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Fitting a R31 Skyline B/W diff to LH/X


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#26 _rocket_

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Posted 16 October 2008 - 05:03 PM

Top set up Rory, Im ditching the 9in for this conversion atm, hopefully ready for Bathurst at easter, thanks for sharing your work with us.

#27 _rorym_

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Posted 16 October 2008 - 05:37 PM

Well you needed a new diff...Aussie Diffs at Currumbin will do it..NOS' is nearly finished I think...The weight saving is a bonus as well. Whistle if you need a hand fitting it...Just a drive down the road. You should be $ neutral after you sell the 9"...NOS has another Nissan housing also...not sure if he wants to sell it.
R

#28 _rocket_

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Posted 16 October 2008 - 05:53 PM

Ive got everything, just need to change the brackets.Thanks for the offer.

#29 _rorym_

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Posted 16 October 2008 - 09:48 PM

Talk to Mark down there...nice guy..knows his shit...
R

#30 sl308

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Posted 16 November 2008 - 07:25 PM

just fitted the nissan diff and discs brakes this weekend.
made up a couple of brackets to use the standard torana handbrake cables using modified handbrake cable joiners(thanks tuf308)
question, do you have to change the brake proportioning valve for the rear discs
thanks,
steve..

#31 76lxhatch

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Posted 17 November 2008 - 07:15 AM

Yes remove the proportioning action entirely from inside the valve (make sure it seals properly afterward)

#32 sl308

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Posted 17 November 2008 - 04:01 PM

Yes remove the proportioning action entirely from inside the valve (make sure it seals properly afterward)

thanks for that

#33 ls2lxhatch

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Posted 17 November 2008 - 05:48 PM

If you disable the factory prop valve you may want to look at fitting an adjustable prop valve. You can expect the rears to lock before the front brakes if you do not have a prop valve.

#34 76lxhatch

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Posted 17 November 2008 - 05:51 PM

The rears shouldn't lock with discs all round, especially when the rears are only the smaller Skyline ones. I have no proportioning front to rear and there's no way the rear is going to lock first, although I do have bigger brakes up front.

edit: the reason I went that way was because Hoppers Stoppers recommended it, and has worked out well

Edited by 76lxhatch, 17 November 2008 - 05:56 PM.


#35 ls2lxhatch

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Posted 17 November 2008 - 07:05 PM

Hopper Stoppers gave me the same advice regarding disabling the prop valve.

I decided to fit an adjustable prop valve for two reasons.

1. My car has to pass an engineering brake test.
2. I like the idea of being able to adjust the brake bias if required.

The Skyline callipers without a prop valve should have no problems locking the rears before the front brakes under heavy braking on a street car.

#36 _rorym_

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Posted 17 November 2008 - 07:25 PM

Yes remove the proportioning action entirely from inside the valve (make sure it seals properly afterward)



Think you 2 are talking about different things...one to remove is the brass olive in the big hole on the master cylinder...the prop valve is the one bolted to the inner guard...Yes??
R

#37 ls2lxhatch

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Posted 17 November 2008 - 08:10 PM

I think we are both talking about the proportioning valve fitted to the guard. We all agree on removing the residual valve from the master cylinder however that is only half the job when converting from rear drums to discs. If you leave the standard drum brake prop valve as fitted then the rear disks will hardly work at all due to the low pressure required for drums. The disc/drum prop valve is around 150 psi and the disc/disc prop valve is around 450 psi.

This is the email I received from Peter Koning regarding deleting/disabling the proportioning valve. I was rather suprised by his suggestion of deleting the prop valve.

If going 4 wheel discs remove the residual valve and fit a 450 psi prop valve, or maybe delete it totally as this is a pretty high pressure that doesnt occur in practice.


He also mentions disabling the prop valve on page 5 of this document.
http://www.hoppers.c.....and pumps.pdf

Combined fail switch and Proportioning valve, discard nylon poppet if no rear prop valve required, better still fit an adjustable unit.



#38 76lxhatch

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Posted 18 November 2008 - 06:10 AM

Yes definitely talking about the prop valve not the residual pressure, and I see where you're coming from. All I can say is that mine has the Hoppers 290mm twin piston front brakes and Skyline rears with the factory proportioning valve modified so that it no longer closes and I can't lock the rears first. It has recently passed certification for these and other changes. I do have more rubber on the rear than the front if that makes any difference at all.

My car is just for street and the occasional off street drag racing etc, if it were anything more serious I would certainly be looking into an adjustable prop valve. I used to have a ute that would lock the rears with factory brake setup and it used to piss me off no end, if the Torana started doing anything like that it would be fixed pronto.

#39 76lxhatch

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Posted 18 November 2008 - 06:11 AM

Anyone who has Commodore rear brakes may find a different situation as they are larger diameter

#40 _rorym_

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Posted 07 January 2009 - 10:11 PM

I think we are both talking about the proportioning valve fitted to the guard. We all agree on removing the residual valve from the master cylinder however that is only half the job when converting from rear drums to discs. If you leave the standard drum brake prop valve as fitted then the rear disks will hardly work at all due to the low pressure required for drums. The disc/drum prop valve is around 150 psi and the disc/disc prop valve is around 450 psi.

This is the email I received from Peter Koning regarding deleting/disabling the proportioning valve. I was rather suprised by his suggestion of deleting the prop valve.



He also mentions disabling the prop valve on page 5 of this document.
http://www.hoppers.c.....and pumps.pdf



Just revisited this thread..LS2 has a point..maybe an adjustable prop valve is the way to go for me as I am convinced the rears are not performing to their max.
R

#41 _LHoon_

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Posted 07 January 2009 - 11:04 PM

The Nissan diff is about 10mm wider each side but you pick that up with the discs which bring it back into line at the same length,remove the 3mm backing plates/dust covers behind the rotors will help.


If you remove the 3mm backing plate, doesn't that mess with the way the axle is bolted onto the tube? It seems like the 3mm backing plate also acts like a spacer. I tried doing this on mine and the plate on the axle started bending and was placing too much force on the tapered axle bearing. Or am I doing something incorrectly?

#42 76lxhatch

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Posted 08 January 2009 - 05:48 AM

Maybe cut them up or make a new plate that just provides the spacing required but doesn't cover the disc?

#43 _rorym_

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Posted 08 January 2009 - 06:48 AM

Run mine since day one and they are fine.
R

#44 _rorym_

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Posted 08 January 2009 - 08:49 AM

From Konig's above document.
R

You might be able to delete the nylon spool from inside the existing prop valve so that it no longer works at all, this means that in an emergency you might lock the rear brakes if you press hard enough, but usually well after the front brakes have locked. The acceptability of this will depend on how the rears perform in emergency situations, which means a careful road test.

Edited by rorym, 08 January 2009 - 08:49 AM.


#45 _LHoon_

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Posted 08 January 2009 - 09:53 AM

Maybe cut them up or make a new plate that just provides the spacing required but doesn't cover the disc?


But that would defeat the purpose of removing it (to try to remove an extra 6mm from the overall diff length)...

#46 _rorym_

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Posted 08 January 2009 - 10:21 AM

All it does is push the seal in a bit tighter...dont think there is any more load on the bearings.
R

#47 _rorym_

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Posted 09 January 2009 - 10:46 AM

OK..Removed the prop valve plug and bought a Wilwood bias adjusting valve to plumb into the rear line...that way I done have to do it again later..Now the rears will work better I am sure.
R

#48 76lxhatch

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Posted 09 January 2009 - 02:06 PM

Out of interest Rory I pulled mine apart this afternoon (going to change ratio) and the discs have seen plenty of work in a short time by the looks of them, so they are definitely working well with the original prop valve in place but disabled.

#49 rodomo

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Posted 09 January 2009 - 02:12 PM

I think on Commodore there are 2 different seals. 1 thicker than the other, 1 for drum the other for disc.
Might be the same with Nissan?

#50 _rorym_

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Posted 09 January 2009 - 02:39 PM

Out of interest Rory I pulled mine apart this afternoon (going to change ratio) and the discs have seen plenty of work in a short time by the looks of them, so they are definitely working well with the original prop valve in place but disabled.



Thanks Karl...thats good news.
R




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