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gear ratios seem all wrong to me on my 6psd TT - opinions please


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Had my 1997 6psd TT for a few months now and as i'm getting used to the car the ratios of speed vs RPM in various gears just seems wrong to me going from online information.

 

I asked Jurgen who imported the car and he said the cars got a V160 gearbox, but i've not had it on my ramp yet to confirm myself so looking at all options.

 

Tonight i was testing a few speeds out and at 80mph (speedo and gps) my tech is reading 3100rpm (i'll confirm this digitally once i get the avcr installed)

 

so 80mph = 3100rpm on my car

 

going from internet information it should be

 

80mph = 2666rpm on a V160

80mph = 2751rpm on a V161 (not taking that mines a v160 for granted)

 

the 80mph i'm 100% sure is correct, i checked the other speeds as well at quick glance and there running higher RPM that listed as well.

 

Can anyone confirm these numbers on there 6psd TT, or is there a shorter final drive kit available for the supra that i don't know was fitted? I don't mind just curious, Started when i saw people claiming the stock gearbox ratios will do 205mph and 197mph at stock 6800rpm redline just seemed stupidly high when calculating revs and speed as i'm driving. Going on the maths i've seen then at 6800rpm mine would do 175mph so quite a bit shorter if there are modifications done

 

Tim:blink:

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yes sorry forgot to say they are running on standard facelift 17's wheels and tire sizes.

 

speed is just confirmed on the satnav and both read the same, not the most accurate i know but better than a guess.

 

I'd say speed is about right as if its reading under it would be setting off the 30mph speed cameras lol,

 

as for spec of the car its all very standard, but that doens't mean it has always been standard in japan and some bits left in i don't know about. At this point i'm totally in the dark on its appearance underneath as well, i have planned to get it on my ramp and give it all a good check over but i've got the project from hell in my garage at the moment hogging my ramp, anyone who knows me will have been informed all about this haha. So at this point anything is just a guess until i can get underneath.

 

Just seems funny that its so far off.

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3100rpm on a V160 should give 89.1mph in 6th (70.6mph in 5th).

 

2783rpm on a V160 will give 80mph in 6th.

 

3100 on a V161 should give 86.3mph in 6th with the same 70.6mph in 5th.

 

2873rpm will give 80mph in 6th on a V161.

 

*EDIT* These values are for a 255/40/17 rear tyre with a 3.266:1 diff. :)

Edited by James (see edit history)
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A tt auto diff with a v160, and stock tyre sizes at 3100rpm = 77.2 mph, there's a gearing calculator here:

 

http://mkivsupra.net/vbb/showthread.php?184490-Supra-specific-gear-diff-ratio-and-tyre-size-calculator&highlight=gear+calculator

 

If you have 255/45/17's on the rear, with the auto diff and the v160 it comes out at 80.3mph if that helps at all

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The tachometers on these are known to read high and are classed as within tolerance even when displaying something like 10% (can't remember the exact figures) over actual rpm. I'm sure the figures are in the workshop manual somewhere. Once the engine is spinning at 3-4000rpm, the permitted tolerance is only to read high, not below actual rpm.

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right ok thanks guys for the feedback.

 

i'll get a better understanding once i get the avcr in and can take a digital display from the ecu RPM feed.

 

Is there any strength differences between the Auto and Manual diffs?

 

i understand there is 2 different diffs you can get a large and small or something depending on years

 

Tim

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right ok thanks guys for the feedback.

 

i'll get a better understanding once i get the avcr in and can take a digital display from the ecu RPM feed.

 

Is there any strength differences between the Auto and Manual diffs?

 

i understand there is 2 different diffs you can get a large and small or something depending on years

Tim

 

Correct,

 

A03B = Small Case LSD

B03B = Large Case LSD

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