13 replies to this topic

[Gazman]

Hi,

I just bought onme of these to put into my Mini.....

http://www.halfords....ategoryrn_31456

I thought I would go with the cheapest option to start with and can always upgrade if I'm impressed with it.....

My question is where/how do I mount the sensor? I will extend the caling but am unsure where I should put the sensor and the magnet - front back, topor bottom of wheel. All help gratefully received

[Turbo Nick]

i used to have mine on the back wheel, i araldited the magnet to the outside of the drum and made a bracket for the sensor that was fixed to the backplate. It worked fine for ages but one day the magnet parted company on the M5.

We fitted one to my mates car aswell but put the magnet on the pot joint and made a little L bracket off the diff cover for the sensor, the only trouble with this one was that anything over 50mph and the speedo started reading backwards but this could have been down to a poo speedo or just that it was spinning too fast for the sensor.

[paulrockliffe]

Just thought I'd check, it IS an MOT fail to not have a working speedo right?

[jayare]

I had one on my Mini for a bit - that was a cheapo Halfrauds one! I araldited the magnet to the N/S pot joint and made a little bracket to fix the sensor to like Bud666 says they fitted to his mate's car. Mine didn't go backwards over 50 though! The magnet came off after about 6 months or so and I finally found it several years later when changing the timing chain gasket & seal!

paulrockliffe - I think you are correct about a speedo being needed for the MoT, but can't say for sure.

JR

[black jack1275]

i have one like that,
[attachment=44754:24_11_07_1407.jpg]
i am puting it in my new dash, got it to fit in to an old smiths gauge with a bit of filing

[Dan]

Just thought I'd check, it IS an MOT fail to not have a working speedo right?

Have you ever seen the tester take a car being MOT'd on a test drive? Or use the rollers for anything other than the brakes? The speedo is not part of the MOT. It is however a legal requirement to have a working speedo which is lit at night with the rest of the dash lights, if you get pulled and the Police find it's not working or can't be read properly you can be prosecuted.

[dklawson]

I couldn't get the link you posted to work but from the description... but this is a bicycle computer isn't it?

I have a Sigma BC800 bike computer in my car. I do not like the idea of mounting the pickup and magnet on a rear wheel. There are four reasons you don't want to do that. First, brake drums get hot. Epoxy (or whatever glue) does not like heat. Second, the rear arm moves up and down which means you need high-flex rated extension wires for the pickup... or the wire will fatigue prematurely. Third, the sensor is a reed switch and it is subject to inertial effects (false triggers from arm motion). And last, the added wire length (required regardless of whether the pickup is mounted in the front or rear) increases the system capacitance. The extension wire length should be kept to a minimum to avoid problems. Too much wire length will eventually dampen out the pulses the speedo is looking for.

My car has yoke-type inner joints and I bonded and wired the magnet into one of the U-joint cups. I mounted a pickup on a heavy bracket I bolted to the end of the gearbox. The baracket should be heavy. If the bracket is too light, the switch will vibrate and at some speed (unique to your car) the speedo will stop working or read way too high. I have an acquaintance who has bonded his magnet to a pot joint and his has not come off. However, it would be a SMART move to use stainless safety wire in addition to the epoxy to keep the magnet in place.

I have asked Santa Clause for a new Sigma bike computer for Christmas. The new models have an eeprom so the programmed settings aren't lost if the battery dies. VERY handy. There are other advantages to Sigma computers. Most bike computers aren't able to operate at high-speed because... bikes don't typically go over 40 mph... so why support displaying speeds that high? Sigmas WILL operate at high-speed. They also have very fine resolution on their calibration/scale factors. You can get them programmed for extremely accurate results. Lastly, they have a programmable odometer (not just a trip meter). This means you can set the Sigma odometer to match your standard Mini odometer to keep track of service intervals.

Also see this thread:
http://www.minimania...1/msgthread.cfm
There are pictures and additional bike computer experiences discussed there.

Edited by dklawson, 30 November 2007 - 09:57 PM.

[dklawson]

The link below is for the new Sigma model I've asked for for Christmas.
http://www.onyourbik...oduct_info.html
This is a U.K. link and the price for you is about the same as for me... which is a bit surprising based on the current exchange rate.

Here is a picture of the one I currently am using.
http://nicheretail.c...js/300/2858.jpg

And this is a link to a site discussing adding a Sigma to a Lotus-7
http://www.strangely...comp/index.html

[Russ528]

Just thought I'd check, it IS an MOT fail to not have a working speedo right?

For what it's worth, my Mini sailed through the MOT just last week, and my speedo is FUBAR'd as well and I've been using a Cateye bike copmuter for months.

THe only thing you need to be honest about is the mileage, or (as I did) keep track of the mileage on the bike computer then adjust the original speedo mileage reading accordingly before the MOT.

Also, Halfords sell some LED lights (tacky as sin, but actually serve a purpose in this case) that you wire into the lighting circuit so them come on with teh other interior lights, so you can have the speedo lit at night.

Here's s few pics.

Edited by Russ528, 01 December 2007 - 08:47 AM.

[Phaeton]

If you want to do it properly the best way is from the gearbox, buy one of these & use a cut speedo cable Terratrip TERT006 it then doesn't matter if you get a puncture & change the wheel etc. They also are far more reliable & produce very constant pulses.

Alan...

[dklawson]

Phaeton, I couldn't get the link to work. However, once I got to the site I could select "Terratrip" in the manufacturer search field to see their products.

I don't want to get into a technical babble here, but suffice it to say that this thread started with the idea of supplementing the Smiths or Nippon speedo with a CHEAP bike computer. The Terratrip products appear to be very high quality with pricing that reflects that. The gauges/computers are over 200 GBP each and the sending units over 20 GBP.

On the technical side, employing the high quality Terratrip sending units to trigger the inexpensive bicycle computer is not going to work. The bicycle computers are looking for contact closure from a reed switch. They cannot accept the voltage pulses generated by the two and three wire sending units used by traditional electronic speedometers. I have tried this, it is not speculation.

With regard to the effect of a punctured tire, you're quite correct... that will mess up a bike computer if the pickup and magnet are mounted as Bud666 did his. However, if you bond the magnet to a driveshaft joint as Jayare and I did, the sending unit and magnet are not affected by wheel changes.

I have found some disturbing news about the new Sigma units though. At Amazon.com I found a review of the model I wanted for Christmas. A man who tried outfitting this model to his Vespa scooter found the display speed limited on the new models and he's contacted Sigma tech support regarding this. It's an issue involving the wheel/tire circumference. I've got some ideas to get around it but they won't be useful to most of the people who might consider installing the new Sigmas. I've sent my own email to their tech support people to ask them some technical questions before I consider getting one of the new computers. I'll keep you posted with my findings.

[Phaeton]

Phaeton, I couldn't get the link to work. However, once I got to the site I could select "Terratrip" in the manufacturer search field to see their products.

I don't want to get into a technical babble here, but suffice it to say that this thread started with the idea of supplementing the Smiths or Nippon speedo with a CHEAP bike computer. The Terratrip products appear to be very high quality with pricing that reflects that. The gauges/computers are over 200 GBP each and the sending units over 20 GBP.

On the technical side, employing the high quality Terratrip sending units to trigger the inexpensive bicycle computer is not going to work. The bicycle computers are looking for contact closure from a reed switch. They cannot accept the voltage pulses generated by the two and three wire sending units used by traditional electronic speedometers. I have tried this, it is not speculation.

With regard to the effect of a punctured tire, you're quite correct... that will mess up a bike computer if the pickup and magnet are mounted as Bud666 did his. However, if you bond the magnet to a driveshaft joint as Jayare and I did, the sending unit and magnet are not affected by wheel changes.

I have found some disturbing news about the new Sigma units though. At Amazon.com I found a review of the model I wanted for Christmas. A man who tried outfitting this model to his Vespa scooter found the display speed limited on the new models and he's contacted Sigma tech support regarding this. It's an issue involving the wheel/tire circumference. I've got some ideas to get around it but they won't be useful to most of the people who might consider installing the new Sigmas. I've sent my own email to their tech support people to ask them some technical questions before I consider getting one of the new computers. I'll keep you posted with my findings.

Sorry about the link the unit I was pointing to is only £20.50, it should work with the cycle speedometers, we've used it very successfully on Acewell units which use the same principles, being 2 wire & we've converted them to 3 wire.

Alan..

[dklawson]

Thanks for that. So is it this one?
http://www.gprdirect...rge/TERT006.jpg
It looks like the price has gone up just a bit.

I've worked with two wire magnetic pickups on industrial equipment and these give a sine-wave output that was not compatible with the bike computers. I assume this device must be different but I didn't see a tech data sheet for it on the GRP web site.

Regardless, thanks for the information.

[Russ528]

My Cateye OS1 claimed not to read speeds about 60mph, but it does - and still very accurately, as I've compared it to the GPS speed reading from standstill up to 74mph (lil mini doesn't like doing much over that!) - which is reassuring!

The good thing about the cateye one is that all the settings are stored on an internal chip, so when you replace the battery you dont' loose all your sttings and mileage, etc.

Just something else to consider.

I think they have brought out an OS2 which is supposed to be better, but mine was end of the line and only cost me a tenner!