Seals

We begin with the O-rings.  If the rubber is smoothly in the center broken, it can be usually repaired after appropriate cleaning with second adhesive.  These adhesiveadhesive adhesives are outstanding suitable for the flexible material.  As emergency repair on the way or on weekend this solution offers itself, because second adhesive is to be gotten at gas stations also outside of the store opening times.  During groeáeren damages at the O-ring this must be replaced naturally.  Often you can cut a piece out from a sealing ring of larger diameter, but same material thickness, with a sharp meter and obtain so the desired dimension.  But which do, even if this possibility is not to be implemented due to missing material?

The manufacturer Loctite holds ready for this case an O-ring set, with whose assistance almost any sealing ring can be produced. Differently thick rubber strands of one meter each of length, a meter, a cutting and a sticking template, as well as a flaeschchen adhesive are in the plastic case - for approximately 100 Marks a genuine aid in the NOT.  For the cleaning of the splices you should by the way never use dilution or brush cleaner, because when both leave petroleum products a light film, which leads fast to the fact that the splicing tape solve itself again.  Entfetter or acetone, which guarantee a really arrearsless cleaning, are better suitable.

SURFACE SEALS

We come to the surface or housing seals blocked at each vehicle.  We have to do it with materials such as paper or cork, with high pressure and to temperature-fixed material, as well as with special material for exhaust and cylinder head gaskets.  With which we would already be during the first and only restriction:  Cylinder head gaskets are to be manufactured unique a thing for the specialist and of the hobby nut runner hardly, but in addition later more.

We visited an operation, which produces all erdenklichen seals for over ten years, but to hobby nut runners also the necessary base material as disk or role commodity supplies with.  Alfred black, owner of the company DS in the Middle Franconian Grosshabersdorf, let itself be looked by us over the shoulder and betrayed so some useful trick.  " important is first the selection of the suitable material. The defective seal is usually reference point:  Where paper was blocked, one should use also again paper ", means introductory he.  " some Japanese engines make an exception, with which ex factory also with neither printing nor temperature-loaded seals high-quality pressure resistant material was used.  Even one with motorcycle engines of the seventies is often to be found that.  Here also a high-quality seal can be replaced every now and then by paper. "

Also seal papers are not to be compared naturally not easily with typewriting paper or cardboard and may under any circumstances by it be replaced.  Special fibers and an impregnation lend only the characteristics required by it to the seal paper.  Probably each nut runner admits to be might the manufacturer ELRING with its seal papers named ABIL.  They withstand temperatures up to approximately 100 degrees and a printing of approximately six bar, are in strengths from 0.25 mm to 4 mm available and thus for many housing seals to be used. High pressure celebration material (likewise starting from 0.25 mm) however is to be used up to 400 degrees and up to 100 bar.  Becomes clear already here:  Paper is unsuitable for a thermally highly loaded seal.

PRACTICE

We assume, you a festgebrannte surface seal with the disassembly of a frame cover tore up, them however as a whole piece be replaced could.  This is the simplest exercise, because you have a torn up, but nevertheless complete collecting main for reproduction. First you measure caliper gauges now with a caliper gauge, again-German also mentioned, the strength of the old seal and select the suitable substitute.  Often you, if nothing different one is available, can use thinner seal material.  Caution however, if in the cover for example a Kickstarterwelle or a like is stored!  Here you run the risk to change on use of thinner seal material the bearing geometry.  Sometimes it can come even to wedging the wave!

If the correct material is selected, fix the old seal with tape and draw with a as thin ball-point pen or a pencil as possible all outlines after, also the screw holes.  These should work you out afterwards as the first work procedure, the specialist recommend in addition a suitable drilling tool.  Don't you have?  Then only the grasp helps to the small (gnawing l) shears the more exactly you to operate already now, the better the finished seal will fit later.  The reason, why you should begin with the holes, is fast avowed:  During seals, with which around these openings only very few material stops approximately, the workpiece can tear when punching otherwise easily. Particularly with cork that occurs frequently.  Then you re-cut the interior and outer contour with shears successively, already are a functional seal reproduced.

NO COLLECTING MAIN?

Away of the ideal case, to the reality: Assume confidently you damage the seal with dividing so strongly that it is not to be used no more as collecting main - you know, mostly kommt's quite thickly! In this case the outline of the frame cover must be transferred to the material. The often given tip to use Touchierfarbe Alfred black advises against: " too inaccurately. " With simple forms the cover can be naturally put on a paragraph seal paper, in order to after-draw the outer contour, but with our specimen, that cannot be done to the engine cover of a Honda CB 750 Four. Here a third of the seal is situated only within the cover, after-draw is thus omitted.

Black macht's quite differently and first the new material puts on the sealing surface of the cover. With aluminium  hammers, to the NOT tut's also one from plastic, he realigns now carefully the outline, in each case at the materialfixed between the spread fingers. The relatively sharp edge of the poured cover cuts in such a way piece out for piece the material. So if the outer contour is created, the specialist expresses the screw holes with the approximately polished end of an old Koerners. Finally it " hammers out " the internal contour. The thing required patience and much intuitive feeling, works however well.

A further possibility, the seal after the cover for finished, is abrading the outlines with a round iron bar. The professional used in addition the extension of a ratchet box and abrades centimeters around centimeter the form inside and outside until the material splits is. For which way you decide now, remains for you left. Result of careful work is in each case a suitable seal - also on weekend. Not unmentioned to remain is here the tip of a reader already published: It photo-copies all seals of its vehicles before the installation and has so always a suitable collecting main. However you should check the accuracy to size of the copy, some devices distort quite beautifully.

NOT ONLY FOR BOTTLES:

CORK in the seal production comes more particularly, usually pressed cork with oil resistant characteristics to the use. Also this material is available in disks of most diverse strengths. Cork bears temperatures up to approximately 150 degrees, however as well as no printing. Thus its application type reduces naturally to pressure-free applications such as valve cover or oil pan seals. Cork must be always cut with a meter or shears, the outline can thus not be knocked off or not abraded. Screw holes should be punched in each case, otherwise the material breaks out too easily. The old seal must be assembled thus, even if this unite expenditure meant, somehow as collecting main. If that cannot be done absolutely, you must access to pin and ruler. It applies then to make a drawing on cardboard to cut it out their form at the cover to check, possibly to correct and it only then for the cork

SEALS OPTIMIZING?

Optimizing of seals is quite possible and in some cases even advisable. Scratches and scoring on sealing surfaces become well balanced by so-called liquid seals. Manufacturers such as Loctites, Elring or Teroson hold there some products ready. They also often facilitate the assembly, because they fix the seals well on the surfaces. Also SILMOUNT the company RoTECH (Tel is well suitable: 069/94413778). This means which is based on silicone seals not only well, but enabled often to use a seal several times because it prevents on a long-term basis that it " sticks "  on the metal surfaces (35 gram of approximately 10 Marks).

SEALS STAMPING MACHINES - LIKE THAT GEHT'S

the thicker the material which can be processed is, can it the worse be naturally cut. Above all materials for exhaust or heading seals hold still another another difficulty ready: Good material is not only high-pressure resistant and temperature-steadily up to approximately 400 degrees, but is reinforced also with a so-called " Spiessblech " (wavy punched layer of metal). It prevents a too strong pressing of the material together and enables actually only the required even surface pressure with heading seals. Even ones for English vehicles are completely frequent without reinforcing inferior seals. Still used for it materials, which full-suck themselves with oil or cooling water, there necessary metal verges to be missing again and again. By the way: Often are still asbesthaltige seals (note: Special refuse!). Modern copies consist for example of " Aramid" fibers.

As said, to cut these materials leave themselves very badly, ideally are punching, with many seal manufacturers the laser chute already held. They do not have a punching device? No problem, it is relatively easy to manufacture. We assume, the holes for the staybolts of the exhaust seal have exactly ten millimeters of diameters. Bore then exactly this hole into a broader flat iron and tighten you it with two fastening clamps on the desk of your status drill press. Now you cut a ten-millimeter screw off at the heading and grind at this plane of section a V-shaped recess in. You stretch the screw now with the processed page into the drill chuck and finished are the punching device downward!

With the spider of the status drill press, with which you normally exert the pressure necessary when boring, create it easily, also thicker and reinforced seal material to punch. Now first all drillings are worked out, then the interior and last the Auáenkonturen, punch hole for punch hole. Only in order to avoid misunderstandings: The production machine remains naturally always switched off thereby! Thus for example exhaust auspuff-oder intake manifold seals can be made of reinforced material easily.

ONLY FOR SPECIALISTS

everywhere, where by the manufacturer verges made of metal are intended, seals also after-manufactured must be accordingly structured - and that is always a job for the professional. Manufactured with DS many exhaust and heading seals of this type, also in Kleinstserien or as unique pieces. The verges are cut thereby from steel sheet and pulled with much know-how. Often at it after old original plans or after customer drawing one operates. So also very rare vehicles can be equipped with cylinder head gaskets after the current state of the art.

The price for example a after-manufactured cylinder head gasket depends and varied therefore strong thereby on the number of cylinders, the recesses for staybolt, Wasser-und of oelkanaele as well as on the form of the verges. From heading seals from copper one thinks nothing at all in Grosshabersdorf by the way. The thought is much enticing to manufacture with only one punching process easily a seal practice shows however that copper is not flexible also after burning enough, in order to seal permanently reliably. With DS regularly copper seals with the request land to after-finished it from modern material including steel verges.

ALMOST NOTHING IS IMPOSSIBLE

also for Tuning and running engines manufactures DS seals. More importantly for old IE friends: It is possible up to a certain measure to use strengthened heading seals in order to exert influence on the compression of an engine. Necessarily this can become for example with strongly planned headings, in addition, then, if an engine is to be prepared for operation with fuel with small octane number, for example of remote journeys. With DS material up to a strength is processed by 1,8 millimeters, thicker material is not approved of the manufacturers. Seals also strengthened do not cost surcharge, since the material hardly more expensively, which is work expended however the same.

Adress:
DS - Dichtungen A. Schwarz
Am Galgenbruck 12
D-90613 Grosshabersdorf
Germany
Tel. 09105 - 9220, Fax 9230

Heinz STAHL

(Quelle: "Oldtimer-Praxis" 11/97)