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Modifying speedo for use with t5

icwbmx

icwbmx

New member
Joined
May 10, 2005
So as i understand it i can "calibrate" a stock 240 speedo by changing the resistance between pin 4 and 13.

My question is will the speedo work off an 8 pulse or a 16 pulse sender unit? Would one be better than the other?

And how would the speedo gears come into play?

Thanks
IAn
 
You've got an electronic speedo in your '83?

I've heard of people using a T5 speedo cable and changing the fitting at the speedometer end.
 
Well i have a cable driven (85mph) speedo in there now, but i have an electronic (120mph) one laying around.
 
There is a VSS available for the T5 that will generate an electronic signal proportional to speed. With that in the speedo cable hole you should be able to fashion a circuit that will let the speedo talk to the VSS.
 
Didn't Sean (hackster) just do this by putting a electronic speedo from a later car in and using the 2.4 speedo pickup/diff cover? I remember just seeing the thread.

I suppose this would require the tone ring but if you were swapping to a g80 anyway...
 
Not sure -- the one I'm referring to is designed to go into the opening in the T5 manual tranny where the speedo cable would normally go. On the Mustangs the VSS sent a signal to the ecu that was used for various things and also used for cruise control function. The VSS had the plastic gear that went into the tailshaft housing on the T5 and then the speedo cable plugged into the VSS. Of course, if you're using an electric speedo then there's no need for the cable... Looks like this....scroll down when you get to the page. http://www.partstrain.com/store/?N=...294963722+4294967147&Nr=AND(part:Speed Sensor)
 
Yah I think we are talking about the same thing.

I called a local transmission/driveshaft shop today. The owner said if he has any in laying around in the back I can have one. Ill try it out and see if I can get it all sorted out. It's a pretty simple/cheap solution if it works.
 
Works like a charm.

So what i did was:
1. Install a mustang speedo sender (one with an electric cruise output) into the tranny with a gear set that was somewhat close.

2. Wire up the cruise control output to the volvo speedometer the same way the stock volvo speed sensor would be wired. (Diagram can be found in the back of any haynes manual.)
IMAG0098.jpg


3. Then calibrate by way of a potentiometer. See thread below. http://forums.turbobricks.com/showthread.php?t=239021


I havnt had a chance to drive the car and fully calibrated it yet but with the rear jacked up it was giving me rock solid readings. Much nicer than the jumpy cable driven m46 speedo.

Thanks
Ian
 
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Can I swap a 120 mph electric speedo from a later model Volvo into my 82 cluster - and then make the switch? I already have magnets/pickup on the driveshaft for a cruise control - wonder if I can use that output to make the electronic speedo work.

I have questions about calibration -- I'll ask them in the other thread; it's an old one - I wonder if JW240 is still subscribed? Hmmm....
 
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Yah, that's pretty much wat I did. Swapped a late model 120mph speedo into my '83 cluster.
 
Hmm-I have to hack up my early cluster to fit an electronic speedo in the back anyhow, and I've got a later T5 with the electronic speedo out already. I wonder if wiring up that speed sensor would be any easier or harder than using the one in the 3.73 axle that'll be going in soon...
 
Seems to me the biggest difference is this -- if using the 3.73/tone ring/sensor will allow the speedo to work accurately without calibration -- that's easier than using the T5 hardware and having to recalibrate.

My speedo is off with my new tires -- and I was going to use a simple speedo gear change to fix it -- but there may be a better mousetrap available.
 
I'll be putting in a G80 from a car that I forgot the axle ratio of, and in order to use the 240 speed pickup, I'll have to mod the tone ring on the G80 by grinding off a bunch of teeth. I'll have to see whats up with the tone ring in the axle when I pick it up, and see if the tone ring on the G80 can be converted.
 
Really struggling here - at that link I see the same discrepancy between units. There are 2 that both have what appears to be a metal cylinder of some sort -- is that behind and above the actual gauge? I think I can see the needle on the top pic. Where is all that relative to the white plastic thingy where JW240 shows the resistor(s) going in?
 
What you see in the pics is the back of the actual gauge. the white plastic thing is part of the cluster board. remove the screws from the back of the cluster and the whole back "board" will separate from the black housing. then the gauge will come out of that if you remove the small screws located on the white plastic piece. I will take pictures in the next day or two and better illustrate the process.
 
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