Advice- Can these parts be modified?

[Mike B]

Hi everyone, I'm looking for some advice. I'm trying to fit different brake calipers to my vehicle. Here are images of the two hub assemblies, front and rear. My question is, would it be possible if need be, to weld either a bridging plate, or a new mounting tab, if the holes in the hub dont line up with the holes in the calipers. I was thinking of say, welding a thick crescent-shaped plate in the gap between the two caliper mounting tabs, allowing me to machine out new holes as required. I'm hoping that I may be able to utilise a four hole adpater plate to fit the caliper, but this may not work depending on wheel offset etc. Ideally I dont want to space the caliper further outboard from the original position.

All suggestions welcome. I'd rather not hear from people asking why I intend to change the calipers. Let's just accpet that I want to do this. My question is whether or not this is technically (structurally and metallurgically) possible. I'd also rather not hear from people about how this may or may not affect my insurance. It isnt for use in this country. I'll be having brake discs custom made to fit the calipers as required, so they shouldnt (fingers crossed!) be an issue.

Would the components need any specific heat treatment once they've been welded? Would the welding affect the strength?

I'm not sure exactly what material they're made of. Guessing they're cast steel with machined facings etc.


Thanks

 

[normspanners]

The normal way of doing it is to make a plate to bolt into the original holes, then a plate welded onto that the same thickness as the original bolt holes drill fresh holes in it to suit the new calipers, even if it means rotating the caliper around slightly. rather than welding to the upright.

 

[Mike B]

Thanks norm. What if there isnt enough room to rotate? The new calipers will be larger in all three dimensions. On the front hub (Top image) I think I'd struggle to ratate at all due to the casting shape (steering linkage etc) Would a plate, or mutiple thinner plates welded in, not be strong enough? Ideally I want to end up with one large solid tab encompassing both old holes, which I'm able to drill, tap and remove surplus material from, to create two new tabs.

 

[normspanners]

Well if it were I, I would on the front upright as pictured rotate the caliper clockwise slightly even if it meant having to die grind some out of the web inbetween the two std mounts rather than welding to the upright. that for me would be a very last resort

 

[Mike B]

Is this a better option? I'm concerned it may be weaker as there is more flex, plus more "links in the chain" to fail.

 

[normspanners]

That is the way,! I have done loads like that on competition cars, usually use ally plate to keep the unsprung down, saw some a few weeks ago on a drift car and they where made from 3mm steel plate!! and seemed to be ok, I didnt like it and No way would I make them from that thin a plate but someone had

 

[hotrodder]

As said adaptors are a better option. Don't use stainless bolts (ideally use class 10.9), obviously the caliper determines the thread for one set of bolts; these are often a fine thread (m10 x 1.25 class 10.9 on my daily for example) for a good reason...
FWIW ally caliper adaptors are often machined from a 6xxx series grade which is around 2/3 the strength of mild steel and (like virtually all flavours of ally) around 1/3 the stiffness of steels [/gross generalisation]

Would the components need any specific heat treatment once they've been welded? Would the welding affect the strength?

I'm not sure exactly what material they're made of. Guessing they're cast steel with machined facings etc.

Without knowing what they're made from it's impossible to say how welding will effect things. I know you said things like the MOT don't apply but one of the reasons why the MOT pretty much forbids welding of suspension & steering components is because they're often "cast steel", "cast iron", or "forged steel" all of which are meaningless when it comes to working out how weldable the part may be or whether it was heat treated etc

 

[normspanners]

3mm steel is easily strong enough (and as strong as what, 7-8mm alu?)

not as rigid though, when std caliper brackets are 12mm or more and the calipers are even thicker a 3mm plate is not enough IMO, when pushing pistons back you can easily bend 3mm plate, If I make them out of steel I usually use 8-10 mm and 10- 12 with ally

 

[normspanners]

Also if 3mm plate is used if one piston is a little sticky the opposite piston it will just bend the caliper plate over before forcing the skicky piston out and then you will have the caliper putting fatigue stress on the plate, IMO

 

[normspanners]

Is this a better option? I'm concerned it may be weaker as there is more flex, plus more "links in the chain" to fail.
View attachment 83886

THAT is a grotty looking upright in that picture for a nice shiny brembo caliper ??

 

[normspanners]

On Atlas axles we used to weld 8mm steel, short brackets onto the axle tube then use 10mm ally adapters out to the calipers to keep the unsprung weight down.

 

[Mike B]

I understand that the main force is in the direction of rotation, I'm guessing the only thing that may be required is to mill the back of the cast tab flat to allow the plate to sit flush. My only concern is if I need the holes on the new calipers to sit closer to the centre of the hub, meaning an adapter plate is not feasible. In which case, I'm back to square one. cutting and welding...

That is only a google image, but you're right, the whole assembly looks horrible! I'd be using brand new, but as hotrodder has advised, We dont know what the casting is made of. I'll wait till the parts arrive, do a load of measurin and see where I stand. Any other advice greatly appreciated. Thanks for your thoughts up to now guys. Your experience is valued.

 

[normspanners]

the adapter bracket does not have to be flat we usually make them flat to be easy but you can step them to what ever you need.

 

[normspanners]

I've done have been on bikes, and usually coupled with larger discs so the calipers are placed further away from the axle centre

also the forces are not as great I would think, psi or rotational or even side thrust. due to the disc dia is easily 1/3 bigger than that of a std car.

 

[Johnseat]

Caliper carriers are made of steel for a reason and they are always at least 12mm or thicker as normspanners says.
I've seen the adapters plates loads but always use as thicker plate as possible.
The plate stops the caliper from pushing over due to the caliper pot coming out forcing the pad onto the disc which then slides the caliper across onto the outer pad and pushes that against the disc, these are small forces and with a seized slider or pad your could bend the plate.

 

[roofman]

The side forces are not much with opposed type pistons..sliding type calipers are another story iff the slide pins seize up.

 

[normspanners]

The side forces are not much with opposed type pistons..sliding type calipers are another story iff the slide pins seize up.

UNTIL a piston gets a little sticky !! then all hell breaks loose with cocked pistons gripping even tighter

 

[Johnseat]

Does this vehicle have pots on both sides of the caliper?

 

[Mike B]

Yes Johnseat, four pot fixed calipers. If a spacer is required, I inted to mill it from 10-12mm steel if possible. If Icant acheive this thickness, I'll have to revisit to option of plating / reinforcing the original hub to fit the calipers.

 

[Johnseat]

You'll be fine then, even of you get a seized piston then the other will pop out and not cause the caliper to bend.