mx5cartalk.com

Just a general question, why are 4.1 ratio LSD's so uncommon?

There are plenty if 4.3's for sale at any time, even 3.9's now and then. I don't see why there aren't as many 4.1's, given all 1.8L 5-speed NA and NB's are on this ratio in the open diff. I'm sure there are plenty of 1.8 owners that would prefer to avoid real world compromises by changing ratios, but only want the benefits of the limited slip. Hence the 4.1 LSD should be more popular?

They never used to be uncommon.At one stage that's all you could get.
a lot of the NA6 guys upgrade to the 1.8 drive line but a 4.3 diff is what came with the NA6. putting a 4.1:1 reduces the power a little
There isnt a lot of Torsens about with the AUDM NA8's as very few had them fitted from factory or even the dealerships
its probably more to demand & potential asking price those diffs have been brought in from Japan. Because in the past, 4.1 is all that was available. price in the past has been a lot higher for a 4.3:1 than say a 4.1;1
so when someone imports a bunch of parts they are more likely to go for parts which are sought after like the 4.3:1 which atm there seems to be almost an over supply.

when i upgraded to the Torsen on my NA6 about 12 years ago......4.3 Torsens were like hens teeth.

Agreed 4:3 use to be the hard ones to find. I went from open 4:3 to LSD 4:1 in my NA6, made an improvement at my local track. There was a couple of places neither 2nd or 3rd worked that well with a 4.3.

4.1's in general are getting harder to get hold of...... I have been asked by race guys with other models of Mazda's for 4.1's and I am struggling to get any at a reasonable price. I just managed to get hold of some gear sets in Japan but in unknown condition will only be suitable for race cars. I do have a 4.10 T1 complete diff with just over 100k on it so have been very reluctant to sell off the gear set to a race car guy. Also got a 4.3 T2

3.90's seem to be the main ratio available in Japan at the moment in the reasonable price range.

Interesting how things have changed - as mentioned 7" 4.3 LSD used to be scarce & 7" 4.1 common enough, even though the Aust domestic market didn't get many 4.1 LSD factory fitted in NA8. Aust domestic market NB8A were 4.1, but none with factory fitted LSD. Only 10AE had LSD & that was 3.6. Aust domestic market NB8B-> were 3.6, but only SE had LSD.

I read all this and think of the fact I'm considering changing to a 4.7 since I don't do anywhere near the amount of highway kms I used to.

Nik......Why not try a 4.44 first?