Running a speedo without speed sensor

[81rolla]

Hi all.

I am in the middle of an S15 SR20DET conversion (with six speed) into my KE55 at the moment and am unsure what to do about running a speedo. The 6 speed box does not have a speed sensor as in the S15's, the sensor is located in the diff.

I have seen something about a magnetic pickup or something but am unsure where to buy it from and how to hook it up into my car. Something about putting magnets on your tailshaft.Well something like that anyway. I will be using all speco gauges so will be (well wanting to) running a speco electronic speedo.

Can you buy these in kits or do you buy separately and put together yourself?

Thanks in advance for your help

Anthony

[Devils]

Hi Anthony, sounds interesting!

Depending on what your planning to spend, but going on the conversion i don't think this will be an issue.

The best option for you is a dual pickup type, these use two (some times more) magnets, One typically on the tail shaft and another on an undriven wheel, this is where they sometimes use 3 pickups one for each front wheel (for hard cornering).

Reason for using dual or more pickups is so that you get as close as possible "actual" car speed when out on the track etc.

If your just using this car for a daily then by all means, any normal single magnet pickup on the tail shaft will do the job! Do some wheel spins and get that needle off the clock

They are sold as kits, usually available from big companies that deal in gauges. I think Dakota Digital do one. Other wise it's not hard to buy the parts and make one up. Just have to make sure the pickup - brains - gauge will work together. Don't think you'll have any problems as a lot of people use them for after market ECUs either for Track Work where accurate car speed is desired or for launch/traction control!

[Norbie]

Autometer sell a driveshaft sensor and rare earth magnets for use with their super-fancy programmable tachometers (which read road speed as well as engine speed for some reason). This should provide the 2 pulses per revolution you need for your speedo.

Product info here:

http://www.autometer.com/cat_accesso...st.aspx?pid=22

[oldcorollas]

random things

i'm still re-reading this post trying to work out how you were trying to help


Speco has the pickup methods on their site.
http://www.speco.com.au/Downloads/sp...tionmanual.pdf

can use either hall effect or inductive, there is no listing for speed sonsor on the site.. just says one may be required.

is there no way at all to incprporate a sensor in the box? ie, set up sensor in extension housing and put magnet/chopper ring on the output shaft? idea being the small diameter will gave the magnet/chopper lower velocity and less likely to fly off or get hit by something.

next best is to put it on driveshaft. if you put it near the gearbox end, then you need to be sure that rear axle movement will not make the sender on the driveshaft move forwards or backwards too much, and out of the way of the sensor.

you could put it near the diff, and have the sensor mounted offf the diff itself, but need to make sure diff will not roll too much and disrupt signal or damage sensor/sender.

could put it in an axle tube, and mount the sender (magnet/chopper) on the axles themselves! bonus is that the sender/sensor distance will stay pretty much the same, you can make shield around the sensor, and the sender will nto get hit by rocks or anything.

for sensor, you could even use something like the pickup used on the front of ford 4.1 (and maybe 4L?) motors for RPM. they will be sturdy enough.

reed switch is not ideal as it is mechanical and will fail eventually
inductive has issues with speed of sender vs voltage output
hall effect is best bet... as it is on/off and sender is just a metal ring with teeth cut.


that autometer driveshaft sensor looks like a hall effect, as it has three wires....
nicely packaged.. $$?

[thanhngo]

Im gonna try fitting a S15 box as well and its on my "list of problems to overcome"

Heres what I've gathered (without having a box);

From the service manual, the output shaft looks like it has grooves to hold a worm drive with circular/pin clips? (I don't trust the service manual as it actually shows a worm drive present in some drawings and none in others)


The housing seems to have a casting for a VSS (speed sensor) for mechanical drive? (drill/dremel can fix that)


Basically I suspect the gearbox may be able to have a worm drive/speedo gear housing using some simliar parts (supsect a S14 box or similar output shafted gbox).

I need a actual gearbox and photo to confirm (which will probably be tommorow) - will also be ALOT poorer then as well...

Assuming this will work, I suspect it could be installed like this;


If I get the box tommorow and report back...oh and if this works, you could just slap a electronic sensor on top of the housing M12x1.5.

[thanhngo]

short answer: needs some twinkering

long answer:
Ok opened the box and it doesn't have grooves or dimples for a worm drive ><. I think the service manual recycled pictures from the S14 box...

The shaft does have a bulge which I think is designed for the worm drive to be there so the VSS housing cast should align up still.

Looking into alternatives:
J160 worm drive system - aparently has a speedo drive and one variation of the AZ6 from aisin.
S14 worm drive system (this will definitely need a dimple and grooves to be machined into the shaft)
aftermarket - painful guessing work.