-
Hi Guest!
You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
There are some perks with a member upgrade!**Upgrade Now**
(PS: Subscribers don't see this gawd-aweful banner
Hey - did you know if you click on the title of a thread it will take you to the first unread post since you last visited that thread?
but were afraid to ask: 
STOP!! Never post your email address in open forums. Bots can "harvest" your email! If you must share your email use a Private Message or use the 
smilie in place of the real @
Pretty Please - add it to our Events forum(s) and add to the calendar! >> 
General Tech Speedometer Pointer Bouncing Around
- Thread starter KVH
- Start date
Share this page
dklawson
Yoda
Offline
Try the cable first as your least expensive option.
You would think a brand new cable would be ready to use out of the box. However, there are many accounts of people needing to lube the new cable prior to use. Check yours if you buy a new one.
As Randall said, if the new cable does not address the problem it can be binding in the odometer mechanism (including the worm and pinion gears). It can also sometimes be drag in the needle bearing for the needle's shaft. These problems can be addressed by cleaning. The next question is do you want to clean these yourself or send the gauge away for a professional reconditioning?
You would think a brand new cable would be ready to use out of the box. However, there are many accounts of people needing to lube the new cable prior to use. Check yours if you buy a new one.
As Randall said, if the new cable does not address the problem it can be binding in the odometer mechanism (including the worm and pinion gears). It can also sometimes be drag in the needle bearing for the needle's shaft. These problems can be addressed by cleaning. The next question is do you want to clean these yourself or send the gauge away for a professional reconditioning?
Geo Hahn
Yoda
Offline
I'd give the cable an inspection, clean and light lube.
Lots of opinions on what lube to use - Peter at Nisonger recommended a very light lube with Lubriplate so that is what I am using. Whatever you lube with it is important not to over-do it.
KVH - The local speedo shop can make a new inner cable for your existing housing, probably for much less than a total replacement. But that should only be necessary if inspection reveals damage.
I have a spare speedo head here if you want to hook it up - might give you a clue whether it is a problem with the cable or the unit.
Lots of opinions on what lube to use - Peter at Nisonger recommended a very light lube with Lubriplate so that is what I am using. Whatever you lube with it is important not to over-do it.
KVH - The local speedo shop can make a new inner cable for your existing housing, probably for much less than a total replacement. But that should only be necessary if inspection reveals damage.
I have a spare speedo head here if you want to hook it up - might give you a clue whether it is a problem with the cable or the unit.
2liter4cyl
Senior Member
Offline
If you are Inclined to open the spedo case, I suggest TeriAnn's Triumph page: www.tr3a.info/ Scroll down to articles and find very good help. So much so I printed it all for future use. I found the lube on shafts very dry. In fact the cable broke because of a frozen input shaft. Work on the cable is definently the first step. Le
TR3driver
Great Pumpkin - R.I.P
Offline
There is a slightly updated version of that speedo article at https://www.triumphtech.x10host.com/PDF/speedo.pdf
The author, Tony Rhodes, also has a lot of other good articles posted at https://www.triumphtech.x10host.com/index.html
The author, Tony Rhodes, also has a lot of other good articles posted at https://www.triumphtech.x10host.com/index.html
OP
Offline
Incredibly, I have a fantastic access piece right there. Not sure it's stock, but it's perfect. I'll lube the cable and re-insert and see if that was it. On my last install, I had the cable protruding a bit at the speedo end, and I fear "forced" into the speedo, so I hope nothing got ruined.
Years ago, we were told not to oil the cable but to use graphite lube only. If Nisonger says Lubriplate is ok (I use it for other applications like a dab on the distributor shaft because it doesn't melt and get into where it shouldn't), that would be good enough for me. Many years ago when I restored an MG TD, they actually sent me rubber gaskets for the tach and speedo with no charge. A good oufit.
OP
Offline
I now have a new "shorter" cable and the Speedo checked out fine at the shop. Not to be too negative, but I'm certain my speedometer needle will continue to bounce around as I've posted above. I guess, in retrospect, that I really can't recall it ever being steady. I'll install the new cable tonight if I get the time.
But here's a thought that's been bothering me. When I pressed the annulus back into the new bearings at the rebuild of my transmission overdrive, I distinctly remember forgetting to remove the angle drive and internal speedo gear. The manual clearly says that can damage it. How likely is it that my whole problem is that I've distorted that speedometer drive gear? (true to form, always imagining, sometimes expecting, the worst)
Also, should I be able to remove that gear and inspect it while the transmission is still in the car?
But here's a thought that's been bothering me. When I pressed the annulus back into the new bearings at the rebuild of my transmission overdrive, I distinctly remember forgetting to remove the angle drive and internal speedo gear. The manual clearly says that can damage it. How likely is it that my whole problem is that I've distorted that speedometer drive gear? (true to form, always imagining, sometimes expecting, the worst)
Also, should I be able to remove that gear and inspect it while the transmission is still in the car?
Last edited:
TR3driver
Great Pumpkin - R.I.P
Offline
Could be several things, but the head is most likely. If it's something else, the trip meter and odometer will be off as well. If they are reasonably accurate, then it has to be the speedo mechanism.
If the error is fairly constant, it might be as simple as taking it apart and moving the needle on the shaft.
Offline
It shows that I am driving way faster than I am. I drove behind a friend and my speedometer said I was going roughly 75 (maybe 80) but my Buddy told me we never got over 65.
Don't have the 30mph numbers and the car is in for winter maintenance and a swapout of the gearbox for an OD one. Its tough working in an unheated garage in Connecticut in January....especially when the employer expects me to be working doing company work!
Don't have the 30mph numbers and the car is in for winter maintenance and a swapout of the gearbox for an OD one. Its tough working in an unheated garage in Connecticut in January....especially when the employer expects me to be working doing company work!
CJD
Yoda
Offline
Likely the rotor needs to be re-magnetized. That's no big deal, but the unit does have to come out of the dash to do it. If you give the numbers at 30, we can verify that magnetization is the cause.
If you think there is a chance the rear end ratio has been changed, you can verify that by comparing your odometer to a measured mile. It should be within 2-3%.
If you think there is a chance the rear end ratio has been changed, you can verify that by comparing your odometer to a measured mile. It should be within 2-3%.
Geo Hahn
Yoda
Offline
Since it is reading too high I doubt it is an issue with the magnets as that would mean they are too strong. More likely the spring has weakened - this can occur with old age, someone messing with it or even an engine cranked with a poor ground connection (seeks a ground through the speedo cable and head causing heat and loss of spring temper).
Certainly Randall's suggestion of just repositioning the needle is easy to try and requires little disassembly. This will correct it for one speed only (e.g. 60 mph) so if the error is non-linear you will still be off at higher and lower speeds.
In my experience Nisonger cannot or will not calibrate speed other than a one data point adjustment - they (they say) do not know how to adjust the magnets or the gap between the drag cup and magnet bar and they will only reluctantly replace the spring with a different strength.
Morris at West Valley on the other hand seems very conversant with the full range of adjustment options available.
Certainly Randall's suggestion of just repositioning the needle is easy to try and requires little disassembly. This will correct it for one speed only (e.g. 60 mph) so if the error is non-linear you will still be off at higher and lower speeds.
In my experience Nisonger cannot or will not calibrate speed other than a one data point adjustment - they (they say) do not know how to adjust the magnets or the gap between the drag cup and magnet bar and they will only reluctantly replace the spring with a different strength.
Morris at West Valley on the other hand seems very conversant with the full range of adjustment options available.