260Z front brake upgrade: solid or vented?

[macks]

I'm halfway through an upgrade from the standard rotors and calipers to 4x4 hilux 4-spot calipers and DBA slotted discs on the front. There are mixed opinions regarding the effectiveness of this setup, and I'd really like to avoid having to redo things to correct initial mistakes. The car will have in excess of 200rwkw in a little while, so these brakes must work, and work well. :) The car will see everyday spirited street use, with occaisional track days, hill climbs, etc..

The trouble is - they're still solid rotors. Brand spankin new slotties, but still solid. The only significant difference to stock is the caliper, and different people say different things about the potential effectiveness of this setup. The old stock calipers were shagged anyway, so this was a cost-effective upgrade. Some say the problem is heat dissapation from the rotors, and as such no brake upgrade is worthwhile unless you go to vented rotors. This bothers me, and I've already spent $$$ on parts.

My question is - will this new, but still unvented, setup work adequately with cooling ducts and whatnot, or do I throw it all on the shelf and go and find a vented setup?

Cheers..

[dbasteve]

Originally posted by macks
I'm halfway through an upgrade from the standard rotors and calipers to 4x4 hilux 4-spot calipers and DBA slotted discs on the front. There are mixed opinions regarding the effectiveness of this setup, and I'd really like to avoid having to redo things to correct initial mistakes. The car will have in excess of 200rwkw in a little while, so these brakes must work, and work well. :) The car will see everyday spirited street use, with occaisional track days, hill climbs, etc..

The trouble is - they're still solid rotors. Brand spankin new slotties, but still solid. The only significant difference to stock is the caliper, and different people say different things about the potential effectiveness of this setup. The old stock calipers were shagged anyway, so this was a cost-effective upgrade. Some say the problem is heat dissapation from the rotors, and as such no brake upgrade is worthwhile unless you go to vented rotors. This bothers me, and I've already spent $$$ on parts.

My question is - will this new, but still unvented, setup work adequately with cooling ducts and whatnot, or do I throw it all on the shelf and go and find a vented setup?

Cheers..

Increasing the diameter of you disc rotors will help reduce operating temperatures. The problem with solid discs is that the recovery time from excessive heat is slower.
If your rotors don't get too hot then recovery is not such an issue.
Driving style and the type of track work you do will control the success of any upgrade. For 4 to 8 lap sprint work, I doubt you will have a problem.

[Zed]

what setup are you running on the back macks?

[macks]

at the moment, strutless mcpherson strut rear suspension

...because i've got the car up on blocks, with the rear struts out having a bracket made for the caliper. It's a cast iron bitch of a job to get them out, too =/

On a serious note, R31 rear calipers and rotors. It *is* possible to do it with the struts still in the car, if I didn't need to get the brackets measured+made. It'd probably be a comparable pain in the ass to do it on the car as it is to force out the transverse link pivot bolt to remove them.

The procedure, in short - remove wheel, unbolt unijoint from back of hub, undo hub nut (requires a 1x >1m lever, 2x cans of spinach, 1x popeye), remove everything but the backing plate from the drumbrakes, pull hub/bearing assembly and remove backing plate. Bolt on bracket in place of backing plate, and reassemble. It's a strange one, the R31 rotor isn't bolted to the hub, it fits over the wheel studs and the wheel bolts on, on top of it to hold it in place. Obviously the caliper prevents it coming off if you remove the wheel, but it's not physically bolted to the hub like the front brakes, just sandwiched between wheel and hub. This could be normal, I haven't pulled apart a rear disc brake before :)

I've got a schematic from hybridz.org for a bracket to hold a caliper, but it's likely for a different offset disc/caliper combo. I'm trying to figure this out at the moment. I'll post what I find out :)

[lambs]

If your using the R31 rear cals and discs you don't need a special mounting bracket made up - just use the stock R31 bracket. I have this setup on my 260Z (actually for many years now). The bracket does need to be modified - the centre needs to be bored out to suit the Z strut and the bolt holes need re-drilling, plus the strut itself needs some grinding to get the bracket to mount flat on the original Z backing plate mount. Once this is all done, the offset is correct for the R31 disk. None of this is rocket science, with only the boring of the centre of the bracket requiring machining assistance for most people (I did my own). Cheaper than having a bracket made from scratch too.

As for the front brakes, I use Ford XW vented discs and BMW 6-series 4-spot cals (heavy but cheap). There's a bit more work involved in fitting these, so I won't go into that here, but it's cheap and they work extremely well, plus these all fit under 14" rims and so good performance tyres are cheap :)

At the moment I'm looking into fitting Z32 cals and discs to the front while still using 14" rims - I think it can be done.

[macks]

Originally posted by lambs
If your using the R31 rear cals and discs you don't need a special mounting bracket made up - just use the stock R31 bracket. I have this setup on my 260Z (actually for many years now). The bracket does need to be modified - the centre needs to be bored out to suit the Z strut and the bolt holes need re-drilling, plus the strut itself needs some grinding to get the bracket to mount flat on the original Z backing plate mount. Once this is all done, the offset is correct for the R31 disk. None of this is rocket science, with only the boring of the centre of the bracket requiring machining assistance for most people (I did my own). Cheaper than having a bracket made from scratch too.



how did you go with engineering approval of the (now arguably weakened) bracket?

[lambs]

Originally posted by macks


how did you go with engineering approval of the (now arguably weakened) bracket?

Engineering approval ??? what's that ??? :)

I really don't have the time or typing skills (let alone the patience) to 'argue' over this 'weakening' theory - it isn't/doesn't. This is a common, well proven conversion for early Z's and is also very common in Datsun 1600's.

[macks]

Originally posted by lambs


Engineering approval ??? what's that ??? :)

I really don't have the time or typing skills (let alone the patience) to 'argue' over this 'weakening' theory - it isn't/doesn't. This is a common, well proven conversion for early Z's and is also very common in Datsun 1600's.

oh, I don't doubt that it's perfectly safe, and fairly common. I'd just like this thing to be on the road one day, legally :)

If I go and make a R31 bracket fit a zed, is it going to be engineer approvable? Is yours registered?

[Zed]

Im with lambs and have the exact setup he is talking about on my z, recommended by the Z car workshop. I'm a engineer, looks ok to me..that mean its got engineer approval? :rolleyes:

[macks]

haha, yeah if only it was the case, in 3.5 yrs I'd be approving all kinds of rediculous things :p

That's all good tho, if a workshop recommended it, there's a fair chance they've got cars registered+approved with that setup. That's exactly what I want to hear, cheers :)

[macks]

Right. I rang around a bunch of wreckers today, and they either didn't have an "R31 rear caliper bracket" or told me there was no such thing. Sure. I'm on the phone to these guys trying to explain what it looks like, where it bolts to, etc, and all they keep talking about is how the strut mounts to the diff, and the bracket is either pressed on or integral to the strut. What's going on here?

[lambs]

Obviously the wreckers your going to don't know much about R31's...see if you can find one that specializes in this model. The bracket is definately a bolt-on - once the disc comes off (just slips over the studs), the bracket is 'behind' the axle, bolted to the end of the diff housing, also holding in place the brake backing plate. After removing the axle, it's just a case of undoing 4 bolts and the brackets in your hand. At most takes 10 minutes each side from wheels off.

I tried to find a picture of the bracket by itself, but this is the best I could do. It shows a 1600 rear brake conversion kit. The brackets are at right in the photo, but they have been modified to suit a 1600 (a section cut out). Hope this helps.

[macks]

Cheers lambs, thats very helpful. I'll stop in at the wreckers armed with that info later this week, and see how I go. Thanks :)