Schijven vervangen vanwege krom: Klauwen gelijk reviseren?

Hallo Volvisti
Binnenkort ga ik eindelijk de remschijven aan de voorkant vervangen. De oude schijven zijn al een tijdje geleden in hoepels veranderd, waardoor stevig remmen resulteert in het rammelen van de hele voorkant.
Is het handig of nodig om dan gelijk middels een revisiesetje de remmen cq. remklauwen te reviseren?
Wat zit er eigenlijk in zo'n setje en waaruit bestaat zo'n revisie?
BTW op de schijven zit een olieachtige substantie. Krijg ik die er met wasbenzine helemaal af? Kan ik dat dagen van te voren doen of is het beter om dat net voor de montage van de schijven te doen?
groetjes
Mathy

laat de remmen maar voor wat ze zijn. Het vet krijg je er af door ze even af te nemen met een keukenrol gedrenkt in aceton.
Robert 

Jaren geleden heb ik de voorremklauwen ook laten reviseren. Dat kostte iets van 240 euro voor de hele voorkant. Het betrof vervangen van de remklauwen en opnieuw ontluchten en montage.
Weliswaar voor een 960 uit 1991, maar toch.

Hoi Mathy,
Het is erg verstandig dit vettige laagje weg te halen met remmenreiniger, dit zit in een spuitbus en kunje bij iedere automaterialenhandel kopen. Het is echt heel goed ontvettend spul, binnen de kortste tijd gebruik je dat spul overal voor.
Een remklauw revisie bestaat volgens mij vooral uit stevig borstelen met een goeie roestborstel en op alle glijdende delen een beetje kopervet te smeren. wat misschien wel bij een revisiesetje zit zijn de keerringen van je remcylinder, de rubbertjes die het stof bij de remzuigers weghouden en de busjes en boutjes waarmee de remklauw inelkaar zit.
Bij je remmen kun je zo wel zien of je rubbers nog goed zijn, en als er geen olie uitloopt zitten die keerringen ook wel goed. Een optische inpectie is voldoende om te zien of je een revisiesetje nodighebt. til het rubbertje van om je zuiger even op en kijk of alles schoon is, zo ja... niets aan doen.
Groeten, Frans

Mathy,
Kijk naar de geleidepennen,bij mij was het kromtrekken mede te danken aan de geleidepennen: die zaten helemaal vast. 
Ik heb hier ergens eens post betreffende de geleidepennen,inclusief de kosten.
groet, Mischa

reviseren is nooit weg, soms zit er wel wat roest op de zuigers of is een pin wat vast.

om te zorgen dat de remschijven nu niet weer krom gaan zou ik het montagevlak van de schijf zeer goed schoonmaken en alle roest er af halen. montagevlak binnenkant schijf ook schoonborstelen. 
Misschien staat <a href=" www.powerbrake.co.za/downloads/tech_01_judder.pdf ">hier nog iets interessants. 

Na stevig remmen op de rem blijven staan.
Dan koel je de schijven ongelijk af. Af en toe even lossen een paar decimeter laten kruipen.
Kromme schijven kun je ook weer recht "boetseren".
Roodgloeiend remmen en rijdend af laten koelen.
Mijn V90 en daarvoor de 940 beiden automaat heb ik zo ook weer recht gekregen. 

Hoi,
Kromme schrijven is geloof ik een 700 Volvo kwaaltje, mijn 760 rammelt ook.
Indien je het zelf aankunt, altijd schoonmaken (kleine revisie).
De keerringetjes in de klauw gaan bijna nooit stuk (of het cupje was verroest).
Ik zou:
Klauwen loshalen (evt. slangen laten zitten). Hoesjes verwijderen en de cupjes dmv remmen naar buiten drukken.
LET OP!!!!!!! Dat je niet te ver pompt, want dan druk je ze eruit, evt. moet je er een borgen omdat ie makkelijker gaat als de andere. Niet haasten, rustig en met beleid. Dit kun je ook doen met een ingebouwde klauw, dan kun je een cupje tegenhouden met een remblokje.
Rubber hoesjes verwijderen (liefst weer nieuwe plaatsen, behalve als de oude nog echt goed zijn).
Met tandenborstel en WD40 of Peut de cupjes reinigen, slechte plekken met waterproof 'heel' fijn. Daarna met remmen vet of keramische pasta (als het maar hitte bestendig is) de cupjes en binnenzijde hoesjes lekker insmeren en weer monteren.
Klauwen weer plaatsen met blokken lekker in het kopervet, alle klauwgeleidingen (mits geen alu in de buurt) met kopervet insmeren.
Succes en ehh aan dit schrijven kunnen natuurlijk geen rechten ontleend worden ....

Dit gedoe heb ik lange tijd met mijn 780 gehad en uiteindelijk waren nieuwe klwauwen vóór de oplossing. Ook bij de V90 doet het probleem zich voor - zelfs rondom in de garantie een keer nieuwe schijven gehad. Nu heb ik het gezeur enkel aan de achterkant(!). Zo nu en dan de schijven laten afdraaien maakt het leefbaar maar vrolijk word ik niet van dit remsysteem.

Brake Tech #01 The final word on brake judder and “warped” discs In simple terms brake judder is experienced by the driver of a car as a pulsation through the brake pedal and/or side-to-side vibration of the steering wheel under braking. The above symptoms can be frustrating, disconcerting and result in driver complaints about “warped” brake discs. The phrase “warped brake discs” is used almost universally by uninformed vehicle owners to describe the cause of brake judder. The actual underlying causes of brake judder are, without a doubt, the most misunderstood aspect of automotive braking. While it is possible for a brake disc to “warp” or distort (i.e. change shape) - disc distortion is responsible for relatively few brake judder complaints in our experience. The overwhelming cause of brake judder is a condition called Disc Thickness Variation – period! In other words the disc develops a lack of parallelism between its inboard and outboard friction surfaces. I say, “develops” because even discs that are machined to the very tightest tolerances during production can easily develop Disc Thickness Variation (hereafter referred to as: DTV) due to incorrect fitment or driver abuse. When the brake pads are pressed up against a disc that has developed DTV they will pass over a series of thinner and thicker areas on the braking surface of the disc in rapid succession. Considering that the brake pads are being pushed together with substantial force they will be forced down into the ‘cavities’ or thinner areas only to be kicked back violently when reaching the bumps or ‘thicker’ areas. The frequency of this ‘bouncing’ action is typically over 100 Hertz when braking from highway speeds of around 130kph. This results in pulses that are transmitted through the caliper pistons, via the brake fluid to the driver, who experiences them as brake judder.. Causes of DTV Once you understand the causes of DTV it becomes clear that brake judder problems can be almost completely eradicated by following a few simple rules. So, what causes DTV? DTV can be caused by a number of factors including disc fitment errors, driver abuse and poor manufacturing processes. The causes above are mentioned in order of their likelihood of occurrence. DTV Cause No. 1: Failure to ensure that the mounting surface of the brake disc and hub are perfectly clean prior to disc fitment. One of the most common causes of DTV is the failure of the fitter to properly clean the mounting surface of the disc and the vehicle’s hub. The smallest fragment of dirt or rust scale caught between the mating surface of the disc and hub is magnified as you move towards the outside diameter of the disc. This results in an unacceptable amount of axial run-out (inboard-outboard movement) at the friction surfaces of the brake disc (the areas of the disc that come into contact with the brake pads). To put this into perspective, the maximum axial run-out measurement that Powerbrake™ will accept on a newly fitted disc is 0.08mm (measured in the centre of the friction surface of the disc). A single spec of rust scale measuring only 0.05mm (50 microns) in thickness trapped between the mounting surface of the disc and the hub can easily cause the axial run-out value to exceed this tolerance! Once you have a brake disc that is fitted with unacceptable run-out you have entered a downward spiral that will lead to brake judder and irreversible disc damage over time. Every time you apply your brakes the pads will first come into contact with the disc at the point of maximum run-out. In fact, due to the fact that your brake pads retract only fractionally when you release your brakes, excessive run-out often causes a light, continuous rubbing of the disc against the pads at the point of maximum run-out. This is happening when you are off the brakes completely! To understand what happens next we need to briefly discuss two broad categories of brake pads. The first category of pads relies more heavily on the concept of abrasion to slow your car down. In simple terms this involves the mechanical gripping and breaking off of opposing pad and disc materials at a molecular level. The materials literally wear each other away in the process. The harder material (typically the disc) will wear slower than the softer friction material of the brake pad. The second category of pads relies more heavily on the concept of adhesion. In this case some of the pad friction material is transferred to across to the contact surface of the disc, where it forms a thin, uniform layer of friction material. Essentially you now have the friction material of the pad coming into contact with identical friction material that has been deposited on the surface of the disc. Under braking, the bonds between the friction material of the brake pad and the friction material deposited on the disc are constantly breaking and reforming. Material crosses the pad/disc interface in both directions as the molecular bonds continually break and reform. All pad formulations use a combination of both abrasion and adhesion but some pads (such as common semi-metallic formulations) rely more heavily on abrasion and others (such as many high temperature ‘Ferro-Carbon’ fast-road and race formulations) rely far more heavily on adhesion. Abrasive and adhesive pads affect the formation of DTV in different ways. Back to our brake disc that was fitted without the hub and mounting surface of the disc being carefully cleaned. Let’s assume that the rust scale on the hub caused the disc to have a run-out of 0.1mm. On many vehicles this will NOT be felt as brake judder by the vehicle owner when he collects his vehicle from the fitment centre. He drives off a happy customer. However, after a period of between 1000 and 6000 kilometres of driving the brakes begin to develop a judder, which gets progressively worse. The vehicle owner complains to the fitment centre, who assumes that the discs have “warped”…right…wrong! Even the best quality discs money could buy would have developed the same brake judder. Here’s why…. As explained above, the disc was continually coming into contact with the pads at the point of maximum run-out first. If abrasive pads were being used this area of the disc would wear down quicker than the rest of the disc surface causing DTV, which is felt as an intrusive judder. If adhesive pads were being run then the pads would have deposited more material on the initial contact point (the area of max. run-out) than on the rest of the disc surface. Again this leads to DTV and brake judder. 
It gets worse! Once you have the development of DTV the surface of the disc will begin to heat unevenly. The high spots will get extremely hot compared to the rest of the disc. When the temperature around these high spots reaches 650 – 700°C. the cast iron in that area will change structurally and transform into a material called Cementite. Cementite is far harder than the cast iron of the unaffected parts of the disc and will therefore wear considerably less as the disc wears down with use. Cementite also has very poor heat sink properties and will therefore continue to run extremely hot resulting in the rapid spread of the Cementite formation deeper and deeper into the disc. As a result the DTV will get progressively worse with time until it becomes literally unbearable to use the brakes. Depending on the pads used and the driving style of the vehicle owner this process could take 1000 – 6000 kilometres to develop and, NO, the initial run-out will not necessarily be felt by the driver. Hence the confusion and clinging to the concept of brake discs “warping”. The disc has now entered as self-defeating spiral that will very quickly become irreversible. Disc ‘skimming’ will only help if the formation of Cementite has just begun on the disc surface. Once the formation of the Cementite has spread deeper into the disc material, skimming will only remove the surface layer but the DTV (and judder) will return as the Cementite wears less than the surrounding cast iron. If you consider that VERY few mechanics ever bother to clean the disc mounting surface or the  inevitable rust scale from the surface of the hub when fitting new brake discs, the magnitude of the problem becomes clear. Of course, the exact same thing will occur if a new disc is fitting to a distorted hub that is not running true. Distorted hubs are a reasonably common occurrence after a vehicle has been in an accident but we find that the overwhelming cause is a dirty hub! DTV Cause No. 2: Improper bedding-in of new discs and pads.After fitting a new set of discs and pads (or when running a set of used pads on new discs) it is ABSOLUTELY CRITICAL that the correct bed-in procedure be followed! It is important that an even, consistent layer of friction material is transferred from the pads to the disc surface before the brakes are run at very high temperatures. This material transfer is normally best achieved under moderate braking at low to medium brake temperatures. Most pad manufacturers issue clear bed-in instructions. If not, you need to read our Brake Tech article #2: Correct bedding-in of new brake discs and pads. If the flashpoint temperature (the temperature at the interface between the discs and pads) gets too hot, before an even layer of friction material has been established, material transfer will become random and erratic resulting in uneven, spot material transfer and the formation of DTV. (See Figure 3). We’ve already established what happens after that… Apart from causing uneven friction material transfer, failure to follow the correct bed-in procedure can also lead to distortion (change in shape) of new discs. The distortion will once again result in axial run-out, the formation of DTV and brake judder (see article on Distortion). Understand this – brake pads and discs are not like a new performance exhaust system that you can fit to your vehicle and then go out and drive hard immediately to test your new modification. With new brake discs and pads you have a very simple choice - Bed them in correctly or you WILL destroy them and cost yourself money!

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