Brake Caliper Overhaul (GS / 4200)

Gp79

Member
Messages
1,065
Picked up a set of used 4200 calipers in the US for a bargain price of £120.
My plan is to refurbish them and colour change to red. After 15 years probably due some love.
I got a quote to overhaul my existing ones but was put off by the nearly £900 cost.
Since the spare set are from a dry state car they are in great condition, probably better than what is on my car!
I’ll post progress as I go.
Have cleaned up and stripped the fronts so far, after measuring the pistons genuine Brembo seals can be had for about £11 each and dust seals if needed for half that.
These front calipers have two pairs of different piston sizes, 38mm and 46mm, with dust seals marked with Brembo numbers 20487245 and 20487251
Maserati don’t list any spares for these (no surprise there) but spares are common with other Brembo calipers

A few pics:
 

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conaero

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30,446
Nice work. While your in there, remove the metal pad guides and check for corrosion underneath.

This causes the pads to stick so make sure you get all off.
 

TimR

Member
Messages
1,397
Just been through this exact process with all mine...and also serviced the brightware as above, and the replaced bleed nipples require significant cranking up to stem the weeping, which went against my best instincts....
All new hard lines ( incl engine bay ) new braided lines, fluid, new discs and Ferodo pads all round...
Cant say it stops any quicker tbh- although it has stopped trying to veer off at a tangent under hard braking, which was seriously alarming...!!
 

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rockits

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Great work, well done and thanks for sharing. I'm sure we can all make use of the info here
 

Gp79

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1,065
Nice work. While your in there, remove the metal pad guides and check for corrosion underneath.

This causes the pads to stick so make sure you get all off.
Thanks for the pointer, yes I did removed these guides on the spare set, The T27 bolts weren't seized solid so the plates came off quite easily and zero corrosion underneath, tried the same on the set on my GS but gave up as didn't want to round the bolt heads off!
 

Gp79

Member
Messages
1,065
Just been through this exact process with all mine...and also serviced the brightware as above, and the replaced bleed nipples require significant cranking up to stem the weeping, which went against my best instincts....
All new hard lines ( incl engine bay ) new braided lines, fluid, new discs and Ferodo pads all round...
Cant say it stops any quicker tbh- although it has stopped trying to veer off at a tangent under hard braking, which was seriously alarming...!!
You've done it all as well then, I replaced the rigid pipes and hoses for braided myself a few years ago due to corrosion and general age, found the original calipers not too bad then but thought with a bargain set it would be worth doing a bit of an overhaul and the main reason to make them red! I'll definitely replace the nips as they're are quite cheap.

The car does stop well currently so don't expect much change / improvement to be honest.
 
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TimR

Member
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1,397
Sure...I didn’t do the pipe work myself.
I was afraid of destroying the T27 heads too...Pretty sure they use a thread locker, as I think these are straight through the body into fluid at the back, as crazy as that sounds now I relate it here...
Heat, care & patience got them out. I replaced them with new ( hex button head) which I suspect will prove tiresome as Torx offer better purchase when comes time to extract (IME)..Hope that doesn’t come back to haunt me.
Can’t believe how quickly crud starts to build up....! New paint will help inhibit stubborn build up although I didn’t paint more than touch up ...

I replaced & serviced quite a lot in the wheel arches this year. Some of it twice when the FD rear toe bar upgrade ( ? ) went soft inside 3K miles....
Straight through the MOT again this year. I would have been depressed if it failed....!
 

philw696

Member
Messages
10,973
Thanks for the pointer, yes I did removed these guides on the spare set, The T27 bolts weren't seized solid so the plates came off quite easily and zero corrosion underneath, tried the same on the set on my GS but gave up as didn't want to round the bolt heads off!
The calipers from the USA have not been through any British Winters so I would say a Great Buy there for the money.
 

Gp79

Member
Messages
1,065
The calipers from the USA have not been through any British Winters so I would say a Great Buy there for the money.
Yes absolutely, these have definitely not been driven through the annual salt bath for the last 17 years.
 

jasst

Member
Messages
1,218
Just started this today, had only planed on a simple disc, pad and new flexi replacement, but as to form its not going to be that simple, the bleed nipples are seized solid (so much for a service history, brake fluid obviously not been changed for years :mad:) and flexi to small rigid pipe is seized solid, so got new rigid caliper to flexi pipes coming, suspect it will be same at other end too. anyone know of a source of replacement nipples? (of the brake variety before you start:rolleyes:)
 

davy83

Member
Messages
2,191
I stripped all four corners and had the calipers completely re-manufactured by a Brembo specialist and put new discs on at the same time. Its well worth it, these cars are getting quite old and none of them are cars you want problem brakes on. (sorry left the nub nut socket in place on this picture, I also changed the colour while i was there, seemed like a good idea at the time :)
63012
 

Mr S

Member
Messages
372
I stripped all four corners and had the calipers completely re-manufactured by a Brembo specialist and put new discs on at the same time. Its well worth it, these cars are getting quite old and none of them are cars you want problem brakes on. (sorry left the nub nut socket in place on this picture, I also changed the colour while i was there, seemed like a good idea at the time :)
View attachment 63012
My Giallo ones could do with a refurb, so be interested in this thread, and any suggestions on who can refurb and re-sticker them.
 

davy83

Member
Messages
2,191
I got my calipers done by Brake Caliper Specialists, they are bit commercial and will e-mail you special offers for ever but the calipers came back looking great and working very well, they looked like new. They can do any colour and any manufacturers logo, either in paint which will wear or a proper thing under the lacquer which is what I got done and its great.
 

Gp79

Member
Messages
1,065
Just started this today, had only planed on a simple disc, pad and new flexi replacement, but as to form its not going to be that simple, the bleed nipples are seized solid (so much for a service history, brake fluid obviously not been changed for years :mad:) and flexi to small rigid pipe is seized solid, so got new rigid caliper to flexi pipes coming, suspect it will be same at other end too. anyone know of a source of replacement nipples? (of the brake variety before you start:rolleyes:)
sorry to hear that, sounds very familiar...
The car variety the nipples are m10, x 1.0, standard fit on Evo’s, some come up on eBay but might be worth going for recognised seller like demon tweeks
 

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