CharlesM505 said:
Hi Guys,
Looking for some advice from the experts amongst you here, and those with experience. I currently have an M140i Auto on order, and know from previous vehicles that an LSD will be a welcome addition. Question is, should I just save the hassle and add it to my build or get the car then have Birds fit the Quaife. I would like to know if there are any differences in how they operate (I read on another post 30% lock on power from the M - Performance?) and in how they feel.
Obviously there is the advantage of the BMW LSD keeping any warranty and not requiring your standard diff as a donor (correct me if wrong). It would be interesting to hear the best prices people have obtained on either, as well as any comments over this.
Personally I think both options are great upgrades.
On the warranty front, unless it's actually the diff itself that goes bang, it is almost impossible for any inspection to pick up the quaife internals. It's almost how quaife became so popular, apparently the quaife passed the rally car scrutineering in classes where LSD were prohibited. The test at the time was to rotate one wheel by hand, and in normal open diff operation, the other wheel would either stay still or rotate in the opposite direction. They then changed the test to jacking up one wheel and trying to drive. Most LSD will drag the other wheel round in the same direction. The quaife acted just like the open diff in these tests.
So if there was a gearbox or engine failure, unless the diff cover was opened, the quaife would be invisible. There is no reason to open the diff cover for a engine or gearbox failure. The diff needs to come out for this too.
Regarding costs, you are missing that you can also recover money back on a used quaife. BMW dealerships often sell off delivery mileage diffs when MP LSD are fitted. Cotswold sell them for as little as ÂŁ100-150. By the time you sell your car, the scrapyards will be full of cheap diffs anyway. So although a spare diff is not part of the quaife deal, you can acquire one cheap enough to recover some cost.
I do laugh at the people that mention a quaife with the wheel in the air is as useless as an open diff. Well yes but how often do you want maximum traction whilst one rear wheel is flying through the air? And if you are lifting an inside rear wheel often enough to be causing an issue, I think you'd have a bigger chassis problem to solve than how the diff behaves.
Someone mentioned quaife not recommending their TB diff for tracks. Nonsense, I spoke to quaife at the autosport show a month ago. They work very well on track, but are not the best at drifting.....but then neither is the bmw lsd with 30% lock. You want a far more aggressive 2 way diff for drifting.....together with a hydraulic hand brake. Anyway, my F30 performs well on track with the quaife, but it is the street where it is most noticeable. One wheel over a slippery wet manhole cover? No issues, the other wheel continues to push you forward, without TC flickers.
As I say, both diff types would suit me, and probably you too. As quaife can be done for as little as ÂŁ1250 to me, that is a grand cheaper than BMW's MP diff, so probably my route again on my m lite.
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