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I’m still confused because something doesn’t seem to add up.

It doesn’t make sense sport models didn’t come with an lsd but it does make sense that 82 is an lsd option otherwise the used market I don’t think would price it at that large of a premium over the 83. And I’m still not sure how to locate a 4.1 ring and pinion from a Quattroporte gt s which seems to be the same part number or why it would be a different ratio with the same part number if it is a different ratio than sport models at all.



my sources have been parts suppliers like scuderia and car and driver cross referenced against other websites. But something here or there is wrong. Maybe final drive ratio has to do with the manufacturer part number on the diff I’ve found a couple different ones like 3.33950.3, 3.51331.3 and not the part numbers we are discussing. Randy do you have any input on that how did you differentiate amongst ratio? That you referenced above. You also said both 82 and 83 in your research are the same external measurements is that correct?



I’ve also found another part number that some other website claim are relevant for certain years GranTurismo and Quattroporte 234007.

I will get my car on a lift in the next couple of days to see the part number it has and I will test for lsd by spinning the rear tires while in the air. So we can start to narrow it down a bit more and start to confirm some of this online info. Maybe we can get some clarification from the Quattroporte GT S owners as well.



Yes both are the same size, because some crashed gts had 83 while others had 82.

I also verified by spinning one wheel, the other goes the same direction.

And I spoke to about 5 dealers, all had different prices but the two superseded part numbers are ending in 82 and 83.

You can get the part number and ratio on the side of the diff. Jack up passenger rear and it is engraved on the side. Look near the front mount. Top of diff is the ratio number not part, but it is also listed on the side with the part number.
 

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Ive not seen anything to indicate that any GT's came with an open diff.
i went ahead and pulled out ye ole course book for m139/m145 cars and mentioned what i found there earlier. the conversation continued afterwords despite the info about ZF trans = LSD.

additionally, i wouldn't trust 100% maseratis parts look up/application charts. if looked up by VIN, it'll show the right part number. as far as the listings that show fits x y z.... i wouldn't. my info shows GTs use one, QPs use another. that would be the two part numbers likely. i believe they are replaced rarely enough that parts issues haven't made much ruckus yet.
 

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Per Maserati documents... Quattroporte V's with the ZF automatic all have LSD's. So I dont think any of them are open diffs.
 

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Discussion Starter #26
My car differential also has the number 3.45567.3 on it. I’m a 82 part number. Haven’t had it on a lift to confirm lsd yet should get it up next week. Randy differential is a 3.51331.3. I’m wondering what the difference is between the two. Anyone else with something different?
 

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Discussion Starter #28
I think your right but I think it’s still important to distinguish which numbers relate to which final drive ratios.
 

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So, i have a whine in my diff. I always thought i could only replace it with the 82 one (base GT). But from this thread i gather that i can also use the 83 diff that is on the sport auto cars?
 
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Those are the only two ratios that I'm showing in the service information..They show a 15/56 tooth for the M145 and a 13/46 tooth for M139...You can do the math from there....Jason
 
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I'm not sure and a 4.10 ratio would be pretty high considering the high regard for gas mileage these days...I know it is a 6 speed transmission, but when it last time you saw a car come with a 4.10 gear?? J
 

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Discussion Starter #35
3:5 & 3:73 as it works out - Thx J
So where are they getting this 4:10 ratio from ?
Car and driver in the link I included in my previous post as well as the same number is repeated by several other publications who all claim a 4.1 final drive ratio for the Maserati Quattroporte GT S I think years 2007-2011 or 12.

Either everyone is copying same wrong info or that info is in fact Maserati provided and is accurate and they just never changed the maintance manual for one low production car.

If someone can get me a vin number for one of those cars I found someone who has a differential in stock and they can confirm the other part number.

should improve 0-60 and 1/4 mile a lot particularly on a modified car or 4.2 liter which has a stronger redline. You will only be traveling about 200 rpm higher cruising at 70 mph barely noticeable.

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