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Auto to manual diff


russyb

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right guys id like quicker acceleration without doing the valve body mod on my JDM tiptronic.

 

now ive heard that with a little magic you can make the a 6speed MT diff fit into my auto, which would give me shorter gearing and better acceleration changing my diff ratio's from 3.3 to 3.5,

which if my research is good thats about as far as you would want to go with an auto

 

has anyone done this here in the uk and any realtime gains from it ?

 

cheers in advance

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I understand what ur saying but on paper there are gains,

 

I just wondered in a real world situation if it would be worth doing,

 

Not sure if you can compare 2 different cars though but thanks for your comment

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I understand what ur saying but on paper there are gains,

 

I just wondered in a real world situation if it would be worth doing,

 

Not sure if you can compare 2 different cars though but thanks for your comment

 

I meant i've owned both an auto and manual 350z. They were very similar in terms of power delivery. Only improvement on the manual was the ability to be able to control a drift if you're into that sort of thing.

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I've got a 350gt jap import auto/tiptronic that I use as a track car. It had a standard open diff so after the last track day I decided it needed an LSD. I've just fitted an LSD from a manual 350z. To be honest I didn't know they were different ratios, looks like I'm in for a bit better acceleration then. I'll let you know what difference I notice.

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I've got a 350gt jap import auto/tiptronic that I use as a track car. It had a standard open diff so after the last track day I decided it needed an LSD. I've just fitted an LSD from a manual 350z. To be honest I didn't know they were different ratios, looks like I'm in for a bit better acceleration then. I'll let you know what difference I notice.

 

Jonny can I ask if it was straight forward did you need to swap any parts over to make it fit ?

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It was a straight forward swap. All the mounting points, drive shafts, prop shaft etc all bolt up exactly the same. The worst part was man-handling the thing into place, it's a heavy little unit when you're laid on your back on the driveway.

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This is sounding very interesting as it's a simple swap unlike the valve body which is a absolute dog of a job.

 

Cheers for all the extra info though Jonny and keep me posted on the improved acceleration :)

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Cheers for all the extra info though Jonny and keep me posted on the improved acceleration :)

 

I've just got the brakes to swap over for a set of brembos I've bought, then I'll be getting another track day booked. So it'll be out again within the next few weeks hopefully. I'll report back if I notice much difference with the diff.

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  • 3 weeks later...

I meant i've owned both an auto and manual 350z. They were very similar in terms of power delivery. Only improvement on the manual was the ability to be able to control a drift if you're into that sort of thing.

 

Its less a case of comparing an auto gearbox car fitted with an auto diff, to a manual gearbox car fitted with a manual diff, as fitting a diff meant for a different gearbox would have a different final drive (think thats the correct term?).

 

Best way to think of it is in terms of numbers, rather than gears. If you wanted to add two numbers together to equal 10, you could use many combinations.

If we say that an auto car is 4+6, and a manual car is 5+5 (the first number being the gearbox the second being the diff).

Swapping the diffs would give you an auto car with a manual diff and a manual car with an auto diff.

Auto car 4+5= 9

Manual 5+6= 11

 

Fitting an auto diff to a manual car will essentially give you different acceleration and top speed; however it was my understanding (from other cars) that fitting an auto diff to a manual car improved acceleration due to the nature of the autobox. So using that frame of thought, perhaps it would numb the acceleration and in actual fact give you a higher top speed. However, whether that figure above refers to top speed or a rating of acceleration, who knows! I've only had the car for 3 weeks!

 

All that said, if it was me I would be looking into getting an aftermarket LSD with the ratio to suit, one that locks up better for my requirements. Whatever they may be!

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