LT77 Gearbox Speedo Transducer - PINION SWAP

ramon alban · Post by **ramon alban** » Fri Jun 19, 2015 11:54 am

Circa 2010 - 2012.

Does any one recall a V8 Forum Member posting about swapping pinions on the LT77 Speedo Transducer?

The gentleman concerned must have established a method of removing the pinion without damage and exchanging different color pinions to suit his need.

I think he also sold swapped Speedo Transducers on Ebay.

I tried a Forum SEARCH without any success!

Does any one remember the member concerned or know of the method he used to make the exchange.

stevieturbo · Post by **stevieturbo** » Fri Jun 19, 2015 6:25 pm

If you need to adjust the output for a different reading, you can buy signal adjusters for that purpose

http://www.jaycar.co.uk/productView.asp ... rm=KEYWORD

DaveEFI · Post by **DaveEFI** » Sat Jun 20, 2015 7:59 am

stevieturbo wrote:If you need to adjust the output for a different reading, you can buy signal adjusters for that purpose

http://www.jaycar.co.uk/productView.asp ... rm=KEYWORD

Interesting - thy appear to have produced a new version. Cheaper than the old, too.

But the problem Ramon is asking about is failure of the drive unit, and not being able to obtain the exact replacement. If you fitted one with a different drive cog, you'd also have to change the one inside the box.

ramon alban · Post by **ramon alban** » Sat Jun 20, 2015 10:21 am

Thanks Stevie.

I can see that could be part of my solution.

Dave, you are right.

Currently I have an intermittent faulty unit in the car and several spares with the wrong gear wheel (pinion).

If I can swap my existing pinion on to one of my spare units, I can solve the problem.

If not I could try to fit a unit with the wrong pinion(s) and correct the signal with the Jaycar unit you suggest.

Ideally I would like to swap pinions and to do that I first want to contact the chap who knows how to do it.

Thanks all round.

Does anyone remember the member who posted about this?

DaveEFI · Post by **DaveEFI** » Sat Jun 20, 2015 11:01 am

The SD1 type as used on the GM auto is perhaps a better design. The actual electronics part unscrews from the gear part - and since it is usually the electronics which fail, a simple fix as the electronics are the same regardless of axle ratio.

If you can't change the gear on the sensor, I've no idea how difficult it would be to change to gear inside the box to use one you can get.
The Jaycar corrector does work though - MobyDick has one on the GWW. The latest version is hopefully less of a fiddle to set up.

minorv8 · Post by **minorv8** » Wed Jun 24, 2015 10:57 am

Ramon, if you are talking about the gear on the sender have a look at Autometer Speedo thread on this same forum. I took one sender apart just for fun and the gears are pretty easy to remove. I have posted some photos there.

DaveEFI · Post by **DaveEFI** » Wed Jun 24, 2015 1:13 pm

Just to clarify, Ramon has a manual box with electronic speedo.

From what I've seen of this drive, the pinion should pull off the shaft. But is there the possibility that pushing it on to the new one might damage the internals, as there's nothing to take the thrust load?

I'm guessing that it is assembled to the shaft before the electronic end is fitted, and that is then crimped in place. But only guessing. And not sure if you can open up the crimp to remove the electronics, and replace.