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#1 |
Registered User
Join Date: Jul 2012
Location: Campbell, CA
Posts: 452
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Clutch fan or flex fan?
Is it worth running a flex fan vs. a clutch fan?
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1971 C/10 - Orange & White 2009 GMC 1500 - Lowered 3/4 22' KMC Slides |
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#2 | |
Old member
Join Date: Jan 2002
Location: Liberty, & Garden City S.C. , U.S.
Posts: 19,936
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1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 ![]() Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs. |
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#3 |
Registered User
Join Date: Nov 2011
Location: Sheffield, ALA
Posts: 2,471
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Re: Clutch fan or flex fan?
BEEN ON MINE SINCE DAY 1.But been wondering about a flex fan I think it would be quieter.
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#4 |
20' Daredevil (Ret)
![]() Join Date: May 2003
Location: Jefferson State
Posts: 13,628
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Re: Clutch fan or flex fan?
In the 35 years I've owned my truck the only time it ever ran hot was when I temporarily had a flex fan on it. No problems ever with a clutch fan. Mine is OEM with an 18" seven-blade fan (factory A/C). I will never recommend a flex fan.
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#5 |
Registered User
Join Date: Jul 2012
Location: Campbell, CA
Posts: 452
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Re: Clutch fan or flex fan?
No A/C and it sounds like I need to forget the flex fan idea. Electric fans with the 4 core it is.
Posted via Mobile Device
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1971 C/10 - Orange & White 2009 GMC 1500 - Lowered 3/4 22' KMC Slides |
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#6 |
Registered User
Join Date: Jan 2012
Location: Redondo Beach California
Posts: 146
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Re: Clutch fan or flex fan?
I would keep the clutch fan on if you still use your truck in hauling stuff and towing up steep grades ,and on long trips. A flex fan is good for around town drives and if you don't use your A/C a lot during hot weather conditions. I have a Perma Cool flex fan and I wish I would of got a new clutch fan.
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343 NEVER FORGET 9-11 FIGHT ON!!! GO USC!!! PROUD OWNER OF A 1970 ![]() |
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#7 |
Registered User
Join Date: Nov 2011
Location: Sheffield, ALA
Posts: 2,471
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Re: Clutch fan or flex fan?
Been wondering about that. Mine doesn't have ac.
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#8 |
20' Daredevil (Ret)
![]() Join Date: May 2003
Location: Jefferson State
Posts: 13,628
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Re: Clutch fan or flex fan?
When my truck ran hot with a flex fan (posted above) I wasn't running the A/C.... but I was hauling a load of firewood uphill. Might have been OK if I just drove around but not when gets worked like a truck, which mine still does.
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#9 |
Account Suspended
Join Date: Oct 2012
Location: phx, az
Posts: 868
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Re: Clutch fan or flex fan?
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#10 |
1969 Custom 30 wrecker
Join Date: Sep 2001
Location: Pottsville, Pa
Posts: 2,611
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Re: Clutch fan or flex fan?
Every so often I like to post these pictures of my truck that HAD a flex fan on it. It was on the truck when I bought it and I will never use one again for obvious reasons!
Note, the strange looking hood ornament! ![]() BTW, that didn't just go through the flat sheetmetal but half way through the support under it!
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Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10 |
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#11 |
Cruzin
Join Date: Dec 2009
Location: on the road
Posts: 2,835
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Re: Clutch fan or flex fan?
I ditched my flex for a factory type clutch fan , im not much on electric just more stuff to fail
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Lime Wife's 67https://www.google.com/url?sa=t&rct=...wZEMODaS2d94u8 Back to the Fifties 59 https://www.google.com/url?sa=t&rct=...NAeStpydfrcj_U Proverbs 3:5,6 "Thanks to the Interstate Highway System, it is now possible to travel across the country from coast to coast without seeing anything."Charles Kuralt In memory of our first baby daughter, daddy and mommy love you. Danica Grace 6/26/14
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#12 |
C/10 junkie
Join Date: Nov 2010
Location: Stockton Ca
Posts: 9,093
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Re: Clutch fan or flex fan?
I have a flex fan now and will be switching to a fan clutch real soon.
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Shawn 70 LWB C10 current driver/project http://67-72chevytrucks.com/vboard/s...d.php?t=663051 68 SWB C10 Work in progress.....SOLD http://67-72chevytrucks.com/vboard/s...d.php?t=559520 72 LWB C10 Sold 71 LWB C10 Sold 68 LWB C10 CST Sold http://youtu.be/kbB0QrBIs9k My mom always had the best advice. It was just a tad late. After a fall that involved blood, she'd say....."Careful!" ![]() |
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#13 |
Cluster King
![]() Join Date: Nov 2012
Location: Junction City, OR
Posts: 5,263
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Re: Clutch fan or flex fan?
Reasons NOT to have a flex fan:
1. See photo above from bobs409 2. They are very noisy while on the gas. 3. You need kevlar gloves and sleeves to work around them. Very sharp. 4. They rob horsepower. |
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#14 |
Registered User
Join Date: Feb 2000
Location: Center City, MN, USA
Posts: 3,254
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Re: Clutch fan or flex fan?
The very first thing I did to my convertible when I bought it in 1989 is take that noisy, POS flex fan off that the PO put on. It made no sense to me then. After seeing that fan stuck through that hood, it makes even less sense. You could be working on it when a blade comes off. That could be your head!
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'70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN |
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#15 |
Registered User
Join Date: Jun 2012
Posts: 1,089
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Re: Clutch fan or flex fan?
My truck had the stock steel fan on it and it was very loud so I switched it over to a 18" clutch fan and it is so much better now and the flex fans are still noisy at low rpms.
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#16 |
Registered User
Join Date: Jan 2011
Location: Chattanooga, TN
Posts: 2,151
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Re: Clutch fan or flex fan?
Car Craft Magazine article, May 2000, page 50 and 51
Dyno test on fans: alternator, no fan=496 HP plastic flex fan=460 HP low profile flex fan=466 HP High-performance flex fan=476 HP Rigid steel 6-blade fan=449 HP Rigid steel 4-blade fan=473 HP Thermal clutch fan=487 HP non-Thermal clutch fan=485 HP HD Thermal clutch fan=476 HP alternator, electric fan (Black Magic 150)=494 HP So, stay away from any rigid fans and flex fans. On their engine the clutch fan only used about 10 HP as opposed to 30 for a flex fan. The electric fan only used 2 HP!
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'83 K20-TPI '73 C10 '79 C10-ex-diesel(SOLD) '07 Tahoe(Son driving) '14 Suburban-DD '71 C10-current project |
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#17 |
Registered User
![]() Join Date: Dec 2012
Location: Chandler AZ
Posts: 1,149
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Re: Clutch fan or flex fan?
I wonder about the reliability. I have had thermal clutch fans fail and had to take them off and bang them with a hammer to lock up just to get home. I did also have a fiberglass flex fan come apart, while I was at idle thank goodness. It only banged out through the bottom.
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1970 Longhorn, Front Disc, 350/4 bolt, 882 heads, HEI, Edelbrock, 700R4, HO-52/4.11. 1996 Corvette, Collector Roadster, LT4, 396, 450RWHP, 6sp, 4.11/Dana44/posi 5 point roll bar And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9 |
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#18 |
Registered User
![]() Join Date: May 2012
Location: Anton, Texas
Posts: 2,364
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Re: Clutch fan or flex fan?
rigid style fans and flex fans do come apart and do use more gas.and are very noisy . i always try and go with fan clutch fans....that is not the first hood with a fan sticking through it that i have seen....ask ford motor company back in the 1970's....they have stacks of broken fans...
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#19 |
Registered User
Join Date: Mar 2010
Location: Scranton,Pa
Posts: 423
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Re: Clutch fan or flex fan?
I had a fan sticking through my hood and it was a clutch fan. Now I run an electric one....problem solved!
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"When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car. " |
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#20 |
Registered User
Join Date: Jul 2012
Location: Central florida
Posts: 178
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Re: Clutch fan or flex fan?
Tossed out my flex fan and got a clutch and clutch fan from summit. 18" flx-5718 and hda 2705 .. Love it, simple to install... your real question should be, thermal or non thermal clutch fan? Hope i dont insight a riot!! good luck!
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" You are only coming threw in waves,... Your lips move, but i can't hear what your saying" |
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#21 |
20' Daredevil (Ret)
![]() Join Date: May 2003
Location: Jefferson State
Posts: 13,628
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Re: Clutch fan or flex fan?
^^ Thermal, of course!
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__________________
- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#22 |
~Rest In Peace~
Join Date: May 2005
Location: CALIFORNIA NOR CAL
Posts: 9,707
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Re: Clutch fan or flex fan?
take those POS flex fans off ASAP just sayin' never did like them any fan blade really ,
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is it fast ? it has a lighting bolt donut? B___H please, I can remove 90% of your so called "beauty" with a kleenex |
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#23 | |
Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,403
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Re: Clutch fan or flex fan?
Quote:
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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#24 |
Cruzin
Join Date: Dec 2009
Location: on the road
Posts: 2,835
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Re: Clutch fan or flex fan?
i think about this now alot (older and smarter) all that moving stuff could mess you up i've heard of the piece behind of the alternator pulley breaking and messing a guy up. i've had my hand smacked by a fan and thank God it wasn't a flex fan still numb for a couple hours.
__________________
Lime Wife's 67https://www.google.com/url?sa=t&rct=...wZEMODaS2d94u8 Back to the Fifties 59 https://www.google.com/url?sa=t&rct=...NAeStpydfrcj_U Proverbs 3:5,6 "Thanks to the Interstate Highway System, it is now possible to travel across the country from coast to coast without seeing anything."Charles Kuralt In memory of our first baby daughter, daddy and mommy love you. Danica Grace 6/26/14
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