How do fan clutches fail?

[Joe L.]

Re: How do fan clutches fail?

I'm sorting out the last few details on my '75 coupe, and it occurred to me that there seems to be an inordinate amout of fan noise throughout the RPM range, and a very slight vibration that occurs as I run the RPM up. I thought that I remembered that unless the engine compartment was warm, the fan noise would drop out as RPM increased, and cycle back in as the radiator heated up

The clutch did leak a small amout of oil ( stored sideways ) during the rebuild, but if anything, it appears that the fan is staying coupled all of the time.

The fan does spin freely with the motor off...

Let me know what you think,

Happy Memorial Day, and God bless those who paid the ultimate price for our freedom.

Tommy------


Can you post a photo of the clutch on your car?

[Tommy F.]

Re: How do fan clutches fail?

Joe,

Out of hundreds of pictures, this is the only one that I can find that shows any of the fan clutch...this was taken right after I get the motor in and running last year. Let me know if it shows anything...

Thanks,

[Tom M.]

Re: How do fan clutches fail?

I have my original dated 69 427 fan clutch that i need to get rebuilt, the bearing has some play in it,
Who rebuilds this part ?

thanks Tom

[Joe L.]

Re: How do fan clutches fail?

Joe,

Out of hundreds of pictures, this is the only one that I can find that shows any of the fan clutch...this was taken right after I get the motor in and running last year. Let me know if it shows anything...

Thanks,

Tommy------


Yes, it shows everything I need to see. What you have here is a GM #343721. This fan clutch was used for 1974-75 Corvettes with C-60. It was also used for many 76-81 Corvettes with C-60 and/or HD cooling.

The 343721 is noisy. Or, I should say, when you have one installed on your car the fan makes a lot of noise. That's because this clutch stays engaged a lot more and, thus, the fan pulls a lot more air a lot more of the time. This is a good thing notwithstanding the noise created.

I absolutely LOVE the 343721 and its nearly identical successors. It's the best fan clutch ever installed on a Corvette. Period. The extra sound a fan makes when this fan clutch is installed is "music to my ears".

[Larry M.]

Re: How do fan clutches fail?

I have my original dated 69 427 fan clutch that i need to get rebuilt, the bearing has some play in it,
Who rebuilds this part ?

thanks Tom

The only two I know are Fred Olivia, and Vinny at Pampered Vettes.

Fred is the most well-known, but typically has 6 months + turnaround time. Outstanding work

I have also heard good reports about Vinny, including excellent work and quick turnaround. He often advertises in the Driveline.

Phone numbers for both are listed in the archives....just search. Or let me know and I will go through my files for you.

Larry

[John D.]

Re: How do fan clutches fail?

...very interesting piece of data. What years/engines does this fan clutch apply to, and who took the data a plotted the curves?

Duke

duke,

Lifted directly from the Eaton part drawing...not sure on the specific usage for this clutch maybe joe can help..

[Duke W.]

Re: How do fan clutches fail?

My '77 vintage P&A catalog shows 3916141 for 60-67 except 427, so this is probably "tuned" for a 180 degree thermostat and the ...141 is probably an "assembly" consisting of the ...139 and something else.

Duke

[Joe L.]

Re: How do fan clutches fail?

duke,

Lifted directly from the Eaton part drawing...not sure on the specific usage for this clutch maybe joe can help..

John------


As far as original applications are concerned, the GM #3916141 was used as follows:

L1967 passenger car with 6 cyl and C-60

L1967 passenger car with 396 and 427

L1967 Chevelle with 396

L1967-68 Chevy II with 327 and C-60

L1967 Camaro with 396

E1968 Corvettes with L-36, L-71 w/o C-60

1968-69 Corvettes with L88 or ZL1

The 3916141 eventually replaced for SERVICE all 1960-70 Corvette fan clutches as well as most 1960-68 fan clutches used for other Chevrolet models.

[Joe L.]

Re: How do fan clutches fail?

My '77 vintage P&A catalog shows 3916141 for 60-67 except 427, so this is probably "tuned" for a 180 degree thermostat and the ...141 is probably an "assembly" consisting of the ...139 and something else.

Duke

Duke------


The GM #3916139 is a fan clutch originally used for Corvette small blocks in the L1967-69 period. It has a slightly longer shaft than the 3916141. I do not know if there exist other "calibration" differences from the 3916141.

The 3916141 eventually became SERVICE for Corvette small blocks, but it was not originally used for Corvette small blocks. However, it was originally used for some small block applications in other Chevrolet cars.

[John D.]

Re: How do fan clutches fail?

The 3916139 drawing shows the coil type thermostat in the front of the fan clutch. The distance form the water pump mouting surface to the fan surface is 1.80 inches. The drawing for 3814560 shows the bar type clutch with the exact same performance curve and the distance is 1.85"

[Dennis S.]

Re: How do fan clutches fail?

The only two I know are Fred Olivia, and Vinny at Pampered Vettes.

Fred is the most well-known, but typically has 6 months + turnaround time. Outstanding work

Larry
Fred has had my original '69 427 fan clutch for a year now. It too had a noticable wobble in the shaft. I am waiting with great anticipation for the day it can become reunited with my car, as I am using a loaner. I have heard it said that patience is a virtue.

[Tommy F.]

Re: How do fan clutches fail?

Tommy------


Yes, it shows everything I need to see. What you have here is a GM #343721. This fan clutch was used for 1974-75 Corvettes with C-60. It was also used for many 76-81 Corvettes with C-60 and/or HD cooling.

The 343721 is noisy. Or, I should say, when you have one installed on your car the fan makes a lot of noise. That's because this clutch stays engaged a lot more and, thus, the fan pulls a lot more air a lot more of the time. This is a good thing notwithstanding the noise created.

I absolutely LOVE the 343721 and its nearly identical successors. It's the best fan clutch ever installed on a Corvette. Period. The extra sound a fan makes when this fan clutch is installed is "music to my ears".

Thanks for the information Joe...I guess a little "music" is better than the overheating alternative!