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I tripped over some square tubing on my garage floor, and I decided to make a crankshaft holding fixture.
After about 8 hours of futzing around and $15 in some nuts and bolts, the (semi) final product... http://forums.pelicanparts.com/uploa...1717987985.jpg http://forums.pelicanparts.com/uploa...1717987985.jpg M12 bolt threads into the crank snout and "floats" in the fixture. http://forums.pelicanparts.com/uploa...1717987985.jpg 5/8" bolt threads into the fixture and the unthreaded portion (can't be seen here) locates in crank. http://forums.pelicanparts.com/uploa...1717987985.jpg It's not pretty, but functional. Since I can't find my flywheel right now, this will come in handy for when I start checking clearances and bolting up the rods. |
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After a lengthy hiatus, intermediate shaft teardown, inspect, and rebuild, part B...
The first order of business is to measure the intermediate shaft bearings. Bearing #1 (big end) measured within tolerance at 24.980mm and bearing #2 (small end) measured within tolerance at 23.968mm. Okay, good... When I went to check axial play, there was none. Hmm...Gave some taps to each end of the shaft to seat the thrust bearing and still nothing. Hmm...does the shaft turn smoothly? Nope. So, I set up my dial indicator and measured about 0.040mm of runout. Yikes! Shaft must be bent...? http://forums.pelicanparts.com/uploa...1736027166.jpg Since a new intermediate shaft is about $1,200, I decided to see if I could find a decent used one on ebay. Found one for $140... Bearing #1 measured 24.978mm, which is just barely out of spec by 0.002mm but within the accuracy of my micrometer of +/- 0.004mm. I'm calling it good... http://forums.pelicanparts.com/uploa...1736027166.jpg Bearing #2 measured within spec at 23.975mm. http://forums.pelicanparts.com/uploa...1736027166.jpg It rotates nicely in the case and it seems to be good, confirming my fear the original shaft was bad. I will tear the "new to me" one apart, clean it, and rebuild it... |
Ward , sorry I'm late to the party , it looks like nice work.
Just a note about new timing sprockets , in post 73 the new shinny sprockets have a reputation for being soft or not heat treated correctly. The correct new sprockets have a grey tone to them . Just thought I would share this with you Carry on , VERY NICE CLEAN WORK Ian |
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I've read those discussions about the soft sprockets. Hoping, that Porsche would ensure they were up to spec, I bought genuine Porsche sprockets from our host. Appear to be manufactured 3/9/2019? http://forums.pelicanparts.com/uploa...1736221533.jpg But me being me, I purchased some HRC files to see if there was a difference. http://forums.pelicanparts.com/uploa...1736221533.jpg First up was the original sprocket at HRC40. Scratched... http://forums.pelicanparts.com/uploa...1736221533.jpg Next up was the new sprocket at HRC40. Scratched, but not as easily as the original... http://forums.pelicanparts.com/uploa...1736221533.jpg Just for fun, I tried to scratch a con rod and it didn't scratch using the HRC40 file. What to do? Since both sprockets have an HRC less than I can test with my files, I don't actually know which one is harder or softer, but both are less than HRC40. Anyone have an HRC tester to check for an exact number? Tsubaki suggests an HRC of 35-50 for small sprockets. According one of their tables, HRC30 sprockets have a tensile strength of 138,000 PSI and HRC35 sprockets are 160,000 PSI. http://forums.pelicanparts.com/uploa...1736222533.jpg I'm not sure what I'm going to do yet, but I think the genuine Porsche sprockets seem okay. |
I'm not sure where you are located but we sourced a local heat treating Co. to do Rockwell C scale testing for us when we want to know how tired various parts are we are considering reusing or putting in to service or that we have welded on (heads) , when race engines are torn down. These were mostly aluminum components- Pistons. I'd call one of them and learn exactly what you are putting in there. Wouldn't be surprised if nice old used parts are a better choice.
Sad that we are at this point even with "Genuine" parts today, the repro parts situation is even more dodgey. Kevin GAS Motorsport |
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I sourced a materials testing lab in San Diego that I might take the sprockets to for HRC testing. They charge $150 for up to six parts. Before doing that, I ordered two sprockets made by Rauch & Spiegel that claim that they "are the good ones, made in Germany for us from the proper material with the proper heat treatment." However, I was skeptical of this claim. Rauch & Spiegel on the left, new genuine Porsche on the right... http://forums.pelicanparts.com/uploa...1736707684.jpg I didn't get a "real" scratch on the Rauch & Spiegel sprocket until I used the HRC65 file. The original part came in at less than HRC40. I think this confirms their claim that they are properly heat treated. http://forums.pelicanparts.com/uploa...1736707684.jpg This settles it for me. I'm going to use the Rauch & Spiegel sprockets. |
Got the case hardware yellow zinc plated. Thanks to this post by ErrorMargin (https://forums.pelicanparts.com/porsche-911-technical-forum/1164377-1st-batch-parts-back-zinc-plating.html#post12285151), I used Cadillac Plating.
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http://forums.pelicanparts.com/uploa...1737316355.jpg Got everything sorted using calipers and a combination of photos with handwritten notes with stud dimensions from the parts manual. http://forums.pelicanparts.com/uploa...1737316355.jpg All installed! I didn't have anything left over, which is unusual for me, but I was extremely methodical... http://forums.pelicanparts.com/uploa...1737316355.jpg Also checked to make sure the piston squirters were working. Had a little trouble with the squirter for the #2 piston (not pictured), but got it cleared. http://forums.pelicanparts.com/uploa...1737316355.jpg |
Being a doofus leads to an expensive intermediate shaft saga...
Back in post #83, I thought that my intermediate shaft was bent due to excessive runout, and it wouldn't turn smoothly in the case. I bought a used one off ebay, which measured in spec and turned smoothly. When I went to check axial play, there was none. So, like with the first shaft, I decided to tap on each end to seat the thrust bearings. Recheck...Argh! Now it won't turn! Turns out that my "tapping" bent the flange inward, causing the binding. Intermediate shaft #1... http://forums.pelicanparts.com/uploa...1737918326.jpg Intermediate shaft #2... http://forums.pelicanparts.com/uploa...1737918326.jpg While I admit to being a doofus on a regular basis, I am experienced in the use of a hammer. I was a carpenter in my youth, before nail guns were commonplace, and have driven hundreds of thousands of nails. This may have actually been my downfall because I wasn't expecting the flange to be so soft and my usual hammering force was too much. All of my fiddling marred the bearings a bit... http://forums.pelicanparts.com/uploa...1737918326.jpg After learning from my mistakes, I bought another ebay special. Cleaned it up a little and found some pitting on the journal. Argh! Not using this one... http://forums.pelicanparts.com/uploa...1737918326.jpg And the aftermath... http://forums.pelicanparts.com/uploa...1737918326.jpg Intermediate shafts: $700 (1 original and 3 ebay) Bearings: $300 (Glyco and Porsche) Total cost of being a doofus: $1,000 |
Moving on with the intermediate shaft teardown, inspect, and rebuild, part C...
Measured the 0 gear with two 4.5mm pin gauges. Came in at 136.97mm and the minimum spec is 136.5mm. On to the next step... http://forums.pelicanparts.com/uploa...1738277706.jpg Installed new Porsche intermediate shaft bearings. End play came in 0.042mm and the minimum spec is 0.040mm. On to the next step... http://forums.pelicanparts.com/uploa...1738277706.jpg Prepared the shaft with some studs to guide lining up the holes... http://forums.pelicanparts.com/uploa...1738277706.jpg Heated the gear in my thrift store bearing and gear heater (AKA toaster oven)... http://forums.pelicanparts.com/uploa...1738277706.jpg After assembly (no pics), installed the intermediate shaft and crankshaft to measure backlash. Came in at about 0.135mm (ignore the rev counter) and the maximum spec is 0.049mm. Argh! Not on to the next step! http://forums.pelicanparts.com/uploa...1738277706.jpg I was taught by the "old timers" to always change gears in pairs and the Porsche Technical Specifications booklet says to "replace intermediate shaft gears and crankshaft gears in sets only." Off to order a new 0 gear for the intermediate shaft and a new 0 gear for the crankshaft. |
draw , you should follow PeteKz's advice for a deck height of .75 to 1 mm for better squish and chamber turbulence . Machine the piston tops instead of adding cylinder base shims . From my experience this is a difference you can notice when driving .
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Here's where my lack of engine building experience definitely shows. I've spent a lot of time juggling the different options, and I think I've settled on using a 1.25mm shim, which puts my calculated deck height at 1.04mm. Pretty close to the 1.0mm standard spec. I've chosen this as a tradeoff to keep my compression ratio (about 10.1, calculated) in a decent range for street use with 91 octane premium gas and twin plugs. If I was more experienced, I would feel more comfortable with stacking shims of varying thicknesses to reduce the deck height a little. I did seriously consider stacking a 1.0mm and a 0.20mm shim, which would put my deck height at 0.99mm, resulting in a compression ratio of 10.15. But I'm concerned that stacking these two shims would lead to a leak. Also, I'm running the LN cylinders without a head gasket/sealing ring and I'm trying to keep everything as stable as possible. Anyone with experience stacking shims care to chime in? |
I would expect twin plug at 10:1 static on 91 to be safe, especially if you tune for it and don’t advance ignition too far.
What cams are you planning to run and (thus) what is your dynamic compression ratio? If you run a decent amount of overlap + lift your DCR will probably be more like 7.5:1 (approaching ~8 at higher RPMs) and thus plenty of margin. |
Moving forward after my saga...
I ordered a new intermediate shaft gear from Pelican for $270 and a NOS crankshaft gear from Aase for $360. Pulled the gear stack off the crankshaft and reinstalled with the new gear. http://forums.pelicanparts.com/uploa...1738544721.jpg Rebuilt the shaft with all new gears and used Loctite 574 on the end plug. http://forums.pelicanparts.com/uploa...1738544721.jpg Checked backlash, which came in at 0.023mm. Much better! http://forums.pelicanparts.com/uploa...1738544721.jpg Checked end play on the crankshaft. Minimum spec is 0.110mm (I believe) and it came in at 0.123mm... http://forums.pelicanparts.com/uploa...1738544721.jpg And "bob's your uncle"... http://forums.pelicanparts.com/uploa...1738544721.jpg Test fit the new oil pump. (I know the pump is overkill, but I got a good deal on it...) http://forums.pelicanparts.com/uploa...1738544721.jpg |
Moving on to prepping the rods...
I had Ollies recondition the rods and resize the big end with ARP rod bolts. Need to break them down and give them a good cleaning... http://forums.pelicanparts.com/uploa...1739150719.jpg I am using the "stretch" method for the rod bolts instead of relying on a torque value. And, I've discovered that there are several differing techniques to measuring. Taking inspiration from Tony's post (https://forums.pelicanparts.com/911-engine-rebuilding-forum/1070821-stretch-gauge-beginner-question.html#post10994234), I came up with my own technique... I've decided to set the dial indicator to a known value of 2.750 inches by using two gauge blocks. This will allow me to measure and record the pre-stretched length with a repeatable method. http://forums.pelicanparts.com/uploa...1739150719.jpg Using this bolt as an example, it measured 0.009" from the baseline of 2.750", so the length is 2.759". When I go to install the rods, I can just add the stretch value to each bolt's original value. For example, 0.009" + 0.0095" = 0.0185 on the gauge. http://forums.pelicanparts.com/uploa...1739150719.jpg On to cleaning... |
Hey Draw,
You are doing great work especially for a non-pro, with meticulous attention to detail! I am learning a lot as I am following along, thanks for sharing your journey with us. I have an engine rebuild coming up myself and the note file with tips and tricks is getting longer and longer. http://forums.pelicanparts.com/support/smileys/clap.gif Cheers from Austria, Lukas |
That pump isn't overkill - I have the same pump in my 2.7. You'll appreciate the extra flow, oil pressure, and cooling (assuming you're fitting an external cooler). It's cheap peace of mind.
Great attention to detail! |
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I'm using the DC43x-102 cams from John Dougherty. I should be okay, but I am paranoid of the dreaded "ping" of detonation. Quote:
There's no way I would be able to undertake this project without:
Tony's engine rebuilding class... Quote:
And especially Kurt at Klassik Automotive Training School. Kurt covers almost everything in the rebuild process and shows how to do things not covered by any book https://www.youtube.com/@klassikats. Quote:
I agree with you and the pump was 30% off when I bought it. And, I wanted to have a pump capable of working with a front mounted oil tank and dual oil coolers if I decide to go that route at some point. |
As I get closer to closing the case, I wanted to know how much time I really have before the Loctite 574 cures. Is it 15, 30, or 45 minutes? Opinions seem to vary widely...
Reading the Loctite TDS, cure time varies due to many factors, including whether the metal is active or inactive. Hmm, since the case is a magnesium alloy, which is "inactive," I thought an experiment was needed... First, using an old magnesium chain housing as a proxy for the engine case, how long can I leave the 574 sitting there before it hardens? After 1 hour, the 574 was still in a gel state and there was some "shrinkage," but it wiped right off. I did not try a longer timeframe, because I figured an hour is more than enough working time. http://forums.pelicanparts.com/uploa...1739653495.jpg Next, I clamped the cover and housing together to test how well it would cure in an anaerobic environment. After an hour, I opened it up and the 574 was still in a gel state (not pictured). I reapplied the 574 and closed it back up to see how things would fare after 24 hours. http://forums.pelicanparts.com/uploa...1739653495.jpg After 24 hours, I opened it up and the 574 appears to have cured. The empty spots of 574 seen in the picture were adhered to the other side. http://forums.pelicanparts.com/uploa...1739653495.jpg My takeaway is that (1) 574 can sit on the case in open air for at least an hour; (2) on an inactive metal like magnesium alloy, the 574 takes longer than an hour to start curing so I don't need to be in an extreme rush bolting things back up; and (3) full cure probably takes at least 24 hours and probably longer. I called Henkel's technical support, and they suggested that the SF 7649 activator be used on magnesium. They said that without the activator, it's possible that the 574 may take 24-72 hours to cure or may not cure at all. From my testing, it seems the 574 does cure, and so I will forgo using the activator. |
It's always good to have more working time, just in case the assembly doesn't go together quickly.
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