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Rear Brembo Calipers on a Sept 94 S4 - Suspension/Brakes/Wheels/Hubs/Steering/Geo - The Lotus Forums #ForTheOwners Jump to content


Rear Brembo Calipers on a Sept 94 S4


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I have a quandry. I have a quite large gap between the moving piston and the pad on the back wheel on the RHS (2 to 3 mm). The pads are still well within wear tolerance. Applying the footbrake does seem to apply the brakes. The issue is when the handbrake is applied. The actuating arm has to move through a very long travel to move the piston. At full handbrake application, I could move the disc by hand. All handbrake adjustments are correct according to section JF of the workshop manual. As a consequence of the large arm travel, the handbrake cable is bent at quite an angle over the arm which I would say has contributed to the cable snapping at this point initially.

The only thing I can come up with is that the 'automatic' screwthread adjustment, which is meant to occur on normal pedal application, is not working correctly.

The LHS caliper handbrake comes on much earlier than the RHS. At this point I have not had the LHS wheel off to look at the the piston to pad gap.

Has anyone else had an issue with this mechanism not working correctly and is it fixable? The manual, unfortunately, does not show this mechanism very well. It does say that the caliper should not be disassembled as recommended by Brembo. A special tool is available to wind the piston back in if installing new pads, so I presume I could wind the piston out, but this doesn't fix the auto mechanism working if that is the problem?

Any help would be greatly appreciated.

All we know is that when they stop making this, we will be properly, properly sad.Jeremy Clarkson on the Esprit.

Opinions are like armpits. Everyone has them, some just stink more than others.

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Ok. Just removed the LHS rear wheel and checked things on that side. As I suspected (from seeing many disc brake setups) the moving piston to the pad distance on the RHS is incorrect. The LHS piston is right up to the pad and the pads are a fair bit thinner than the RHS pads. My conclusion is that the RHS rear caliper is not working correctly. I have no idea for how long it has been like this.

So I am back to my question of whether the caliper can be disassembled, corrected and reassembled and installed again.

Is it possibly just getting the RHS piston rotating on the screwthread mechanism and everything will be ok?

All we know is that when they stop making this, we will be properly, properly sad.Jeremy Clarkson on the Esprit.

Opinions are like armpits. Everyone has them, some just stink more than others.

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Well I have sorted it out. You do not need Lotus special tool (insert # here) as you can rotate the piston on the screwthread with a pair of pointy nose pliers. I worked the piston back and forth along the thread until it was much easier to move. Adjusted it up so that the piston to pad gap was removed and fitted it all back together.

Handbrake now comes on at about 3 clicks and the cable alignment on the RHS is much better now.

Brakes will also work better though most braking is through the front brakes anyway and they are fine.

It is a pity to have to do all this sort of work to simply get the car ready to sell.

All we know is that when they stop making this, we will be properly, properly sad.Jeremy Clarkson on the Esprit.

Opinions are like armpits. Everyone has them, some just stink more than others.

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I had an awful time changing my rotors and pads on my Brembo setup back in 2003 when I first bought the car.  Never remember having an issue with gaps though. and with regard to the special tool, I used a piece of wood with a couple of screws in it.

BTW Michael -  I have a guy I talk to on the Aussie Exotics forum who is very much interested in 'buying' your car.  I'll pass on his details if your interested.

Simon  (94 S4)      My Esprit will be for sale in late 2017

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The work on the rotors etc has been easy. After I sorted the RHS brake out, the clutch slave cylinder was whipped off. I'll get a rebuild kit for that and that should sort the little weep out.

PM me his details if you want Simon. I have a few things to do to the car before it is ready. I just want to make sure that when I move it on the next owner will be happy.

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All we know is that when they stop making this, we will be properly, properly sad.Jeremy Clarkson on the Esprit.

Opinions are like armpits. Everyone has them, some just stink more than others.

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Ack! Safe to say mine do not look like that. I didn't take any photos. I was filthy. My LHS pads are slightly worn. The RHS pads look new.

Even the slave cylinder I took off is in pretty good nick. I don't know if it is as old as the car (22 yrs), cylinder bore is spotless and the piston looks fine. Piston seal even looks ok, but I will put a seal kit through it anyway.

All we know is that when they stop making this, we will be properly, properly sad.Jeremy Clarkson on the Esprit.

Opinions are like armpits. Everyone has them, some just stink more than others.

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2 hours ago, s4simon said:

This was the state of my pads when I bought the car in '03.,....

On a mate's non-Lotus he said thepads were probably getting low, went for a journey somewhere and the noise was horrendous so I said it was a matter of urgency to get them done. Next day I swapped pads, the friction material had gone (warn away not flaked) on most of the pad area, with metal to metal causing the disc to be wearing metal away, getting so hot the dust was actually welding itself to the side of the metal backing of the pad.

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Are the cracks visible from the ends of the piston or are they on the piston walls? With the amount that you can get the piston to come out from the caliper, I can't imagine you would see much of the piston wall? There were no cracks in the piston visible on the end.

All we know is that when they stop making this, we will be properly, properly sad.Jeremy Clarkson on the Esprit.

Opinions are like armpits. Everyone has them, some just stink more than others.

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That part of the piston shouldn't go into the bore of the caliper, so it's not necessarily the crack in that location that causes a problem, but the same stress that causes the crack, or corrosion, or debris, could cause the rear pistons not to move correctly, and retract away from the rotor, causing extra dragging and friction, and heat.

Travis

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You're right. I did check the braking etc before putting the wheel back on and the piston was moving away. I don't know why the internal screw mechanism did not seem to be working correctly.

All we know is that when they stop making this, we will be properly, properly sad.Jeremy Clarkson on the Esprit.

Opinions are like armpits. Everyone has them, some just stink more than others.

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