Hey guys,

I recently did a T5 manual swap into my 89 Formula.

The WC T5 I used was set up for a cable-driven speedo at the tailshaft (drive gear mounted on the tailshaft instead of a reluctor for a VSS) but my speedo is electric so to solve it, I installed one of these a 89-95 Firebird large-can speedo sensor VSS units (p/n 10456087):
https://www.ebay.com/itm/176658035778



However, the gear on this VSS unit now causes the speedo to read about 10% low - I've confirmed this with GPS. It makes sense since a factory car with one of those sensors in it would've had a 3.08 rear, but my car has a 2.73.

Does anyone know if the gear that is present on this VSS can be had in a different tooth count? The drive shape is a D, whereas a drive shape for a cable-driven speedo gear is square (and these are readily available online).

I've spent the last hour or so scouring the internet and can't seem to find one of these D-shaped driven gears... I presume I'll need to go the route of an electronic ratio adaptor if these gears don't exist in different tooth counts

Thanks in advance for any help!

 

I think most if not all the t5 are nla new. Can convert the signal with a Dakota digital sgi-100bt

 

Thanks for the recommendation re: signal converter

What do you mean by "NLA"?

 

No longer available

 

A few options: Your T5 car would probably drive better with more gear. AFAIK, GM didn't offer a V8 T5 / 2.73 conbo.

Jagsthatrun probably has a thread-on VSS to use with the plastic gear and sleeve. This would let you change speedo gears to calibrate. Be careful selecting which type of VSS.

Since your car is wired stock for speedo and ECM, you only need to adjust the VSS to DRAC signal. There are affordable single-in, single-out solutions for motorbikes that could work.

If you need to have a single-in, multi-adjustable outputs, Dakota is good and the newest versions are easier to work with.

 

Yes - totally agree. The trans swap became a bit of an unbridled cost due to needing some parts that were not included in the pile of parts I bought for my swap.

When I've recovered financially I'll probably go with 3.23 or 3.42 gears. I had 3.23 in my 88 Formula with an automatic and liked it. 3.42 might be a little more fun I think though.

The VSS solution in place is largely a sunk cost at this point, so I need to go with a ratio adaptor. Thanks for the Dakota recommendation. I decided to go with an Abbot ERA - a little more money, but I like the idea of having a piece of hardware set with mechanical dipswitches instead of the Dakota unit which relies on a smartphone app to set/calibrate.