Speedometer packed up

Discuss mechanical problems here.

Moderator: Moderators

will.broad
Minor Friendly
Posts: 32
Joined: Sun Oct 15, 2017 3:40 pm
MMOC Member: No

Speedometer packed up

Postby will.broad » Wed Dec 05, 2018 3:48 pm

I was driving home today and the speedo stopped working. I got the speedo out and the inner cable is ok. I put a screwdriver in the square slot on the speedo and the speedo is solid. Is there any way of oiling the speedo? I managed to turn the square slot a few times with the screwdriver but its still stiff.

I rocked the car back and forth and i can see the inner cable turning but I will replace the cable anyway.

Just wondered if there is any way of freeing up a stuck speedo?

Cheers

will.broad
Minor Friendly
Posts: 32
Joined: Sun Oct 15, 2017 3:40 pm
MMOC Member: No

Re: Speedometer packed up

Postby will.broad » Wed Dec 05, 2018 7:33 pm

Also my speedo is 10mph out. What is the correct speedo. There seems to be different ones.
I have a 1098 engine. Not sure what ratio the speedometer should be.

Online
Sleeper
Minor Fan
Posts: 259
Joined: Tue Nov 08, 2016 3:18 pm
MMOC Member: No

Re: Speedometer packed up

Postby Sleeper » Wed Dec 05, 2018 7:48 pm


Online
Sleeper
Minor Fan
Posts: 259
Joined: Tue Nov 08, 2016 3:18 pm
MMOC Member: No

Re: Speedometer packed up

Postby Sleeper » Wed Dec 05, 2018 7:49 pm

Will
Plenty of WD40 in the drive ( leave it face down overnight ).

John :wink:

charlie_morris_minor
Minor Legend
Posts: 1985
Joined: Wed May 10, 2006 1:47 pm
MMOC Member: No

Re: Speedometer packed up

Postby charlie_morris_minor » Wed Dec 05, 2018 9:09 pm

if you pm me your email address i can let you have a pdf document on stripping down a speedo

oliver90owner
Minor Addict
Posts: 580
Joined: Thu May 12, 2016 6:33 am
MMOC Member: No

Re: Speedometer packed up

Postby oliver90owner » Thu Dec 06, 2018 6:20 am

If your speedo is always 10mph out, it will not be the ratio. Think about it.

simmitc
Moderator
Moderator
Posts: 3332
Joined: Thu Apr 15, 2004 9:43 am
MMOC Member: Yes

Re: Speedometer packed up

Postby simmitc » Thu Dec 06, 2018 9:17 am

Speedo out by 10 mph? Measured against what? Does it indicate 10 mph when the car is stationery? Does it sit at zero and only start to register 1 mph any speed after you have reached 11 mph? If you drive for a known measured distance, what does your odometer read - correct / under / over, and if out, by how much over what distance? Has the car been modified in any way - engine, gearbox, back axle, wheels, tyres? All info will assist with diagnosis.

You are correct that there are different models of speedo depending on the car. A 1098 speedo should be marked 1408 just below the right hand end of the odometer. Of course, that's no guarantee that it hasn't been modified, but it's a good starting point.

will.broad
Minor Friendly
Posts: 32
Joined: Sun Oct 15, 2017 3:40 pm
MMOC Member: No

Re: Speedometer packed up

Postby will.broad » Thu Dec 06, 2018 5:12 pm

I have just looked at the speedo it has 1378 or 1376 on it. I have a bog standard 1964 saloon 1098 engine unmodified but I think the speedometer may have been changed in its lifetime.
would that make it out by 10 mph.? I was doing 60 mph and looked at my satnav and it was showing 50 mph, about 36 is 30 on satnav.

Its a 90mph speed. needle sits at 0 when stationary.

cheers

Declan_Burns
Minor Legend
Posts: 1654
Joined: Wed Apr 18, 2007 7:32 am
MMOC Member: No

Re: Speedometer packed up

Postby Declan_Burns » Thu Dec 06, 2018 6:02 pm

My car is also 1964 with a 1098cc engine but has 1408 tpm speedo. I am running a 3.9 diff and the speedo is very accurate since I changed from the 4.22.
Regards
Declan
Attachments
speedo_tpm.jpg
speedo_tpm.jpg (292.56 KiB) Viewed 147 times
speedo_tpm2.jpg
speedo_tpm2.jpg (88.08 KiB) Viewed 147 times


Regards
Declan

Online
Sleeper
Minor Fan
Posts: 259
Joined: Tue Nov 08, 2016 3:18 pm
MMOC Member: No

Re: Speedometer packed up

Postby Sleeper » Thu Dec 06, 2018 8:18 pm

My first guess from your figures is you need something like a 1653 tpm Speedo, but I think you need to do a measured mile ( or 10 ) and check the mileage....the speed reading can be sorted afterwards..

John

simmitc
Moderator
Moderator
Posts: 3332
Joined: Thu Apr 15, 2004 9:43 am
MMOC Member: Yes

Re: Speedometer packed up

Postby simmitc » Thu Dec 06, 2018 9:59 pm

I was doing 60 mph and looked at my satnav and it was showing 50 mph, about 36 is 30 on satnav.
So it's not out by 10 mph across the range, it's reading over by a percentage. 60/50=1.2 36/30=1.2 fairly constant. I suspect that it is the speedo calibration that is wrong, but someone may have fitted a different diff as well.

The only strange thing is that the TPM you have quoted is not 20% different from the correct value; and the above post may well be the best bet. However, you can pick up the correct standard speedo quite cheaply from autojumble or Club Spares, so the simplest thing to do is to swap for a another and see what happens. Remember that a Minor speedo is never going to be as stable or accurate as a modern unit.

Declan_Burns
Minor Legend
Posts: 1654
Joined: Wed Apr 18, 2007 7:32 am
MMOC Member: No

Re: Speedometer packed up

Postby Declan_Burns » Fri Dec 07, 2018 9:00 am

You can always fit one of my custom built speedo head correction gearboxes.
Not the cheapest solution to your problem! They have the same M12x1mm thread as the Moggy speedo.
Regards
Declan
Attachments
Corrector_gearbox_1_1_2.jpg
Corrector_gearbox_1_1_2.jpg (32.18 KiB) Viewed 86 times
Corrector_gearbox_2.jpg
Corrector_gearbox_2.jpg (258.9 KiB) Viewed 86 times
Corrector_gearbox_1_1_5.JPG
Corrector_gearbox_1_1_5.JPG (59.51 KiB) Viewed 86 times


Regards
Declan

will.broad
Minor Friendly
Posts: 32
Joined: Sun Oct 15, 2017 3:40 pm
MMOC Member: No

Re: Speedometer packed up

Postby will.broad » Fri Dec 07, 2018 2:14 pm

Thanks for the replies, I have taken off my speedo cable and for some reason it is 3 inches longer than standard, I know it wont make any difference to the ratio but at least I have a working speedo now. It was strange that the inner cable never broke when the speedo locked up but I have just gone for a drive and the needle is steady now.

liammonty
Minor Addict
Posts: 848
Joined: Mon Apr 23, 2007 2:32 pm
MMOC Member: No

Re: Speedometer packed up

Postby liammonty » Fri Dec 07, 2018 2:39 pm

I think you're experiencing what most Minor owners do, although many don't notice it. Of my 6 or so Minors I've owned over the years, all had speedos that over-read by around 10-20%, despite them all being fitted with the correct ones. People won't necessarily know their speedo over-reads though, unless they've checked their speed against GPS. There are a couple of reasons, I think, that cause this.

1. The speedos were set up for cars with the original spec crossply tyres, which have a higher profile, and therefore greater rolling radius than today's radials (meaning the car travels a little less for each revolution of the wheel on today's tyres, so at a given engine speed, the car travels slightly less distance, meaning a false high speedo reading)

2. Springs in the speedo mechanism can weaken over time, meaning the speedo is prone to read a little faster as the years go by (this won't affect the odometer though).

I totally agree with Declan's point that fitting a (non-standard) 3.9:1 diff to a standard 1098, in place of the 4.22:1 diff makes for a more accurate speedo - that was certainly the case in my Traveller.

So the point is, you're experiencing what most of us do with your speedo over-reading :-) You can fix it as outlined, or leave as is and pretend that your car is faster than it really is!!!
Last edited by liammonty on Fri Dec 07, 2018 2:47 pm, edited 1 time in total.

will.broad
Minor Friendly
Posts: 32
Joined: Sun Oct 15, 2017 3:40 pm
MMOC Member: No

Re: Speedometer packed up

Postby will.broad » Fri Dec 07, 2018 2:46 pm

I will keep it as it is, as least I won't get a speeding ticket as I always keep to the limit, although I get a lot of plebs tail gating me.

Myrtles Man
Minor Fan
Posts: 161
Joined: Wed May 16, 2018 10:49 pm
MMOC Member: Yes

Re: Speedometer packed up

Postby Myrtles Man » Fri Dec 07, 2018 5:06 pm

Traditionally, all car speedo's used to over-read by up to 10% as it was (probably still is) illegal for motor manufacturers to sell vehicles with speedo's that under-read and, with the technology in use at the time, no manufacturer could guarantee totally accurate readings. An under-reading speedo will, of course, lead to speed-limit violation whereas one which under-reads will tend to keep the driver within the limits.


Who is online

Users browsing this forum: Sleeper and 19 guests