Aluminum Torque Ratings [Archive] - BigBlockDart.Com

: Aluminum Torque Ratings



jacks62440
01-08-2008, 07:14 PM
When you are tightening a bolt into aluminum, I would assume that you wouldn't torque it to the same Ft# as Cast Iron. What would be the correct Ft# for a Aluminum water pump bolt into a Aluminum Housing ??? Manual Say's 30 Ft# in a Stock Pump. 3/8-16 bolt. Is there an Accepted Reference somewhere ??? My gut tells me to go 25 Ft# ???

bOb shingler
01-09-2008, 01:20 PM
not relly sure on the question but i just use a 3/8" rachet or the regular size 9/16" wrench and tighten it up real good but not with all of your strength.

Ruster
01-10-2008, 12:28 PM
The bolt governs the torqe rating rather than the part it's going into so you would torque to the same spec.

jacks62440
01-12-2008, 10:19 PM
Something you all may find interesting that I got from a Sister Site.* http://dodgeram.org/tech/specs/bolts/SAE_bolts.html
I was mainly concerned with stripping the threads in a Aluminum water pump. I was sure that Aluminum would not be the same as cast iron.* *-0*(

jbarker
01-13-2008, 06:46 AM
Hi Jack-
I'm not positive, but in the chart you provided a link to, I think the "aluminum" column was referring the the composition of the bolt, not the material the bolt is going into. The reason I think this is that the other columns were listed as grade 2, grade 5, and grade 8, which are common designations of bolt material strength.
I know that you are concerned with torquing a steel bolt into an aluminum manifold, (not using aluminum bolts) so I don't think that this chart provides the info you are really after.
I agree with what Ruster stated above.
Good luck Jack!
-Jason

Ciscodog
01-13-2008, 07:30 AM
If it's not inside the motor or trans, it doesn't need to be torqued. Okay so the intake bolts should be, but everything else is just "tight". And lugnuts LOL

speedymopars
01-13-2008, 02:38 PM
I use studs on the WP. Makes teardown a whole lot easier - esp with motor plates (you don't need a cherry picker to play with the WP housing like when changing a cam, etc). PLus in an AL block, less wear and tear

jacks62440
01-13-2008, 11:13 PM
Hi Jack-
I'm not positive, but in the chart you provided a link to, I think the "aluminum" column was referring the the composition of the bolt, not the material the bolt is going into.* The reason I think this is that the other columns were listed as grade 2, grade 5, and grade 8, which are common designations of bolt material strength.
I know that you are concerned with torquing a steel bolt into an aluminum manifold, (not using aluminum bolts) so I don't think that this chart provides the info you are really after.
I agree with what Ruster stated above.
Good luck Jack!
-Jason
I Don't know, But I've never seen a aluminum bolt ???* And a far as not needing to touque bolts. Some may get away with it for a long while, But Why would the Factory give specs for everything from rod bolts to water pumps ???

ksdartguy
01-14-2008, 07:44 AM
Torque tables are to tighten evenly and are usually posted for nearly every
nut and bolt. I don't torque my water pump, valve covers, timing cover, etc.
Its still not a bad idea. I would not go 35ftlbs though. The alum housing is pretty
thin there. Not much material, and I would'nt want to strip it.25ftlbs. is better.
Rick

79ramcharger
01-14-2008, 06:51 PM
There maybe some misconceptions here everyone torques a nut or bolt whether or not they use a torque wrench. In the world of nuclear powered subs an acceptable method of torquing an item is to use the feel method. This where an experienced mechanic calibrates his arm so that he knows what the proper torque feels like. So in my case when I build an engine I do not use a torque wrench on any fastener that is external to the motor and less than 20 ft-lbs. My reasoning is that I can feel the proper torque for the items that should be tightened. Is it a time bomb for me? It could be but has not yet. The worst that can happen is that I would have a fluid leak that I would see and fix.

Now Jacks has a different problem he does not know what the torque should be. Most torque tables that are found on the internet assume steel flanges and the table is based on the fastener material. Unfortunately there is a little more to it that that. To properly look up a torque for his joint he needs to know what his fastener material is, what grade aluminum his pump housing is made from, what grade aluminum his pump is made from, and the fact that he is threading into a blind hole not a nut (a lot of the torque tables on the internet assume nuts).

That all being said I find that I am a bit heavy handed and have broken the cast iron pump on a 440 by over tightening. So Jacks my recommendation is use a quality sealant and go with your gut. Reasoning is that Aluminum expands faster with heat than iron so as the motor heats up the bolts get tighter. I will also see if I can look it up tomorrow at work.

Clear as mud?

Steve

jacks62440
01-14-2008, 10:24 PM
That makes pretty Good Sense. I favor the use of a Torque wrench mainly because I don't have the "calibrated arm"* yet and no one is paying me by the hour* LOL* And it just make me more aware of what I am doing. I went with the charts suggested 20# for a 3/8" 16 { NC }* *Thanks for the help* -0*(* Jack

73swinger
01-14-2008, 10:39 PM
There maybe some misconceptions here everyone torques a nut or bolt whether or not they use a torque wrench. In the world of nuclear powered subs an acceptable method of torquing an item is to use the feel method. This where an experienced mechanic calibrates his arm so that he knows what the proper torque feels like. So in my case when I build an engine I do not use a torque wrench on any fastener that is external to the motor and less than 20 ft-lbs. My reasoning is that I can feel the proper torque for the items that should be tightened. Is it a time bomb for me? It could be but has not yet. The worst that can happen is that I would have a fluid leak that I would see and fix.

Now Jacks has a different problem he does not know what the torque should be. Most torque tables that are found on the internet assume steel flanges and the table is based on the fastener material. Unfortunately there is a little more to it that that. To properly look up a torque for his joint he needs to know what his fastener material is, what grade aluminum his pump housing is made from, what grade aluminum his pump is made from, and the fact that he is threading into a blind hole not a nut (a lot of the torque tables on the internet assume nuts).

That all being said I find that I am a bit heavy handed and have broken the cast iron pump on a 440 by over tightening. So Jacks my recommendation is use a quality sealant and go with your gut. Reasoning is that Aluminum expands faster with heat than iron so as the motor heats up the bolts get tighter. I will also see if I can look it up tomorrow at work.

Clear as mud?

Steve




Wow, I find it hard to believe that on Nuke subs the 'feel method" is acceptable practice. I also work in the nuclear industry (power generation ) and where I work absolutely everything gets torqued. Not only that but before and after every job the (Snap ON no less) wrenches get checked on a load cell. Also the serial numbers are recorded...on every job. This may be going a little overboard but consider the consequences.

In my training there I have learned that the feel method is inconsistant at best. They had a special rig set up just to prove this fact. It was a 6 bolt pipe flange with load cells at every bolt. We couldn't see the results at the time and were asked to tighten it evenly by hand. Nobody in the course got less than about 30% variation, and we were all Industrial Millwrights with years of experience.

At home, when it's my money, If some procedure says torque it to X, then I torque it to X

79ramcharger
01-14-2008, 11:18 PM
The feel method is a last resort only used when there is no possible means to see the dial (snap action wrenches are not allowed) on the wrench. Things can be tight on a sub.

Steve

Ruster
01-15-2008, 12:29 PM
Torque to the spec of the bolt. If the thread engaugement is more than about 2X the diameter of the bolt and there not dammaged previously the aluminum threads will take it.

NYRR496
01-15-2008, 01:03 PM
I agree. I've done LOTS of diesel stuff and the torque spec for a 3/8 bolt was the same whether it threaded into aluminum or iron.

satellite65
01-15-2008, 02:07 PM
Consider this....
Several years ago I owned a Chevy Beretta GTZ w/ an HO Quad 4. During the warranty period it blew a head gasket. While it was in the dealership being repaired I got to talking with the mechanic actually working on it and he shared some info with me. While this is probably common now it was pretty new in '92. The engine was a cast block / aluminum head motor. The fasteners were called "torque to yield" and could not be re-used. They were torqued by using a torque wrench in a staggered pattern to about 15 foot lbs. After that they used a digital device (protractor?) to measure the amount of degrees the bolt was turned until it reached its spec (in degrees). Their reasoning for this was because aluminum expands so much more than iron that a specific grade of hardware is required to provide the correct clamping force under all conditions, hot or cold. The bolt "stretch" is much more critical. Just thought i'd share this as so many of us are considering (or are already using) aluminum cylinder heads.

As for a water pump and housing, I work on vacuum pumps and compressors, most of the components of these pumps are aluminum and from years of experience all I can say is that aluminum is a pretty shitty material to be threading a bolt into! I would use the "torque wrench + common sense" method. How tight does a water pump need to be anyway? One more note, if you can avoid it, try NOT to disassemble hot parts. The aluminum thread can gall to the steel bolt and come out with it. Steel threaded inserts would be nice.

NYRR496
01-15-2008, 08:32 PM
The method you're talking about is called "Torque Turning". The bolt gets torqued to an initial, usually low setting and then turned a specified amount of degrees. Cat's been using that method for years on mains and rods. There's a tool for doing it, but the EASY way is to use a paint pen... Mark one corner of the bolt to a reference point on the iron and paint another corner as your "finish". On a six point bolt, each point represents 60 degrees, so torque turning 120 degrees meant turning it two corners. 12 points are 30 degrees per point. Easy.