TS conversion - speedo drive

BradGTV · January 12, 2012, 06:09:11 PM

im currently converting my 83 gtv to twinspark running gear and have the gearbox ready for installation. i have searched the this forum and others but havnt came up with the awnser im looking for.

when putting a ts gbox in gtv what needs to be done so the speedo can work as normal? the ts speedo pickup has 3 wires where the gtv has 2, the ts pickup is plastic so im hopping 1 of the 3 is an earth and the other 2 wires get connected to the plug in the gtv. is this the normal way to go about it? i noticed a box under the back seat of the 75 does this need to be used aswell?

cheers, Brad

festy · January 12, 2012, 07:33:13 PM

A 3 wire speed sensor is usually a hall effect type, whereas 2 wire is reluctor.
The signal output between the two types is very different, I don't suppose the sensors are interchangable?

BradGTV · January 12, 2012, 09:38:49 PM

no there not

local alfa mechanic vagley told me it should work (earthing 1 of the 3 and conecting the 2 reamaing to the 2 wire gtv plug) anyone else??

Cool Jesus · January 12, 2012, 10:08:45 PM

Brad, here's a thread which discusses the swap and the speedo issue your having... good luck

http://www.alfabb.com/bb/forums/engine-conversions/162720-116-twin-spark-conversion-thread.html

Also found this whilst surfing which may be of interest and give some pointers for the swap???

http://www.alfacentro.com/features/twinspark/index.html

Cool Jesus · January 12, 2012, 10:21:22 PM

Just found another on our forum...

http://www.alfaclubvic.org.au/forum/index.php?topic=5023.0

Darryl · January 12, 2012, 10:28:31 PM

You can fix it electronically or fix it mechanically - neither is entirely straight forward but if the box isn't being comepletely rebuilt/modified then the electronics is the way to go....

I know there is a lot on alfagtv6.com about various approaches and in particular an electronic interface module from Dakota Digital that is proven in doing this job (note I haven't used it myself).

And MD will probably chime in with some first hand experience if you can't find his posts there (I think it was there - the internet is too big!).

Darryl · January 12, 2012, 10:32:05 PM

Ah - I see MDs post was here - Jesus has of course

found the correct path/thread....

BradGTV · January 13, 2012, 08:42:09 AM

cheers for the help and links.
hmm, the speedo issue is sounding like it will be a big headache

as i want the car ready to drive in no more than a week im going to put the gtv gearbox back in the gtv but with the TS dedion for 5 stud hubs. when i have the dekota in my hands with the manual and i know how its going to work i will swap the TS box in.
cheers, Brad

Tristan Atkins · January 13, 2012, 09:14:30 AM

Hi Brad,

Like Darryl said you can get some sort of black box and fix it electronically or mechanically. I had mine done mechanically and this requires you to take the TS shaft along with the original shaft so that Vin Sharp can swap the sensor ends. I chose this option as I wanted to have the parts inspected. This turned out to be a good option as one of the gears had a tooth missing. I also installed new syncromesh.

In addition I had to modify the wiring connectors on the reverse gear sensor so that I had working reverse lights.

Tristan

BradGTV · January 13, 2012, 07:29:26 PM

Hi Tristan, thank you for the info!
i did however see my mechanic today and he advised me on how to change the selector rod over, so i did and whilst gearbox was apart i noticed the speedo pickup (trigger wheel) on the end of the main shaft, i then had the idea of swapping main shafts with my gtv gearbox solving the issue, however as the pinion is on this shaft i may need to change my crown wheel to suit the pinion. but first id like to know what a 1983 gtv's diff ratio is? im lead to beleive its 4.30?? i would prefer to pull a part an old gearbox i have, can anyone confirm that a 1978 gtv's diff ratio is 3.91?
cheers, Brad

Tristan Atkins · January 14, 2012, 12:54:32 PM

Hi Brad,

I totally forgot about the selector rod. My TS box originality has the iso-static selector. For simplicity I swapped the selector rod over to the original selector and it has since worked without issue. Be careful putting the selector end onto the gearbox as the spine has no key way and its easy to be one spline out. Marking it prior to removal would be a really sensible idea.

As for the crown and pinion, I'm not sure if the ratio's are compatible. Crown and pinions are also a couple. They ware together and most documentation I've read recommends to swap both the crown and pinion for new if either component becomes damaged. If you can use both the TS crown and pinion I would go down this path for the sake of reliability.

Tristan

Storm_X · January 14, 2012, 01:02:28 PM

do you have pictures of both senders ?

BradGTV · January 14, 2012, 06:12:48 PM

well, i have done everything, even swapped 5th syncro onto 2nd. but can not get the gear assembly back into the rear housing, no matter how much i jiggel, tap and move the selector rods around

GTVeloce · January 16, 2012, 10:14:05 AM

I wanted to keep the isostatic linkages as mine were in great shape and so installed a Dakota Digital (little black box). It was a very simple install.

I can vouch that you can't just swap a crown and pinion from different boxes! I tried (and failed!). It was fine at idle but once the revs started to pickup the vibrations and a horrible whining sound was too much. Lesson learnt.

BradGTV · January 16, 2012, 03:22:21 PM

interesting, did you swap a matched pair (crown and pinion) over? or just install a different pinion with a differnt crown?