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I've been doing my own research on LSD's because I'm going to have one put into mine when I start driving it again. The LSD from S4 RX-7 turbos (1986-1988) should fit all 929's, FD's, and some miatas. The s4 turbo LSD is an 8 inch unit. I assume this is the same for the s5 rx-7 (1989-1991). FC gears don't fit the HC that one we all know for sure. So at the moment if you want to regear your HC you need to source gears from the HC. From the factory, USDM models got (3.7, 3.9) gears on the sereis 1 HC's. 3.7 on the manuals only and 3.9 on the autos only. I'm not sure about the USDM series 2 929 but most likely it's the same.

Someone should post all the gear and diff options for the were AUS and JDM Luce. I know nine2nine said his car has 4.1 gears. So gear wise that means we have three options available 3.7, 3.9, and 4.1

If I posted some any incorrect info some please correct me. This is just compiled info from notes I've taken while searching online. Also I'll have the info for what was available for the KDM Potentia.[/b]
s5 units will work, but they are VLSD and garbage. I swapped all 3 of my s5's vlsds for CTLSD
 

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Aussie DOHC 929 has 4.11 also.
 

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Just to put this to rest. A photo out of my owners manual. Owners manual out of a 1990 DOHC Aus delivered 929.

 

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hmmm maybe i should go up to the wreckers and get the DOHC diff then....
 

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So from what i know

Aussie 929's came with 3.7 & 3.9 ratios only

My JFT Luce has a 4.1 and so do the 13B Luce's

The rx7 crown wheel and pinion can be machined to fit fairly easily to accept the 929 bearings.
So if you get an FD rx7 4.3 you can slap her in the 929 :)[/b]
So how does this work? like whats involved?
 

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Isn't 4.3 a little over the top? They will greatly reduce your potential mph at the strip and make it rev harder on the highway. Im thinking about swapping to the 3.9.
 

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Does anyones HC on this forum get bad axle tramp?
blew my diff
thinking its probably the rear subframe bushings are rooted
 

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Discussion Starter · #72 ·
whats axle tramp ?

mine diff is vibrating like a bitch these days, it shakes the ride when the oil isnt warmed up...
 

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Axle tramp is when you go to do a burnout or drop the clutch and the drive wheels bounce up and down violently do to the shock loading on the drivetrain.
this is caused due to either worn suspension bushing or a wrongly setup suspension.
my fuel flap was coming open the tramp was that bad haha
quick explanation ;)
Maybe your diff bearings have had it 9ine Deuce?
 

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Axle tramp is when you go to do a burnout or drop the clutch and the drive wheels bounce up and down violently do to the shock loading on the drivetrain.
this is caused due to either worn suspension bushing or a wrongly setup suspension.
my fuel flap was coming open the tramp was that bad haha
quick explanation ;)
Maybe your diff bearings have had it 9ine Deuce?[/b]
I thought that was called wheel hop.
 

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Discussion Starter · #75 ·
How big of a job are the diff bearings ? I noticed the vibration the most around 1500-2200 rpm
 

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Your diff will have nothing to do with what revs your engine is at, as it turns at road speed, not engine speed. Sure its not at a certain road speed?

They are easy to get to, however they are not easy to get off the centre, they need to be pressed off. Once off, its as easy as knocking on the new ones and following procedures to put the diff back together.
 

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Discussion Starter · #77 ·
Your diff will have nothing to do with what revs your engine is at, as it turns at road speed, not engine speed. Sure its not at a certain road speed?

They are easy to get to, however they are not easy to get off the centre, they need to be pressed off. Once off, its as easy as knocking on the new ones and following procedures to put the diff back together.[/b]
Now that you mention it, I seem to get this vibration at lower road speeds. Somewhere between 15 - 50kms/hr. More noticeable at time when the car is cold but still there even when warmed up. An example would be when I let of the gas at 50ish and roll to a stop.
 

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Oh right, well just make sure you give your uni joints a good check over before you go to the effort of pulling your diff out. Uni joints can be checked by simply twisting them with your hand, or jerking them back and forth. There should be virtually no slack in them.
 

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What model HC 929 what i have to find to get a 3.7 ratio? And how can i tell?

Cheers.
 
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