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damper question
- Thread starter tomshobby
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TR6oldtimer
Darth Vader
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Thanks for bringing this up. I have wondered about the damper and how it worked. Here is a link to a brief discussion of the damper and why they are used.
https://www.atiracing.com/products/dampers/101/index.htm
What I found interesting, and made sense to me, is the statement that an increase in HP could cause additional torsional harmonics the the stock damper was not designed for. No idea if this applies to triumph iron, or if it is just the racers edge guys to worry about.
https://www.atiracing.com/products/dampers/101/index.htm
What I found interesting, and made sense to me, is the statement that an increase in HP could cause additional torsional harmonics the the stock damper was not designed for. No idea if this applies to triumph iron, or if it is just the racers edge guys to worry about.
OP
tomshobby
Yoda
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Ray,
Much appreciated and very interesting information. I am going to study this closely. From the first glance it seems that I need at least as much weight as the original or maybe a little more. It also tells me that would be a good idea to rebuild our old original dampers. And brings into question a light solid aluminum damper pulley that I have seen on a car.
Just the kind of information I was looking for, thanks again.
Much appreciated and very interesting information. I am going to study this closely. From the first glance it seems that I need at least as much weight as the original or maybe a little more. It also tells me that would be a good idea to rebuild our old original dampers. And brings into question a light solid aluminum damper pulley that I have seen on a car.
Just the kind of information I was looking for, thanks again.
R
RonMacPherson
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Tom, recommend you do a little research on Kas Kastner's work on these engines.
Main failing he found was with the crankshafts. Being only a four main bearing, non fully counterweighted crank, it flexes waaaaay too much. Torsional vibration, I believe it is called.
Actually a heavier damper on the front to approach the weight of the flywheel will help to lessen the torsional vibration....
Main failing he found was with the crankshafts. Being only a four main bearing, non fully counterweighted crank, it flexes waaaaay too much. Torsional vibration, I believe it is called.
Actually a heavier damper on the front to approach the weight of the flywheel will help to lessen the torsional vibration....
OP
tomshobby
Yoda
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Ray, following one of the links in the page you posted was quite interesting and seems to blow away the lighter damper theory.
https://www.popularhotrodding.com/enginemasters/articles/ford/smallblock/0306mm_windsor2/index.html
I am beginning to wonder if the bad rep TR6 cranks have for high revs may be due at least in part to a poor damper design.
It also seems the damper might be more critical for longer crankshafts like ours.
https://www.popularhotrodding.com/enginemasters/articles/ford/smallblock/0306mm_windsor2/index.html
I am beginning to wonder if the bad rep TR6 cranks have for high revs may be due at least in part to a poor damper design.
It also seems the damper might be more critical for longer crankshafts like ours.
TR6oldtimer
Darth Vader
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We must also keep in mind, the TR6 engine is based on a 2 liter 6 with a lot less rotational mass and shorter stroke where the fewer main bearing design may not have been a problem.
This up grade, costs about a grand, that's $100/HP, but it does support your contention that the original was not optimal, then again, the stock engine red lined at 5,750 rpm which tells me the designers where aware of the limitations of the longer stroke engine.
https://www.goodparts.com/shop/index.php?categoryID=22goodparts said:
This up grade, costs about a grand, that's $100/HP, but it does support your contention that the original was not optimal, then again, the stock engine red lined at 5,750 rpm which tells me the designers where aware of the limitations of the longer stroke engine.
TR3driver
Great Pumpkin - R.I.P
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Kas did talk about rather extreme crankshaft flex, but not in the torsional direction. Due in part to the lack of overlap in the stroked (from 2.0 to 2.5) crank, it also flops around like wet spaghetti. He measured something like 5/8" deflection at the rim of the flywheel, due to lateral flex. But that was likely somewhat above factory redlineRonMacPherson said:
OP
tomshobby
Yoda
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Hi Randall,
I was actually thinking of sending you a PM. Glad you came in here. I have been reading a number of papers on this subject and want to learn as much as I can about it. Up to know what I have been learning has been more of engines in general rather than specifically the TR6 engine.
Do you know which book that Kas might have written about this in?
Thanks much,
I was actually thinking of sending you a PM. Glad you came in here. I have been reading a number of papers on this subject and want to learn as much as I can about it. Up to know what I have been learning has been more of engines in general rather than specifically the TR6 engine.
Do you know which book that Kas might have written about this in?
Thanks much,
TR3driver
Great Pumpkin - R.I.P
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Net Nuggets
Sorry, Tom, I don't know offhand which book that would be in. I most likely read it on a mail list, as I'm not that interested in 6-cyl TRs. Here's a sample, posted by Kas in 2000:
<span style="font-size: 11pt"> <span style="font-style: italic">In answer to several inquiries about the 5/8" wobble I found on the TR-6 while on the dyno and using a scope and sensors on each side of the wheel:
Yes it was .625" ( approx, memory) but that is total from deflection "A" to "B' or fore and aft not a figure in each direction. As I was no longer working on the 4 cylinder TR's at that time I do not have a number the Spitfire or the 3's and 4's.
But the 3's and 4's do not have anywhere near the problem due to the better crankshaft stiffness. By the same token the GT-6 is not as bad as the TR-6 as the GT-6 has a lot more overlap on the journals and thus is stiffer also.
As the first resonance with the 3's & 4's is about 2800 to 3000 rpm and second about 5200 you shouldn't expect the terrible third until about 7000 or a little more. The third cycle on the TR'6 was so bad the pen went off the page. This is dead stock now, not a modified and special unit. In the end I increased the weight of the crank throws with brass plates and all the heavy metal the throws would hold and this raised the resonance level to a point of the rpm range and we were then looking good.
</span> </span>
PS, I just found another post in my archives where he said that was at 6200 rpm before modifications.
Sorry, Tom, I don't know offhand which book that would be in. I most likely read it on a mail list, as I'm not that interested in 6-cyl TRs. Here's a sample, posted by Kas in 2000:
<span style="font-size: 11pt"> <span style="font-style: italic">In answer to several inquiries about the 5/8" wobble I found on the TR-6 while on the dyno and using a scope and sensors on each side of the wheel:
Yes it was .625" ( approx, memory) but that is total from deflection "A" to "B' or fore and aft not a figure in each direction. As I was no longer working on the 4 cylinder TR's at that time I do not have a number the Spitfire or the 3's and 4's.
But the 3's and 4's do not have anywhere near the problem due to the better crankshaft stiffness. By the same token the GT-6 is not as bad as the TR-6 as the GT-6 has a lot more overlap on the journals and thus is stiffer also.
As the first resonance with the 3's & 4's is about 2800 to 3000 rpm and second about 5200 you shouldn't expect the terrible third until about 7000 or a little more. The third cycle on the TR'6 was so bad the pen went off the page. This is dead stock now, not a modified and special unit. In the end I increased the weight of the crank throws with brass plates and all the heavy metal the throws would hold and this raised the resonance level to a point of the rpm range and we were then looking good.
</span> </span>
PS, I just found another post in my archives where he said that was at 6200 rpm before modifications.
OP
tomshobby
Yoda
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Hi Randall,
I e-mailed Kas after I read your response and we had a few exchanges. A gracious man for sure.
This was part of one of them;
"In my book The Triumph Preparation Handbook I have written about the
crankshaft on pages 114- 120. But there is not much specific to the damper.
I did continue to run the stock damper so that my efforts of solving the
problems would be easily applied to other Triumph owners."
So I will be buying that book.
I was surprised that he stayed with the stock damper, but I also don't think it was as much of a science then.
I have noticed first hand the difference at higher rpms between my GT6 and TR6. The GT6 just seemed rock solid at 7,000 rpms. My TR6 is very much better since it was balanced but before that I was not comfortable over 5,000 rpm.
I e-mailed Kas after I read your response and we had a few exchanges. A gracious man for sure.
This was part of one of them;
"In my book The Triumph Preparation Handbook I have written about the
crankshaft on pages 114- 120. But there is not much specific to the damper.
I did continue to run the stock damper so that my efforts of solving the
problems would be easily applied to other Triumph owners."
So I will be buying that book.
I was surprised that he stayed with the stock damper, but I also don't think it was as much of a science then.
I have noticed first hand the difference at higher rpms between my GT6 and TR6. The GT6 just seemed rock solid at 7,000 rpms. My TR6 is very much better since it was balanced but before that I was not comfortable over 5,000 rpm.