Paul G
Well-known member
Hi, My buddy just picked up a 78 L82 from California. The car does not have a fan clutch. Is that normal? Or has it been changed.
Thanks.
Thanks.
L82 fan clutch
- Thread starter Paul G
- Start date
Tom73
Well-known member
They all used fan clutches. Someone, sometime, thought they knew more then the factory engineers and changed it.
tom...
tom...
7
78SilvAnniv
Guest
Its been changed.
I changed my own out a few summers ago to a flex fan. I have nothing but good to say about the solution, its' results and performance.
Does your buddy have a flex fan installed, or electric fans? I feel that both of these systems work better and are more reliable than the fan clutch system.
Heidi
I changed my own out a few summers ago to a flex fan. I have nothing but good to say about the solution, its' results and performance.
Does your buddy have a flex fan installed, or electric fans? I feel that both of these systems work better and are more reliable than the fan clutch system.
Heidi
GWHITE75
Well-known member
Heidi Dont' hit me, but I think there should be a word of caution added to changing any aspect of the cooling system. It should be looked at on a case-by-case basis.
The OEM system is an excellent system, if maintained. Factors, like climate, engine modifications and car useage will determine whether or not a person can effectively substitute parts on the cooling system, with no adverse affect on cooling.
I believe if you live in a moderate climate, have not modified your motor significantly and you are not hard on the car, then you might be able to put aftermarket fans on without any apparent decline in the cooling systems ability to do its job.
I can tell you from experience that I drive my car to work, during the summer, up to and over 100+ degree days with the A/C on and neither flex fans nor dual 11" Spal electric cooling fans will perform well enough to keep my lightly modified 454 below an acceptable 205* in stop and go traffic. Only the OEM system will do this, so I have conceded the HP drain on the motor, in order to maintain proper cooling.
I did have a flex fan on the original small block motor and it worked adequately, before I modified the motor significantly.
The OEM system is an excellent system, if maintained. Factors, like climate, engine modifications and car useage will determine whether or not a person can effectively substitute parts on the cooling system, with no adverse affect on cooling.
I believe if you live in a moderate climate, have not modified your motor significantly and you are not hard on the car, then you might be able to put aftermarket fans on without any apparent decline in the cooling systems ability to do its job.
I can tell you from experience that I drive my car to work, during the summer, up to and over 100+ degree days with the A/C on and neither flex fans nor dual 11" Spal electric cooling fans will perform well enough to keep my lightly modified 454 below an acceptable 205* in stop and go traffic. Only the OEM system will do this, so I have conceded the HP drain on the motor, in order to maintain proper cooling.
I did have a flex fan on the original small block motor and it worked adequately, before I modified the motor significantly.
7
78SilvAnniv
Guest
I don't hit...
...it bruises my knuckles!
I agree with your comment about a case-by-case basis for changing factory equipment. One person's solution may not be a good solution for another vehicle. Every vehicle is different!
However, ours had a terrible run-hot problem for the entire time we owned the vette, UNTIL we installed the flex fan about 2 years ago. I'd like to add that the flex fan was pretty much a desperate grab as a last resort.
We've had the 78 for over 13 years, daily driver, none to light modifications to the engine, never driven hard and properly maintained.
Every summer I had to lower my driving speeds to accomodate the CA summer temps. A/C? Try shooting the coolant up to 240*! I had to suffer through the summers.
We changed the fan clutch more than 10 times, almost yearly, with no improvement, also:
Radiator.
Belts.
Hoses.
Thermostats.
Water pumps.
Fan shroud. (and checked air dam pieces)
Still ran hot.
Installed a GM crate engine with new belts/parts/hoses and such.
STILL ran hot!
Replaced A/C parts.
If I used the AC the temp climbed to 240* within minutes.
After the flex fan:
Never goes above 195* at any speeds, any ambient air temps or whatever the traffic is doing and I can use the AC at hwy speeds or in town with no significant change in temp. For me and my vette, this has been the only solution that gave me any positive results.
I still have nothing but good to say about the flex fan for my particular application. I am only sorry that it took me over 11 years to switch to the flex fan.
Heidi
Another note:
I understand that fans are only designed to help cool at town speeds and stop and go traffic, and that fan clutches, electric fans and flex fans don't do anything at hwy speeds.
What I don't understand, is why I could not drive above 55-60 in 100* weather with the fan clutch, but now with the flex fan, I can drive 70+ at 100* weather with no problems.
Something must be making a difference somewhere! The only change to my vette has been the flex fan...
h
...it bruises my knuckles!
I agree with your comment about a case-by-case basis for changing factory equipment. One person's solution may not be a good solution for another vehicle. Every vehicle is different!
However, ours had a terrible run-hot problem for the entire time we owned the vette, UNTIL we installed the flex fan about 2 years ago. I'd like to add that the flex fan was pretty much a desperate grab as a last resort.
We've had the 78 for over 13 years, daily driver, none to light modifications to the engine, never driven hard and properly maintained.
Every summer I had to lower my driving speeds to accomodate the CA summer temps. A/C? Try shooting the coolant up to 240*! I had to suffer through the summers.
We changed the fan clutch more than 10 times, almost yearly, with no improvement, also:
Radiator.
Belts.
Hoses.
Thermostats.
Water pumps.
Fan shroud. (and checked air dam pieces)
Still ran hot.
Installed a GM crate engine with new belts/parts/hoses and such.
STILL ran hot!
Replaced A/C parts.
If I used the AC the temp climbed to 240* within minutes.
After the flex fan:
Never goes above 195* at any speeds, any ambient air temps or whatever the traffic is doing and I can use the AC at hwy speeds or in town with no significant change in temp. For me and my vette, this has been the only solution that gave me any positive results.
I still have nothing but good to say about the flex fan for my particular application. I am only sorry that it took me over 11 years to switch to the flex fan.
Heidi
Another note:
I understand that fans are only designed to help cool at town speeds and stop and go traffic, and that fan clutches, electric fans and flex fans don't do anything at hwy speeds.
What I don't understand, is why I could not drive above 55-60 in 100* weather with the fan clutch, but now with the flex fan, I can drive 70+ at 100* weather with no problems.
Something must be making a difference somewhere! The only change to my vette has been the flex fan...
h
- Thread starter
- #6
Paul G
Well-known member
Re: Its been changed.
It must be a flex fan. There is no clutch like I would epect to see on your average GM cooling fan. So if I got this right it is an aftermarket substitute for the original GM clutch type fan?
78SilvAnniv said:
It must be a flex fan. There is no clutch like I would epect to see on your average GM cooling fan. So if I got this right it is an aftermarket substitute for the original GM clutch type fan?
GWHITE75
Well-known member
PaulG I suspect it is aftermarket as GM did not make a practice of installing fans without clutchs on them.
Heidi Thanks for sparing the punches. I am glad that you were able to use the flex fan successfully. As I stated earlier, I had one on my SB and it worked effeciently. It was a heavy duty flex fan. The clutch I now use is heavy duty and I went to an 18" fan blade, where my OEM was around 17".
I've read and heard people say that fans don't really do anything, say past 30 MPH, but I disagree with that as it pertains to our vehicles.
The clutch reduces the drag of the fan blade on motor, but it is theramlly controlled and still rotates the blade. There is just less effort at speeds. I believe the blade still creates pull and allows incoming air to flow through the radiator smoother or more uniformly, than it would if there were no rotation. Our radiators aren't mounted like those in a truck, where there is only a grill between it and the air. Our air has to go past some significant pieces of the car, which disrupts the flow, creating turbulance. Fans help to pull the turbulent air through the radiator. Your flex fan does that job real well, when the motor is at speed.
Heidi Thanks for sparing the punches. I am glad that you were able to use the flex fan successfully. As I stated earlier, I had one on my SB and it worked effeciently. It was a heavy duty flex fan. The clutch I now use is heavy duty and I went to an 18" fan blade, where my OEM was around 17".
I've read and heard people say that fans don't really do anything, say past 30 MPH, but I disagree with that as it pertains to our vehicles.
The clutch reduces the drag of the fan blade on motor, but it is theramlly controlled and still rotates the blade. There is just less effort at speeds. I believe the blade still creates pull and allows incoming air to flow through the radiator smoother or more uniformly, than it would if there were no rotation. Our radiators aren't mounted like those in a truck, where there is only a grill between it and the air. Our air has to go past some significant pieces of the car, which disrupts the flow, creating turbulance. Fans help to pull the turbulent air through the radiator. Your flex fan does that job real well, when the motor is at speed.
D
Dynamic Corvettes
Guest
My 77 is an L82 and it still has the GM fan clutch on it which is a very expensive piece to replace. I see a number of cars with aftermarket fan clutches that fail pretty quickly. This may be one of those cases where the original GM designed part is the best.
Was the a/c condensor removed and cleaned from the car ?
Was the a/c condensor removed and cleaned from the car ?
R
resto75
Guest
I have a nylon Flexfan on my 75 and it works great. It's just black nylon and keeps my temps at 180 all the time. I have a aftermarket radiator (Griffen) and that probably has the biggest cooling effect but the fan causes no problems.
I am planning to change it to a alumium flex fan with the red blades just for the looks.
I am planning to change it to a alumium flex fan with the red blades just for the looks.
- Thread starter
- #10
Paul G
Well-known member
Replacing the flex fan
Okay it seems like we need to replace the flex fan because it has a broken blade. What size fan is it 17" or 18" and what is the hub size 5/8" or 3/4"? We called the local parts people and they asked these questions. The dealer said the factory fan is 18". Is a 17" flex fan okay to use?
Thanks for all the help.
Okay it seems like we need to replace the flex fan because it has a broken blade. What size fan is it 17" or 18" and what is the hub size 5/8" or 3/4"? We called the local parts people and they asked these questions. The dealer said the factory fan is 18". Is a 17" flex fan okay to use?
Thanks for all the help.
GWHITE75
Well-known member
resto75 Make sure you check the blades occasionaly on the new aluminum unit. I ran an aluminum fan for a while and the blades started to fatigue at the bolt holes. I have also seen metal fatigue at rivets of other flex fans.
Paul G Because it's aftermarket, I suggest you take it off first. It's probably a 17" and 5/8", but you can save some frustration and a possible extra trip if you take it with you. Typically, you want the largest blade that will fit in the shroud and maintain at least 1/4" clearance all around, to give you maximum CFM. The factory blade was probably an 18", but you can't rely on an 18" flex fan to fit, so measurements should be taken. Also, make sure you buy a good one. If not, you will be replacing it again for the same reason.
Paul G Because it's aftermarket, I suggest you take it off first. It's probably a 17" and 5/8", but you can save some frustration and a possible extra trip if you take it with you. Typically, you want the largest blade that will fit in the shroud and maintain at least 1/4" clearance all around, to give you maximum CFM. The factory blade was probably an 18", but you can't rely on an 18" flex fan to fit, so measurements should be taken. Also, make sure you buy a good one. If not, you will be replacing it again for the same reason.
mvftw
Well-known member
I also have a factory cast iron water pump, fan, & clutch with 91K miles. I'm planning on replacing the water with a GM aluminum pump. I'm also going to replace the clutch, maybe GM ($$$) maybe not. Do you think there may be a problem using the a clutch fan & aluminum pump? I hate to see it brake apart.
GWHITE75
Well-known member
mvftw There shouldn't be a problem. I am running a Weiand aluminum pump and a Hayden replacement clutch with an 18" blade now. The clutch is a heavy duty model and I think the number is 2575, but don't shoot me if its wrong. They will list a lighter duty model, so ask for the heavy duty, if you need to replace the clutch. I would recommend you get a good aluminum pump.
Now, I did have to rebuild my pump, after the shaft came loose from the impeller and destroyed my radiator, shroud and ego. I took it to a very good local shop where they rebuild water pumps for cars and commercial motors like Catapillers.
The rebuilder was exteremely knowledgable and recommended that I have him install better bearings and a heavier duty impeller. This was the actual guy doing the rebuilding, not a counter person. Always try to speak with the person that physically does your work. I believe the failure stemmed from improper belt tension and spacers, when I ran it without the clutch. I have sense paid more attention to tension adjustments.
Now, I did have to rebuild my pump, after the shaft came loose from the impeller and destroyed my radiator, shroud and ego. I took it to a very good local shop where they rebuild water pumps for cars and commercial motors like Catapillers.
The rebuilder was exteremely knowledgable and recommended that I have him install better bearings and a heavier duty impeller. This was the actual guy doing the rebuilding, not a counter person. Always try to speak with the person that physically does your work. I believe the failure stemmed from improper belt tension and spacers, when I ran it without the clutch. I have sense paid more attention to tension adjustments.
mvftw
Well-known member
Thanks GWHITE75, I have the factory cast iron pump on the now, I thought about having it rebuilt by a pro, but decided to buy a GM pump new and keep the old one, I can get either cast or aluminum, I can get the aluminum for about $85+shipping seems like a good deal. A heavy duty GM clutch fan is about $80 also.
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