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Re: Building an RX7 LSD diff
Posted: Tue Jan 13, 2015 3:11 pm
by ian65
Lucky wrote:MR TOOL, can you offer any advice as to which flavour of MX-5 diff will fit in this process? I might be able to get hold of a Torsen diff from a top-spec Series 2 MX-5, will that be OK? I'm guessing a Torsen diff is preferable to a multi-plate one
viewtopic.php?f=11&t=170
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Re: Building an RX7 LSD diff
Posted: Tue Jan 13, 2015 3:39 pm
by Lucky
Ta. Damn, how many threads did LSDs run to?
Re: Building an RX7 LSD diff
Posted: Tue Jan 13, 2015 7:17 pm
by TOOL
As that other thread says, you need a 7 inch diff head (that's measured by the crown wheel size).
Afaik, all the 1.8 MX5 diffs are 7 inch. The trick is working out which ones have the Torsen diff though, not the open diff. I prefer Torsen type 2 over type 1, they just look more robust. I prefer clutch type LSD over Torsen, as you can rebuild them and "tweak" them.
Note, some MX5 are 3.9, 4.1 and 4.3, but I've never been able to find a 4.3, and no-one seems to know how to work out which cars had them (if any in the UK market)
Here's a useful link for IDing Torsen centres:
http://www.miata.net/garage/diffguide/
Re: Building an RX7 LSD diff
Posted: Wed Jan 14, 2015 5:29 am
by re japi
Here is one link which has good info
Re: Building an RX7 LSD diff
Posted: Wed Jan 14, 2015 8:40 am
by ian65
re japi wrote:Here is one link which has good info
some great info there, where did that come from?
Re: Building an RX7 LSD diff
Posted: Wed Jan 14, 2015 8:49 am
by TOOL
That's from the Mazdaspeed Competition Parts Catalogue.
It's right near the bottom of the RX7 manuals on
www.foxed.ca
Re: Building an RX7 LSD diff
Posted: Wed Jan 14, 2015 10:27 am
by Lucky
Great stuff, thanks guys. I'll try to snare one then
Re: Building an RX7 LSD diff
Posted: Wed Jan 14, 2015 11:45 am
by re japi
Friend of mine found it.
Lucky, I have diff for sale. Just started a topic in sales section. Also, its for sale in Facebook rx7fb site...
Re: Building an RX7 LSD diff
Posted: Wed Jan 14, 2015 12:46 pm
by biznatch
The competition part manual mentions the torsen type 2 being a higher ratio than the type 1 - anyone on here know which torsen is closest to our stock ratio?
Re: Building an RX7 LSD diff
Posted: Wed Jan 14, 2015 2:15 pm
by TOOL
They were talking about the bias ratio, not the gear ratio.
Note GSL-SE is 4.11 gears and UK S3 is 3.9.
When fitting one of these diffs, you need to remove the Torsen cerntre and fit it in the RX7 carrier, with the RX7 ring and pinion, otherwise you'll get binding on the RX7 suspension components (watts link).
See page 1 of this thread.