The Stovebolt Site Forums The Shop Area Driveline Ratio change

Hey about ready to tear into the rear diff. and am thinking of changing ratio's for better highway speeds. Any suggestions on the best place to purchase these rather expensive parts. I have several kits in catalogs. I did find one in classic parts that "seemed" (dont usually use that word)to be ok.

any input would be great.

Happy Holidays

What type of truck do you have?

Based on your user name, if you have a 1953, Patricks Speed Shop makes the 3:55 gearset and rebuild kit. This kit can be found at almost all the online truck sites. Shop them around or contact Patrick Directly and get the gearset and rebuild kit from the cheapest vendor.

The swap itself can be intimidating but taking it step by step with a high attention to detail, it's not too bad. I have done 4 sets to date so I've gotten pretty good at it. Feel free to send a PM or email with any questions. You can check out my WebShots page. When I did the first set on my own truck, I tried to take as many pics along the way as possible.

I apologize yes I have a 53. I have a very extensive background in diff work mostly heavy class eight vehicls so I don't think the mechanics should be too far out there. I just see several kits that look to be very similar and not sure which road to take.

I'm sure if you look into it, you will find that Patrick is the one having them made and is
the distributor to the other vendors. This is a common practice for a lot of the parts the
vendors carry in their books. It wouldn't be very profitable if every vendor was having all
their parts made by his own favorite shop.
For instance I’ve been told by the phone staff that the steering box rebuild kits for most of
the vendors come from JC and at one time he also supplied a lot of the reproduction
upholstery fabric to some of the other vendors.
Counterpart Automotive supplies a whole bunch of the smaller reproduction parts to the
retailers and you will find their items sold by all the vendors.

Denny Graham
Sandwich, IL

I would just figure the best price including shipping. You will get the same thing no matter who you buy it from. Occasionally someone will buy a gear set and never get around to installing it and put it on eBay. If you have experience seting up class 8 gears, you won't have any trouble with these. Its all the same principle.

Thank you the good info.
I see alot of posts regaurding the overdrive transmision and since the diff. parts are hidden that is the way I would like to go.

thanks again

I am not trying to hi-jack this posting but have a related question that may go along with the original question.

I am also thinking about upping my rear end ratio to Pratric's 3:55 set of gears. What affect would this change have on a 58 1/2 ton with a stock I-6 235 and 3 speed? Would changing the rear gears lower the the engine RPM so much that I would be below the HP and Torque ranges thereby increasing down shifting or having to run up RPM to produce the needed power and toque before up shifting, thereby negating any savings on either wear or fuel use? I would be doing mostly stop and go on local streets.

Thanks,

Bob

Bob - if you don't get on the highway much it hardly seems worth spending the time and money, you won't see any real fuel savings - and for the TF years the gearset is 3.38, so yes, you would be using 1st and 2nd more to avoid lugging it down

Bill

I think that the R/P gear set that Patrick's sells for your truck is a 3.38 ratio.

Your questions are still pertinent (if not more pertinent) with this much decrease.

You could do an easy bolt-in transmission swap to a 4-speed SM420, which has a very low first gear.

Way back in ‘63 when I was a parts man at a Chevy dealership I bought a cherry 1960
Biscayne 2dr sedan 235 Blue-Flame 6 with a manual 3speed transmission.

I drove that car for nearly 5 years, several of which I was in the service. I made many trips
from Illinois to my duty stations in Texas and California. While in Northern California I
put a lot of miles on her in the hills surrounding the Sacramento Valley. Trips to
Yosemite, many weekends up to Truckee and Donner pass fishing and sightseeing. I
drove up to the Shasta and Redding areas often and never felt it was underpowered.

The stock gear ratio in that Biscayne was 3.36:1. So I wouldn’t worry at all going to a
3.38 gear in a driver. If your thinking of putting that 45 year old truck back to work again
then that‘s another ball game, leave it stock and learn to live with it at 55 mph.
Denny Graham
Sandwich, IL

If its a Chev with a 216, its going to struggle with 3.38 gears and with the big gap between 2nd and 3rd it will be awkward to drive. Patrick used to recommend a close ratio 4 speed in front of his 3.55 gear sets. The 3.38 gear sets are for later vehicles that were born with more hp. Back in the 50's and 60's I drove GMCs 70 all day long. I grew up with the noise. If you put a tach on the engine, you will be surprised at how fast they go before you reached the advertised hp rpm.