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Jan 29, 2008 9:34 pm
Jan 29, 2008 9:34 pm
Subject: Re: Speedo / rev counter instrument o'haul
Hello Don,
Some thoughts.
1. Firstly if it was not my 'best' spedo, my non-recommended action would be to take it to bits and play with the spring that counterbalances the bob weight and then recalibrate on the lathe running at various speeds. Try different springs and tensions...not recommended with anything other than a 'spare' spedo picked up at an autojumble! Of course if you do not have a lathe, go straight to step 2.
2. Recommended action for your precious device. Do a calibration run to produce en error curve - percentage error at various speeds. This should produce a graph of percentage error vs 'indicated speed'. Decide the error over the range - say 15%, then contact Speedograph Richfield http://www.speedograph-richfield.com/ and discuss your needs. They are very helpful and have told me they can make up a gearbox of a suitable ratio to fix most problems. This is very useful if you have geared up you back axle - for example putting a Rapide ratio into an M45.
By the way I fix my own capilliary temperature gauges. You do need courage to attempt one but I love doing them. Its probably the smell of ether, but of course nowadays it is getting more difficult to persuade ones local pharmacist to sell it to you.
Regards to all
Colin Mallett
Hello Don,
Some thoughts.
1. Firstly if it was not my 'best' spedo, my non-recommended action would be to take it to bits and play with the spring that counterbalances the bob weight and then recalibrate on the lathe running at various speeds. Try different springs and tensions...not recommended with anything other than a 'spare' spedo picked up at an autojumble! Of course if you do not have a lathe, go straight to step 2.
2. Recommended action for your precious device. Do a calibration run to produce en error curve - percentage error at various speeds. This should produce a graph of percentage error vs 'indicated speed'. Decide the error over the range - say 15%, then contact Speedograph Richfield http://www.speedograph-richfield.com/ and discuss your needs. They are very helpful and have told me they can make up a gearbox of a suitable ratio to fix most problems. This is very useful if you have geared up you back axle - for example putting a Rapide ratio into an M45.
By the way I fix my own capilliary temperature gauges. You do need courage to attempt one but I love doing them. Its probably the smell of ether, but of course nowadays it is getting more difficult to persuade ones local pharmacist to sell it to you.
Regards to all
Colin Mallett