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Are harmonics killing my engine?

Started by _jklumpp_ , May 14 2013 11:10 PM

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140 replies to this topic

#126 _Dansthemanow_

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Posted 18 April 2014 - 06:58 PM

I ended up finding Seal Lock brand tapered plugs which are stocked by some guy in qld.I already drilled,tapped and inserted the plugs in situ. I pressure tested and so far its water tight.Time will tell how long it lasts.
The crack formed very close to the bottom of the water jacket literally a few mm above.The main issue is that the cracks are virtually invisible to the naked eye.I didnt do a crack test,just kind estimated where the crack ended judging by the water seepage.
I think plugging beats welding.Your just opening a can of worms putting a welder to it.Even pros reckon they only get a 50/50 success rate welding cast iron.

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#127 _Dansthemanow_

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Posted 18 May 2014 - 09:40 PM

Given it a couple good workouts now,no trace of leakage from the repaired crack.

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#128 _duggan208_

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Posted 23 November 2014 - 11:41 PM

Hi, everyone, I've only just joined this web sight. this is a good issue to start with. Heaps of excellent info to think about and consider. Learning heaps already. I have had my run ins with TV. Several years ago my LC Torana (still have it) ran the same blue motor crank (not knife edged but want to shape the counterweights like a tear drop) B&M balancer (4.2 Kg), Steel flywheel (5 Kg) as I do now. The flywheel is custom made by a bloke (I think his name was Keith Croft, lived next door to the old Amaroo Pk Raceway), it is an interference fit, ARP 3/8 bolts and it has never come loose, no dowels. It is a street car and doesn't see to much stress, however, I used to rev it to 8000 and never had anything come loose, even with running it over the 1/8 mile, until I fiddled around with the 45mm webers fixed some tuning issues and it would destroy any clutch with those bloody horrible straps. After destroying another new clutch, with 4 straps a piece, the flywheel was not loose. the press fit flywheel seems to be working so far. As for the clutch I saved up and bought a AP clutch (2nd hand) out of a Cosworth Seirra, Never busted another clutch.

Currently I'm now concerned with where those TV are going and if the cranks shaking like hell, must be robbing power. I limit my current engine to 7200 as it makes power to just over 7 grand, Nothing is coming off yet. However, I can't give it WOT until I sort out low oil pressure issues. Another bloody rebuild. I do take a risk and give it bit of a boot to test for vibrations and other issues to sort out in near future rebuild. Might try a lighter balancer.

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#129 _Dansthemanow_

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Posted 06 December 2015 - 04:34 PM

This threads a bit old now, but I thought I would report that my flywheel came loose again about a year ago.That was after I had the crank checked and 4 ,1/4 inch dowels fitted.The crank flange was machined and crank checked for straightness.The flywheel was machined at the mounting face.I ensured perfect assembly routine with bolts torqued/loosened/retorqued untill seated.It still worked loose relatively quickly......
Im looking at fitting a heavier steel flywheel now,and probably gonna restrict my rpms to 6000 from now on.I think between 6k and 6.5 these things just do their absolute damndest to spit of the flywheel,and im yet to hear of any method of flywheel fixture which has not come loose for somebody or the other.The best thing Ive read is to weld steel between pairs of bolts.....

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#130 _STRAIGHTLINEMICK_

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Posted 07 December 2015 - 10:41 AM

This threads a bit old now, but I thought I would report that my flywheel came loose again about a year ago.That was after I had the crank checked and 4 ,1/4 inch dowels fitted.The crank flange was
machined and crank checked for straightness.The flywheel was machined at the mounting face.I ensured perfect assembly routine with bolts torqued/loosened/retorqued untill seated.It still worked loose relatively quickly......
Im looking at fitting a heavier steel flywheel now,and probably gonna restrict my rpms to 6000 from now on.I think between 6k and 6.5 these things just do their absolute damndest to spit of the flywheel,and im yet to hear of any method of flywheel fixture which has not come loose for somebody or the other.The best thing Ive read is to weld steel between pairs of bolts.....

Gday mate,
I have a simple old school fix for this problem that works every time if done properly .have a look at my posts a couple of pages back.like most people i was reluctant to try it and tried more modern fixes first.Now i do this to every 202 cause it just f..n works.

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#131 greens nice

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Posted 10 December 2015 - 10:43 PM

This threads a bit old now, but I thought I would report that my flywheel came loose again about a year ago.

No surprises there, there's plenty of good info on this subject on this forum, fitting kryptonite bolts won't get you anywhere.

The fluidampr might have been a step forward ?

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#132 _Dansthemanow_

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Posted 14 December 2015 - 12:24 PM

As far as i,m concerned,there is no proven fix for the issue.Dowelling was supposedly the ultimate fix,yet I know of several dowelled wheels that still came loose.Mine had 4*8mm dowels.Those dowels were very tight fitting.But
maybe the ally was too soft.Also some say you need 6 dowels....
A fluidampr might help,or just as likely not help.Do you go through the exercise to only find it doesn't help?
In any event,I just fitted a new steel 10.6kg wheel, high strength locktite threads,with 24Hr araldite around the shank of the bolts.Torqued the ARP bolts a bit higher than standard spec.From now on,its going to be limited to 6k,as I'm not having the S÷%t happen again.I can say the new steel wheel is a much tighter fit on the crank flange.Maybe that will help.

Edited by Dansthemanow, 14 December 2015 - 12:33 PM.

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#133 _oldjohnno_

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Posted 14 December 2015 - 06:38 PM

Think about this: at high rpms the unsteady torque loads applied to the crankshaft due to the inertial forces generated by the piston, pin and rod outweigh (pun intended) those produced by combustion. These forces are a product of accelerating and decelerating the mass of those components, and are in direct proportion to their mass.

Obviously then, there is something we can do that will have a very real and measurable effect on torsional vibration of the crankshaft.

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#134 jd lj

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Posted 14 December 2015 - 06:46 PM

I've heard that knurling the back of the crank helps to ensure the flywheel doesn't come loose and that if one of these items gets damaged you'll pretty much be needing to replace them both because they won't come apart again.

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#135 _STRAIGHTLINEMICK_

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Posted 15 December 2015 - 08:14 AM

I havnt had a failure since mounting flywheels this way , it works for me. You can either try and reduce the problem and have a heavy rotating assembly or use a method to hold the flywheel on that will resist the forces acting on it. The choice is yours.

Edited by STRAIGHTLINEMICK, 15 December 2015 - 08:15 AM.

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#136 _Dansthemanow_

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Posted 21 December 2015 - 11:50 AM

I've heard that knurling the back of the crank helps to ensure the flywheel doesn't come loose and that if one of these items gets damaged you'll pretty much be needing to replace them both because they won't come apart again.

I would say you could get them apart with some heat and a special puller.

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#137 jd lj

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Posted 21 December 2015 - 12:54 PM

I'm sure it's possible to do, I'm merely quoting what I was told by an old forum member (82911).

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#138 _Dansthemanow_

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Posted 27 December 2015 - 07:42 PM

I might add that the responsiveness of the vehicle is pretty much identical to how it was with a sub 5kg flywheel.Apart from being a little nicer taking off,the standard weight flywheel doesnt reduce the performance at all.

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#139 LC-GTR-1969

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Posted 28 December 2015 - 06:43 AM

My observations...

I had no trouble with flywheels coming loose when using a 4.5kg interference fit aluminium flywheel. This had seen many 1/4 mile passes but never shook itself loose.

I put an 8.6kg steel unit and within a few weeks, she was loose.

When I looked closer at the 8.6kg unit, it had heaps of play on the crank. Very sloppy fit.

I have now upgraded the bolts to 7/16 and double doweled it, which has worked well thus far, however my belief is that the poor design of the YT flywheels is in part the issue- the flywheel was seriously sloppy over the crank, and the bolt holes were too far oversize.

I would look at buying a new interference flywheel if you can afford it, and having this doweled with 7/16 bolts.

You may be able to have your existing flywheel either knurled, or copper spun with a few thou of copper to create a slight interference. Then as per StraightlineMicks advice, use some areldite when you assemble.

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#140 _Dansthemanow_

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Posted 10 January 2016 - 02:44 PM

The YT flywheel i bought seemed quite a snug fit on the crank flange, and I would think all off the shelf flywheels would be machined to the same diameter as the OEM flywheel.There was definately some interference, as it took a reasonable amount of torque on the bolts to draw the flywheel over the flange.
I thought of upgrading to 7/16 bolts but 2 points deterred me from doing that.The 7/16 bolt holes almost break through the outer radius of the flange.Not ideal.Secondly, it appears numerous people have had flywheels loosen with the larger bolts.Thirdly, it isnt recommended to drill the holes in situ, rather the crank should be removed to correctly perform this operation.Been there, done that when I had it dowelled.Not pulling it apart again for a while.
Interestingly my ally 4.6kg wheel never came loose for years, untill one day it did, and refused to stay put forever thereafter.Maybe it stretched out so wasnt tight on the flange, and being ally becomes ever looser as it heats up.Its in the scrap heap now anyways.

Edited by Dansthemanow, 10 January 2016 - 02:51 PM.

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#141 LC-GTR-1969

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Posted 04 June 2017 - 04:32 PM

Gday mate,
I have a simple old school fix for this problem that works every time if done properly .have a look at my posts a couple of pages back.like most people i was reluctant to try it and tried more modern fixes first.Now i do this to every 202 cause it just f..n works.

Just supporting Micks advice- a while back he advised me about his method, and it fixed my flywheel issue. We drilled the dowels with the crank in engine and engine in car using a jig I made, and tapped the threads out to 7/16 again with crank in engine and in car. All up only a few hours work and she has held strong with many 7000rpm runs. I was hesitant to do it without removing the engine and removing the crank, but meh, we gave it a crack and it works fine.

If anyone would like some advice on how we did it in car, just pm me.