ISOA Tech Tips - 1999

Last updated September 27, 1999

Quick Index

• The Tapered Pin? Fix that low clutch pedal!
• When you don't heed the warning! Use this procedure if your bonnet cable has broken, leaving the bonnet "Sealed for Life".
• Kill Switches - They aren't just for race cars anymore! September 27, 1999

The Tapered Pin?

I will start out by stating unequivocally that this pin is not tapered, has never been tapered, and will never be tapered. Now with this ranting out of the way, we can begin. What I'm speaking of is buried deep in the darkest recesses of your Triumph. The item is the dreaded clutch fork pin, referred to as the tapered pin. Although I don't know why.

My first encounter with this device was ten years ago when I first got my TR4. One of the first things that had to be fixed was the hydraulics for the brakes and clutch. Having finished with this job, I couldn't understand why I seemingly had almost but not quite enough travel (hydraulically) to operate the clutch. It had to be adjusted to almost no play instead of the .100" called for in the manual. My problem was a broken pin but this was not known to me at the time. Soon after, I joined the ISOA. I can still remember in hushed conversations on the fringes of the room, me being an observer, a few words, "the tapered pin" and then the knowing smirk, the nodding of heads and the "Yeah, they're always broken". It was, at the time, like some kind of Triumph folklore.

Since then, I have been into four Triumph bellhousings, and found them all to be broken. If your car has not had attention in this area before, then this pin will be broken. The reason the pin breaks is that it doesn't fit very well in the yoke (or fork) and the shaft. The shaft works back and forth to operate the clutch and this eventually shears the pin. (This is shown in the drawing.)
 
Picture #1 shows how to get it apart, drill a hole in the fork from the inside as shown and tap out the broken piece. Now you can remove the fork and shaft. #2 shows how to put it back together. [This photo will be uploaded shortly - WM] Once the shaft is out, put the fork back on the shaft. Position it the same way it was in the bellhousing. Lock it down the best you can with the threaded portion of the broken pin. (Look at the picture & drawing.) Now you drill a 1/4" hole through the center of the fork and shaft at the same time using a drill press. Go all the way through. Get a 1/4" roll pin 3/4" long and press it into the fork and shaft with your vise. Once this is done the fork and shaft are held solidly together with no slop. You now take the fork & shaft back to the drill press and drill through the original hole for the pin with a 3/8" drill. Only go as deep as the factory did originally.

The next step is making the new pin from a 7/16" x 20 allen head cap screw 1-1/2" long. Have this turned in a lathe so that it has only 5/16" of thread left just under the head and the body is 3/8" (.375") in diameter. Also take off 3/32" from the face (length) of the new pin. From the bottom of the head to the end of the pin should measure 1-13/32". Put a good chamfer on the end and drill the head for safety wire. Don't omit the safety wire. The pin should fit so that the end of the pin bottoms out in the clutch fork with the head seating on the boss at the same time. If it doesn't (pin too long) drill the 5/8" hole deeper to achieve this. If the pin is too short, file the boss where the bolt head seats until the pin gets to bottom out like it should. Take your time. A good fit here will ensure that you will never have trouble with this again. The picture and drawing should tell you along with the text everything you need to know. I have made up a few pins. If you need one, you can contact me at a club meeting. One more thing - don't over tighten your new pin. Just snug it down good and safety wire it to the shaft after you have reinstalled it in the bellhousing.

It is my belief that this fix of a new stronger 3/8" pin together with the 3/4" long, 1/4" diameter roll pin to be absolutely bullet proof. Don't under any circumstances put a new standard pin back in. It will only fail again. Think about it. This is the nucleus of your car. Few parts are harder to get at. With that I will sign off.

Your low tech advisor at large, Pat Lobdell
January 27, 1999

Return to Quick Index - Return to ISOA Tech Tip Master Index

When you don't heed the warning!

The warning is plainly stated on page 53 of the Roadster Factory Glove Box Companion: "Be careful to replace frayed bonnet cables, as they cause a fair bit of trouble when they break...".

In addition to having read the above, I also saw the Snic-Braaapp article on an auxiliary hood release cable for the TR6 last year.

When I picked up my new/used TR6 this spring, it came with a new hood release. Like quite a few other members, I am more of a Triumph lover than a repairer. When I picked up my Spitfire ten years ago, I also adopted a mechanic named John Volkert in DeKalb. The teaming has worked well over the years. John works on many varieties of foreign and domestic automobiles and what knowledge that I pick up at club meetings saves me money when John and I have a project.

Over the years, both John and I have aged and the "simple" jobs at Barb City Automotive are given to trainees. What could be difficult about installing a new hood release? We later learned that I had only been given the inside cable by the former owner. The mechanic dutifully threaded the new cable through the remaining chords of an old housing.

While getting the TR6 ready for painting this winter, I noticed a half quart of oil on the workbench. Knowing that this could easily fit in the crankcase, I attempted to pop open the bonnet. You may have heard "awwww s**t" wherever you were sitting that afternoon. Though I have seen several warnings about avoiding the above problem, I have never seen anything in print about what to do when you screw up.

Having just purchased a replacement rear bumper from British Miles, I called them first. I was told that it is sometimes possible to push a long pole through the grill area and reach the release. I was also told that by removing the glove box an access becomes visible. The second approach, but I had a long pole handy. With the pole, we promptly shredded the throttle linkage and did not get the stupid bonnet open. The second method really works well.

Luckily a vintage car owner in Sycamore had a TR6 in his showroom. John and I were able to open the bonnet on that vehicle and take measurements. Having done that, John removed the glove box from my car (not a difficult task). This may not be necessary if you are or have access to a small woman. Two openings in the firewall will then become accessible. The left opening will be the one you want to try. A long bladed screwdriver was then inserted through the opening and pointed up at the bonnet. A push towards the right fender immediately popped the latch.

I would like to say that I am going to install an auxiliary bonnet release, but probably I will just use this method if I break another cable. I also have a feeling that knowing this procedure will probably get me a few beers at Triumph events. Jake Jaquet gets his beer at an upcoming meeting for suggesting British Miles for my bumper.

Tom Thomas
January 27, 1999

Return to Quick Index - Return to ISOA Tech Tip Master Index

Kill Switches
They aren't just for race cars anymore!

Quite a few years ago, Dr. Spuds told me about a friend of his who was (is) a TR6 owner. Spuds' friend had not driven his TR6 for a couple of years, and then had decided to start using it again. One day, the friend was out with the TR6. While the TR6 was parked and shut off and the owner was in a store, the TR6 caught fire.

This story had quite an impact on me. While we joke about the Prince of Darkness and the frequency of electrical component failure, the thought of my TR6 catching fire while unattended was very disturbing to me. Under the worst of circumstances, this could result in the loss of my TR6, and depending on where it was parked, the loss of my garage and my other cars. For those who have an attached garage, it could result in the loss of a home.

I knew from my experience as a corner worker that race cars were required to have a master power disconnect. These master power disconnects, also known as kill switches, are required so that the electrical system of a race car can immediately be shut down in the event of an emergency. I decided to buy and install one of these switches in my TR6, and to shut off the electrical power whenever I parked my car.

My son and I were driving home from the VTR Convention in Portland, Maine on Sunday night, August 1st. It was about 10:30 PM and we were on a back road in western New York State, heading back to the main highway. We had about 120 miles to go to get to our motel. My TR6 was the 4th car in our 4 car ISOA caravan. I drove over a bump, and suddenly my dash lights went out. I could also smell smoke. I pulled over to the shoulder and turned off the headlights and the ignition. The dash lights came back on and the smoke continued! I reached over to my kill switch and turned off the power, and the smoke stopped. Thanks to the resourcefulness of those I was travelling with, I was ultimately able to drive the car home. However, this winter, I will need to replace the entire wiring harness. Maybe someone can tell me why my wires melted but my fuses did not.

While lying awake in my motel thinking about what had happened earlier that night, I was convinced that without the kill switch, I would probably be the owner of the burned out remains of a 74 TR6. This failure had occurred on an unlit side road. Without the kill switch, in the total darkness, I would have had to find my tool bag in the loaded trunk, find a ½" wrench from within the tool bag, open the hood, and disconnect the battery. All of this would have needed to happen while the wiring was burning and melting and maybe igniting. Much of the melted wiring harness runs under carpeting, 25 year old, dried out carpeting. An electrical fire was definitely a possibility. Not a good scene.

Master power disconnects, or kill switches, are not expensive and are readily available. They are easy to install (if I can do it, anyone can). If you're worried about losing a point or 2 in Concours judging because you have one of these, they can easily be hidden with a little thought, and still be accessible to do what you need to do if you ever have to. I hope you never have to.

A couple of additional thoughts:

• The style of switch I use has a removable key. A side benefit of this installation is that it makes an effective yet simple anti-theft device.
• I have carried a fluorescent 12v in the trunk of my car for years. With that in the car, I never felt the need to carry a flashlight. WRONG! I now know that a good flashlight is still a necessity even with the trouble light.

Irv Korey

Return to Quick Index - Return to ISOA Tech Tip Master Index

Don't forget to remove ISOA from any email address or mailto link that you may find on the ISOA web pages.
Copyright © 1999 Illinois Sports Owners Association