ENGINE REBUILDERS PTY LTD
7 BARRETT STREET, FLEMINGTON VIC 3031,
TEL: (03) 9372 3111, FAX: (03) 9372 3122
ACN: 006 798 492 ABN: 74 006 798 492
TECHNICAL NEWSLETTER 01/07
MAKE SMALL DIAM. SHIMS IN AN EMERGENCY
The variety of shim sizes we now need to cover all makes and models can present a problem to your customer of a Friday afternoon with a stranded interstate vehicle because a small shim was lost by the mechanic. This happened last week to a new dealer client of ours and even by removing the sump they could not locate the missing shim.
The vehicle was a Toyota V8 Land Cruiser from Newcastle, owned by the dealer principle’s brother-in-law, on LPG (why would you?), and suffering from tight shims.
We made a shim in the following manner, and got the result for the client.
We carry a range of bar stock in Silver Steel. This material is a water hardening material used for numerous purposes in all tool rooms because it is easy to heat treat to a very high hardness level with an oxy torch and a bucket of water. Whilst generally used for hardened dowels, we have been using it to make odd small diameter shims.
The shim we needed was approx 11mm diameter and 2.25mm thick. This type fits under the bucket and in contact with the valve stem tip like the old Jag, Alfa and one of the WRX engines.
Machine the blank up on the lathe, allowing 0.005″ each side for finishing on the shim grinder.
Place the blank onto a flat piece of bar over hanging a bucket of cold water. Heat the blank to a very bright red going onto orange and flick it straight into the bucket of water. Do a file test to confirm that the hardening has been achieved.
Now, using a piece of emery paper, polish one side of the blank to a bright shiny surface. Back to the welding bay and place the blank, shiny side up, onto the flat bar again. This time, apply the oxy from underneath the flat bar so that the colour of the blank’s shiny surface can be seen. Approach this heating with some care and without haste. We are after a temperature that will be uniform throughout the blank and witnessed by a light straw colour appearing on the shiny surface. This will be the level of temper that is needed to retain a workable hardness, yet not be brittle. The moment that the straw colour appears, flick the blank into the bucket of water.
Now grind the blank both sides to the desired thickness and deburr the edges.
Whilst not as economic as buying a new shim, the method will get you out of trouble.
Regards
Hedley J