Fitting Holden IRS LSD

1Hotmx5 · Post by **1Hotmx5** » Thu Sep 13, 2007 3:32 pm

Hi there im new to this forum (so be gentle

)and happy to be part of it. Im interested in fitting a 3.08 IRS LSD to my NA. Ive seen that some people in this forum have done this and was wondering how difficult it was to do and certification Thanx

Anthug · Post by **Anthug** » Thu Sep 13, 2007 4:37 pm

Hi,

Not sure about the Holden diff but an NB LSD will fit.

There is a guy who has fitted Nissan LSD's (Skyline etc) but new mounts had to be made.

Regards,

Anthony.

1Hotmx5 · Post by **1Hotmx5** » Thu Sep 13, 2007 7:29 pm

Hi there Thanx for that info Anthony . Do you have any idea what gear ratios the NB diffs offer ?? Im looking for a ratio between 3.0 and 3.5 Cheers John

Ian · Post by **Ian** » Thu Sep 13, 2007 9:05 pm

Series 4/5 RX7 rear ends are a popular fit for guys running V8s or high power rotaries. Is this why you are contemplating the Holden?
If you are in ChCh you could check with some of them....
I believe the Aussie MX5 SP (runs a 3.6 cwp) and is about the tallest of the NA/NB ratios.

Ian

Ian · Post by **Ian** » Thu Sep 13, 2007 9:12 pm

PS Jeremy (ChCh member MX4000) is in the process of fiting a commodore diff ...his NA has a Lexus V8 which sometimes sports a turbo!!

Ian

MX4000 · Post by **MX4000** » Thu Sep 13, 2007 10:25 pm

Just got it going tonite. The revs are far more sane than with the 4.1 RX7 rear. Mounting the diff head is pretty easy. The rear rubber mount can be bolted to a tapped plate welded straight on the rear subframe. I cut a piece of angle into the front subframe member to pick up the front mounts and bolted a bar to the centre of the diff to attach to the normal MX5 pick up points. Used Nolathane shock mounts to isolate it. I'll post some pix.

No issues with the driveshaft (as long as you measure it right - don't ask!)

Hoped to find a suitable CV to go on the inner end of the RX7 axles but no joy. Ended up getting them welded. I'll see how they last!

1Hotmx5 · Post by **1Hotmx5** » Fri Sep 14, 2007 7:22 am

Hi there I appreciate the helpful responses Thanx

1Hotmx5 · Post by **1Hotmx5** » Fri Sep 14, 2007 7:25 am

Hi there I just thought that it would be an easier swap being from an IRS and yes looking at a V8 so stock ratios would be no good. Cheers

SLYDIT · Post by **SLYDIT** » Fri Sep 14, 2007 5:01 pm

the lowest available factory ratio is 3.6:1 as found in some 6 speed "NB" mx5's although there is a group buy trying to get started in the states for a 3.3 gearset to be made up.....

you may find that a combination of 3.6 diff gears and an RX7 gearset may get you what you want..have a look here:

http://forum.miata.net/vb/showthread.ph ... hlight=3.3

if your doing a v8 swap then this is the place for you...everything from LS1 v8's to windsors and lexus v8's stuffed into mx5's....

http://forum.miata.net/vb/forumdisplay.php?f=38

1Hotmx5 · Post by **1Hotmx5** » Fri Sep 14, 2007 8:07 pm

Hi there thanx for that great site (interesting to see what state side are doing) Cheers again John

Fitting Holden IRS LSD

Fitting Holden IRS LSD

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