Patrick's build thread. (IT RUNS!)
12-15-2014, 12:23 AM
#976
Three Wheelin'
Something does look odd there. Nobody has ever said anything about that so I assumed it wasn't totally unusual and must have been to do with balancing the crank when it was done initially. Now I look at that and think it doesn't seem right. I'll ask some more questions.
Cheers,
Mike
12-15-2014, 01:58 AM
#977
Rennlist Member
Thread Starter
Crank before and during engine assembly over the years. Old pics so it was like that from when I took possession of it. Definitely something 'odd man out' with the furthermost counterweight.
12-15-2014, 02:16 AM
#978
Rennlist Member
Thread Starter
On a sidenote. Today I went out to our local track where Paul was doing sponsor rides in the Aussie V8 Supercar. I brought my race gear in the hope that I might be able to sit in the passenger seat for a hotlap. Well as luck would have it I was able to do so and Paul put the car through it's paces. Very impressive is all I can say. Both the car and Paul's driving! They feel quite different to our car but quite similar power to weight levels. Quite nervous and wanted to get the tail out pretty easily. Paul's driving skills simply amazed me and made me feel like a kid in a pedal car by comparison. Amazing control and didn't hold back. The sponsor rides were only getting 1-2 laps but Paul squeezed out about 5 hotlaps for me. When he finally came back into the pits and were about to roll to the garage and I started taking my gloves off. He said "Leave them on". I thought perhaps you had to be super secure with the safety regs or something. I said why and he said "because you're going out now". All I could keep saying was "No"...he'd nod and say "Yep"...I'd say "No Way"..."Yes way"...! Then our engineer and this V8's owner Robbo came up and confirmed as I was getting out of the passenger seat. Went around and got strapped in and said "How do you drive a sequential gearbox??" First things first. Starting and pit limiter. Push button start and then apply very little throttle opening. It's an ign cut control and if you open up the throttle too much you blow up the Air box basically. Once on the track I realised that I couldn't quite reach the base of the pedals at full extension so that made things 'interesting' coming into T2 first time around. Gearchanges...feels really odd to hold foot flat to the floor and just pull on the shifter. If you're too early or late it doesn't like it. Dog engagement rings don't mesh properly. Downshifting you do use the clutch but I can't say I mastered this whole thing within the 3 laps that I did. Still, quite an eye opener and much respect to the pros. A real man's job in that cockpit banging those cars around like they do. Especially for 2 hour plus stints. Serious skills, commitment plus physical and mental fitness. I certainly couldn't do it.
Last edited by 333pg333; 12-15-2014 at 05:47 AM.
12-15-2014, 02:31 AM
#979
But on the picture you posted it still looks like it hit something, the question being if it was damaged before or after the girdle and block broke.
Where was the lunched nut as showed on the first picture found upon disassembly?
Two of the main studs where the nuts were removed show some kind of sleeves around them, what are they for and why do they stick out? If these were added to avoid the girdle to slide on the block, were they short enough? If one of these nuts came loose rod #3 could have banged it onto the girdle.
Last edited by Thom; 12-15-2014 at 03:01 AM.
12-15-2014, 05:46 AM
#980
Rennlist Member
Thread Starter
Good question Thom. Will find out more in the near future.
12-15-2014, 05:52 AM
#981
Nordschleife Master
Very sorry to see this Pat! 
Hard to know what caused what. How did the bearings look? If the girdle nuts came loose first that would have caused a LOT of inbalance and could in turn break the rest of the stuff.
Hard to know what caused what. How did the bearings look? If the girdle nuts came loose first that would have caused a LOT of inbalance and could in turn break the rest of the stuff.
12-15-2014, 06:34 AM
#982
Rennlist Member
Thread Starter
Yes, hard to know what let go first. The loose nuts could be a sign of all the vibration too. If a nut wasn't torqued correctly it would have become apparent way before this...let alone a few of them. Seems symptomatic rather than causal to me.
12-15-2014, 08:17 AM
#983
That sucks! To me it looks like something came loose and caused the damages. I find it very hard to believe that this is caused by vibrations alone.
Are you using stock pins for the girdle? With the torque on these bolts it does not make sense that vibration alone caused them to come loose. Then again you keep breaking stuff that should be a none issue, and that with balance shafts that should keep second order vibrations to a minimum. Even if they are slightly off in regards to the none stock pistons and rod weight.
I have always thought that if I have to redo the bottom end, it would be a good idea to glue the girdle on, instead of using sealing compound. This should increase the block stability. And also use thread lock on the nuts.
Are you using stock pins for the girdle? With the torque on these bolts it does not make sense that vibration alone caused them to come loose. Then again you keep breaking stuff that should be a none issue, and that with balance shafts that should keep second order vibrations to a minimum. Even if they are slightly off in regards to the none stock pistons and rod weight.
I have always thought that if I have to redo the bottom end, it would be a good idea to glue the girdle on, instead of using sealing compound. This should increase the block stability. And also use thread lock on the nuts.
12-15-2014, 08:38 AM
#984
I guess from the size of the threads on the main studs that they are Raceware or ARP... Sure they were torqued to the right amount?
I always found interesting that the RW studs installation instructions mention the need to retorque the head after the first heat cycle while nothing is mentioned regarding girdle studs.
I always found interesting that the RW studs installation instructions mention the need to retorque the head after the first heat cycle while nothing is mentioned regarding girdle studs.
12-15-2014, 01:42 PM
#985
Rennlist Member
Order of events were that when Paul went out on the brand new (treated [shaved/heat cycled]) tyres he came straight back into the pits after thinking that the vibration might have been loose wheel nuts. Assured that this wasn't the case he went out and did one hot lap. He came back in and the next session he went out on supposedly less affected tyres. The CV broke straight away and he came back in. We cobbled together a replacement setup and waited for the next session. He then had the first motor hardware failure which was the dry sump pulley. So he drove back to the workshop and made a whole new one out of a block of alu. Came back and fitted this and we thought we were going to be ok but had to come back in immediately after that when the b/shaft pulley sheared in half. Oh, and there was also a big crack in the intake which we also attribute to this high vibration / harmonic issue. We didn't discover that the rear suspension X member was also bent badly to such a point that the car actually had really high rear wheel toe out. It's easy enough to pontificate about what might have been the first domino. I am still not so sure it wasn't issues at the rear of the car that might have transferred down through the torque tube into the motor. There has been a big evil harmonic that has affected many parts but what caused it to start when we seemingly had none of these problems throughout the year. I say seemingly as there would appear to be evidence (metallurgically speaking) that the b/shaft pulley didn't break in one event. It looks like there are different colours in that break which might suggest it was stressing prior to failure.
12-15-2014, 05:22 PM
#986
Intermediate
That is terrible news Pat (and Paul). Only one solution to this ... get back on the horse! Merry Christmas and hope to see you early in the new year.
Cheers
Cheers
12-15-2014, 08:45 PM
#987
Rennlist Member
Thread Starter
Just a ton of possibilities with this. My engineer says he's seen this before on Kent Formula Ford motors due to vibrational issues. Yet again it's frustrating as we can't be 100% sure of the cause. Hence the possibility of repeating the process looms in the back of my mind. Having said that, we will be making significant changes to the new motor and other parts of the car which should remove much of the risks. In the meantime we will study the remains to see if anything else stands out. Just hard to determine which is the Chicken and which is the Egg at this stage.
12-15-2014, 10:31 PM
#988
Three Wheelin'
Hi Patrick, just an observation: the counterweights on that crank have been significantly lightened, is this relevant?
https://rennlist.com/forums/911-foru...ml#post1031968
Another interesting comment here:
http://www.network54.com/Forum/16624...edged+fj+crank
"I like that the grinding was conservative or absent on the arms in your pic. You want to be cautious about weakening the crank. It is worth mentioning that if you lighten the counterweights of a crank substantially you should strongly consider a high-end dampener. A failure mode that is not immediately apparent when lightening components is the increased higher order vibrations. In engines like the Porsche 944 and 968 these commonly result in cracked pickup tubes. In engines like the Nissan KA24XX the snout of the crank can snap off. In other engines with sintered geroter pumps on the crank the vibrations can encourage gear failure."
Cheers,
Mike
P.S. Apologies for being an armchair quarterback, I'm bored. Awesome to have a ride and drive in the Supercar, recognition for your commitment to fast cars! Fully deserved.
https://rennlist.com/forums/911-foru...ml#post1031968
Another interesting comment here:
http://www.network54.com/Forum/16624...edged+fj+crank
"I like that the grinding was conservative or absent on the arms in your pic. You want to be cautious about weakening the crank. It is worth mentioning that if you lighten the counterweights of a crank substantially you should strongly consider a high-end dampener. A failure mode that is not immediately apparent when lightening components is the increased higher order vibrations. In engines like the Porsche 944 and 968 these commonly result in cracked pickup tubes. In engines like the Nissan KA24XX the snout of the crank can snap off. In other engines with sintered geroter pumps on the crank the vibrations can encourage gear failure."
Cheers,
Mike
P.S. Apologies for being an armchair quarterback, I'm bored. Awesome to have a ride and drive in the Supercar, recognition for your commitment to fast cars! Fully deserved.
Last edited by mikey_audiogeek; 12-15-2014 at 11:19 PM.
