Jump to content
SAU Community

Recommended Posts

hi folks,

my speedometer in my nissan hatch is out by something around 15 - 18 km/h according to my GPS.

so when I'm doing 100 km/h on the clock my GPS shows my 82 - 85 km/h...

(that is why I never got booked speeding, because I never had the GPS on... >_<

and I was wondering why a truck can overtake me when I'm doing 110)

how could I fix this problem ? is there any chance that this is just a adjustment

of something ?

thanks guys,

zee-german

Link to comment
https://www.sau.com.au/forums/topic/256172-speedometer-is-out-by-15-18-kmh/
Share on other sites

Michael,

Where are you in Sydney?

There is a couple of reasons; 1. The speedo could be knackered. 2. Your tyre size might be wrong. 3. You could have a worn drive gear in the box and it is slipping. 4. The diff/drive gear combination is wrong.

This being said the service manual suggests only one (1) possible option and that is the speedo is faulty.

I'm in Sydney's south west (Campbelltown area) if you want another speedo, I'm sure I would have a spare laying around somewhere from when I had mine rebuilt by Jenesis.

Cheers, D

If the odometer is correct, then all the gearing (tyre sizes, diff ratios) are correct.

The speedo works off a magnet spinning inside a metal "cap". A spring controls the "cap" from just going on and on. With age, I reckon, the spring loses its tension, and lets the "cap" rotate further than it should, thus indicating a higher apparent speed.

If the odometer is correct, then all the gearing (tyre sizes, diff ratios) are correct.

The speedo works off a magnet spinning inside a metal "cap". A spring controls the "cap" from just going on and on. With age, I reckon, the spring loses its tension, and lets the "cap" rotate further than it should, thus indicating a higher apparent speed.

hmmm, sounds good... but it shows me a slower speed... so the other way round.

I know that I have the right tyres on the car. right size ect... just changed them a few months ago.

and the gearing should be ok as well. it is an auto transmission, it works fine and solid.

Michael,

Where are you in Sydney?

There is a couple of reasons; 1. The speedo could be knackered. 2. Your tyre size might be wrong. 3. You could have a worn drive gear in the box and it is slipping. 4. The diff/drive gear combination is wrong.

This being said the service manual suggests only one (1) possible option and that is the speedo is faulty.

I'm in Sydney's south west (Campbelltown area) if you want another speedo, I'm sure I would have a spare laying around somewhere from when I had mine rebuilt by Jenesis.

Cheers, D

hi,

I'm on the other side of the city (north sydney, neutral bay)

I bought this car of an old lady 16 months ago with only 116.000 km on it.

and it drives well... engine and auto sounds solid, just changed the injectors and the waterpump.

but my speedometer problem is since I have this car.

hmmm, sounds good... but it shows me a slower speed... so the other way round.
No, it's not (the other way round).

You said the speedo shows 100 when you are actually - according to the GPS - doing 85. So the spring isn't retaining the speedo needle enough. The speedo is indicating a speed HIGHER than actual. (which is what I believe I said the first time, perhaps not so succintly)

I have always gone by gearbox ratio, diff ratio and tyre diameter with tacho reading. So in a manual you can work out exactly what speed you are doing, but in an auto you have to decide whether the torque converter has locked up.

There are places on the freeways where you can clock time against the actual tyre diameter will drive you at a predetermined tacho indication. But you must have an accurate tacho.

My new Ti hatch in 1984 was pretty close to 50 clicks per 1000. So about 2000

Hi, To check if your speedo is working properly go find a 5km odometer check and record how far your odo shows over the 5k's (do the test at the posted speed limit as speed has no relevance with this test) - if the odo shows around 4.2 k's or even under 4.5k's then the problem is unlikely to be the speedo - if the odo shows between 4.9 & 5.1ks then the speedo is likely to be the problem. If the speedo checks out, then you are looking for a component in the gearing so the speedo cable is not spinning at the correct number of revs/km eg speedo drive, the diff changed to a lower ratio and the speedo drive not changed to suit, or wheels/tyres are not standard but i doubt that as the wheel/tyre combination would have to be a lot smaller than standard to make that much difference - most of us put wider & higher tyres on which reduces the revs per km and this causes the speedo to read slightly slower relevant to actual speed ie more accurately - which is why most speedos have a 5% fast read built in ex-factory. If you need help with correct speedo drive ratio i would need to know your diff ratio & tyre size. Cheers, Tel

Hi, To check if your speedo is working properly go find a 5km odometer check and record how far your odo shows over the 5k's (do the test at the posted speed limit as speed has no relevance with this test) - if the odo shows around 4.2 k's or even under 4.5k's then the problem is unlikely to be the speedo - if the odo shows between 4.9 & 5.1ks then the speedo is likely to be the problem. If the speedo checks out, then you are looking for a component in the gearing so the speedo cable is not spinning at the correct number of revs/km eg speedo drive, the diff changed to a lower ratio and the speedo drive not changed to suit, or wheels/tyres are not standard but i doubt that as the wheel/tyre combination would have to be a lot smaller than standard to make that much difference - most of us put wider & higher tyres on which reduces the revs per km and this causes the speedo to read slightly slower relevant to actual speed ie more accurately - which is why most speedos have a 5% fast read built in ex-factory. If you need help with correct speedo drive ratio i would need to know your diff ratio & tyre size. Cheers, Tel

thank you guys for all the answers ! I will check it with the 5 km test..... :-)

"My new Ti hatch in 1984 was pretty close to 50 clicks per 1000. So about 2000"

What a hoot old man, my new 180B SSS in 1973 used to get 20mph/1000rpm in top (4th) so when I was sailing across Mooney Mooney bridge on F3 at 6750rpm, I sorta understood the fowl looks I got from the boys in blue doing radar duty. lol

Cheers, D

Sorry for hijacking your thread temporarily

my speedo is stuffed with the vl gearbox.

the speedo drive is for 3.45 gears and i have 3.9.

i just work out how fast i am going from the RPM's.

100kmh is 2500rpm in 5th and every 500rpm is 20kmh.

speedos are always wrong from factory.

only shit thing is it clocks up klms quicker on the odo

but who cares. just buy another dash.

My first RMR30Ti had 600 on it when I gave her a decent burial. Changing the speedo is (illegal) a bit of a waste.

"Changing the speedo is (illegal) a bit of a waste".

Not if your old one is broke, it's not.

In NSW the annual rego checks require an odometer reading on the inspection slip, so the RTA knows wether the speedo has changed and or been repaired.

My PNV when it goes on the road will have a Jenesis 260kph speedo with ZERO on the clock & a 9000rpm tacho and that wont be illegal.

I suppose it's a bit diferent for these backward states that don't have regular inspections eh?

Cheers, D

I suppose it's a bit diferent for these backward states that don't have regular inspections eh?

Shhhhh, I like these backward states that don't have regular inspections.

otherwise my turbo conversion may never get done, or my aftermarket ECU, wouldn't past muster (emissions), but then again, I have never looked into what is or is not illegal.

Nigel

"Changing the speedo is (illegal) a bit of a waste".

Not if your old one is broke, it's not.

In NSW the annual rego checks require an odometer reading on the inspection slip, so the RTA knows wether the speedo has changed and or been repaired.

My PNV when it goes on the road will have a Jenesis 260kph speedo with ZERO on the clock & a 9000rpm tacho and that wont be illegal.

I suppose it's a bit diferent for these backward states that don't have regular inspections eh?

Cheers, D

I thought as much, its more illegal to have an odo that is not working.

I think we should have regular inspections. Get all the shit heaps off the road.

Maybe not every year but every three or five years. You see cars driving around

with smashed lights, rust everywhere, some real junk boxes.

skybt1, might I suggest you change the drive in your gearbox to the correct one - the RB30E gearbox should take the same pinions as the old FS5W71B/3N71B/4N71B that the car came with.

Dennis, if you were doing 6750rpm (as indicated on a 1973-accuracy tacho!) in a stock 610 SSS in 4th, then it must have been downhill :blush:

(and you must have been out of your mind)

I've got a 4.375:1 LSD in my DR30, but in order to get the speedo correct (within ~5%) I've had to fit the 4.625:1 speedo drive. A combination of slightly shorter tyres (225/50/16) and a 25-year old speedo have resulted in extra compensation being required to get things right.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Seat of the pants assessment of the new intake: The car is way less "doughy" when hitting the loud pedal, especially off idle when stopped or in traffic, I did use a cheapo lazer thermal thingo to measure the temp around where the pod filter got its air, it was between 55 - 60°C, in saying this the car was shut off and not moving, so the OEM intake pipe was not supplying any fresh air to where the pod was when the car was at least moving A weird bonus was induction noise on the throttle in the cabin increased a bit,  I was worried that I was actually going to lose some of that induction noise I love so much, outside though, when I got the daughter to do a WOT drive by pass for me, the induction noise has increased alot when on the throttle, not quite ITB doort, but well up there I'm extremely happy with the results and have been exploring the country roads in the region  As for house mods: 1.New front fence is up and is awesome, it really upgraded how the joint looks from the street, and the added security is nice 2. Electricians have replace some interior lights, and with more lighting in the garage, a few new motion detecting lights out the front above the garage, front room, and at the front door, which I have already found heaps helpful coming and going, also now has fancy pants CCTV all round the house The only hold point for power though is the solar and batteries due to supply issues, although this will happen over the next few weeks 3. I have done a heap of landscaping out the front and I'm almost ready to do a new small retaining wall with some nice blocks to replace the brick and cemented in rocks around the raised garden beds cemented in river stone "was the fashion at the time" the house was built. I currently have a pallet of retaining wall blocks and 2 bulka bags of 20mm blue metal to replace the wood chip that is in the raised garden beds around the house 4. I now have 3 big raised garden beds for out the back to grow some vegetables, about 70cm high, 200cm long and 100cm wide 5. My 2 compost bins are already pretty full with brown, green and kitchen waste from the landscaping I'vedone so far, but they will probably take a few months to break down, so anything else that gets chopped, trimmed, and kitchen waste will just start filling the base of the raised garden beds to about 30cm before I start throwing 40cm of good compost, and stuff, for the vegetables to grow in, I'll need a few ton of compost and soil, but the local supplier can sent me bulka bags of the stuff Basically the logs, wood chips and a few strategically placed rocks for drainage, will give the beds some good organic materials down low to break down over time, and they will hold moisture during the warmer months to save the water in my big arse water tank if we don't get alot of rain So, all in all, the car and house mods are going well, and I'm really enjoying being retired, I sleep in too 0700 and slowly plod around inside until I feel like actually doing anything, and only work in the yard for as long as want, which has actually been alot over the last few weeks,  although when you look at it, it seems that not a huge amount of work has been done,  until I look at the before I started the work pics Happy days and good times indeed 
    • hahaha yeah. Plan is to get side skirts and probably just rear pods. But going to do them one-by-one. I've got a set that I really like from RHDJapen, but that one isn't shipped to AU. So need to find someone who can get it for me
    • Here's an idea, answer the questions I asked you as they are trying to work out WHY the LSD will be binding up in a straight line.
    • You haven't driven many modern cars then have you? Most of them have sfa steering feel with their stupid electric bullshit steering systems.
×
×
  • Create New...