Mustang MonthlyHow To Tech Qa
Vintage Tech Advice - January 2014
Beyond the Basics
I have installed two new speedometers in my 1966 Mustang but I have the same problem with both of them – the needle moves slow or sticks. Sometimes it does not move at all. I replaced the cable and speedometer gear at the transmission, but the problem is still there. Do you have any suggestions about what to check next? I still have the original speedometer but it needs to be rebuilt/restored. Would it be best to have it reworked instead of getting a reproduction? Do you know the name of a good speedo shop?
Via the Internet
Mustang speedometers are quite rugged and usually trouble-free. If you have been having difficulties with replacements, including the new reproductions, then I would consider having the original restored. There are many restoration shops that provide this service, such as D&M Restoration (864/722-0854; www.dandmrestoration.com) in South Carolina. Most shops that specialize in instrument restoration also perform speedometer repair.
I would also try locally as speedometer repair was quite common in the past and some shops still survive today.
Narrow Whitewall Radials
There is no question that today’s wheel and tire combos look great on both modern and vintage Mustangs. It’s just a matter of personal taste. But some of us want to keep our Mustangs with the most possible originality. For that iconic classic look, you can purchase styled steel wheels from any Mustang mail-order store. But the problem for most of us is 195/70R14 or 205/70R14 tires with the standard 1-inch or so narrow white sidewalls. Where can I get those and what brands are available?
El Paso, TX
Unfortunately, 14-inch metric sized radial tires are becoming difficult to find, particularly narrow whitewalls. Some brands that were available only a few years ago, such as Dunlop GTs, are no longer produced. BFGoodrich still makes a few tires but not with the narrow 1-inch whitewalls. I’m afraid you are going to have to use bias ply tires supplied by the reproduction tire companies. The quality is excellent, however I still prefer the handling and ride qualities of a radial tire. I hope the aftermarket will sense the need and begin to reproduce narrow whitewall radials as this new market emerges for them.
(Editor’s note: Two years ago during the restoration of my ’66 Mustang GT, I purchased a set of Firestone FR380 radial tires, 205/70R14. They have the narrow sidewall that resembles the original tires. They appear to still be available today).
I am building a ’66 GT convertible with an A-code 289, automatic transmission, and Paxton supercharger. Where do I connect the line for the modulator at the carburetor? And do I need some sort of check valve?
My next problem is that I have a stock ’66 automatic transmission and a ’67 Fairlane GTA transmission; I cannot tell them apart. I would like to use the later Fairlane transmission.
Via the Internet
The automatic transmission modulator line connects to a vacuum fitting on the back of the intake manifold. The addition of a Paxton supercharger does not require a new source or a check valve. However, you will have to equalize pressure in the fuel pump diaphragm with the addition of a line from the top of the fuel pump to the Paxton blower outlet. Simply drill the area above the fuel pump diaphragm and add a hose fitting. There is a hose nipple on the Paxton outlet for this purpose.
The automatic transmission for the early car should have casting numbers on the case, tailshaft, or valve body that start with C4 or C6 to indicate 1965 through 1966. The Fairlane trans will have C7 for 1967. Oversimplified but quick. Also, the Fairlane may have used a column shift whereas Mustangs were all floor shifts. The bolt-on linkage arm differs on the column and floor shifts but they can be interchanged on your two units. The floor shift arm is short and flat to stay close to the transmission case. The column shift arm is longer and angled to extend away from the case for clearance.
The ’67 GTA valve body eliminated the older ’65-’66 Cruise-O-Matic “green dot” start in Second gear only feature and will allow you to select and hold First gear at will.
Let us hear from you. Send your ’65-’73 Mustang questions to: Beyond Basics, c/o Bob Aliberto, P.O. Box 205, Salt Point, NY 12578. Send email to firstname.lastname@example.org.