Speedo Recalibration

Post by **d_harris** » Sun Oct 19, 2008 8:34 pm

Who does it?

What info do they need and how much does it cost?

I've discovered that my speedo reads stupidly quick (i.e. it reads 85 when the speedo reads 70)

Post by **Judge** » Sun Oct 19, 2008 8:39 pm

Only a suggestion

http://www.jdo1.com/

Post by **d_harris** » Sun Oct 19, 2008 8:43 pm

I don't know what you mean

Post by **bmcecosse** » Sun Oct 19, 2008 8:48 pm

What tpm does your speedo have Dan ? There are a range of speedos about (mostly ex Mini) with different tpm - there may be one to suit you rather better! That will be a MUCH less expensive way to go.

Post by **d_harris** » Sun Oct 19, 2008 8:55 pm

tpm being?

Post by **alex_holden** » Sun Oct 19, 2008 8:56 pm

Turns Per Mile, I think.

Post by **d_harris** » Sun Oct 19, 2008 8:59 pm

aaah. That would make sense. How can I find that out?

Post by **Matt** » Sun Oct 19, 2008 9:31 pm

it will be whatever is standard for a 1098 with standard wheels and 1098 diff

Post by **bmcecosse** » Sun Oct 19, 2008 10:51 pm

It's written on the speedo - just above the mileometer readout - a 4 digit number probably something like 1408 for a 1098 with 4.22 diff, if it still has the original speedo fitted of course. You really need to do a mileometer accuracy check against a known distance or a GPS. Then decide what tpm you need to put that right. The actual Speed reading can be 'adjusted' by tweaking the spring - although obviously it will be best matched if you can get a unit where the mileometer reads close to correct.

Post by **d_harris** » Sun Oct 19, 2008 11:06 pm

so is 1408 the correct figure for standard 1098?

The difference comes from my wheels I suspect

Specification...Revs/Mile..Difference
145/80-14......872...........0.0%
175/65-13......919..........-5.1%

Therefore I would be looking for TPM of 1325?

Post by **jock299** » Mon Oct 20, 2008 12:20 am

found this

http://www.speedycables.com/calibration.html

Post by **Matt** » Mon Oct 20, 2008 10:13 am

you need to add that 5.1% Dan. The smaller wheels are doing more tpm and therefore the speedo should do more tpm too

Post by **bmcecosse** » Mon Oct 20, 2008 2:20 pm

Yes - somthing more like 1480 - that's IF your speedo is 1408 - is it ?? Of course if you go for a 3.9 diff that would near enough cancel out the difference! I would think that's a better way to spend the money than recalibrating the speedo!

Post by **d_harris** » Mon Oct 20, 2008 8:51 pm

Yep, but I don't have a spare £150.00 odd lying around!

and on the TPM adjustment. D'oh!

Post by **Mogwai** » Mon Oct 20, 2008 10:12 pm

is this a useful manual http://tr6.danielsonfamily.org/Files/SpeedoRepair.pdf has a bit about calibration near the end

Post by **mrbenn** » Tue Oct 21, 2008 12:13 am

jock299 wrote:found this

http://www.speedycables.com/calibration.html

These people seem to be mentioned pretty regularly in Practical Classics