simon's learning what to do with the polo thread

**Sydneykid** · 02-07-2018, 02:10 PM

Originally Posted by simon k

I'm seeing lots of people saying 6061, and others saying 7075 - I might need some convincing about making them out aluminium and not steel - there is a good chance that they'll never be removed from the car, and only be looked at when changing rotors, so I'd prefer to make them out of something that can be ignored and trusted to do its job...

There is a noticeable weight difference and it's unsprung weight so twice as bad being heavier.

Cheers
Gary

**sambb** · 02-07-2018, 03:05 PM

steel you could actually weld on I guess. I would wonder with a 10mm plate and NOT keeping the existing caliper mounts (to through bolt with from the inside which would add rigidity) and the stub axle was through bolted through to the beam with longer bolts and you have a plastic toe shim wriggling around under there too, whether things could move? Might be totally ok but not sure. I guess you could dowl pin it pretty easily. But if the plate took in the caliper mounts too, that's another pair of bolts running right through both surfaces and I doubt it could ever move. You'd need longer caliper bolts in this case though.
Aluminium would be easy to machine, easier to mill to an angle in case you decide against plastic shims, and lighter. At 10mm thick the caliper mount part of it would have to be strong as by itself even if the existing caliper mounts are removed.

so (in no order):
1. weld steel on
2. aluminium plate that includes caliper mounts (wouldn't shift as caliper bolts through bolted through beams mounts)
3. aluminium plate with stock caliper mounts removed (dowl the plate to the beam face so it wont move under cornering/brake load)

that's the way I see it, but I'm not doing it

**simon k** · 02-07-2018, 03:05 PM

Originally Posted by Sydneykid

There is a noticeable weight difference and it's unsprung weight so twice as bad being heavier.

Cheers
Gary

yeah, but it's the brakes - the brakes!!

I used to be able to iridite aluminium stuff, that'd make me more comfortable. At least we don't have salt on the roads, some of the pictures of aluminium parts I've seen while googling are very ugly

Originally Posted by Sydneykid

I'll confirm it with the machinist but from memory our caliper brackets are 6082 T6.

I asked for a quote on 6082 and 6061 if they can't supply. Doesn't look to be a lot of difference.

6061 Aluminum vs. 6082 Aluminum :: MakeItFrom.com

If I was going to make it out of steel, 350 grade?

**sambb** · 02-07-2018, 03:41 PM

yeah the bloody brakes complicate everything - spacing it to match the stub, bolt angles through the plate to match stub shims etc etc

**simon k** · 02-07-2018, 04:45 PM

yeah, just ditch them I reckon... I wonder how much it'd cost me to have them anodised in fancy colours... or black

they came back with $25 each, but in 5083 H321, they don't keep any 6xxx. It's about $20 to cut without the material. Waiting for them to tell me what piece size they need before hunting out some material

EN AW-5083	It is sea water resistant and has an average strength, high corrosion resistance and good for welding Medium for anodizing
EN AW-6061	Is suitable for anodizing, and has a high corrosion resistance and good for anodizing. The alloy is suitable for welding.
EN AW-6073	Is a variant of the EN AW-6082, and it is better for anodizing than EN AW-6082, since the aluminium with this alloy gets a more homogeneous surface.
EN AW-6082	Has a high strength and a good corrosion resistance. The alloy is good for welding, and you can anodize it.

**Sydneykid** · 03-07-2018, 09:39 AM

Originally Posted by sambb

yeah the bloody brakes complicate everything - spacing it to match the stub, bolt angles through the plate to match stub shims etc etc

Over thinking it a bit Sam?

So what if the pads run a small taper angle, if it makes you feel better simply linish them to suite the angle delta between the rotor and the caliper or just let them wear (bed in) that way. It's a fixed angle and hardly huge, we get more taper using production car calipers, where a starting off with 16mm pad material can end up at 11 mm on the leading end and 13 mm at the trailing. That's way more angle than a couple of degrees of toe.

There are thousands, maybe millions of cars running around the world with shimmed stub axles, it's been common place for decades. From memory I first used them on a Suzuki Swift back in the 80's, and it did a Bathurst 12 Hour race without issue, plus quite a few 1 hour, 3 hour and 6 hour enduros.

Cheers
Gary

**sambb** · 03-07-2018, 10:50 AM

Ok cool then. I thought the angle changes on mine were quite big, but then I was going from 3-4mm toe in per side to 0.5-1mm toe out per side but using the original pads that had bed in for toe in and were now toe'd out which probably exagerated the appearance of the angle. I was forced to run washers under the caliper mounts to account for the spacing of the shims and to compensate for the camber change I'd made too, otherwise the disc was hitting the sides of the void in the caliper that the disc runs in, but yes the pads just re bed themselves for the new toe angles. Just didn't know how far you could push things before it was considered bad practice. I guess you could throw in a fresh set of pads at the same time which would speed up the bedding process going from a toe'd in to a toe'd out condition?
All good then. Alright Simon with that cleared up... get on it!!! ha ha

**simon k** · 03-07-2018, 12:24 PM

lol...

I've sent off another couple of quote requests, but seems like 6082 is a bit hard to get for the average bunny like me

350 grade mild steel has come back dirt cheap, I can carve extra metal out of them to get the weight down too