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Putting R31 Front Brakes Onto R30

MrBFrederick
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  • 1 year later...
MrBFrederick Apprentice

MrBFrederick

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Eff, time flies.

Finally got around to trying put R31 discs/calipers onto R30 struts. Short story is it doesn't appear to work.

First problem is the much deeper grease seal (assembly?) on the hub has a diameter that is too large to pass through the hole in the baffle/backing plate. Took a few photos to compare easy fit over R30 hub but not R31 and the diffferent approach to sealing the hub but they're too big for upload. Anyway easy solution would be to relieve this baffle/backing plate, except for the next problem...

The there is not enough clearance between the torque member and the knuckle arm when the brake is used. Cruddy photo below shows it hitting the knuckle arm. Only really allows a few mm of movement. So you could have bigger brakes but not be able to use full pedal pressure because you'd foul your steering. You could of course relieve some of the (what appears to be cast iron) knuckle arm, but not sure what that would do for its strength...

post-68475-0-59594900-1327923193_thumb.jpg

Good points are that (without the baffle/backing plate) the disc slots onto the spindle perfectly with the inner and outer bearings lining up perfectly. The caliper bolt spacings are also an exact match (but you'd have use the longer R31 bolts) and the R31 brake lines also graft onto the R30 system perfectly. I would also say this system would have to perform better than the original CL22V calipers as they act over a wider area on the disc and the discs themselves feel quite a bit heavier with more vents so most probably could accumulate more heat and disburse it more easily.

So the conversion has a few positives. I know others say they've done it before so I'd love to know what enabled them to complete the conversion. Perhaps there's a really simple thing I'm missing here; bits, brains whatever?

If it matters, my R30 is complied/built Sept 84 so is update with sharper-edged bumpers etc. Can't speak to the R31 parts but they appear the same as those I've seen in photos of R31 brake systems.

chinna Collaborator

chinna

Posted
Posted

hey mate

i have a set of brakes laying around from my R30 i took them off as i have upgraded to R33 calipers the brakes worked great no leak and they have brand new bendix pads travelled like 200km before car was put off the read for upgrades

i u want shoot me an offer

  • 3 months later...
rb20-into-mr30= Collaborator

rb20-into-mr30=

Posted
Posted

Hi guys, I just tried recently to swap r31 s2 discs onto my mr30 and nothing but trouble.

i found as i drove home i had all sorts of noises an crap so i swapped the r31 struts on too. that worked ok

but the shocks were shot and the offset ended closer to the inside of the car..

so my +25 wheels scrubbed out on the inside.

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