Putting R31 Front Brakes Onto R30

[MrBFrederick]

Hi,

Front brakes on my r30 (Aust delivered L24 engined, prob built Aug 1984) are leaking so a bit of work has to be done to repair them. Seem to remember that people have grafted R31 front brakes onto RMR30 struts. Has anyone done this? How easy is it and are any additional parts needed? Not interested doing the S13 strut/brake upgrade - really just looking to put on some brakes that look reasonably original and where parts are readily available. Grateful for any help!

thanks.

[FJ20DR30]

Hi,

Front brakes on my r30 (Aust delivered L24 engined, prob built Aug 1984) are leaking so a bit of work has to be done to repair them. Seem to remember that people have grafted R31 front brakes onto RMR30 struts. Has anyone done this? How easy is it and are any additional parts needed? Not interested doing the S13 strut/brake upgrade - really just looking to put on some brakes that look reasonably original and where parts are readily available. Grateful for any help!

thanks.

not sure about the r31 swap idea. but if your interested i have a good set of Dr30 turbo brakes and struts etc if you want to save time.

Marc

Edited September 12, 2010 by FJ20DR30

[eL Cid 26]

R31 struts will bolt in as far as I can tell, no need for any grafting.

Only issues I see are that it will change the height of your car (pretty sure it lowers it), and brake lines and such will be different.

May also need the R31 LCA/balljoint what ever so probably best to get the whole kit and kabudle.

[OUTATIME]

discs and calipers fit straight on r30 struts. cant remember if ya use r31 or r30 bearings tho. but theres no gain in r31 brakes. just put a kit through your current r30 calipers..

[MrBFrederick]

discs and calipers fit straight on r30 struts. cant remember if ya use r31 or r30 bearings tho. but theres no gain in r31 brakes. just put a kit through your current r30 calipers..

Gain w/ r31 brakes is that you can get parts for the things! Have you done this conversion before? Apart from getting a set of discs, calipers and perhaps bearings, is anything else needed?

[MrBFrederick]

not sure about the r31 swap idea. but if your interested i have a good set of Dr30 turbo brakes and struts etc if you want to save time.

Marc

Thanks Marc. Might keep it in mind (but I'm sure you'll get a few takers before I make up my mind)! Strangely, I'm interested in making sure the factory 14" steelies fit over the top of whatever I get...

[Factory 5]

send me an email marc.... those struts sound good.

[racsov500]

so you can use aus r31 calipers / shitty intergrated hub rotors on dr30 struts? do the r31 bearings fit the spindle?

also, if youve done this, what brake lines did you use, do aus r31 fit the flare nut fitting on the solid line?

[OUTATIME]

dunno about dr struts. but mr30 struts they do. just use r31 flexable hose from caliper to r30 steel line. and as for bearings i cant remember. but if have both on hand should b able to work it out

Edited September 14, 2010 by OUTATIME

[BensDR30]

R31 brakes bolt on the ®MR30 struts - you may have to swap the struts left/right as the caliper may foul on the steering ball joint. The braking is better than the standard setup, but it's still no sports-car.

The Aus-spec R31 brakes do not fit the DR30 struts, as they have 100mm bolt spacing (as opposed to the 89.9mm for the Aus-spec stuff). Apart from that the DR30/Z31 brakes are bigger than the Aus-spec R31 brakes (274mm vs. 258mm from memory...)

[Factory 5]

Recently on the R31 foum they have been useing a VT commodore pad, bendix ultimate (with a 5 mm tab trimmed off

Seems to be some good results.

Might look at it as a budget option

[Ghostrider]

Can I ask some stupid questions on this subject?

If it's the leaking of the caliper that is causing this enquiry, why not just put a kit through the caliper unless of course the piston is rusted and pitted??

Your saying parts are available for R31 calipers and not R30, which sounds interesting, because both pistons are the same diameter, so why wouldn't an R31 seal fit the R30 piston when it's the same diameter and for that matter the pistons might be the same as well.

Recently I had similar troubles with brakes in my Cressida, brake calipers are out of the donor car UZS131 Crown Majesta where the motor came from and with a bit of searching and measuring, I found I had an 60mm piston and SV21 Camry's also have an 60mm piston, so problem solved.

R31 & R30 both share the same size piston 54mm and a caliper kit is only 2 items, the piston seal & dust seal, so I can't see your problem with parts???

Cheers, D

[MrBFrederick]

Can I ask some stupid questions on this subject?

If it's the leaking of the caliper that is causing this enquiry, why not just put a kit through the caliper unless of course the piston is rusted and pitted??

Your saying parts are available for R31 calipers and not R30, which sounds interesting, because both pistons are the same diameter, so why wouldn't an R31 seal fit the R30 piston when it's the same diameter and for that matter the pistons might be the same as well.

Recently I had similar troubles with brakes in my Cressida, brake calipers are out of the donor car UZS131 Crown Majesta where the motor came from and with a bit of searching and measuring, I found I had an 60mm piston and SV21 Camry's also have an 60mm piston, so problem solved.

R31 & R30 both share the same size piston 54mm and a caliper kit is only 2 items, the piston seal & dust seal, so I can't see your problem with parts???

Cheers, D

D,

You're right that a simple seal kit may all that's needed but the likelihood is that the pistons are not serviceable, given the age of car and the amount of leaking. Therefore piston will most likely need replacing and if you have a look around, these parts aren't readily available any more; check out PBR site for instance. And, if I'm going to spend a bit on the R30 brakes, it's may actually be more cost effective to put on the more common and, relatively, more abundant R31 parts. Although R31 parts are getting a bit rarer, no matter which way you slice or dice it, they're usually 2/3s the price of R30 parts.

As for the interchangeability of parts, a quick internet research suggests that, while piston diameter may be the same, R30 and R31 pistons are sufficiently different for them to have different part codes - which increases the likelihood they're not the same part. However happy for you to tell me they're the same part and completely interchangable!

Cheers,

baz

[Ghostrider]

D,

You're right that a simple seal kit may all that's needed but the likelihood is that the pistons are not serviceable, given the age of car and the amount of leaking. Therefore piston will most likely need replacing and if you have a look around, these parts aren't readily available any more; check out PBR site for instance. And, if I'm going to spend a bit on the R30 brakes, it's may actually be more cost effective to put on the more common and, relatively, more abundant R31 parts. Although R31 parts are getting a bit rarer, no matter which way you slice or dice it, they're usually 2/3s the price of R30 parts.

As for the interchangeability of parts, a quick internet research suggests that, while piston diameter may be the same, R30 and R31 pistons are sufficiently different for them to have different part codes - which increases the likelihood they're not the same part. However happy for you to tell me they're the same part and completely interchangable!

Cheers,

baz

Well Baz,

After today, I would be putting R31 pistons & seals in the R30 calipers if I couldn't buy the R30 parts I required. Pistons and seal kits.

The obvious diferrences between the 2 pistons is the R31 piston is shorter by 4mm, has a recess in the back and has full 54mm dia contact area on the pad.

I can't see how anyone can say the R31 caliper, on the R30 is better than the original, as the only operational diferrence between both pistons is the contact surface area of the piston to the pad and IF it is better, it would be very marginal.

The seals are both 3mm wide x 3mm thick and fit in each opposing caliper the same.

The dust cover seals, although marginally diferent in shape and design, both fit in the opposing calipers the same and fit each piston the same.

The pistons:

R31 is 44mm long x 54mm dia and R31 contact face area to pad is full dia 54mm.

R30 is 48mm long x 54mm dia and R30 has reduced contact face area to pad of 49mm.

Both have the same dia dust seal groove, 48mm. Both have same distance from contact face to piston of 8.5mm.

IMHO both pistons & seal kits would serve the purpose the same way.

The only reason I can see for these obvious changes to piston design is the fact that the R31 was made in Australia and had to have something like 85% local content, so that Nissan could get their imported parts & cars into Australia under by-laws and lower import tariffs, therefore these parts were sourced locally and not imported.

Below are some pictures that will show what I have found and suggest.

Cheers,

Dennis

[Factory 5]

Excellent work D,

[BensDR30]

There is one aspect of the situation that's being overlooked;

When putting the R31 bits on, you don't just use the calliper - you also fit the thicker disc (R30 - 250mm X 18mm, R31 - 250mm X 22mm)

So, between the slightly thicker disc and the slightly better calliper, the brakes are certainly better than OEM R30 - been there, done that.

(and parts are cheaper too).

The other brake upgrade that I can recommend for Series 1 R30's its the use of a 15/16" 720 4x4 master cylinder (OEM is 7/8") - just don't forget to remove the residual pressure valve if you have a disc-brake rear end.

[Ghostrider]

Dunno that the thicker rotor is so crash hot? Depends on the application, but for an average daily driver the stock R30 brakes would be adequate I would think.

The exercise was put up to remedy a leaking caliper, not as a requested performance upgrade. Unless MrB wants to spend heaps of bucks, he might be sticking with the stock brakes.

Something I didn't mention as well is, that ALL of the R31's I looked at today had seized calipers and would also need to be rebuilt before use and that's the chance taken buying from the wreckers.

The 15/16" master cylinder is a great upgrade, but best used with a bigger (10") master vac and they aren't easy to find.

D

[BensDR30]

[Factory 5]

The 30 Brakes are ok for 1 or 2 stops in an agressive environment, then after that its mush or unpredictability, and many lockups and flatspot tyres...

Thicker rotors would make a difference, as it has a greater mass to absorb the thermal energy.

Just like a small radiator versus a bigger one.

[Ghostrider]

MrB owns an WRX & an MR30. Somehow I can't see him trying to drive his MR30 at speeds warranting the extra thickness in brake disc rotors.

I might be wrong but ?????????????????????

The R31 is also 100kg heavier that the heaviest of R30, so it needs something otherwise it would never have complied with the ADR's.

If after 1 or 2 aggressive stops your MR brakes have gone to mush, maybe your pads are the wrong compound for the application?

Most standard pad compounds are rated at 350~400 degrees C and are perfectly satisfactory for the average day to day driver.

JMHO