Wobbly speedo and tachometer.

[WarrenL]

Hi all,

Yesterday Brown Rover GF148 was finally WOFed and registered, after 2 years of trials, tribulations and mishaps. A triumph! More to be detailed elsewhere. Relevant to this section however, the maiden voyage reminded me of an old bugbear - the rather wobbly speedo and tachometer. The situation is bearable at round-town speeds, but blasting down the highway at high speed the speedo and tachometer can best be described as rough guides to what the car is actually doing. I mean, I think I was travelling at 70mph, but that is based on an appraisal of the needle's approximate centre of swing.

Because both instruments suffer the same problem, I'm veering away from the idea of, for example, a dodgy speedo cable. I recall seeing other P6s suffering the same thing, but surely even in 1972 the existing technology allowed for steady needles?

I apologise in advance if this is covered in a thread elsewhere: I searched but didn't turn anything up. Please point me there if so.

 

[chrisyork]

I'm afraid that's two seperate problems, Warren.

The speedo is actually the easiest to fix. The cause is going to be one of three components: right angle drive at the gearbox end, right angle drive at the speedo end or the speedo cable itself - or all three! Now that you have the WOF, why not start by pulling the instrument pack forward and detatching the speedo end right angle drive. See if it will submit to dismantling (they are rivetted together sometimes) and if it will, wash it out with petrol and regrease with a reasonably light graphite grease. While that is going on, form a funnel over the end of the speedo cable with some insulating tape and leave it for a few days with 3 in 1 oil or similar soaking down into the cable. Then reassembly is the reverse of dismantling! If the result is already satisfactory you can dap out of doing the same strip and regrease to the gearbox end right angle drive. If not then get scrambling under the car!

I'm afraid I'm a bit at a loss over the wavering rev counter. A good start might be to simply push it home nice and firmly into the printed circuit board - they have been known to work loose. Beyond that there's a careful bit of detail work cleaning up all the contacts in the rev counter circuits. And make sure the voltage regulator in the instrument pack is OK - the quick check is to be sure that temperature and fuel gauges are consistent.

Hope that helps

Chris

 

[WarrenL]

Two separate problems? I was never going to be so lucky!

The dash pad is coming out some time soon for recovering (when my Rover fund has recovered from the latest fork-out for tune-up/idler/WOF/rego) so that'd be the time to do the instrument pack end of things, Chris. I can meanwhile confirm that the temperature and oil gauges are working beautifully, so the voltage regulator is probably OK. Also, I had the instrument pack serviced by a local specialist firm (Parrotts) about 10 years ago and the car has done bugger all mileage since then. I'd like to think that all those bits are fine, but I will be checking based on your advice.

 

[ghce]

Warren, I wouldn't wait it really is a dodle to get the right angle out and the speedo cable relubed in situ, whole operation can be accomplished in 1/2 an hour. I have had mine out and done several times in my ownership of my p6 for this purpose.
Same for the rpm counter, the whole instrument cluster is very easy to detach and remove for more advanced dissasembly, you dont need remove the dash top at all.

Graeme

 

[WarrenL]

I anticipated you, Graeme. I pulled the instrument panel back this afternoon and lubed the speedo cable by withdrawing the whole inner cable, liberally dosing the sheath full of some Teflon cable lubricant I had in a drawer and then sliding the cable in and out until it was well goobered up. Slid it back into place and then twisted it back and forth until you could hear it engage with the gearbox end. Quite easy, really. I also lubed up the right angle drive and applied some copper grease to the tacho terminals. Didn't get a chance to go for a drive so a report on the results will have to wait.

 

[SydneyRoverP6B]

Hi Warren,

My Rover also suffered from a wobbly Speedo needle, but unfortunately lubricating the existing cable which incidently was the 1974 original, did nothing to solve the problem
Not so long ago I removed the original casing with cable and fitted a new one complete in its place. I lubricated the cable with Castrol EPL-2 for it's high temperature resistant properties, although as Chris mentioned, Graphite grease would have been equally suitable. The upshot of all this was a totally wobble free needle, rock solid, I was very pleased.

Must say that I am not fast like Graeme, took me a couple of hours to do mine from start to finish.

I wrote up about it with lots of photos included on this page....viewtopic.php?f=21&t=9726&start=180

The wandering tacho could be down to the instrument itself requiring a service, which an instrument repair business would (should) be able to resolve.

Ron.

 

[darth sidious]

And make sure the voltage regulator in the instrument pack is OK - the quick check is to be sure that temperature and fuel gauges are consistent.

Chris

Does the tacho actually get fed from the instrument panel regulator? This may not apply to NZ-built P6's, but don't 1972 UK-built P6's have the tacho wired between the ignition switch and the coil + supply? (i.e. the tacho gets it's 12V feed from a (white, I think) wire terminated in a spade, then that spade also has a 'pigtailed' wire terminating in female bullet connector, which mates with the male bullet connector on the tacho)

 

[ghce]

And make sure the voltage regulator in the instrument pack is OK - the quick check is to be sure that temperature and fuel gauges are consistent.

Chris

Does the tacho actually get fed from the instrument panel regulator? This may not apply to NZ-built P6's, but don't 1972 UK-built P6's have the tacho wired between the ignition switch and the coil + supply? (i.e. the tacho gets it's 12V feed from a (white, I think) wire terminated in a spade, then that spade also has a 'pigtailed' wire terminating in female bullet connector, which mates with the male bullet connector on the tacho)

I have found when it comes to RV8 Tachos that the phrase " beyond 'ere be Dragons" as my stock Oct 1974 P6B does not conform to any official supplied wiring diagrams regardless of suffix or late or early cars, luckily the tacho is relatively easy to sort being usually just bad joints or dodgy connectors and I am sure diving into the electronics should it be necessary would be no obstacle to you Warren.

Graeme

 

[WarrenL]

...the tacho gets it's 12V feed from a (white, I think) wire terminated in a spade, then that spade also has a 'pigtailed' wire terminating in female bullet connector, which mates with the male bullet connector on the tacho...

That's the way it goes on my instrument panel. Still haven't driven the car to see if it's made a difference. Work's getting in the way, although I can still drop in on the forum when the boss isn't looking. :wink:

Incidentally, some of the black paint is starting to wear off in places on the instrument panel cover, exposing the green plastic behind. I might take it apart again soon for a refurbish using the proper matte black paint you can buy for plastic.

 

[darth sidious]

I have found when it comes to RV8 Tachos that the phrase " beyond 'ere be Dragons" as my stock Oct 1974 P6B does not conform to any official supplied wiring diagrams regardless of suffix or late or early cars, luckily the tacho is relatively easy to sort being usually just bad joints or dodgy connectors and I am sure diving into the electronics should it be necessary would be no obstacle to you Warren.

Graeme

LMAO! I think P6's have more wiring variation than Imelda Marcos has in shoes!

I was just thinking the "regulator being faulty" suggestion was a bum steer

 

[WarrenL]

I went out for a drive tonight and I'm pleased to report that the wobbly speedo is not so wobbly now. In fact, at 60mph it had the merest suggestion of a waver. All it took was time and Teflon. The rev counter is still dancing a bit, but that's another problem for another day. Out of interest, what engine speed should I be pulling at 60mph?