Diff Ratios

[Bl4cK32]

Ive got a Nismo GT Pro 2 way centre in my r32 GTst diff.

Im thinking about swapping to a s13 ratio to get some more use out of the gearing, BUT i wanna keep my 2 way diff.....

What part of the diff determines the actual ratios? Someone said it is the ring gear(?) inside the housing? Ive found sfa info on it (hard to find) - is it a simple job of :

a : swapping the centre and half shafts from my diff housing to a s13 housing with the s13 ring gear?

or

b : sell my 2 way and buy a s13 lsd centre and have it shimmed up (dont wanna go this route)

So is it the centre, the housing, or the ring gear? inside the housing that determines the ratio in the car?

thanks

Edited October 23, 2005 by Bl4cK32

[blind_elk]

The ratio is determined by the number of teeth on the crown wheel and the pinion. The number of teeth on each should be stamped on the crown wheel somewhere.

The crown wheel should un-bolt from the centre. You need to swap both parts (the CW and the pinion).

[Bl4cK32]

so could i swap these parts over from a s13 lsd to my 2 way centre, lowering the ratio?

[predator]

Crown and pinion gears like above.. thankfully you can just swap the correct ratio of these from another suitable diff to get a new ratio, and keep your fancy 2way centre.

just pull them out of the s13 diff and get them swapped across.. shouldn't cost much.

[Bl4cK32]

WOOHOO thanks guys - made my day

[Trust33]

So all he needs to change the ratio of the diff to the taller s13 ratio is to swap thw crown wheel and this is a sraight fit.

Would somthing like this Work for a r33.What is interchangable in the 33gts-t

[blind_elk]

So all he needs to change the ratio of the diff to the taller s13 ratio is to swap thw crown wheel and this is a sraight fit.

Would somthing like this Work for a r33.What is interchangable in the 33gts-t

<{POST_SNAPBACK}>

And the pinion gear - they are a matched set.

Should work for any (R200) combo - I recently did this to fit Stagea ratios (4.083) in my R32 GTS4 (4.375).

[Bl4cK32]

how did the revs change blind_elk?

whats it like at 60km/h in 4th and 100km/h in 5th?

[blind_elk]

Haven't actually got it back on the road yet. But the speedo will be out by the ratio of the 2 gearsets. The Stagea gearset is approx 7% less than the GTS4's. It used to do roughly 3000 rpm @ 100 kph, so I expect to be doing roughly 2800 rpm with the new gearset.

I certainly plan on getting the speedo re-calibrated to suit the new ratios so I don't forget that the speedo now reads less than actual, and get photographed a few too many times.

[Gav]

Haven't actually got it back on the road yet. But the speedo will be out by the ratio of the 2 gearsets. The Stagea gearset is approx 7% less than the GTS4's. It used to do roughly 3000 rpm @ 100 kph, so I expect to be doing roughly 2800 rpm with the new gearset.

I certainly plan on getting the speedo re-calibrated to suit the new ratios so I don't forget that the speedo now reads less than actual, and get photographed a few too many times.

<{POST_SNAPBACK}>

I was just about to post asking the question of speedo recalibration. Is this a difficult or expensive job?

I assume that if a PFC is fitted this will read wrongly for speed?

Cheers

Gav

[Paradizzle]

What are the gear ratios for a standard r33 gtst?

[blind_elk]

I was just about to post asking the question of speedo recalibration.  Is this a difficult or expensive job?

<{POST_SNAPBACK}>

Already asked that one myself. I think they quoted $275. Not sure how it's done - someone suggested they fit a new speedo drive gear in the gearbox.

$275 sounds a lot, but it's only 2 photographs!

[tom_g]

Already asked that one myself. I think they quoted $275. Not sure how it's done - someone suggested they fit a new speedo drive gear in the gearbox.

$275 sounds a lot, but it's only 2 photographs!

<{POST_SNAPBACK}>

It cost $418 for mine to be done, but they also repaired some wiring and tested the oil pressure gauge so I don't know what the speedo adjustment really cost. They used some sort of ratio conversion box to do the speedo adjustment. eg. speedo cable from gearbox goes into conversion box. Conversion box outputs adjusted speed to speedo.

It seemed like a strange way to do it but it works. I've tested it with a GPS and its fairly accurate.

$418 seems like a lot but luckily it was before i bought the car.

[Gav]

Thanks guys - does anyone know where the CPU take it's speed information from?

[Oosh]

This is a good question, my speedo (and tacho i think) reads ~10% high, but the figures reported via the consult port is accurate.

[Bl4cK32]

im guessing, but id say it takes the speed reading off the dash, as i havent got my speedo cable working atm (no speedo reading on the cluster) and the pfc hand controller shows no speed.

Cubes has his speedo working, and the speed reading works on the pfc.

I dont know if its the same as for the std ecu though...?

[Oosh]

I've got a lot of the surround stuff off at the moment so i might pull my dash out and see what happens...

[blind_elk]

Just followed up on the fix. They insert a converter between the gearbox and the speedo cable. One of the firms I spoke to will fit it for you in a day, cost $275. The other test then supply the converter (you need fit it) for $175.

Pretty sure I could fit it myself in under 1.5 hrs (at approximate labour rates).

[Gav]

Just followed up on the fix. They insert a converter between the gearbox and the speedo cable. One of the firms I spoke to will fit it for you in a day, cost $275. The other test then supply the converter (you need fit it) for $175.

Pretty sure I could fit it myself in under 1.5 hrs (at approximate labour rates).

<{POST_SNAPBACK}>

Would this be a mechanical type converter or an electronic type?

[Oosh]

Would this be a mechanical type converter or an electronic type?

<{POST_SNAPBACK}>

Mechanical, if you have a wholey electronic send then there's an Autospeed/Jaycar kit lets you DIY.