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T-5 AND 6 volts!

By Robert French

    Thanks to Jack Halton for sending Robert to us from the Inliners' site (What would we do without those guys??) with this excellent tip to go with Grant's T-5 conversion article.

        You are sick and tired of hearing the ole Babbitt Pounder scream, so you converted to a 5-speed transmission -- a T-5, no less. The only problem is, you love the old foot starter (or the 6-volt system in its entirety) but it won't mesh with the later flywheel used with the later clutches, etc. So what can you do to...

Keep the foot starter with the T-5 Transmission?

Sure! Just update your clutch!

        I was glad to see the addition of the T-5 section to our website. Some time back I saw Grant Galbraith’s article on the T-5 conversion for A-D pickups at Stovebolt.com. I had already done a 3.55.1 ring and pinion conversion in the original rear-end of my ’50 Chevy ½ ton before tearing the truck down for a total rebuild. This beat the heck out of the stock 4.11 gears, but I was still turning 3000 rpm at 70 mph – too much for an old 235/261 six.

        After weighing the options I decided a T-5 and an open drive rear-end was the way to go. I set about acquiring one from an S-10 (Camaro/F-Body boxes are expensive and hard to come by in these parts). In Grant’s article he said he used a small block flywheel and pressure plate along with an 11” disc from an ’85 Astro Van. Here’s where I ran into a problem… First of all, I like my 6 volt floor pedal starter!

        In order to keep it, I’ve had to stay with a ’53 or earlier flywheel and ring gear combo. Later model (’54 or’55) ring gears have the wrong number of teeth to mesh with the old 6 volt starter; nor can one swap a drive gear from a later starter, it won’t fit. An Astro Van disc won’t work with the early 6 cylinder flywheel. (Also note that the spline pattern on an S-10 T-5 input shaft is not nearly as long as the earlier 10 spline pattern.) The hub protrudes too far out on the back (transmission side) to allow the transmission to bolt up to the bell housing.

        I tried two different Astro Van discs. I lacked ¼ and 3/8” of going all the way to the bell housing. I won’t go into the story of how I screwed up one of the Astro Van discs, trying to make it work!

        Now, for a little background: v 47-53 ½ tons with 3 speeds and cars came originally equipped with a 9” clutch. v 47-53 ½ tons with 4 speeds and ¾ ton and larger trucks came with a 10 ¾” clutch. Earlier I’d decided I wanted a bigger clutch so I found the correct ‘47–‘53 flywheel for the 10 ¾” clutch in a salvage yard. I had it lightened somewhat and balanced with the crank in my 261 along with the 10 ¾” pressure plate I’d acquired from Crow-Burlingame. With the time and money invested in this flywheel I wanted to keep it if I could.

        After ruining one of the Astro Van discs I started searching the internet to see what I could find out about clutch discs with the correct hub for the 14 spline 1” input shaft on the S-10 T-5. I already knew that an 11” disc would fit in my 10 ¾” pressure plate. But alas, the only 11” disc with 14 spline by 1” hub listed anywhere was for the aforementioned Astro Van.

        Then, I was saved by my dad, the pack-rat, and his humongous collection of parts, interchange, how-to and repair manuals. We found an old clutch parts book from the early ‘80’s (with pictures no less!). I’d already found an early usage of the T-5 was in the late seventies (76-77) Chevy Vega. Sure enough, there was a picture of a Vega Disc. The hub protruded way out in the front (flywheel side) and none at all in the back. It had 3 rivets and 6 slotted holes for springs; although, only 4 were used. The hub appeared to be made the same way as in my original 9” and 10 ¾” discs. The only difference being the 14 spline 1” hole as opposed to the original 10 spline. It also appeared it would fit in some of the larger 11” GM discs pictured in the book (Vega discs were 8 and 9 1/8” and the 9 1/8” is currently available – new or reman.)

        Meanwhile, after finding their website I contacted the good folks at “Best-Bilt Parts” in Springfield, MO. Among other things, they remanufacture clutches. They also advertise “custom clutches”. I talked with Scott, their clutch man, and told him about my problem and the possible solution I’d found in the old parts book. He put me on hold for a short time and came back saying he found an old Vega disc and that the picture I’d seen in the book was accurate: 3 rivets, 6 slotted holes for springs, and yes! The hub would fit in a larger 11” disc. This 3 rivet 6 slot pattern was common to GM for years.

        After asking Scott to make one up and ship it to me it arrived via UPS about a week later. The hub was shaped exactly as I’d expected protruding out about 7/8” on the flywheel side and none in back. The OD and ID was right for my pressure plate and flywheel mating surface (approx. 10 15/16” OD and 6 ½” ID on the friction material). I installed the clutch disc and transmission on my 261. The tranny slid all the way to the bell-housing and bolted up snugly. I slid underneath and found I could slide the disc back and forth on the input shaft about 3/16 of an inch. Eureka! I’d found my solution.

        Scott, from Best-Bilt Parts, told me that these Vega hubs were still available to them new. The custom disc only cost me a little more than a new remanufactured disc. This seems the perfect solution for someone not wanting to use a small block flywheel and pressure plate or the more expensive F-Body style T-5. A 9 1/8” Vega disc is still available new or reman.

        It would probably work as is with 9” pressure plate and flywheel for a 47 – 53 AD truck or early fifties car. If the OD is too large a clutch remanufacturer or machine shop could grind it down. I hope this information can save someone else a lot of time and trouble.

Thanks a lot,
Robert French

Source: Best-Bilt Parts
2527 East Kearney Street
Springfield, MO 65803
(417) 869-0703


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