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Got a price on getting the inertia ring hydro cut and I think I may give it a miss at this stage :( they said they will have to source the 40mm plate as 32mm is the largest they stock and a final cost of $500 I think this is way out of the equation considering I still need to then machine the thing so last option is get a mate to oxy cut one and hopefully get it nice enough to be able to be machined...
All sorted will hopefully have a disc precision oxy cut by Monday off a mate so will start machining next week
Thanks for all the pics. I've got a rough idea of what I'm going to do for a gear linkage now. It'll be very different to Grubb's and on my usual schedule. So call back in about 8 years.:D
hahaha i like thatQuote:
Originally Posted by Dougal
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I am wondering the theory behind us needing additional weight for the flywheel ? I understand that the 4bt has a heavier flywheel than the 4bd (16kg) but is adding weight the only way to reduce torsional vibrations ? it is not a real well known topic but from what I can gather it seems to be a lot of factors mainy to do with driveline stiffness and Internal inertia being less than load inertia causing resonance at a specific rpm will result in torsional vibrations so increase the load inertia and then the vibrations will be either decreased or moved somewhere else in the rpm range...Im not sure but looking at a dual mass flywheel in modern diesels I picture this may be to help with vibrations....could there be something that can be placed elsewhere in the system to reduce this occurrence maybe ? surely there will be side effects of extra weight ? Dougal and myself have talked about this previously and I agree with everything he has told me Im just throwing it out for discussion :angel:
It's got me thinking as well. Why can't you add weight to the front of the crank???. Just thinking out loud. I am at the point of spending more money to solve this or
Strip the car, sell the bits and buy a "Rubicon"
The Rubicon is ahead on points at the moment!!!!!
Justin
I find it's a problem but there isn't to much solid evidence in explaining the occurrence... What you said about adding it to the front of the crank I think it is feasible...some sort of rubber or vicious coupling may be used as a dampener but I'm not sure if it would be quite as good as being on the drive end of the crank...i am just curious to find out more about it and if it's worth a this effort or learn how to drive in a manner as to avoid this happening ...Quote:
Originally Posted by DRanged
Rubicon jeep I'm asuming ? What motors do they have ?
The root cause of the vibrations is an engine putting out two large power pulses per revolution.
The flywheel stores energy from these pulses and returns that energy to the crank in between pulses. Effectively smoothing them out. The more inertia the flywheel has, the smaller the torsional speed variation becomes and the smoother the power output is.
At factory torque levels the factory flywheel inertia is sufficient. But double the torque and unless you double the inertia, you'll get double the torsional vibration.
There are two ways to minimise the vibration, damping or mass (inertia). Damping burns the energy to heat within the damper, mass (inertia) simply stores and releases at close to 100% efficiency (bearing drag and windage are the only losses).
You can add inertia to either end of the crank, even the middle if you like. But the flywheel already has the biggest radius so it's the place extra mass will give the biggest inertia increase and the biggest improvement.
Yep, the only downside (and it may not be, depends on the driver) is less throttle response with more flywheel inertia.Quote:
Originally Posted by Dougal
The reason the 4cyl engine hammers the gearbox, etc. is that the peak/instantaneous torque delivery of an engine is a greater % above the mean torque output the less cylinders you have, as well as the fact that there are less firing pulses/degree of crank rotation too.
Explanation here Torsional Characteristics of Piston Engine Output, by EPI Inc.
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