TR2/3/3A "TR3A Crankshaft & Fan Question":

[toysrrus]

Hi Folks;

This is a New one on Me:

Someone I know removed the Fan from the Crankshaft & In Its place put an Elec Fan:

In the "Orig. Triumph TR2/3/3A" book; It states: "The Fan acts as a crankshaft damper, and, if it is removed, crankshaft problems can result":

What does this exactly mean; "Damper" & what sort of Problems can result relative to the Crankshaft?

Who out there has ever done this before? I`ve never heard or seen anything like this:

Regards and /bcforum/images/%%GRAEMLIN_URL%%/thankyousign.gif Russ

 

[TR3driver]

What does this exactly mean; "Damper" & what sort of Problems can result relative to the Crankshaft?

The crankshaft will resonate (basically ring like a bell) at certain frequencies. A harmonic dampener (or damper) works to reduce the resonance. Wasn't really the fan, but rather the rubber bushings that the fan mounts on. In extreme cases, the crankshaft can snap from the extra loading imposed by the ringing. (Think of the Liberty Bell.)

That said, I've been running my TR3A engines without the mechanical fan since about 1977 (ever since it picked up a rock and bent the fan into the radiator) and haven't seen any problems yet. According to people who should know, the only resonance within the regular rpm range isn't too bad and doesn't usually cause a problem. There are other resonances above 5000 rpm that do cause problems, so extended operation at those speeds without a damper is a bad idea. I've been told the first one is around 5200 rpm, and another near 7000; but so far I don't spend much time up there /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

 

[Geo Hahn]

...the only resonance within the regular rpm range isn't too bad and doesn't usually cause a problem...

Just out of curiousity... is that one at 2800 RPM? These motors certainly seem to pass thru a buzzy spot about there.

 

[TR3driver]

I don't know, but it seems likely. I'm just repeating what I've picked up from local racers.

BTW, Kas Kastner also claims the harmonic vibration is why it's hard to keep flywheels on racing TR6 engines. He said he once measured some 5/8" wobble on the flywheel at 5800 rpm, caused by crank flex. But, the 4-cylinder crank is much stiffer than the 6, so I presume it's less of an issue on a TRactor motor.

 

[toysrrus]

Hi There Randall;

"Thanx" for the info:

What do you have hooked up right now to keep the TR running Cool?

If Its an Elec Fan set-up; Would you be able to send me a pic of your set-up?

Regards and /bcforum/images/%%GRAEMLIN_URL%%/thankyousign.gif Russ

 

[Deleted member 451]

I ran mine without a fan for about 4 years before I converted it to the thin belt pullys that Moss sells. I didn't have any problems but I never get above 5000 RPM.
My engine also has the 2800rpm 'zone' but I don't think this is related.I think this is more likely the spot where the intake runner length and the exaust manifold configuration just happen to match. The reason I think this is because when I put my long (2") ram pipes on it shifts to about 3000rpm. If you want a really sweet sound take the resonator off the exaust and replace it with a straight pipe. Moss sells the exact pipe for $24 and is worth every cent.
As for fans I run two electric, one push one pull, This is overkill but Florida summer heat and traffic are killers.

 

[TR3driver]

What do you have hooked up right now to keep the TR running Cool?

Well, that's the car that is wrecked, so I guess you could say I don't have anything hooked up "right now".

But the setup I had worked quite well for me. The fan is a 16" Hayden, mounted as a puller, with the little plastic ties through the radiator core. I was worried about that setup, but my radiator guy said it was fine as long as the ties are in the middle of the fins (not touching the tubes) and it's never given me any trouble. Never did get my home-brew electronic control to work the way I wanted, so it was just wired to a switch on the dash (wiper switch mounted in the former heater control hole, plus relay under the hood). The fan is mostly only needed when idling or in stop-and-go traffic.

The radiator has been recored with a Modine core and no crank hole. Bypass is open and no sleeve on the thermostat. Thermostat plate has been drilled to allow some water to flow even when cold.

I modified a Stant "Lev-R-vent" cap to fit the stock TR3 neck and hold 7 psi (but next time, I'm just going to have the neck replaced with a modern one so I can use a standard cap). Next time I'll also see if we can add some braces for the filler extension.

If Its an Elec Fan set-up; Would you be able to send me a pic of your set-up?

Sorry, I haven't cut the front apron off yet. Probably won't for a while, either, at least until I get the Stag back on the road.

 

[JFS]

I went to a thin belt conversion about 15 yrs ago after the original two-piece pressed steel crank pulley flew apart taking the water pump and generator with it. I bought it from British Frame and Engine and it included well made alluminum pulleys, a new front seal and a harmonic balancer. I added an electric puller fan behind the radiator. Very pleased with the results.

 

[Don Elliott]

I cool my TR3A with a pusher fan I bought in England. It's a 10-blade shrouded Kenlowe fan and is located between the grille and the radiator. I assume the judges at VTR docked me the normal 2 points if the saw it.

I have blocked the by-pass with a threaded brass pipe thread plug where I drilled a 1/8" diameter hole to allow air to bled past when I fill the cooling system. I also run an original 185 deg. sleeved thermostat.

 

[TR3driver]

Aha ! Your secret is out now, Don, you can kiss those two points goodbye !
/bcforum/images/%%GRAEMLIN_URL%%/jester.gif