Technical 130+ MPH sei.. :S

[sei16v]

Hey all. Just swapped a gear box over in my sei and took the car out for a spin.... Its a 1.1 box on a 1.2 16v 85 punto engine (14" ABARTH wheels).... The speedo now goes off the clock, unlike before.... Ive tested it against a sat nav, and when im doing 30, the speedo says 40.... etc...

Any ideas how to sort this problem out?

The box i took off was a 1.1 box also apparently...

 

[fingers99]

What tyres?

A 10% optimistic speedo isn't illegal, and probably not more than 5 or 6% more optimistic than usual.

Bear in mind that GPS isn't as accurate as it should be, due to the US military (etc.).

 

[bulldog5046]

probably the speedo sender unit on the box, seen it happen a few times on bravo/a/marea

 

[craigb244]

Hey all. Just swapped a gear box over in my sei and took the car out for a spin.... Its a 1.1 box on a 1.2 16v 85 punto engine (14" ABARTH wheels).... The speedo now goes off the clock, unlike before.... Ive tested it against a sat nav, and when im doing 30, the speedo says 40.... etc...

Any ideas how to sort this problem out?

The box i took off was a 1.1 box also apparently...

Does it stay 10% off? (40=50 50=60....) if so I would just remove the needle and place place it at 30 when the satnav says 30

edit* sadly your cars mileage will go up %10 faster... on the other hand you MPG will be MUCH better hehe

 

[ivantate]

I think 10% is 40-44 and 50-55 ???

The standard 1100 has different ratios in the gearbox, I guess the sensor uses a gear with a different number of teeth in that box.
You best option is probably to get the speedo recalibrated. A company called speedycables can do it if you tell them the ratio.

(providing it isnt the sensor that has failed)

 

[sei16v]

The wierd thing is it didnt do it on the box before.... Is there any chance parts could be swapped over, as i still have the previous box? My cars low mileage, so i really want to get this sorted out asap.
Not sure what % it goes up by, but i was doing about 50 and clocks reading 70.... Its deffinatly a problem rather than the car actually doing over 130mph lol.... (although it is pretty cool when it goes off the clock)...

 

[fingers99]

Might be possible.

For reference, the stock Cinq/Sei set up over-reads, even on 195/45/14s, but not by a huge amount.

The most reliable indicators I've found are those radar ones by the side of the road which display your speed on a screen as a warning, but I don't know if there are any near you.

I wonder if it is some kind of cable issue? My mate's BMW used to show 110 while being overtaken by white van man, but we never investigated further as he was in a state of denial!

 

[gazzaman2k]

ive had mine off the clock before on gps it was 135mph bouncing on 5th gear limiter on 15" wheels the gearbox doesnt do anymore then that

mine reads out too but its never bothered me

 

[Stickman]

If the wheels (you mention abarths) are a different size from the ones that the gearbox and/or dashboard are desinged for, any 3 of those could be set against one another in various ways. Putting together bits from different cars is bound to cause confusion in speed detection. But I agree with Fingers99, Satnav's are known to give innaccurate speed readings.

Best off driving with a mate who has an accurate speedo and getting measurements from him/her. That way you'll at least know whether its your speedo or the satnav that's giving wrong readings.

Anyone know if the Sei's speedo is eddy-current or electronic? If it's eddy-current then it relies on the transmission, so popping in a box from elsewhere is bound to cause reading confusion.

Wikipedia suggests: Excessive speedometer error after manufacture can come from several causes but most commonly is due to nonstandard tire diameter, in which case the

percent error = 100x("standard diameter"/"new diameter" - 1).

Erm... yes.

Good luck

 

[Slosei]

Running very lean well so lean that the temps shot up 20degrees in seconds! on 16inch wheels car did 120mph in 6th sat nav aint accurate but car does 70mph and tom tom reads 69mph