Overdrive for R-130


IHC in the early to mid-fifties.

Rookie
Rookie

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Joined: Thu Oct 08, 2015 3:08 pm

Location: West Virginia

Post Fri Aug 03, 2018 5:08 pm

Overdrive for R-130

I have a 5-speed trans from a L-160 in my R-130. Lo is all the way to the right and down, reverse is right and up, rest of pattern is simple "H" with 1st at upper left.

I was told that this transmission also came with an overdrive.Seems like it would be on the shaft that now has "Lo" and reverse. Would it be practical to convert this trans to the OD config? Parts rearrangement or new parts required?

My other option to go faster with less engine revs would be to repair the original 4 spd which spat out its rear bearing, and add an auxiliary ( I have one, not too big, with under, direct, and over.)

Suggestions appreciated.

Golden Jubilee
Golden Jubilee

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Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Sat Aug 04, 2018 7:54 am

Re: Overdrive for R-130

No, O/D 5 speeds are done by raising all ratio's and thus making the gear below direct into a O/D gear and the shift pattern is reversed on the last two gears, direct is where it is now and top gear is against the dash.
O/D 5 speeds were mated to lower (slower) rears, the idea was to reduce driveline torque and make U joints and driveline last longer.
Aux is a better way to get more speed (gives more flexibility).
On any ratio change be it trans, rear or tire size, do the math, both on what you have now and what you are planning, to be sure you end up where you want to. Seat of the pants engineering often disappoints.

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Posts: 24

Joined: Thu Oct 08, 2015 3:08 pm

Location: West Virginia

Post Sat Aug 04, 2018 4:27 pm

Re: Overdrive for R-130

Thanks, Cornbinder. You're the first I have heard confirm my reasoning that the purpose of OD gears is to reduce stress on driveshaft in low gear. Otherwise one would just use higher final drive ratio and lower gearing in transmission

Golden Jubilee
Golden Jubilee

Posts: 5170

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Sat Aug 04, 2018 7:06 pm

Re: Overdrive for R-130

Yeah, with cars, it isn't a big deal, but with heavy loaded trucks it is. Real heavy trucks use planetary reduction in the hubs combined with high speed diff's.
'Back in the day" they didn't have the big U joints and driveshafts we have today, so they used Aux trans and O/D main trans to get the ratio spread needed. The problem is that it generates a lot of heat, gearing up and back down. Lots of friction losses, but they didn't have a lot of choice. It was one reason 2 and 3 spd rears were more popular back then.

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