Changed diff, speedo not reading correct

[Lex]

Pulses Per Kilometer

Thanks Immortality

 

[Lex]

All you do is take the current PPK, divide it by the old ratios (probably 3.08) and then multiply it by the new ratio. I did this whe I fitted 3.46 gear to my VX using my tech 2 and have had no issues. speedo is spot on.

Hi
So l just did the calculation (with calculator of course). I don't know old rate. Looking at Snap-ons pulse rates, my old rate would be 6272
New pulse rate would be 7045? Is that your pulse rate?
Mine has been set at 6800 pulses.
My speedo is only 2 kmh out. ex. speedo reads 60 kmh, gps reading is 58 kmh.
Lex

 

[Husky]

If it works leave it. The calculation I posted assumes you still have factory sized wheels and tyres. even things such as tyre wear can (slightly) effect the accuracy, so the only way to be truely accurate would be to reset it every time your rear tyres wear down a bit, which would be way more trouble then it's worth.

That said i used the calculation i posted earlier with my car which is now running 18" wheels, and at 100km/h (GPS speed) the speedo reads 102km/h. It's not worth the hassle trying to get it any closer, as that's already way closer than the tolerance allowed on a brand new car.

 

[Lex]

If it works leave it. The calculation I posted assumes you still have factory sized wheels and tyres. even things such as tyre wear can (slightly) effect the accuracy, so the only way to be truely accurate would be to reset it every time your rear tyres wear down a bit, which would be way more trouble then it's worth.

That said i used the calculation i posted earlier with my car which is now running 18" wheels, and at 100km/h (GPS speed) the speedo reads 102km/h. It's not worth the hassle trying to get it any closer, as that's already way closer than the tolerance allowed on a brand new car.

Thanks Husky
Lex

 

[Jeff Piha]

Hi, I recently changed my VX 2001 S Series diff for the second time [3rd diff total]. The previous diff was a VY and now have got another vx diff in [both second hand] When I put the VY in there was no problem but since putting in the VX the car is driving rather rough all round. So the other day I got it hooked up to diagnostics which apart from the odometer and fuel mileage everything else made no sense. For example voltage was just 2 extremely fast flickering digits and all different digits, temperature of engine was fluctuating from 600deg celsius to over 1000 but temperature gauge was normal while another category was all FFFFFFFFFFF. No faults came up other than electrical fluctuation on the drivers seat airbag. The car is not always going into 4th gear when it usually would and 2nd gear is like 1st now. And the ride is just not smooth anymore. oh yeah the speedometer is way out - 50km appears to be 70-80km 100km is around 140km and at times its told me im doing 180km [may have been doing slightly over 100km then]

This all started when I changed the diff over which is according to the supplier the right diff. There are no details left on the id label, there is a casting print but i cant find any info on such id except those that have been deleted since made available
The battery is new and the terminals
The alternator is second hand but done 200,000. km less than mine [mine has done 389,000km
Tyre size is 225 16 R55 - always has since i got it
No warning lights come on
Advanced servicing is all up to date
Drive shaft and couplings replaced and abs module
have replaced front suspension, all four calipers, both cv axles, water pump, starter motor, reconditioned power steering pump, and muffler.
replaced the inlet manifold gasket etc, rocker cover gaskets, exhaust manifold gaskets etc etc.

That was just so you got an idea of where I might have upset something else. But like i said the odometer and fuel mileage are clear and correct.

Any insight would be fantastic!

Cheers

 

[_R_J_K_]

Any insight would be fantastic!

It's not going to be related to the diff, it's possible you've disturbed something else during install or it's just good timing that another problem appeared, but it won't be the diff itself as there's nothing electrical in it. Good place to start would be to see if you've crushed one of the ABS sensors or nicked the sensor's loom somewhere. Probably also a good idea to measure the battery with a multimeter while the car is on if you haven't done so yet.

Why did you replace the diff so many times anyway? Wrong speedo reading is to be expected if you changed the diff gears to a different ratio, pretty much sounds like you have given the gear change issues too.

 

[Lex]

Hi, I recently changed my VX 2001 S Series diff for the second time [3rd diff total]. The previous diff was a VY and now have got another vx diff in [both second hand] When I put the VY in there was no problem but since putting in the VX the car is driving rather rough all round. So the other day I got it hooked up to diagnostics which apart from the odometer and fuel mileage everything else made no sense. For example voltage was just 2 extremely fast flickering digits and all different digits, temperature of engine was fluctuating from 600deg celsius to over 1000 but temperature gauge was normal while another category was all FFFFFFFFFFF. No faults came up other than electrical fluctuation on the drivers seat airbag. The car is not always going into 4th gear when it usually would and 2nd gear is like 1st now. And the ride is just not smooth anymore. oh yeah the speedometer is way out - 50km appears to be 70-80km 100km is around 140km and at times its told me im doing 180km [may have been doing slightly over 100km then]

This all started when I changed the diff over which is according to the supplier the right diff. There are no details left on the id label, there is a casting print but i cant find any info on such id except those that have been deleted since made available
The battery is new and the terminals
The alternator is second hand but done 200,000. km less than mine [mine has done 389,000km
Tyre size is 225 16 R55 - always has since i got it
No warning lights come on
Advanced servicing is all up to date
Drive shaft and couplings replaced and abs module
have replaced front suspension, all four calipers, both cv axles, water pump, starter motor, reconditioned power steering pump, and muffler.
replaced the inlet manifold gasket etc, rocker cover gaskets, exhaust manifold gaskets etc etc.

That was just so you got an idea of where I might have upset something else. But like i said the odometer and fuel mileage are clear and correct.

Any insight would be fantastic!

Cheers

I'd be looking at the alternator first, if that checks out then the cluster?