View Full Version : Welding hats?
Madhatr
04-10-06, 06:17 PM
I recently imported a car from poland that im having a few problems with. It was involved in an accident and the front end was heavily damaged, one of the struts and axles is totally junk, that means the brake rotors that were on it are too :(
Ive had no luck finding a replacement rotor for them anyway and nobody seems to want to come to the party with a blank rotor which i can drill, so ive been looking at 2 piece options. The only thing ive found so far in the way of hats to suit is a wilwood item, you can get it undrilled in a 2" offset, however the centre hole diameter is too large to fit on my axle (2.44" vs 2.78"). I was thinking, the difference is 8mm, so maybe i could turn down a set of rings to reduce the hole size, then weld them in place reducing the hole size by the 8mm or so i need.
Would there be any problems with this? car still has to remain street registered so im wondering if transport departments might have an issue? thinking i might be able to get it done and have an engineer look over them to make sure they are safe. Was looking at alloy hats, so the rings would be tig welded. Original rotors are held in place by a screw to locate it on the hub, its all hubcentric with the wheels using bolts, if that is going to make a lot of difference.
Trying to avoid using a pair of 255mm rotors which would fit, but are 17mm less in diameter and about 3-4mm thinner than the originals.
I would prefer to get someone to make new hats from scratch.....
Madhatr
04-10-06, 06:48 PM
Have you even looked in to having that done? the number of hours spent actually mapping the dimensions before having them machined is seriously expensive, and thats before you even pay for the stock :(. This isnt a OEM rotor, there isnt anything else like it on any other car but the few of these made, so its not something you can take existing data and punch out another. Casting is cheaper, but only marginally, but then the same problem exists if they reach the end of their service life.
Belly_up
04-10-06, 09:29 PM
make the rings a press fit, or get them shrunk in? Once the wheel is bolted on the rings can't go anywhere anyway, welding is probably overkill.
dattoman1000
04-10-06, 11:13 PM
Got a bunch of dimensions ?
Welding cast iron would be bad....... very bad
Billzilla
04-10-06, 11:18 PM
Dude, the only acceptable standard for brakes is perfection.
If you want to greatly increase the chance of killing yourself, weld away.
Spend the money and do it properly, or park the car.
Gravitykills
05-10-06, 05:56 AM
Long answer
Matching the filler to the hat and the machined ring will be difficult, the preheat required wil also be critical, which I doubt the manufacturer will give you the material specs freely.
You can weld anything, depends on how good you want it to turn out though, and in this case, it wouldn't turn out good.
We did something similar a while back as an experiment, and after we machined the weld back and did UT on it, there was substantial cracking in the heat affected zone.
Short answer
No
Belly_up
05-10-06, 07:59 AM
just to clarify, as i understand the hats he is wanting to weld are alloy, not cast iron. The spacer ring would only be under compression, not shear or tension, so any heat affected zone *shouldn't* cause issues, assuming the welding was done well. Having said that, theres no guarantee that you won't still have issues matching filler to the hat and rings, and there's not even any guarantee that the alloy is a weldable grade.
Chris XR6
05-10-06, 08:56 AM
Last time I asked around to have a set of hats machined up it was $600ish! My life is worth more than that, and im sure you will believe yours is!
do that.........
Chris XR6
05-10-06, 08:57 AM
Oh and the amount of time spent stuffing around to machine rings to fit then weld and re machining sounds like a pita!
make the rings a press fit, or get them shrunk in? Once the wheel is bolted on the rings can't go anywhere anyway, welding is probably overkill.
I'm thinking along the same lines.
Maybe make the "rings" this shape
27247
and machine the bore of the hats slightly to make a snug fit.
The ring can't escape once the disc is bolted on and will provide the required centering funtion.
cheers
Gaz
The Pupat
05-10-06, 01:21 PM
Hmmm. I wouldn't be welding it. It's quite likely that there would be funny grades of material in the hats that wouldn't like being welded to. I think the press fit/ just get a hat machined up is a much better idea. Heat Affected Zones caused by welding on funny grades of materials are nasty nasty shite and you really don't want to be playing with it around part you can't afford to fall off.
has anyone told you not to weld it yet ?
i wouldnt weld it :D
Rz do you wear a welding hat?
I prefer masks myself.
PS Don't weld it :D
I thought welding hats were those ones with the beer cans on either side?
I thought welding hats were those ones with the beer cans on either side?
Nah mate; they're wedding hats. Help you through a long day :D
well , i once had a welding cap , but overheads be fucked , im a bench welder nowdays :D
Madhatr
05-10-06, 04:40 PM
Got a bunch of dimensions ?
Welding cast iron would be bad....... very bad
What cast iron? didnt you read? aluminium.
The original rotors are
272mm diameter
24mm thick (dont really know 100% based on what is left)
4 x 100mm pattern
63mm ID centre bore
53.1mm offset
75.1mm height
Difficult finding anything with such a small centre bore, and with such a large offset.
Madhatr
05-10-06, 04:48 PM
Dude, the only acceptable standard for brakes is perfection.
If you want to greatly increase the chance of killing yourself, weld away.
Spend the money and do it properly, or park the car.
Think you are confused about the part i wanted to weld. The hat isnt changed in any way or shape. belly up is right too, could make it press fit.
It doesnt effect the way they bolt up to the axle, the weight is still transfered through the right places, the only difference is the hat will locate correctly on the hub so it isnt off centred or out of balance. I thought i made it clear in the first post im only talking about 2 piece.
dattoman1000
05-10-06, 04:56 PM
What cast iron? didnt you read? aluminium.
The original rotors are
272mm diameter
24mm thick (dont really know 100% based on what is left)
4 x 100mm pattern
63mm ID centre bore
53.1mm offset
75.1mm height
Difficult finding anything with such a small centre bore, and with such a large offset.
No I didn't read it
It started off with something about Poland and I lost interest
However as the resident self professed brake know it all I felt the need to comment
Having done my duty I will now leave you alone to do what you will despite popular opinion
Madhatr
05-10-06, 05:05 PM
Long answer
Matching the filler to the hat and the machined ring will be difficult, the preheat required wil also be critical, which I doubt the manufacturer will give you the material specs freely.
You can weld anything, depends on how good you want it to turn out though, and in this case, it wouldn't turn out good.
We did something similar a while back as an experiment, and after we machined the weld back and did UT on it, there was substantial cracking in the heat affected zone.
Short answer
No
its 6061-T6. Preheating isnt difficult, have equipment and skills for alloy repair :) Real problem with it is subjecting it to continued heat above 160+ degrees, starts to break down and lose strength. Not really a problem here though as it wont be subjected to those sort of temps, nor duration, plus its a good alloy to weld to begin with.
Oh and the amount of time spent stuffing around to machine rings to fit then weld and re machining sounds like a pita!
Only takes about 15mins to turn them down on the lathe :) Its large enough to take the entire hat, so the ring could be turned down from stock to reach the correct OD, then fitted without having the ID drilled/cut. Then drill through the centre and open the hole back out to 63mm as needed.
Madhatr
05-10-06, 05:07 PM
No I didn't read it
It started off with something about Poland and I lost interest
However as the resident self professed brake know it all I felt the need to comment
Having done my duty I will now leave you alone to do what you will despite popular opinion
Ohh wait, so you told me not to weld cast iron. Your comment had nothing to do with what i was asking. :rolleyes:
Madhatr
05-10-06, 05:10 PM
I'm thinking along the same lines.
Maybe make the "rings" this shape
27247
and machine the bore of the hats slightly to make a snug fit.
The ring can't escape once the disc is bolted on and will provide the required centering funtion.
cheers
Gaz
That would work pretty easily actually, dont know why i didnt think of it before :)
How about steel rings on the hubs? Could be shrunk or pressed on. Would be much better of course if they could not come out if they did come loose.
Madhatr
05-10-06, 10:33 PM
that would be pretty much what gaz suggested and it sounds pretty good. Its sandwiched between the hub and the disc which is screwed into position at the top and bottom, then bolted solid between the wheel and the other side of the hub. Would have to sheer the bolts off the wheel first, then have the disc and the hub seperate before there would be movement between the two surfaces, like bellyup said, it should be under compression. Ill see if i can drop by an engineer up here and see if he thinks it would pass as far as safety goes. Press fit sounds good, though it would sound safer if it was fused together, see what he says anyway.
I would modify the hubs aswell, then for whatever reason in the future you can replace the discs and hats with standard items and not have to make up custom bits.
Madhatr
06-10-06, 06:40 PM
I dont know if there is much out there that would fit the car, ive seen 3 and 5 series bits used for a 5 stud conversion, but thats about it. :(
XEFalconUte
08-10-06, 10:46 AM
As the insert you are talking about are only used to locate the rotor concentrically I don't know that I would bother welding it at all, the studs usually locate hub and prevent movement. I believe a light interference fit is all that would be needed. If you want to tig weld it up and that gives you confidence more power to you, but I doubt I would bother. If the hats are from a heat treated alum alloy you might cook the heat treat out of them with welding.
On the topic of welding cast iron, this is VERY hard to do without cracking the shitta outta either the weld of the base material. Much better to braze cast (with a generous fillet).
have fun
Simon
after reading this i believe my brakes are rubbish !!!
the ser 3 had the disks machined off the hubs and then re-drilled commodore disks put on. then the wheel over the top.
is that bad ??
Madhatr
08-10-06, 01:06 PM
ive seen them redrill commodore rotors for use on other cars, might have gone the same route if the bore was the right size, but thats usually using them on floating setups. If they simply machined your hub flat and removed the outer disc portion, slid commodore rotors over them, then yeah... thats definately... different :lol:
The Pupat
09-10-06, 10:54 AM
after reading this i believe my brakes are rubbish !!!
the ser 3 had the disks machined off the hubs and then re-drilled commodore disks put on. then the wheel over the top.
is that bad ??
I dunno about that. That sounds more like a technical issue.
What everybody is commenting in this thread is that it's not wise to just willy nilly weld any old bit of metal without looking carefully at what grade, what heat treatment it has been through, and how much stress it is being put under. Heat Affected Zones near welds are a very real problem and can be a very large problem with higher grade steels and alloys so you need to be careful in what you are doing. This is the reason most are recommending not welding it since it's too hard to tell what problems might come out of it and you don't want the brakes failing due to HAZ damage.
This might sound wierd, but what sort of strut/suspention are they?
Is there any chance of making/modifying a strut to suit with a more common stub axle/hub arrangement. You could be amazed what could fit.
Madhatr
16-10-06, 01:35 PM
macpherson, series 1.
Yeah, you can replace the stub axles/strut with later model parts when converting to a 5 stud pattern, however it messes up the suspension geometry so you have to space the rear bush, plus it means the original wheels for the car will no longer fit (they are pretty rare).
Ordered a couple of hats and we are going to have a good look at it. In in the end if it doesnt work they can be reused on another car anyway.
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