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The mkiv Supra Owners Club

Supra specific gear/diff ratio and tyre size calculator


Homer

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Thanks for the comments guys.

 

There's a reason I didn't use drop downs - it's not always as clear but as selecting the car type, i.e. TTRickeh who has a facelift with the v160, there's quite a few cross overs.

 

I also preferred to keep the diff ratio box free text so that people can enter custom ratio's to see the output.

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It's not possible to type in the diff ratio in your custom version, gives a nasty error message!

 

What's a ring/pinion ration Homer? :D

 

That's exactly why i'm not using drop downs

 

and, erm, whoops :D

 

Just made a small change to Homer's original with a drop down, but also added some info for the r154 gearbox in case anyone's using that.

 

Don't know if it's useful to anyone?!

 

Good point on the r154, I'll add that option into the final version :thumbs:

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Thanks again for all your input guys, the (hopefully) final version is loaded below.

 

As mentioned before I've left out the drop down menus to allow free text entries in case of custom diff size.

 

Any further feedback for it gets loaded to Tech articles?

 

You are quite "The Man" sir. :)

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I showed this to the guys at work today, one asked a good question. It's about the final drive ratio between the facelift & non-facelift models. It's down as 3.267 & 3.266.

 

Are these figures actually correct, I mean did they create a new diff which was 1/1000th different? Is this even possible, I guess by adding even one more tooth on either cog the ratio would be changed by more than that.

 

Or Is the actual ratio something like 3.267777777777777 with one guy rounding up & the other truncating when the different sources of information were scanned?

 

Or are the diff's actually 2 different values, if so how is this achieved (ie what are the specs on the gears in the diff).

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I showed this to the guys at work today, one asked a good question. It's about the final drive ratio between the facelift & non-facelift models. It's down as 3.267 & 3.266.

 

Are these figures actually correct, I mean did they create a new diff which was 1/1000th different? Is this even possible, I guess by adding even one more tooth on either cog the ratio would be changed by more than that.

 

Or Is the actual ratio something like 3.267777777777777 with one guy rounding up & the other truncating when the different sources of information were scanned?

 

Or are the diff's actually 2 different values, if so how is this achieved (ie what are the specs on the gears in the diff).

 

 

That's a good question Jay :) I did wonder when seeing the figures too. All the data sources I could find (mkiz NZ site, aus site, various versions of epc, Nic, and a few others) all consistently indicated that there was a different ratio on the two models.

 

It is a little odd why they would bother, however there could be an explaination... The pre factlift 6spd came with the 'large' diff casing, apparently the facelift came with the smaller one, therefore a slightly different gear & pinion size

 

Maybe you could help here.. would you be able to post your diff code and ideally a picture of the back end of the diff?

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Top stuff, looks like mine might have a 3.769 ratio :search:

 

Odd, as your one is pre-facelift and has the large casing. Can you let me know the diff code on your VIN?

 

You had the innerds changed to a TRD right? Wonder if that has a different ratio..

 

Edit - just seen Tony's reply in the other thread. Will be interested to see that VIN code Wes. Also, can you let me know the chassis number and month/year of the car?

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Edit - just seen Tony's reply in the other thread. Will be interested to see that VIN code Wes. Also, can you let me know the chassis number and month/year of the car?

 

My mistake, diff code is B03B so should be 3.267, when the car is next running I will get a log of MPH vs RPM in 4th.

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My mistake, diff code is B03B so should be 3.267, when the car is next running I will get a log of MPH vs RPM in 4th.

 

Edit again: Found the problem, Digsy's VIN plate decoder isn't correct with the axle codes. This is getting confusing again! If you could send me your full VIN plate at some point Wez it'd help try and nail all this down :)

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The first B means it's the large casing, 03 means a 3.769, last B means an LSD. An odd combination and not sure I've seen this before. Any chance you can send the model code as well :D Is it an RZ or RZ-S?

 

Its the normal code isnt it :-

 

Crown Wheel Size: A (8'' - 203mm), B (8.7'' - 221mm)

Differential Ratio: 01 (4.083:1), 02 (3.769:1), 03 (3.267:1)

Differential Type: A (Standard open differential), B (Torsen LSD)

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Nevermind :)

 

The issue with those codes is that I have many VIN plate examples which have the B02B code but with the 3.2 ratio diff fitted, all are early model RZ TT 6spds :search:

 

EDIT - the above information is incorrect - see below for update

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