Speedo reading slow!!

[zzr1200]

Roof down, cruising. See a roller sitting in a layby on the A120 in Braintree and didn't think much of it until he screamed after me and pulled me over! Anyway ended up getting a fixed penalty for my un-beknown sins .

I was on my way to Castle TVR anyway so when I got there they had a look at the speedo reading. Hey Presto it's reading at least 10mph slow at 3000rpm in 5th. Many thanks to Castle for looking at it, they are calling the factory to see what can be wrong as it should read OK.

Has anybody else had this problem? (The speedo reading slow, not the ticket!)

TVR's

[jonnyb]

opposit of that, mine reads quick!!! its ok at about 30-40mph but get up to about (what I think is) 80 and it thinks Im doing 140mph (unless you can do 140 at 3000rpm in 5th, and not off a cliff!!!)

[the dodger]

zzr - had exactly the same, and the points to prove it!

Full story here: www.pistonheads.com/gassing/topic.asp?h=0&f=23&t=32853

Still not fixed, still reading very low and still licence-threatening! Please let me know how/if Castle fix it via my e-mail. Thanks.

[raceboy]

And here's my thread on it......

www.pistonheads.com/gassing/topic.asp?t=14453&f=8&h=0&hw=speedo

My problem part was the speedo transducer on top of the diff and as it was a part only fitted to Chimaeras for 15 minutes on a Tuesday it was impossible to get a replacement, but a big to Joolz at Joospeed for making one out of a different part and getting it all working again

[zzr1200]

I'll update you all on what Castle come up with. The guys at Castle did check the gap on the sensor and adjusted it slightly but this didn't change the reading.

I thought all speedo's have to read in the 0 to 10% over band for them to comply with build regs or whatever???

Anyway, I am going to get someone to follow me at exactly 70 in a normal car and mark where my speedo reads so I stand a fighting chance of keeping my licence in the meantime.

[K4TRV]

zzr1200 said:

I thought all speedo's have to read in the 0 to 10% over band for them to comply with build regs or whatever??? Anyway, I am going to get someone to follow me at exactly 70 in a normal car and mark where my speedo reads so I stand a fighting chance of keeping my licence in the meantime.

I'd advise asking around to see if anyone has a hand-held GPS (GPS V would work), these usually give ground speed to better than 5%. Someone following you might also have an under-reading speedo - how are you going to communicate - hands-free I hope ??? Plus, it will check accuracy at all speeds, well up to 450 mph, or whatever it takes to have a sonic whatsit.....;-))

Trev McM

[shpub]

The speed /revs information for various tyre sizes is in the Bible and in the TYRE FAQ on my website, as well as the excel spreadsheet used to do the calcs.
That will tell you what the readings should be and potential speedo errors if the car has non-standard wheels/tyres.

Steve
www.tvrbooks.co.uk

[nchilds]

K4TRV said:

Someone following you might also have an under-reading speedo - how are you going to communicate - hands-free I hope ???

If you follow the other car you won't need to communicate. You'll know that you're at 70 when you stop accelerating.

[zzr1200]

K4TRV said:

zzr1200 said: I thought all speedo's have to read in the 0 to 10% over band for them to comply with build regs or whatever??? Anyway, I am going to get someone to follow me at exactly 70 in a normal car and mark where my speedo reads so I stand a fighting chance of keeping my licence in the meantime. I'd advise asking around to see if anyone has a hand-held GPS (GPS V would work), these usually give ground speed to better than 5%. Someone following you might also have an under-reading speedo - how are you going to communicate - hands-free I hope ??? Plus, it will check accuracy at all speeds, well up to 450 mph, or whatever it takes to have a sonic whatsit.....;-)) Trev McM

......sonic TVR??

[Mark.S]

zzr1200 said:

Anyway, I am going to get someone to follow me at exactly 70 in a normal car and mark where my speedo reads so I stand a fighting chance of keeping my licence in the meantime.

Paul,

If I make it along to the next mid-essex meet, you can borrow my Road Angel for the journey to make a comparison.

Are the replacement wheels/tyres exactly the same sizes as original?

[zzr1200]

Mark.S said:

zzr1200 said: Anyway, I am going to get someone to follow me at exactly 70 in a normal car and mark where my speedo reads so I stand a fighting chance of keeping my licence in the meantime. Paul, If I make it along to the next mid-essex meet, you can borrow my Road Angel for the journey to make a comparison. Are the replacement wheels/tyres exactly the same sizes as original?

Hi Mark,

Yes there the same tyres so it shouldn't make a difference, especially now that they are coming up for replacement on the back. Thanks for the offer, if TVR haven't solved it by then i'll try it. How's the 500 going?? Did you have the chip work done??

Paul

[Mark.S]

zzr1200 said:

How's the 500 going?? Did you have the chip work done??

Mixed fortunes with the upgrades unfortunately.

Hopefully have the car back on Friday - will report back on the results over the weekend.