W58 Speedo gears.....

[GREENVK]

Hi all.

I've recently dropped a W58 into my Commodore.

I'm running 3.45:1 ratio diff gears.

I have both an 11 and a 10 tooth drive gear in my box of parts (the gearbox currently has a 10 tooth one inside it), and I have a 10/33 and 11/33 and 11/32 driven gear sets.

According to threads I've found, I need an 11 tooth speedo drive gear, and a 30 tooth driven gear (based on the 3.42:1 diff ratio).

I made a trip to Toyota today, and had their parts guys looking through the computers, as well as the Japanese spec books.

They could only seem to find a part number for a 31 tooth driven gear, not a 30.

Can someone help me track down a 30 tooth, give me a part number ,or point me in the right direction (if i'm going the wrong way hehe)

Cheers!

[-==L=a=N=c=E==-]

instead of changing the drive gear, perhaps get a speedo cable step down box?

They go for about $110, can get them from most conversion shops (CRS and others). And most times in the ratio you need.

This is what i ended up doing with my hilux, as i couldn't find the appropriate drive gear.

[CrUZida]

I think we discovered a while ago that the 3.42 diff was a myth, and never existed (in F-series land).
So therefore a 30/11 gear never existed.

[GREENVK]

Ah really....

Hmm that's a bit of a bummer.

Might have to do as Lance suggests and use a conversion box....

[GREENVK]

I've done some calculations this evening.

I used a few online speedo drive calculators and they all say I need a 30.1 tooth gear to be dead on accurate.

Working on percentages of 100km/h:

With a 10-32, speedo would read 88.235 km/h (this is what is currently in the box, and seems about right)

With a 10-33, speedo reads 84.146
With an 11-33, speedo reads 92.493
With an 11-32, speedo reads 96.369
and with an 11-30, speedo reads 100.08

So I think with a 11-31 gear, it will be around the 98-99 mark, with is acceptable.

So I might go ahead and order one....

If I still am out, i'll get a speedo convertor unit


Cheers

[CrUZida]

The last thing you want is for your speedo to read lower than the speed you are doing (ie, speedo at 100kph, car speed at 102kph or so).
You really want it the other way for a bit of safety margin.

Your other option is to increase/decrease the tyre height by a few % to counter act the speedo.

Speedo out by 4%, change the tyre height by 4% (in the correct direction), and it will be close enough to spot on.