Home » Public Forums » GMCnet » how much compressor do i need to bust loose BIG bolts
| how much compressor do i need to bust loose BIG bolts [message #66952] |
Tue, 08 December 2009 12:28  |
hertfordnc
Messages: 1164
Registered: September 2009
Location: East NC
Karma: 0
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Can someone explain to me what I need to know about air to break loose the big stuff on my coach?
I really want to know what are the minimums I can get away with to drive a substantial impact wrench.
I'm not a garage and I would not need to do this very often, and I'd be willing to wait for the head to build between bolts, (this ain't NASCAR)
So what PSI and CFM do I need to get 200 ft lb out of a 1/2 inch impact wrench?
thanks
Dave & Ellen Silva
Hertford, NC
76 Birchaven, 1-ton and other stuff
Currently planning the Great american Road Trip Summer 2021
It's gonna take a lot of Adderall to get this thing right.
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| Re: [GMCnet] how much compressor do i need to bust loose BIG bolts [message #66955 is a reply to message #66952] |
Tue, 08 December 2009 12:48  |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Dave,
I did a Google search and came up with:
http://www.engineeringtoolbox.com/air-consumption-tools-d_847.html
http://www2.northerntool.com/air-compressor-buyers-guide.htm
http://catalogue.cp.com/e-catalogue/index_xmlhttp.asp?target=vs-impactwrench
es&BA=it
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of dave silva
Sent: Wednesday, 9 December 2009 5:29 AM
To: gmclist@temp.gmcnet.org
Subject: [GMCnet] how much compressor do i need to bust loose BIG bolts
Can someone explain to me what I need to know about air to break loose the
big stuff on my coach?
I really want to know what are the minimums I can get away with to drive a
substantial impact wrench.
I'm not a garage and I would not need to do this very often, and I'd be
willing to wait for the head to build between bolts, (this ain't NASCAR)
So what PSI and CFM do I need to get 200 ft lb out of a 1/2 inch impact
wrench?
thanks
--
1972 Revcon 250- the other front wheel drive motorhome.
http://www.davesilva.com/revcon
Parting out 1974 GMC 26- http://www.davesilva.com/gmc
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] how much compressor do i need to bust loose BIG bolts [message #66960 is a reply to message #66955] |
Tue, 08 December 2009 14:25 |
hertfordnc
Messages: 1164
Registered: September 2009
Location: East NC
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THanks. That clears it up a little but I think i'm asking for real world applcation.
THose ratings assume you're going to work all day at that output. So if you need to use a 3/4 impact driver you need 8 CFM continuously, you're not expected to wait for the tank to load.
I'm thinking a cheap compressor might be a nice Christmas gift; for the occasional tire flling an brad driving. But will it be capable of busting loose tight nuts in confined spaces on some limited basis?
Dave & Ellen Silva
Hertford, NC
76 Birchaven, 1-ton and other stuff
Currently planning the Great american Road Trip Summer 2021
It's gonna take a lot of Adderall to get this thing right.
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| Re: how much compressor do i need to bust loose BIG bolts [message #66974 is a reply to message #66952] |
Tue, 08 December 2009 16:37 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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| hertfordnc wrote on Tue, 08 December 2009 13:28 |
Can someone explain to me what I need to know about air to break loose the big stuff on my coach?
I really want to know what are the minimums I can get away with to drive a substantial impact wrench.
I'm not a garage and I would not need to do this very often, and I'd be willing to wait for the head to build between bolts, (this ain't NASCAR)
So what PSI and CFM do I need to get 200 ft lb out of a 1/2 inch impact wrench?
thanks
|
Sir: I have found the size of the air line matters. I use a 1/2" air line and the 1/2" impact works much better than with a 3/8" hose. No problem with wheel nuts.
C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] how much compressor do i need to bust loose BIG bolts [message #66977 is a reply to message #66955] |
Tue, 08 December 2009 16:50 |
Gary Casey
Messages: 448
Registered: September 2009
Karma: 0
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Dave,
I think it depends on your intent. If you just need to break loose bolts that are difficult to do with a hand wrench, but don't necessarily need to spin multiple bolts out one right after the other (not NASCAR, as you said), then almost any compressor that can generate 100 psi would work. I used a 1/2-inch gun to loosen a crank bolt that was tightened to over 200 ft-lb and it took just a couple of "hits" with the wrench - almost no air was used. You need enough pressure and enough volume in the system to get the first few impacts, which are the ones that do the job. The most effective volume is that in the hose, so you don't even need a large tank. After one bolt is loosened you might have to wait for the pressure to build up. Even the coach compressor would be more than adequate and I'll bet you could break loose all 8 bolts of a wheel before it lost pressure. I think you need at least 80 psi and probably 100 would be plenty adequate.
Gary
________________________________
From: Rob Mueller <robmueller@iinet.net.au>
To: gmclist@temp.gmcnet.org
Sent: Tue, December 8, 2009 11:48:03 AM
Subject: Re: [GMCnet] how much compressor do i need to bust loose BIG bolts
Dave,
I did a Google search and came up with:
http://www.engineeringtoolbox.com/air-consumption-tools-d_847.html
http://www2.northerntool.com/air-compressor-buyers-guide.htm
http://catalogue.cp.com/e-catalogue/index_xmlhttp.asp?target=vs-impactwrench
es&BA=it
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of dave silva
Sent: Wednesday, 9 December 2009 5:29 AM
To: gmclist@temp.gmcnet.org
Subject: [GMCnet] how much compressor do i need to bust loose BIG bolts
Can someone explain to me what I need to know about air to break loose the
big stuff on my coach?
I really want to know what are the minimums I can get away with to drive a
substantial impact wrench.
I'm not a garage and I would not need to do this very often, and I'd be
willing to wait for the head to build between bolts, (this ain't NASCAR)
So what PSI and CFM do I need to get 200 ft lb out of a 1/2 inch impact
wrench?
thanks
--
1972 Revcon 250- the other front wheel drive motorhome.
http://www.davesilva.com/revcon
Parting out 1974 GMC 26- http://www.davesilva.com/gmc
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| Re: how much compressor do i need to bust loose BIG bolts [message #66997 is a reply to message #66952] |
Tue, 08 December 2009 20:01 |
kingd
Messages: 592
Registered: June 2004
Karma: 2
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I have a 39" Snap On bar (the one with no "business end". I have an end on it like a "Johnson Bar" but various heads are available. This thing does not bend or flex. I bought this to do the wheel nuts on my Dodge chassis motorhome that has flange style wheel nuts like the GMC but the nuts and studs are bigger and the owner's manual torque spec is crazy, like 250 to 400 ft/lbs. With this bar you can get your full weight a real 3 feet from the fastener.
DAVE KING
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada
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| Re: [GMCnet] how much compressor do i need to bust loose BIG bolts [message #67004 is a reply to message #66952] |
Tue, 08 December 2009 21:58 |
Steven Ferguson
Messages: 3447
Registered: May 2006
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Even on small fittings such as brake lines, fuel lines etc, I have
found that slightly tightening first, makes loosening much easier. If
you're using an impact, make sure you oil the air tool first, then run
in the direction that tightens, then reverse and most bolts and nuts
will break loose.
On Tue, Dec 8, 2009 at 11:28 AM, dave silva <gmc@davesilva.com> wrote:
>
>
> Can someone explain to me what I need to know about air to break loose the big stuff on my coach?
>
> I really want to know what are the minimums I can get away with to drive a substantial impact wrench.
>
> I'm not a garage and I would not need to do this very often, and I'd be willing to wait for the head to build between bolts, (this ain't NASCAR)
>
> So what PSI and CFM do I need to get 200 ft lb out of a 1/2 inch impact wrench?
>
> thanks
> --
> 1972 Revcon 250- the other front wheel drive motorhome. http://www.davesilva.com/revcon
> Parting out 1974 GMC 26- http://www.davesilva.com/gmc
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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| Re: how much compressor do i need to bust loose BIG bolts [message #67006 is a reply to message #66952] |
Tue, 08 December 2009 22:37 |
Craig Lechowicz
Messages: 541
Registered: October 2006
Location: Waterford, MI
Karma: 0
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Senior Member |
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Dave wrote:
> So what PSI and CFM do I need to get 200 ft lb out of a 1/2 inch impact wrench?
Dave, the short answer is 4 cubic feet per minute at 90 psi, if you believe all the specs, but more is always better. My experience has been the quality of the air wrench matters a lot more than the quality of the compressor. In it's day, my 25+ year old Ingersoll Rand 231 would take just about anything off, and now it struggles on the really rusty stuff. (Here's where having a neighbor with a newer and nicer Chicago Pneumatic comes in . . .) But, a lot of the discussion has been about reaching high constant torque (3/4 drive breaker bars with long handles . . . I bought a 5' piece of pipe to get my front axle nuts off, and I'm fat) That's typically not where I find an air impact most useful. You probably stand a 3 or 4 x better chance of successfully backing out a rusty exhaust manifold bolt with an air wrench than you do with a long handled tool, as the impact action is much less likely to twist it off. And for that, a one or two hp compressor is probably fine, but a "name brand" air wrench is much more successful than a $39 one that comes with the compressor.
Just what my experience has been,
Craig
Craig Lechowicz
'77 Kingsley, Waterford, MI
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| Re: how much compressor do i need to bust loose BIG bolts [message #67009 is a reply to message #67006] |
Wed, 09 December 2009 00:01 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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I have just about sworn off of impact wrenches. I primarily use them for a speed wrench. I also use them at lower torques settings to loosen stuck (usually rusted) bolts after a thorough soaking for days with Kroil.
As speed wrench example, on wheel nuts I break the nuts loose with a long bar and a socket. Then I spin them off with an impact (speed) wrench. I spin them back on with a quick pull on the trigger of the impact and then finish with an appropriate torque wrench.
On stuck bolts, like exhaust manifold bolts, I soak the bolts for several days with Kroil and loosen them with a lower power 3/8" impact. The jerking motion helps to break them loose, without twisting / breaking them off. I never exceed the torque rating of the bolt. Occasionally on a really stuck I use some heat from a flame wrench to assist the Kroil.
For the above reasons I question the need for a large impact wrench.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: how much compressor do i need to bust loose BIG bolts [message #67020 is a reply to message #67009] |
Wed, 09 December 2009 09:23 |
Smitty52
Messages: 181
Registered: July 2007
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My two cents. To me the biggest part of the equation is the impact gun. Mine is rated for 450lbs and really does not do a lot. I needed to break loose an axle nut on the old Wagoneer and it would not budge it. Nor would a 2ft breaker bar with 4ft of pipe on it. At that point my compressor developed a leak. My Brother-in-Law came over with his 1000ftlbs impact wrench and spun that nut off first try using a Dewalt contractor compressor designed for an air nailer. It is all in how the gun uses the air supplied to it. More air cfm will not increase the torque of a gun.
YMMV
Wayne and Lisa,
Bolton Landing, NY,
Patriot Guard Rider,
Standing for those who stood for us.
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| Re: [GMCnet] how much compressor do i need to bust loose BIG bolts [message #67025 is a reply to message #67020] |
Wed, 09 December 2009 09:58 |
Steven Ferguson
Messages: 3447
Registered: May 2006
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At some point you will need a torque multiplier. I can remove the
axle nuts on my GMC by generating 60 ft lbs of torque with a breaker
bar..........attached to my torque multiplier. They are expensive but
if you watch EBay, every now and then one shows up for a very fair
price compared to the new price.
With it I can easily generate 500 ft lbs of torque necessary to set
pinion depth/crush a crush collar. Handy device.
On Wed, Dec 9, 2009 at 8:23 AM, Wayne E LaMothe <superglider@juno.com> wrote:
>
>
> My two cents. To me the biggest part of the equation is the impact gun. Mine is rated for 450lbs and really does not do a lot. I needed to break loose an axle nut on the old Wagoneer and it would not budge it. Nor would a 2ft breaker bar with 4ft of pipe on it. At that point my compressor developed a leak. My Brother-in-Law came over with his 1000ftlbs impact wrench and spun that nut off first try using a Dewalt contractor compressor designed for an air nailer. It is all in how the gun uses the air supplied to it. More air cfm will not increase the torque of a gun.
>
> YMMV
> --
> Wayne and Lisa,
> Bolton Landing, NY,
>
> Patriot Guard Rider,
> Standing for those who stood for us.
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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| Re: [GMCnet] how much compressor do i need to bust loose BIG bolts [message #67061 is a reply to message #67035] |
Thu, 10 December 2009 05:20 |
Gary Casey
Messages: 448
Registered: September 2009
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Not to create any more ado on this subject, but.... Certainly, with a large shop that might have multiple impact wrenches running at any given time, the capacity of the compressor counts as without that the system pressure could drop. But for the rest of us we will only occasionally be using a single air tool at a time, and an air wrench is almost by definition used very intermittently (remember, no NASCAR pit action :-). My normal technique is to wait till the air is up to pressure and the compressor has shut off. Most times (all the time, actually) a bolt can be broken loose or tightened before the compressor starts, and that is with my very modest sized tank. So how can less compressor CFM yield lower torque? Only the pressure counts, and as someone correctly pointed out, the hose size is important partially because that is the "reservoir" that is mostly used during the first few hits of the gun. And, of course subsequent hits of the gun will
depend on there being as little pressure drop in the line as possible. So, you need a short, large diameter line (just avoid the little 3/8 plastic lines) and a modest tank. I could pump the tank up with a bicycle pump and it would work just as well for the first bolt. Just trying to save the original questioner some money.
Gary Casey
Elbert, CO
'73 23 under "renovation", er, "refurbishment"
________________________________
From: mills <mills@bmi.net>
To: gmclist@temp.gmcnet.org
Sent: Wed, December 9, 2009 11:58:08 AM
Subject: Re: [GMCnet] how much compressor do i need to bust loose BIG bolts
Reduce the CFM below what is specified will reduce the available torque,
but that is only based on 30 years of using impacts from 1/4" square
drives to 1 1/8" spline drives. Of course if the wrench has not been
oiled regularly and overhauled when due all bets are off.
--
Jim Mills
Greeley, CO
1973 CanyonLands 260 TZE-063V100731(under renovation)
1973 Glacier 230 TZE-033V101993
On Wed, 2009-12-09 at 09:23 -0600, Wayne E LaMothe wrote:
>
> My two cents. To me the biggest part of the equation is the impact gun. Mine is rated for 450lbs and really does not do a lot. I needed to break loose an axle nut on the old Wagoneer and it would not budge it. Nor would a 2ft breaker bar with 4ft of pipe on it. At that point my compressor developed a leak. My Brother-in-Law came over with his 1000ftlbs impact wrench and spun that nut off first try using a Dewalt contractor compressor designed for an air nailer. It is all in how the gun uses the air supplied to it. More air cfm will not increase the torque of a gun.
>
> YMMV
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