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Post by Horney on Apr 2, 2017 12:32:39 GMT
Is thed difference between 3.9, 4.1 and 4.3 diffs just the gearing, and therefore improved acceleration but lower top speed / less relaxed cruising? Gears and all that technical stuff makes my head hurt lol That's exactly it. They're the same but with a different ring Gear and pinion to change the ratio. |
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Post by thruxton on Apr 2, 2017 13:22:03 GMT
Hello Kinki.
If you want an lsd for fast road use then you must be driving like a crazy person.
The non lsd is fine for all road use an lsd on the road shows no advantage whatsoever.
You don't drive along and see the hedgerows full of MX-5's or other non lsd equipped cars.
If you want to fit an lsd for the hell of it then fine.
When choosing a final drive ratio to make a performance improvement in any car there are a few things to sit down and figure out.
What is the expected aim of the exercise?
Do you understand about the concept of inter-gear ratios plotted onto the torque curve of your engine graph and where the power band falls back onto that curve after a gear change at any given Rpm?
And then how the chosen ration of the final drive gear affects all of that?
For example.
A engine in our cars producing 240Bhp and 225ft/lbs of torque revving to 7000+ Rpm will gain an alround benefit to performance by running a 3.6:1 diff over the more standard diff ratios.
I only bring this to your attention so as you do not end up with a total lemon of a car with hopelessly awful gearing.
Regards.
Rich.
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Post by martiny on Apr 2, 2017 16:35:22 GMT
Thanks for the info!  Mine is a 1.8 £500 for fitting? Wow. I'd assume a couple of hundred. I heard the Quaife one was just a swop fit. Are the not "set up" out of the box? I guess the trouble in my mind is knowing if the unit is going to last. As you say, some will have been abused for years in 300bhp cars, then offered for sale. Potentially that is a gamble with quite a chunk of money, even used. Torsen failures seem to be pretty rare. And considering how many MX-5 torsen diffs are out there and how few 300hp cars, I wouldn't worry about it. A replacement diff core is just a swap fit, in that it just bolts straight into the ring gear, but it needs the right tools and technique to set up the preload and backlash when you reassemble the whole thing. The technique is described here: www.miata.net/garage/diff_rr.html I did it when I took a 3.6 Fuji to bits to remove all its snapped friction cone tabs so they didn't eventually slip out of the core and get eaten by the gears. Got an old secondhand 8" micrometer off eBay for peanuts and dial gauges are pretty cheap. Note that those instructions on miata.net don't describe how to set up a pinion gear if you removed that too. |
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Post by V6 on Apr 2, 2017 18:26:23 GMT
Thanks for all the info.
I have zero desire to change my ratios as they are perfect.
I was simply looking to have some fun. Sorry if that offends some lol
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Post by Horney on Apr 2, 2017 18:54:21 GMT
I don't think anyone is offended lol. I think we're just trying give you all the info so you can wither spend £1000+ on new diff or buy a used one for £250 and get pretty much the same result. Just looking to save you money bud! |
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Post by V6 on Apr 2, 2017 20:14:14 GMT
Everyone seems to be asking £500-650. I'm all ears for these £250 LSDs!
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Post by Horney on Apr 2, 2017 20:29:13 GMT
Everyone seems to be asking £500-650. I'm all ears for these £250 LSDs! Blimey where you looking? Last two I sold went for £250 each although I proved them for a quick sale. I never paid more than £300 for one. Pm JunkyardDog on here or Nutz. He breaks Mx5's and I've had a few off him. |
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Post by V6 on Apr 3, 2017 6:21:42 GMT
Ok cheers Horney
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Post by V6 on Apr 4, 2017 17:06:09 GMT
Didnt hear back from him. Thinking about it, that's the second time I've been snubbed by that guy wanting to buy stuff. Oh well. Quaife it is!
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rikk
New Here
Posts: 89 
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Post by rikk on Apr 5, 2017 8:41:50 GMT
Is thed difference between 3.9, 4.1 and 4.3 diffs just the gearing, and therefore improved acceleration but lower top speed / less relaxed cruising? Gears and all that technical stuff makes my head hurt lol Pretty much, yea. My 1.8 NA with a 4.3 Torsen 'cruises' at 4kish rpm while at 70mph. But getting up to 70mph is quite an enjoyable affair |
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foxy
New Here
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Post by foxy on Apr 5, 2017 9:06:39 GMT
Is thed difference between 3.9, 4.1 and 4.3 diffs just the gearing, and therefore improved acceleration but lower top speed / less relaxed cruising? Gears and all that technical stuff makes my head hurt lol I'm interested in this too. I'd like the acceleration but find with my '97 open diff 1.8 I'm cruising at about 80, but that's something like 4k or 4.5k revs. I'd rather lose a little acceleration with a more relaxed 80mph cruising speed and get a bit more power out of the engine. |
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Post by minty on Apr 5, 2017 10:49:41 GMT
I'm sure you meant 70MPH  |
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foxy
New Here
Posts: 26
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Post by foxy on Apr 5, 2017 18:48:59 GMT
I have a very long drive.
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Post by baconsarnie on Apr 6, 2017 11:23:21 GMT
Didnt hear back from him. Thinking about it, that's the second time I've been snubbed by that guy wanting to buy stuff. Oh well. Quaife it is! You're better off giving JYD (John) a call than pm or email... |
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Post by NurseHolliday on Apr 8, 2017 1:52:09 GMT
My car has a 2-way Mazdaspeed LSD made by Kaaz. It's expensive, totally unnecessary, but hilarious.
It takes some getting used to, you have to be a bit aggressive on entry otherwise it understeers, but the hook up and drive out of corners feels epic and sideways anywhere and everywhere.
If you're not going 2 or even 1.5 way I wouldn't bother with anything other than a TorSen.
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Mine is a 1.8
le sigh
Jul 15, 2023 20:03:52 GMT
le sigh
Jul 15, 2023 20:03:52 GMT