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Vibration Dampers

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Matthew E. Herd

Jedi Warrior
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I'd like to know if anyone has done/seen any vibration dampers for Spitfire/Midget 1500's? Thanks.
 
Matt, glad to see you made it to the site.
I just run an aluminum pulley on mine, but as you know, it never gets driven on the street. I have heard, however, of someone adapting a dampener from a Ford to the 1500 crank. I'll try and dig up the information, if I still have it.
Jeff
 
Thanks a ton. I'd heard something about someone fitting a ford damper, but no details.
 
Oh, also, is your aluminum pulley a one-off, or did you buy it somewhere? If you designed it, perhaps it could be altered to accept a ford/chevy damper ...
 
I asked this one awhile ago, but I'd like to revive it ... I understand a racer by the name of Rick Cline, supposedly located in FL, sells dampers for 1500's in the vicinity of $300 bucks (that was a few years ago). However, an email provided elsewhere (where I found this information) was invalid. Has anyone ever heard of him? I'd like to know more about this!

Also, to Jeff, my prior questions still apply ... Did you have that aluminum pulley made or was it bought somewhere? I have some drawings of a pulley designed to fit a chevy damper, all I need are the specs for a chevy damper and a few odd items (like appropriate ID for the hub, with that I'm not sure how closely I should tolerance it)
 
Matt, sorry for the delay. I must have been asleep that day.
My pulley was made to the dimensions specified in the Competition Manual for the 1500 Spit, but modified to be one piece rather than pinned to the steel hub. The ID of the portion that fits over the crank snout is 1.373". The major OD of the pulley is 3.405"
There is a Rick Cline listed on the SCCA Production car website, but no email address given, other than contacting him through the website. https://www.coloradoscca.org/prodcar/index.php
Click on Memberlist, then sort by username, and he is on page 13. But, I have no way of knowing if this is the correct person or not.

I still haven't found anything on adapting the Ford damper, though.

Jeff

[ 03-18-2004: Message edited by: Bugeye58 ]</p>
 
Thanks Jeff, I belive that is the same email I sent to before, but I gave it a shot and tried to send another ... perhaps I'll get lucky.

Also, when you say that the major OD is 3.405" does that mean that is the actual pulley diameter? I do not posess a copy of the competition manual as of yet, so I'm not sure what information it contains on this ... My standard pulley seems to be one piece.

The problem with the drawings for the new hub with chevy damper is that it has no accomodation for a belt unless the damper itself has grooves for a belt (which I am not sure of). In this case, it could be modified to work. Otherwise, there is no way to drive the alternator (and fan/water pump either). I'm trying to determine a simple solution, and make sure it will work before I get it machined. The other issue is that GM belts are not of the "V" type, so that has to be accounted for. At any rate, thanks for the dimensions!
 
Matt, the 3.405" dimension is the outside diameter of the pulley itself. I'm pretty sure this is smaller than stock, and my guess it is that way to underdrive the waterpump to slow down the flow and prevent cavitation. It has a belt groove machined in it to accept a 3/8" belt. The OD of the portion that fits the crank is machined to 2.0", and a steel Speedi-Sleeve, NAPA P/N 99199 is pressed on to provide a steel surface to ride on the timing cover seal, at a finished diameter of 2.025".
I don't see why the pulley dimensions couldn't be changed to accomodate any suitable damper, or belt configuration. The 1500 Midget has the dropped steering rack mount, so forward clearance shouldn't be an issue, correct?
If you like, I can whip up an Autocad drawing of this thing for you.
Jeff
 
I have Solidworks, but I assume the Autocad file could be put in a generic format? I have access to Autocad, if not. At any rate, its not really necessary, esp. if there's a drawing in the manual. I understand about undersizing the pulley, wisely done in my opinion. As to the steering rack, there is forward clearance, but not excessively so ... about 2-3" as I recall. The issue (I have the later 2 pulley hub, the outer pulley being for an air pump which was not with the car when i got it. I'm not even sure where it was supposed to mount, for that matter ...) is the fan blades. If the pulley is not fully secured by the crank nut, the blades will brush/be destroyed by the pulley. This limits both the diameter and the forward extension of the pulley unless an electric conversion is done or the blades are reduced in diameter.

Also, I received a response from Mr. Cline, thanks for the info. Turns out the original email I had was off by one digit and therefore didn't work. His reply is as follows: "I modified a GT-6 damper for the 1500. Haven't done of those in while. Find the pieces, and if you can't figure it out I look at the pieces a get one together. As I remember it was quite a simple thing. RC"

I was unaware than GT-6 pulleys included a damper ... Can anyone give me more info?

Also, Jeff, would you like a copy of my drawing to see what I've got thus far? I have never looked at a chevy damper (which is why those dimensions are arbitrary), but I believe the outer surface accepts the belt ... This really couldn't be machined and the above mentioned issue interferes with extending it outward to make room for a pulley. Of course I am willing to go to electric (and even considering it) but want to get everything sorted before I start spending money.

[ 03-19-2004: Message edited by: Matthew E. Herd ]</p>
 
If a drawing is saved in "DXF" format in AutoCAD, it can easliy be opened in Solidworks. I do it all the time. For simplicity, I would stick to a 2D format and keep everything in one layer.

You may want to look at a TR6 damper also. Since it's from the same family of engines as the 1500, the crank nose might be the same. Check here:

https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=36486

I'm not clear on why you want an actual vibration damper instead of a plain pully? I'm don't think anything will make these 1500s run "silky-smooth".

My car is running the iron 2 groove pully, but I machined off the air pump pully and made the water pump pully a bit smaller in diameter. Works well. I also have the nut/pully assembly safety wired: with small holes drilled in the pully nut and pully....but that's just me.

My 1500 has no fan and even for most street use, I can get away without one. The only thing on my water pump is the belt pully...I machined off the fan hub. I do have a Mitusbishi Colt electric fan that fits in front of the radiator. I cut-down the plastic fan blades to about 1/2 size. It works well; I have it switched manually. I only had it installed in August last year...comes off in about 5 minutes.
 
Matt, yes, I would like a copy of your drawing. I was going to have one of the design guys at work do mine in AutoCad, but now I'm on sick leave, and won't be there. I've got A/C 14, and Mechanical Desktop on the box here at home, but am not up to speed on any of it. (Dinosaur that I am!) Of course, now I have at least two weeks to learn, don't I!
I'll run up to the storage unit tomorrow and take a look at both GT6 Engines I have. They are early ones, so only have the single groove pulley.
The Spit 1500 Comp manual is still available from TRF, if you're interested. About the only thing that will apply to the Spridget is the engine section. I do, however have the page with the pulley drawing on it printed out separately, if you want it. If so, let me know, and I will sketch the pertinent updates on it.
As far as the fan goes, I was running an electric fan on the Spit, with a VW radiator, and about the only time I turned the fan on was when I was sitting on the grid for a few minutes waiting to go out. On the track, I switched it off.
You may also want to contact Joe Huffaker, 707 935 0533 for hints on a damper. Jim Lerch is his engine builder, so would probably be the guy you want to talk to.
Jeff
driving.gif
 
Gentlemen, thanks for the assistance. Jeff, I'll send you a solidworks formatted copy of the file because my brand new install of SW2003 doesn't seem to have .dxf format, even though it's listed in the help files ... Like I said, some dimensions are arbitrary.

Concerning Nial's question about the reason for this item, I reference the information David Vizard provides in "Tuning the A Series Engine" 3rd Edition, page 390 (second column) to page 391 (second column). This is in the Blocks, Cranks, Rods & Pistons Part 3. He addresses fatigue life of crankshafts, including smaller bearing, longer stroked engines. Information provided indicates that stock 1275s experience a peak in vibration at 5750 and 6100 rpm. As mass is reduced, the occurrence of these peaks is shifted up in the rpm band, but not out of it entirely. "Having said that the crank damper is critical, let me make one provision: If you are putting together a really high RPM sprinter or a drag race engine, then the chances are the fatigue life of the crank is longer than a lot of other components." He goes on to say that testing on Chevy smallblocks indicated a reduction in vibration by as much as 400% better with fluid versus rubber dampers, that they act over all rpm, and even increase horsepower, probably due to increased precision in valve timing. He proposes that an A series engine would achieve a 2-3 hp increase simply by switching to viscous dampers based on research with the Chevy engines. "It's expensive, but it's the next best thing to insurance as far as crankshaft life is concerned. Not specifically relating to Series 'A' engines, my own experience has been that using a viscous damper compared with an effective rubber damper has the same effect on crankshaft life as moving up one grade of steel. Though its too early to say for sure, it would appear a viscous damper has the ability to more than double the fatigue life of the crank."

Now, I'm no engineering professor like you are, Nial, but this information I believe to be entirely reliable and when cross referenced with the engineering I'm presently learning in my Elements of Mechanical Design course, it sounds entirely plausible to me. As the 1500 engine has no damper whatsoever, I believe that the increase in fatigue life factor of safety is a primary concern, especially for an engine which is heavy when it comes to reciprocating mass (which would increase fatigue life, but on the other hand, seem to lower the point at which vibration peaks occur). It is not my intent to make the engine run like a brand new Honda, but a much more practical one. I want to extend crank life as much as possible under very adverse conditions (racing type conditions). As we both know, increasing the material spec is another easy way to increase your factor of safety. If the damper acts in a similar fashion as is indicated, coupled with a 4340 billet crank, I'd imagine you'd have an absolutely bulletproof bottom end (lubrication and bearing life issues aside). I also want to extend bearing life, and though I have no hard evidence at this time, it is my opinion (you could probably verify or refute this for me) that with increased vibration, bearing wear is also increased ... At any rate, the potential hp gain is also a neat bonus, but even that is not the reason for this alteration. Based on David Vizard's advice, I'd say that not only should higher performance engines be fitted with fluid dampers (or at least rubber ones), but that they should be done with priority.

Concerning the fan, I've found that I could probably get away without one as the cooling seems to be fantastic, however, would still like to fit an electric one at some time for very hot days in heavy traffic (it COULD happen ...) or in a situation where I might be waiting in line at an event.

Jeff, thanks for the input concerning Huffaker. I've contacted ATI and Fluidamper, but ATI only does rubber and Fluidamper was not in the least interested. Also, the engineer at ATI was very slow in getting back to me, so I decided I could have my own done and be sure it'd fit (and if not, I wouldn't be out as much money because I could have another hub made that WOULD fit and would accept a standard Chevy damper rather than buying the whole assembly at 500+ bucks each time).
 
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