cxracer

Hi,

I'm actually a '91 Miata owner and planning to upgrade my open differential with a LSD. After doing a lot of searching on Miata.net I found that I can stick a FC series RX7 in my Miata. From what I have learned after searching for parts, the RX7 LSDs sell for a lot less than the Miata 1.8L LSDs. I'm not racing, just track days and twisty roads, so there's no issues swapping parts other than compatibility.

From my searching in the 2nd generation forum it seems that the FC LSDs changed from Clutch Type to Viscous at some point. I know that for the Miata the Viscous LSDs that were sold on the 1.6L cars are prone to breaking pretty easily. What year did the 2nd gen RX7 change from Clutch Type to Viscous and why did Mazda make what seems to be a step backward in LSD functionality? I can't seem to find this in the FAQs or posts on LSDs.

I found someone selling a 1988 RX7 LSD. Would this be a Clutch Type or Viscous? Is there more value in the RX7 community for one type or the other?

Thanks for the help.

RotaryRocket88

iTrader: (7)

The '86-'88 GXL & GTU will have 4.1 clutch-type LSDs if manual, and 3.9 LSDs if auto. The series 5 cars ('89-'92) switched over to the viscous LSD.

Neither of these will be very expensive. NA stuff goes cheap; it's the turbo parts that will be more valuable.

Kerberos_8

iTrader: (2)

s4 turbo 2 cam with clutch type rear end as well. the turbo 2 diff has six clutch pads and the gxl model had 4 clutch pads

cxracer

Hi again,

I found someone with a 1989 GTS Auto car that they are parting out. I rember reading somewhere that Autos had 4.3:1 or am I on crack?

I'm thinking of rebuilding my Torsen from 4.1 to 4.3 to up the revs in my under powered 1.6L Miata

RotaryRocket88

iTrader: (7)

An S5 GTUs had a 4.3 LSD, but S5 autos had a mix of 4.1 open diffs or 4.1 LSDs depending on model.

GTS is a japanese trim level, and was never used in the US.

cxracer

Hmm

This guy must not know what he actually has http://sfbay.craigslist.org/sby/cto/1340469019.html

Which of the cars have 4.3:1 differential ring and pinion gears with the 7" ring?

Thanks

RotaryRocket88

iTrader: (7)

Only the '89 GTU-s model had a 4.3 LSD with a 7" ring gear. But it was a viscous LSD, and there were only about 1200 of them ever made.

cxracer

Do any of the cars in the first Generation (pre 86) that have 7in ring and pinion gears in 4.3:1 that would work with the second gen 7in differentials?