Scroll Seal Suggestion
FITTING AND LEAKPROOFING A NEW SCROLL - Colin Cuffe 2014
The rear crankshaft scroll can be fully leak-proofed by a high temp. VITON 63mmx4mm 0 ring stretched over the crank flywheel flange and tensioned on the crank web between the surface ground and polished face of scroll and inner flange face - this gap is approx. 4.4mm ( if significantly different may need a thicker or thinner 0 ring ). This 0 ring is permanently tensioned against the scroll by a further H.T. VITON 63mm x2.62mm 0 ring stretched over the flange and which automatically sandwich/tensions itself between the outer upper edge of the 4mm 0 ring and flange. See attached sketch:-
Having obtained a new scroll from Register proceed as follows:- Firstly surface grind the two unmachined casting faces of the outer scroll halves to a flat and smooth surface. I achieved this by firmly holding the two halves together and with light pressure moving them back and forth over fine wet emery paper laid over a piece of 3/4" plate glass. Then polish with metal polish out from the scroll edge to a mirrow finish. Obtain a small sheet of 0.002 of an inch steel shim. With the rear main bearing cap extracted, together with attached half of old scroll, remove 4 bolts from upper scroll half. Rotate anticlockwise the old topscroll half around crank 180 degrees and remove through bearing cap aperture. Cut a strip of shim steel about 25mm wide and 250mm long. Lightly machine oil both sides of shim and inner scroll surface. Lightly coat inner flang face of new scroll with Locktite automative number 3 non-hardening aviation gasket sealant. Lay shim inside scroll half with approx. equal lenghts hanging out both ends. Carefully rotate the scroll half with the shim inside around the crank in the reverse direction to which it came out. The process is to get the top half back in place with the shim entrapped between the two scrolls with a small length of shim protuding at the far end.
I suggest you have a few "dummy runs" (without gasket sealant) until you get the knack of it. Once you get the scroll home and are happy the shim is fully covering the scroll ( not too much hanging out the front face ) insert and finger tighten (then back off 1/2 turn) the 4 bolts. Apply a light to medium downward pressure on scroll, sufficient to sandwich the shim between scrolls, but not so much as to preload the shim to a level that you can't pull it out. Holding tension, fully tighten the 4 bolts. Using pliers pull directy downwards on the long exposed end of shim. If it starts to pull out relatively easily with medium tension and no fear of tearing continue in one motion and pull out completly. If not loosen bolts , apply less downward force and retighten bolts and try again. Don't worry if you need several attempts as you soon get the feel of it. Attach new bottom scroll to bearing (using gasket sealant ) cap leaving bolts loose. Tap home the bearing cap making sure bearing shell is ok and still properly in place. Bolt home the bearing cap and tension bolts per workshop manual (use gasket sealant to top and sides of cap before fitting.) When the bottom scroll is fully mated to the top half there will be 0.002 " clearance at the bottom of the scroll only.
Lateral adjustment is achieved by fully inserting between scrolls a short piece of shim about 25mm wide adjacent to and immediately below the left join. Insert the small shim as above and using forefinger of left hand apply lateral pressure to sandwich shim and simultaneously use left thumb to apply upward pressure to close the halves together. Maintaining pressure tighten bolts with right hand. Repeat as previously if shim is too tight to remove.
If you need a "quick fix " (but unprofessional ) make a small narrow tray out of thin Zincalum fitted directly under the bellhousing to gearbox join fixed by 2 of the bolts to this joint. Fill tray with felt wadding.
DISCLAIMER: Articles are presented in good faith by the author and the TR Register Australia Inc. Some articles may be several years old and items, prices, suppliers, availability etc may have changed. This forum, the web site and our club newsletter, from time to time, print articles containing suggestions and advice for maintenance and modifications to your car, but it is your responsibility to ensure that any modifications or maintenance that you carry out on your vehicle conforms to all applicable safety and design laws and regulations and any stipulation made by your insurance company. Accordingly the TR Register Australia Inc., its officers, directors, any Club committee members or authors of individual articles or items hereby disclaim responsibility for all and any legal liability whatsoever (as may by law be disclaimed) as might otherwise arise.