Tag: gearbox

Rowing your own: Five things to know about manual transmissions – David Conwill @Hemmings

Rowing your own: Five things to know about manual transmissions – David Conwill @Hemmings

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Manual transmissions are an icon of the automobile hobby. The ability to operate a car with three pedals sets an individual apart from the mass of drivers who just see cars as point-a-to-point-b transportation. “Driving a stick” lends a certain air of mystery and adventure to a car owner.

Still, how many devotees of the clutch pedal can tell fact from fiction when it comes to the innards of their beloved gearbox? Most of us don’t know a lot more than the number of forward speeds and how many of them are synchronized. It doesn’t need to be that way. The selection, installation, and maintenance of what was once called the standard-shift transmission can be quite straightforward.

From a three-on-the-tree to the seven-speed in a C7 Corvette, all manual transmissions have certain points of commonality. The muscle-car four-speeds of the ’60s and ’70s are likely the most familiar to Hemmings readers, but five-speeds like the Borg-Warner T-5 have been with us nearly 40 years. Even the beloved T-56 six-speed came on the scene in 1992, with the Dodge Viper. That’s a lot of accumulated knowledge. To get the latest information for gearjammers, we consulted with TREMEC dealer Silver Sport Transmissions. Below are five things to consider when contemplating a manual transmission in your ride.

1. Overdrive in Moderation

Historically, a transmission’s top gear transmitted power from the engine in a 1:1 ratio (“direct drive”) where one turn of the engine causes one turn of the driveshaft. Starting in the Seventies and Eighties, however, manual transmissions adopted overdriven top gears, meaning the engine can be turning slower than the driveshaft. When selecting an overdrive ratio, keep in mind that the lower the number, the more overdrive. On a TXK five-speed trans (shown above), the buyer has a choice of 0.81:1, 0.72:1, and 0.68:1, which offer 19-, 28-, and 32-percent overdrive, respectively. Beware of falling into the “more is better” trap, however. As with camshafts and carburetors, too much overdrive will work to your disadvantage. Unless you have an engine built for it, matched to the proper rear-end ratio, you may find yourself lugging the engine in overdrive

2. Keep things in Sync

Steel and brass synchronizers work fine, but for the ultimate in durability or longevity, consider upgrading to carbon

Synchronizer rings and cones smooth the transition from one gear to another, so that you only have to press in the clutch once per shift. They may date back to the 1930s, but they’re not limited to the technology of that era. While traditional brass construction still persists for most applications, Silver Sport’s experts note that they wear faster than some options now available. Worn synchros lose their grip and exhibit crunching where crisp shifts used to be the norm. “If you plan on high-rpm shifts or if you’d like to extend the life of your transmission before it needs a rebuild, carbon-lined synchronizers are the way to go,” said Silver Sport’s Misty McComas. Carbon linings come in both partial and full varieties. With partial (shown above), only the blocker ring or cone is lined, but with full, the whole synchronizer is lined. The latter is recommended for situations where more grip is desired. Even if you’re not power shifting, a harder-wearing consumable means more fun time versus maintenance.

Read on

Model B Engine & Gearbox Swap – Evaluate the Gearbox

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As the gearbox will be needed for the swap, it needs to be evaluated and work out what’s missing and what may need to be replaced

One of the key points will be properly identify the gearbox case, gearset, shifter and rear mount.

Here’s an example of some of the differences in the shifter housing from Van Pelt

Investigations begin!

Gearshift Tower Overhaul on the Model A Sport Coupe – Part 1

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I’ve been meaning to take a look at the gearshift on the Sport Coupe for quite a while as it seem quite loose in neutral and third gear can be be a bit of a crunching affair when engaging unless you are really careful. John Cochran sorted me out a good used gear stick a while back

As you can see the ball on this one is not too worn

On to removing the shift tower in preparation for taking  over to John’s to be overhauled. Overcame a seized top bolt and then removed quite a bit of sludge from the top of the gearbox and the shift tower. As I had to push the car back into the garage I made a cardboard lid to keep the lidless gearbox clean and fitted it after carefully scraping the old gasket off.

The spring on the shift tower is known as the “spring of death” and is very dangerous to work with without a special tool.

You can find a really good article on the overhaul of the tower by Tom Endy here

 

Visit to John’s

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Took a little pre-Christmas visit to my friend John’s and took a look at the progress on his roadster rebuild and the latest parts he has for sale.

The rolling chassis is just about done and the body is underway, next decision is whether to go Patina/Hot Rod or a restoration? Watch this space!

Parts wise there are a good number of engines and gearboxes available both Model A & B

Triumph Herald Clutch Release Arm Issue

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I was fitting the new gearbox mounting bushes, and generally getting the box ready to go back when I found that whoever had put the gearbox in last time had done less than a perfect job.

The clutch release arm bushing was all missing, and the arm held in place by half a roll pin…

New parts ordered so more delay..