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My guys wanted the rods first and the bearings, also the required clearance. However 2" is a common size and they should have some experience here. With regards to wanting the rods, the secondary reason was to check them for size and defects. In one job they did they found out of spec bearings and rejected them.
Yes, always good to check everything yourself....I trust no one but myself....and I have to watch him really close.
I use this size so much that I bought a 2" Mitutoyo Setting Ring (which is stamped by Mitutoyo as 1.99997") to be able to calibrate all my measuring tools. (I own nothing that can remotely measure .00003", BTW.)
The bearings that I use in this application come in "standard", standard +.001", and standard - .001". I "mix and match' bearings to set the rod bearing clearance I'm looking for, which varies a bit, according to the intended use of the engine and which rod journal I'm setting the clearance for.
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
Fair enough, getting accurate measurements takes time I find, you need to be so careful about pressure and keeping everything perpendicular. Also I am using the so called "extra clearance" bearings which will keep the journals on the large side of the options just in case I get crank wear and need to then go to standard or undersize. I will set all my clearances the same as I have no data to go on regarding changes to that. Also the engine is dry sump so oil supply will hopefully be very pure in having no or very low entrained air in the oil.
For me having someone oversee my work is probably an Overkill but sometimes I don't have the tools either, like my rods which as simple have said are used, the found one small end slightly out of spec. I had nothing to check that size etc.
Fair enough, getting accurate measurements takes time I find, you need to be so careful about pressure and keeping everything perpendicular. Also I am using the so called "extra clearance" bearings which will keep the journals on the large side of the options just in case I get crank wear and need to then go to standard or undersize. I will set all my clearances the same as I have no data to go on regarding changes to that. Also the engine is dry sump so oil supply will hopefully be very pure in having no or very low entrained air in the oil.
For me having someone oversee my work is probably an Overkill but sometimes I don't have the tools either, like my rods which as simple have said are used, the found one small end slightly out of spec. I had nothing to check that size etc.
Having a machinist who does consistently great work, who you can rely on, and trust is of paramount importance.
Because my name is tied to the end product, I like to double check everything.
However, I don't ask my machinist to even look at the bearing clearances....that is something I prefer to do. (I've got a set of "target" clearances that vary, a tiny amount, for almost each "pair" of rods on the crankshaft.) I'll spend 3-4 hours checking all the pieces, measuring everything, and getting the clearances exactly where I want them. Measuring and mixing pieces allows me to vary bearing clearances by ~.0002" (which is as close as I can realistically measure.) Not many machinists have the patience to do this, for me.
Had a conversation with the gent working on the crankshaft. He quoted $1500 to reduce the journals, cross drill the crank to the specs above, knife edge the crank and balance the assembly. The cross -drilling is not easy.
Given the complexity cross-drilling the crank alone I think the price looks fine.
Also, chatted with my engine builder(Gary Grimes). We discussed the 2-6 bearing failures and such. Turns out he has bearing custom made and in different thicknesses. And given the 2-6 failure he says we are going to get them coated. He spoke quite a bit about the role of bearing sizes and engine longevity.
He builds road race engines - He does not sell them - he leases them. That way nobody knows what magic he puts in them - they all pass post race inspection.
S3 engine, pistons and cams arrive the first week of December.
The GTS crankshaft is back. It has been cross drilled, knife edged, mains have been cleaned up to .25 undersized and rod ends reduced to 2".
There is now oil supply up and down the crankshaft. There's new holes and between the new holes and knife edging the crankshaft is nearly 7 pounds lighter.
Greg ordered the Carrillo rods, I have a set of .25 undersized mains sans the nose bearing and my builder is going to have the rod end bearings made by the same folks that make them for their race engines.
I hate to ask, but how much have you spent on this crank compared to getting one of greg's new stroker cranks? Or would that have created a cascade of other costs?
11-05-2018, 08:04 PM
