_Ned Loh_
Posted 20 May 2013 - 07:52 AM
I don't have a definitive answer X damper, with Y flywheel, and Z crank. If you don't want to experiement a little a phone call to someone like Ian Tate might be your next best move.
BTW - I've also had issues with the ultralight in the RPM ranges being mentioned, but in their defense there are applications where they are well suited.
_jklumpp_
Posted 20 May 2013 - 11:10 PM
_jklumpp_
Posted 21 May 2013 - 09:04 AM
... and another question - Would a Girdle be advisable, or overkill for my engine?
If advisable, there are 8mm ones on Ebay http://www.ebay.com....k-/370581579898
and 10mm ones from Sonic http://www.ebay.com....=item3cd1ab77c8
Does anyone have recomendations, or know of anywhere else that sells them?
I assume I would also need to use the ARP studs - I expect the bolts would be too short.
_oldjohnno_
Posted 21 May 2013 - 09:32 AM
I doubt very much that it's a balance problem, assuming of course that your cut-down crank was spun up on a balancing machine. A simple out-of-balance condition will shake progressively worse as the rpms are increased, torsional vibrations on the other hand typically only become apparent at one or more speeds.
And just because the flywheel isn't falling off doesn't mean there isn't a problem. I have a 202 to which I stupidly fitted an ultralight wheel. In normal driving it runs perfectly smoothly apart from some perceptible roughness around 3100. But it gets rough again around 6200 and if it's run for any length of time around 7000 it'll kill the pressure plate and loosen various bolts like engine mount bolts etc. But the (dowelled) flywheel stays tight even with the little 3/8" ARP bolts that many claim will result in instant death. If I didn't intend to replace the engine soon I'd definitely change the flywheel.
_STRAIGHTLINEMICK_
Posted 21 May 2013 - 08:31 PM
There are two major causes of vibration in long crankshaft engines one is a whipping motion in the centre that is accentuated with a red crank because the balance weights are in the middle .The other is a harmonic vibration caused by each power stroke putting a slight twist and springback into the crank ,imagine this at 7000 rpm multiplied by 6 cylinders . All of these forces seem to peak together at around 6200rpm ,give or take. The stronger the power stroke the worse the problem is. Like Jonno said it isnt a balance problem and you can't stop it happening. Best you can do is an attempt to dampen the vibration with as big a balancer and flywheel you gan get away with . Another bandaid solution is to design the engine to make power at higher rpm so you can quickly get through the worst vibration period .
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Posted 22 May 2013 - 06:58 AM
A girdle is said to help aid TV, I have a Sonic unit & you will need studs which he can supply as well. If you fit a sonic unit, make sure that check the dip stick fits correctly.
_oldjohnno_
Posted 22 May 2013 - 09:24 AM
I use the Sonic girdle too. One of the nice things about the little Holden is the very lightweight block, but the downside is that they are not very stiff and liable to being wriggled around by whatever the crank is doing, sometimes to the point that the block cracks or chunks fall out of it... A girdle seems to help a little bit, as does a bit of grout. I'd be interested to see whether attaching passive dampers to the sides of the block had much effect.
I think the flywheel and harmonic balancer selection is absolutely critical, and that the balancer can be made too big.
_double_d_
Posted 22 May 2013 - 11:09 AM
when you say dampeners johnno
i had a thought the other day, dont know if it would work
two dampeners/struts from the firewall connected to like a watts linkage at the back of the engine somehow ?
would that work at all, or a waste of time ?
_stretchlc_
Posted 22 May 2013 - 01:02 PM
Crank Dampener....Crank Dampener built into the Balancer!!..............struts?..hahahaha
CABIN ENGINE CONTROLS GALORE
Posted 22 May 2013 - 01:37 PM
Hi All,
Did a bit of digging around and found some Interesting stuff.
Edited by TORYPOWER, 22 May 2013 - 01:51 PM.
CABIN ENGINE CONTROLS GALORE
Posted 22 May 2013 - 02:01 PM
This is a good read:-
http://www.enginebui...rankshafts.aspx
Extract:-
As we all know, the counter-balance weights get a lot of attention. They are lightened, knife edged and filled with heavy metal to balance the finished piece. The reasons for all this attention are basic: to make the crankshaft revolve in the contaminated atmosphere of the crankcase with as little resistance and/or vibration as possible. Although knife edging is the most common way to streamline the counterbalance there are other methods. One leading crankshaft manufacturer believes that the most efficient leading edge was a rounded radius."
Edited by TORYPOWER, 22 May 2013 - 02:11 PM.
To advertise here, call 13TORANA
Posted 22 May 2013 - 02:25 PM
" I'd be interested to see whether attaching passive dampers to the sides of the block had much effect."
I think Oldjohnno is referring to dampeners similar to what gets bolted to exhausts, diffs, trannys and the like to reduce cabin noise.
Exhaust dampner.jpg 110.59K
2 downloads
Edited by rodomo, 22 May 2013 - 02:28 PM.
_STRAIGHTLINEMICK_
Posted 22 May 2013 - 07:30 PM
Hi All,
Did a bit of digging around and found some Interesting stuff.
Here is an Extract from this link:-Every piston fires at a different instant in time, which creates vibrations in the crankshaft that grow in magnitude with the number of cylinders, the length of the crankshaft and engine speed. The constant pounding and stress may cause small hairline cracks to develop in and around journals, and particularly around oil holes. That's why crankshafts should always be examined with a magnetic particle inspection machine to check for cracks before they are reused.Used crankshafts also have to be checked for straightness. The constant loading and pounding combined with wear in the main bearings may result in a bent shaft. Straightness can be checked by placing the ends of the crank in V-blocks and using a dial indicator to measure deflection in the center main bearing as the crank is rotated. If the crank is bent more than about .0015" (specifications will vary depending on bearing clearances), it must be straightened in a hydraulic press or replaced. Forged steel cranks will typically accept more correction than a cast crank. But if the crank is bent beyond the point where it cannot be straightened without weakening or cracking it, it must be replaced.Now here is something interesting, they are saying that the Steel Billet 4340 (stronger metal than the high end forged) Crankshaft is better than the Forged Steel cranks for Vibration? Dave I
Grumpy Old Man
Posted 22 May 2013 - 08:16 PM
This may add no new info, but there was a book released around 1991 that was called Tough 6's. It had an article that touched on the vibration issue. I have it some where, but because it's a book I can't copy and paste. Other wise I will have glue all over the monitor.
_doucmyuc_
Posted 23 May 2013 - 11:00 PM
What engine and gearbox mounts are you using?
What viscoscity oil are you using?
_Dansthemanow_
Posted 24 May 2013 - 10:09 PM
Im new to this forum and I have some experience to share and also hope to get advice to help with a flywheel issue on my torana.Im running a 234 stroker with 186 block and crank is a pro stroke job based on hybrid ford221/holden 186 cranks.I havnt looked at the crank in 5 years as its remained sealed within the engine,but I do remember it had extra counterweights welded to it.It is one of their "speedway spec" cranks and it was nitrided balanced,blah blah blah.The engine has always been a brilliant performer and I never had any issues with anything breaking or loosening on or around the engine.No signs of welch plugs moving or anything.Nod bad considering this engine is making over 300 hp and possibly 300+ at the wheels if I am to beleive the last dyno readout I had from the thing.I must admit even I suspect that dyno may be reading high,but I could be wrong,this thing really moves.
Anyway never had any issues for the first couple years then one day the lightweight alloy flywheel worked loose(didnt come off).pulled the box and flywheel,a machinist/racer from way bak did mods to it using cap head bolts which seated inside steel inserts pressed into the alloy of the flywheel.put all back.Didnt last long at all,came loose.tried again with a new steel ross balancer(same size as standard but a little heaver)It laste a while but has come loose again.All in all 4 times its come loose.Now from what I have read I definately plan to change to a heavier steel flywheel,and I also have a large romac balancer(about 3.5kg) which i might fit.However I dont know wether I should pull the crank for a full inspection and dowell it,or just fit the heavier flywheel and balancer and give it a go.I heard upgrading to the 7/16 flywheel bolts works well,but does the crank have to be removed to do this?
_jklumpp_
Posted 25 May 2013 - 07:47 AM
What engine and gearbox mounts are you using?
What viscoscity oil are you using?
Std rubber mounts, and HPR30 oil, which I think is 20w60?
_Dansthemanow_
Posted 29 May 2013 - 11:00 PM
HI all.Im new on here.can someone describe the process for upgrading to 7/16 flywheel bolts.Can it be done properly without pulling the crank out?
_Dansthemanow_
Posted 01 October 2013 - 07:31 AM
_Bomber Watson_
Posted 01 October 2013 - 07:45 AM
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Posted 01 October 2013 - 06:27 PM
I would pull the crank out....
and also check for crack's on no.6 rod journal....
_STRAIGHTLINEMICK_
Posted 02 October 2013 - 09:52 PM
You can do it with the crank in the car if you make 2 jigs ,one to drill on center and one to tap square to the flange using flanges cut off other cranks .
_Dansthemanow_
Posted 17 November 2013 - 12:09 PM
o.k.thanks for the advice.I actually re-did the loose flywheel a few weeks back.Had the back of the flywheel machined flat,new 3/8 bolts,used arp bolt lube as ive already tried red thread locker,which did precisely zip to prevent them coming loose.Thought maybe the arp lube would help maximize the bolt tension.torqued,loosened and re torqued the bolts 3 times to seat them in.I took the bastard to the race circuit yesterday and I heard that dreaded vibrating kind of sound after a few laps and i knew straight away the flywheel was loose again for the 5th time.
As you would imagine it was rather frustrating to have it come loose just after taking the car out to the track.I have a few options at this point.Im tempted to pull the engine and crank just to have the crank checked over and then get it dowelled so I know it will never happen again.I think dowelling is the most sure fire cure for this problem.Ive also heard that using a steel flywheel with a 10thou interference fit on the crank flange,along with v8 bolts will stop it coming loose.Sounds like this can be done without removing the crank.Or there is a chance I can stop it happening by ditching the light flywheel in favour of a heavier steel one,and perhaps using a different balancer.Ive got a 3.5kg romac I could try.Ive currently got a powerbond race balancer which is 1.8 kg I think vs 1.6 for the stocker. But there is no sure fire way to know if this will help.its all trial and error.The other thing is lockwirin g the bolts,but somehow I dont think even that will stop the flywheel working loose.Its amazing just how fast they can work loose even with perfectly tightened bolts,it takes seconds once you get up around 6500rpm.
_Bomber Watson_
Posted 17 November 2013 - 12:29 PM
Edited by Bomber Watson, 17 November 2013 - 12:31 PM.
_Dansthemanow_
Posted 17 November 2013 - 01:36 PM
yeah,I think light flywheels are overrated.Like old jonno says,your better off with the stock weight flywheel.The lightweigt mainly helps with rev matching during gear chganges.But like you said,once the clutch is out the flywheel weight becomes much less relevant.Some engines probably like the lighter flywheel,but not a straight 6,and not a holden straight 6.
Another thing ive heard is people doing the bots up to 90ft/lb to stop em coming lose,but I really dont see how they pull that off,as 55 ft/lb is getting pretty close to the limit of what a 3/8 fastener will handle without stripping the thread out.I would say youve got 4/5ths of stuff all chance of doing a 3/8 bolt to 90 ft/lb without snapping it.
Anyway i might see if I can look at those pics with the groove.I might get my guy to make a custom steel flywheel with an extra tight fit over the crank flange,such that you gotta heat it up when fitting it,then when it cools it becomes a tight fit over the flange.Then with the groove as well,i might get away with the standard bolts.Gotta think about that.
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