Speedometer died

[Litespud]

So I'm out this evening, and I noticed that the speedo is dead. Assuming that the cable has either disengaged at the tranny end, or the cable itself has broken. Loath as I am to disassemble the interior to get at the transmission, how accessible is the tranny end of the cable from underneath the car (A-type overdrive)? I can live without the speedo for the moment, and I'll be putting the car up on stands for some general maintenance in a few weeks, so I'll be able to access the underneath. This might also be the time to address speedo calibration - it currently reads ~15% over (reads 70 mph when my GPS tells me I'm doing ~60 mph). This might be because my final drive appears to be non-standard (I measured ~3.9:1, based on the number of half-shaft rotations I got for each complete rotation of the drive-shaft, with the diff on the bench). Tires are 205/70s. Given the current diff and tires (and no plans to change either), where do I start having the speedo recalibrated? Do I take some measurements in the car first? Thanks in advance.

[oppositelocksmith]

I can do the J OD cable easily from under the car. Cannot say about an A-type. I don't route the cable per stock- I route it to make cable replacement easy.

I've had 3 types of failures over the years:

Cable failure (by far the most common)
Angle drive failure (lost 2 in 28 years)
1 speedometer failed

[Tush]

Yeah, I’d probably have a look at the angle drive first...I know you said A type so you might not have an angle drive installed....

I am running a TR6 trans in my 60 TR3A with an A type with angle drive fitted...the angle drive failed in less than 2000 miles.

Cheers
Tush

[Litespud]

thanks folks - yes, there is an angle drive involved - one more thing to check.

[mdrego]

A while back I had the same two issues. A couple of broken speedo cables, and when it was working, a speedometer that read about 10 mph high at 50 - 60 mph. I solved both issues by going with a GPS driven unit from Classic Auto Innovations (NFI). Here's his website:
https://www.classicautoinnovations.com/classic
I've had the Classic Speed unit installed in my 250 for a couple of years now and it works perfectly, with dead-on accuracy and a nice steady needle. It's quite easy to install - takes just a few minutes - and requires no alterations to your speedometer. It's a bit pricey, but as long as your speedometer is in good shape, you'll never have to worry about broken cables or recalibration if you change tires or driveline ratios.

[Tim_Moore]

Nisonger Instruments http://www.nisonger.com/ can calibrate your speedometer. You need to disconnect the speedo cable and tape something to it so you can count the revolutions, of course this is with the speedometer removed, and push the car 52 feet 9.5 inches (100th of a mile) and count the revolutions. Go to their website and read up on what to send and how. You cannot access the angle drive from beneath the car as I recall. Ive had 4 angle drives fail on me so far. The repros seem to be junk. You should have an access plate on the tunnel that will let you get to the angle drive without having to remove the transmission tunnel though you will have to remove the dash support.

[Elwood]

An easy way to check if it is the cable or the speedo itself is to unscrew the cable from the back of the speedo, then drive a short distance while observing the inner cable. If it is turning, you won't have to go under the car. I have 1 of each type of failure in the last 2 years. Replacing the cable was easy (no angle drive) when that failed, Toyota conversion.

[MARKRL]

My car does not have an angle drive on the end of the cable. Is it a necessary item? Got the car without it. I can access my cable from under the car no problem. (1975)

[lfmTR4]

My car does not have an angle drive on the end of the cable. Is it a necessary item? Got the car without it. I can access my cable from under the car no problem. (1975)

I think just the A-type had them. Mine does.

[MARKRL]

Duh! Just realized this was for an OD set up! Mine does not have OD!

[Litespud]

Resurrecting an old thread - so I decided to investigate the angle drive as a possible root of my dead speedometer, and install an access cover in the side of the transmission tunnel at the same time. Use of such access would still require removing the dash support to move the carpet, but I'm not prepared to cut slices into the carpet in such a visible spot. Anyway - as the pics show, the angle drive vomited out its drive pinion (?). I'm presuming that there once was some sort of metal cover staked in place that retained the pinion. I'll order a new angle drive. While it's possible that all the usual sources get their repro angle drives from the same place, any recommendations or cautions would be welcome. One other thing - the whole assembly was slathered in a fairly runny dark grey grease - filthy stuff. Any idea what this is, and do repros come pre-lubed? If not, what sort of grease should I use here? Thanks in advance.

[MARKRL]

Dave,
I'd check the usual sites and see what prices/vs quality people here have to say. I would use bearing grease on that part myself. Its fast spinning so I think a good bearing grease will go a long way for you. That gray gunk is probably a combo of road crap and ?. We use never seize allot at work and it sure looks like that.
Good luck!
Mark

[dingle]

I have had the crimp on the angle drive body fail to retain the cover and the pinion falls out. I have found that drilling 4 very small holes just above the cover and using safety wire keeps the cover in place.
Berry

[Litespud]

Thanks Berry that's a good suggestion - I enjoy a tinkering opportunity. I was reading some Moss blurb on the importance of a washer to reduce end load on the pinion. From where the washer is installed, it appears that, in its absence, the pinion would push against the end plate, possibly even forcing it out over time. Although the washer is listed as a separate part, Moss considered it to be sufficiently important to start including it as standard with the repro angle drive. I'll look more closely this evening, but I'm pretty sure that my angle drive contained no such washer. This might explain why the angle drive failed.

[Litespud]

On a related note - while I'm in there, and with the current speedo cable literally at a loose end, should I consider replacing the cable? Arguments for: no idea how old or close-to-failure the current one is, and it would be a major PITA if I had to pull out the interior again to replace a cable any time on the foreseeable future. Arguments against: In general, repros are of variable quality, and seldom as good as originals (IMO), so I might end up paying for, and installing, a repro that doesn't last (I have no idea if the current cable is original or repro (given that the car is 47 years old, I doubt if it's original).

[SapphireBlue72]

If you decide to reuse your current cable, or even with a new cable, it may help to lubricate it with a thin grease (like white lithium) before inserting it in the cable housing.