Chapter 20: Three point three eight to one
18 December 2000 The turn of finances and time finally yielded a positive move: I finally ordered a new ring and pinion. This eventuality was something I have been contemplating from the time I read my first classic truck parts catalog.
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| The differential, after I removed the bolts. | The third member removed, in it's original state. |
The gearing ratios of the Task Force line of Chevy and GMC trucks is rooted in the pastoral antiquity of America. The Federal Highway Act of 1956 was the first step to creating the Interstate Highway System. Before then, the country was crisscrossed with a loose network of US and state highways of varying quality. Cars and trucks simply didn't have the opportunity to go all that fast.
The rationale for the low gearing of pre-1960 trucks was also based in the role these vehicles were designed for. A 7.06:1 first gear combined with a 3.90:1 differential equals a ridiculous amount of torque, for takeoff with a full load on a questionably paved or unpaved surface. Pickups were for field work, not commuting; vans were for intra-city and local delivery, not for converting into campers and make-out machines. Of course for that extra bit of velocity you could get an optional overdrive system, but these were uncommon (and damned rare nowadays).
Needless to say, the times changed. The speed limit on the new Interstates was set at 70 MPH. The mid-60s trucks were reconfigured for higher gear ratios.
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| The original 3.90 pinion gear. Note the traces of the assembler's markings in faint blue and the "56." It's original, all right... | The shop where the diff was set up. Wish I could remember the name! |
For all of it's sleek styling, Ferrari-inspired grille and Frenched headlights the Task Force Chevy truck with a stock 3.90:1 diff is a slow ride, maxing out about 55 MPH. Nobody goes 55. Nobody went 55 even back when it was the national speed limit. On today's freeways the Beast was a hopeless pokey antique, probably a slow-moving hazard. I'm sure on a genuine stretch of Interstate I'd have needed a big red triangular reflector bolted to the back.
(Interesting sidebar: I have found that different regions tend to different freeway cruising speeds. The fastest general speeds I've ever seen are in the San Gabriel Valley East of Los Angeles, where the middle lanes move at 85. Up here in the Bay Area the average speed tends to be 65-75, with a vast majority of commuters setting their cruise controls at 68. Through Santa Cruz, California Highway 1 is posted at 65 but everybody tends to go 55. They're that mellow.)
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| The new Yukon/US Gear 3.38:1 ring and pinion set. |
The best fix for someone who intends to keep a stock appearance is to go with a lower ratio differential. Several companies offer 3.38:1 ring-and-pinion sets which offer a 15% speed boost. I went with one I found serendipitously on the net via a Yahoo search offered by Randy's Ring and Pinion in Everett, Washington. They offer the best quality parts at the absolutely lowest prices. I'm totally serious. Their ring-and-pinion and installation kit combo is priced lower than everyone else is charging for just the gears. They have the gears made custom for them by U.S. Gear: If you want to see how thay're made, there's a cool on-line plant tour.
The hardware arrived 2 days after I ordered it, and the following Monday I started the process of getting the gears swapped. During the weekend I did the research into getting the swap done. It was really a decision between doing it all myself versus yanking out the third member (the assembly containing the differential gears, also called the differential carrier) and having someone else set up the gears. If I did it all myself, I would need in addition to the regular tools special adjusting wrenches, a magnetic dial micrometer, and a really huge torque wrench to get the companion flange bolt tight. Never mind.
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| The installed gear set. Note the yellow marking compound on the ring gear teeth. |
Suddenly I remembered the last time I went to the Good Guys car show I got a flyer from a company in Hayward that specialized in diff gearing. A short phone call cinched it: they would set up the diff carrier and swap the gears for only $200. Sold.
Monday night I crawled under the truck and unbolted the inspection plate. a small amount of (probably original) black gear oil oozed out of the case. I undid the rear axles pulled them out of their housings. Switching to the other side of the case, I unbolted the carrier and dropped it out of the truck. Damn heavy and covered in 44-year old gunk, the gears were nonetheless in great shape.
The next day I dropped the third member off for re-gearing and replaced the U-joints on the driveshaft. Wednesday I finally put it all back together. It was touch-and-go replacing the third member into the Beast: I almost tore the gasket doing it. But it did go together very well.
I let the gaskets dry overnight, refilled the diff with fresh oil, and drove it around a bit. WOW! The very character of the Beast changed. The shift speeds are different, the first gear takeoff is actually useful, and the freeway cruising speed is.. Well... still not quite late-model, but sufficient. It's still slow, but no longer dangerously so. The Beast still hugs the right lane, but the other traffic no longer monolithically passes it, and there is occasionally slower traffic that must be passed. And all this improvement for less than $500.
All that's needed are taller tires. The extra diameter would increase the effective differential-to-ground ratio. To that end...
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| David Miller, son of David Miller's Dad, from a recent appearance on Craig Kilborn's show, where they played "Christmas In Jail." A sample lyric: "Ain't gonna drink and drive no more." They're set to play at the inaugural festivities of George W. Bush. Coincidence? |
27 December 2000 David Miller has yet again reached out from Austin to San Francisco and did his usual amazing thing. To wit:
Hi Skot, I just found a set of four [16" Stock GM truck] wheels and the guy is giving them away for free. He's in so. Cal. so I'm having my dad pick them up. If they're correct, I'll save them for you until I get out your way again. Keep on Truckin!.......David M.
The Near-Mystical Unspoken Brotherhood of Ol' Truck Owners strikes again!
I arranged a long-overdue out-of-town trip to Los Angeles between Christmas and New Years, visited friends, ate well (The Gaucho Grill is just incredible!), and generally enjoyed the unseasonably warm weather. I love LA!
Anyway, I arranged to meet up with David Miller's Dad* at his home in Orange County. A very pleasant fellow, he greeted Eileen and I warmly and showed us the wheel rims he got for me. What a great guy! Particularly since he drove all the way to Rialto to get them. Rialto is just West of San Bernardino, about a 2-hour round-trip from his Orange County home. Whatta guy. Let this be a great public expression of deep gratitude to David Miller's Dad for all his efforts on the Beast's behalf.
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| From left to right: David Miller's Dad; a picture of David Miller's Dad's Grandkid on the hat; and me. | A 16" GM truck wheel. |
Such fine wheels they are! Original 1950s vintage, very little corrosion, they have all the features I've been scouring the Bay Area for: 16" diameter, six bolt holes, stock 4" width, and those hubcap clips around the inside of the center flange. They're going to a great addition to the Beast's stock rebuild.
We hung out for a bit in front of David Miller's Dad's place, shooting the
breeze and generally got to know each other. After a while I profusely thanked
David Miller's Dad for all his efforts and pressed on to San Juan Capistrano.
Nice place. He gave us a bit of parting advice-- visit Dana Point while we
were down there. So we did, and and were treated to a transcendently beautiful
sunset over the Pacific. Thanks again, David Miller's Dad.
*David Miller's Dad's name has been obscured to protect his
privacy. Oh, all right. His name is Bill and he lives in Hawaiian Gardens.
Or not...
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| A really nice 1955 Suburban from the last Good Guys car show Let it not be said I don't appreciate a good flame job. |
1 January 2001 On this day, the first of the Third Millennium (for real this time) I spent a good portion of the day in Aptos, California, under the Beast, covered in brake fluid, rebuilding the master brake cylinder. Here's how I wound up under there:
I spent Christmas in Santa Cruz with my family. It so happens my sister was moving that week, and needed to use the Beast for furniture hauling. To that end, I drove it down to SC. As advertised the 3.38:1 diff gears enhanced the driving experience: more speed, less noise, better mileage. I gave Karen a few quick pointers about the new shifting speeds and how you have to use Granny low to take off with loads and uphill, then moved on to LA.
The day before we returned to SC, Karen calls me and nonchalantly informs me that the Beast is broken. "Yeah, sometimes the brake pedal goes all the way to the floor, I ain't driving it." Great. It's probably just air in the lines, but still, woo-hoo.
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| The brand-new dual master cylinder assembly, waiting for it's moment of glory. |
It takes a few days to get everything ready to fix it, but that's what lead to New Year's Day under the Beast. I already had a master cylinder rebuild kit: I just yanked the rusty unit out, honed the cylinder, and replaced the worn components (it REALLY needed it, too). I bled the brake lines and it really did the trick. Very tight, responsive braking. Unfortunately, the brake pedal height is different now, which meant the brake lights don't switch right, which was another pain in the ass to fix, but with Garry Owen Gunsett's help the next weekend it was 100% road-ready.
The cruel irony: I have a brand-new dual master cylinder kit I purchased from Brother's a few weeks before. It's still waiting for installation, because it's going to take some custom brake-line bending to adapt it into the Beast. Fortunately, the rebuilt cylinder feels pretty strong right now so I think I can take my time for this next move.