What are the tell tail signs of a good balance job vs a bad?Is there any way to confirm a good balance job?Also what are the right questions to ask to screen out the posers from the real deal?On top of that I also read about volumetric balancing. Is this necessary?
First there is a level of trust and confidence you must have in the shop that is doing the work. It is difficult if not impossible to check the dynamic balance fully, short of taking it to another shop or rebalancing it yourself. After much research here are some of the things you can ask.
1. What parts do you require for a balance job. In the case of a type 4 motor it should look like the following.
- Crankshaft
- Flywheel
- Gland nut or flywheel bolts
- Pressure plate
- Front crank pulley 356 and 911 (Cooling Fan TIV ONLY)
- Connecting rods
- Pistons& pins
- Piston rings
- Crankshaft gears, spacers and retaining hardware (do not install them on the crankshaft)
- Connecting Rod bearings
- Teflon buttons/wrist pin clips
2. Ask for a spec sheet on the balance. It should include weights of the parts to the .1 tenth of a gram. Knowing the weights you can double check the balance at home with a gram scale. If you want to be extra paranoid, weigh all the parts before you take them in for the balance, then compare when you get home.
3. Ask for all the parts to be indexed for reassembly. With indexed parts you can assemble the parts in the way they were balanced. Also if you need to replace an item such as the pressure plate you will know the balanced weight and be able to get close to that spec again. It wont be perfect do to wear in the motor but it will be closer than not knowing.
Still don't know if volumetric balancing is necessary. Here is a pretty good article on volumetric balancing.
http://www.autospeed.com.au/cms/A_109725/article.html
I realized this is not a particular procedure or test that can satisfy this term. As I understand, it's the sum of good fitting parts, valve train geometry, engine balancing, deck height, etc. So basically an engine the has tight tolerance on all parts and assembled with best possible care.
I would like to amend this a bit and add Crankshaft gears to the must balance list. After I read John Maher's articles on engine balancing I am convinced this is necessary. These are great article it really details the process. Read both articles!
http://johnmaherracing.com/2013/01/project-2110-part-4-dynamic-balancing/
http://johnmaherracing.com/2013/01/project-2110-part-5-dynamic-balancing-continued/
