Is 1" too big??

[Cliff Beer]

I just bought a (very large) 1" impact wrench from harbor freight. It's supposed to deliver about 1,400 ft/lbs of torque on about 10 CFM at 100psi. I bought it because I occasionally have to do some heavy work (crank pulley bolt on a mercedes V8 takes about 275 ft/lbs, for example...). The latest one is that I would like to remove the CV axles from my CAV to replace/rebuild the CVs...and the outboard nut (hub end) is on hella tight. It looks very dry and a little corroded. I've tried a three foot breaker bar with my full weight (~600 ft/lbs) and no dice. So, I'd like to try the impact wrench on it.

My problem is that I think I must be short on air. The impact wrench has a 1/2 inch NPT inlet which I reduced down to 3/8th with a reducer....then further reduced it down to the regular 1/4 fitting size (what you normally have on say a 1/2 inch impact wrench). I have a newish 5hp Craftsman air compressor with a standard size air hose (1/4 air fittings). With pressure cranked up and full tank of compressed air, the impact wrench barely turns. It certainly doesn't deliver any meaningful impact torque.

Do I need to re-plumb from the tank out with a larger diameter hose? Get a bigger air compressor?

If nothing else, I'll remove the wheels and the pin drive hub and then use a dremel tool on the nut with a cold chisel to crack it....was just hoping to be able to use my new big toy instead...

Any advice/help is appreciated.

 

[Russ Noble]

I'm rather sceptical of the 10CFM requirement for that tool. I would imagine a 5hp compressor would deliver twice that anyway.

Your hoses and fittings are too restrictive. Make sure you have big orifices everywhere in your supply line. Remember the cross sectional area of a 1/2 " fitting will be about four times that of a 1/4" . Thus your 1/4" fittings will be hugely restrictive to the necessary airflow. With air tool lines big is always better!

The other thing, have you lubed the vanes in the gun? If they are dry they may not be sealing and much of the air could be getting past them. They will hardly turn when this happens.

 

[Cliff Beer]

Thank you Russ, that's good advice. Thinking about it last night after I posted I realized I hadn't put any oil into the thing to get the vanes lubed - will do that now. I'll also up-size the line as you suggest. I think the outlet on the compressor is 3/8th if not 1/2 so shouldn't be too tough.

Incidentally, I also wanted to be able to potentially use this wrench at track events if I can get my F5000/Indy car project back on track. I'm thinking an Indy car center lock nut is going to need some serious torque. So, basically, I'm looking for big torque which is mobile - modest sized compressor that runs on standard 110v, perhaps even with a fairly long extension cord or from a modest sized generator (track setting). In any case, thanks for the tips.

 

[Seymour Snerd]

... I would imagine a 5hp compressor would deliver twice that anyway...

An honest steady-state 5HP compressor will deliver about 15 cfm. I takes 7.5 HP to get to 20. BUT.... Sears (and others) play games with HP ratings such that what they call a 5HP compressor is very likely good for 12 cfm at best.

Also, don't forget that with the tank full, until the motor kicks in, the energy provided by the compressor is unaffected by motor size and determined only by these things:

1. The instantaneous pressure in the tank (starting out at whatever the blowoff valve or regulator is set to; obviously you want this as high as possible consistent with the rating of the tool and the tank).
2. The air flow restriction of the downstream hoses, etc.

So, after the motor has shut down, if you're not getting what you want when you first hit the trigger, look at pressure and air flow. Also, keep the hoses as short as possible. With all that optimized, for a short burst the tank can provide way more than the steady-state rating of the compressor as a whole which is determined by the motor size.

 

[Dave Wood]

Personally I think 1" is more than you will need in almost every application...unless you do Semi tractor work. I have never needed anymore than a good 1/2" impact. I do have a 1/2 to 3/4 adapter for a BMW gland nut socket, but the 1/2 " breaks it loose with ease. I may completely wrong on this, because I don't have an impact that size, but unless you have a large tank you aren't getting enough air. I know that my 1/2 inch acts "stuck" if I have used the die grinder long enough to drain the tank down. I have 5 horse 60gallon compressor, it charges great, but extended die grinder use can cause a short period that seems to have a lapse in strength.

 

[Ron Earp]

I'd say too big to be of a lot of use. When I have to remove crank dampeners, which is a few times a year, I find a breaker bar and a long pipe more than enough to do the job. You can't use a tool like that in situ anyhow. For lug nuts a 1/2 impact, electric or air, will do the job.

With the wheel nuts most teams that I see with that sort of thing again use a specialized breaker bar that is setup for that car/nut/torque. Much lighter and easier than lugging a big impact gun around and air supply. If you start going to the track regularly you start thinking "less is more", unless you're using a tractor trailer rig like some fellows.

Seems like that hub nut is on waaaay too tight......

 

[Seymour Snerd]

Portable air

I'm looking for big torque which is mobile - modest sized compressor that runs on standard 110v, perhaps even with a fairly long extension cord or from a modest sized generator (track setting).

Those are some pretty ambitious and contradictory requirements. A standard domestic 110V 15A wall plug puts out 1650 volt-amps (aka "watts"). So you'll need a generator that size or larger to replicate what's in your garage. If you want a long cord then you have to provide a corresponding amount of copper to move that number of VA to the generator, and those are expensive. So before you buy any of this start with the compressor's VA requirements and make sure everything upstream (long cord and generator) can supply that. Otherwise you're going to end up waiting for one of those elements to play catchup or cooldown. A *real* 5 HP compressor needs ~40A at 110 V or 4,400 VA. That's not a modest generator.

Probably a better approach is a gas-powered compressor (IOW, skip the eletricity; the motor/generator pair is throwing away at least 2/3 of the energy). Smaller, lighter, all in one piece. About the same cost as your current compressor.

BTW none of this has anything to do with CAV. This thread should be moved.

 

[Phil]

Cliff:
Most of the guys I know that vintage race use compressed nitrogen with a high pressure regulator to break the nuts, and I would think a good 3/4" gun would do the job.
I agree with all the guys on the 1/2" line, you will need that flow. I have a friend that does road side tires for big rigs and he uses a 1" gun with a 1/2" line, the only rub there is they run their compressors to 175 psi. to get that breakaway torque they need, and that usually requires a two stage compressor, something you wont find running on 110/115 volt power.
Cheers
Phil

 

[Jac Mac]

Check the thead on the nut you are trying to remove, it might just be LHT, in which case all the pressure/flow in the world will not help.

For removing 'Those' hub nuts I have an old axle flange withe multiple stud patterns drilled into it welded to a piece of 2" box section about 4 ft long which I fit in place of the wheel, drop the car weight back on it & then use a large breaker bar, this takes all the 'flex' out of the job if you were trying to do it with a helper standing on the brake pedal.( Helpers are scarce around my neck o the woods). If you have pin drives you might need to clamp the flange on your hub to do this.

 

[Cliff Beer]

Thank you gents, that's all very helpful information and advice.

Thinking about it, you're right, lugging the 5hp compressor to the track will be horrible (unless perhaps I permanently mount it inside the trailer perhaps).

Duh, I forgot that one of the nuts is probably RHT and one LHT - four small kids in the house is sucking the brain cells right out of my head I think! Good tip.

When I built my new garage I way, way overwired it....in other words, extra 220 lines and super heavy gauge wire all around (220/110), with lots of circuits. The panel in my garage looks like a panel you might see in a 5,000 sq. foot house! So, I'm in good shape for power delivery in there....different story at the track however.....

I up-sized the air lines today and cleared out some accumulated crud in the filters and quick disconnect fittings. Now the impact wrench is working like it should - in other words, it just about twists your arm off when you grab the trigger. As suggested above, I could probably break those nuts free now with a good 1/2 impact. I'll go wrestle with it a bit more. Wait until the kids have gone to sleep and get my helper (my wife) out there to step on the brake pedal....maybe I'll put on some Marvin Gaye on the new garage audio system and see what else she can help with....

 

[Dalton Veitch]

Gee Cliff, go easy on those nuts.

 

[Damian]

:laugh: :thumbsup: I see what you did there ^^^ :laugh:

 

[tom pritchett]

I am glad that you got the gun working. I certainly would leave the wheel on the car and have it on the ground when breaking loose the axle nut. You have access to the nut and it doesn't hold up the car, so.....break it loose, then lift the car and take the rest apart. Let me know if you need any help, this seems intruguing.

 

[Ian Clark]

Hi Cliff

I've had the pleasure of changing about 32 cast rear uprights over to our fabricated steel units. When the old parts are sent here we do the work of separting the stub axles and bearings. Some of them were on extremely tight.

What works the best is for us is a 3/4 drive socket attached to a power bar stuffed inside a six foot long chunk of steel dom tubing. Makes an eight foot lever. Car on ther ground, brake pedal full on, parking brake locked, rear clip open, get positioned for a pull down on the bar. Damm near lifted myself off the ground on a few of them! You will feel the nut yielding before it lets go, be prepared so you land on your nuts or worse yet - scratch the car

It's not pretty but gets the job done, use the same process to tighten the nut. Hope that helps

Cheers

 

[Cliff Beer]

Hi there Ian,

Super, thank you for sharing your experience. Now I know I'm not totally "nuts" and doing something completely stupid (just half stupid maybe....).

That sounds like the right bit of kit to get the job done. I will do the same (think I have a 10' section of 2" steel round out in the junk pile out back that'll work for a lever as you suggest).

Here's a question if you'll humor me Ian: are both nuts (left and right side) the same thread? In other words, is one reverse thread. It would be just my luck (or skill?) to be tightening up one instead of loosening it...and with a 10' lever I could potentially create a mess...

Thank you Ian, much appreciated!

 

[Ian Clark]

Hi Cliff,

Both you nuts are right hand thread, don`t ask me how I know this

Cheers

 

[Cliff Beer]

Took the rear wheels off a couple weeks back and have been tidying up a few things (like motor mounts with no bolts!) and got to work removing the CV axles. The outboard locking nut is a bugger to get off...it had three obviously good sized whacks from a drift to "lock" it in place. I got out the 1" 1,400lbs/tq impact gun (intended for truck axles!), turned up the compressor to 140lbs and both nuts finally eased off after some working on them. I would estimate those nuts were torqued up to around 700-750 ft/lbs. I would think that 450 ft/lbs would be sufficient. But, in any case, the CV's came out just fine.

The left side (driver's side) CV axle was pretty worn and had a lot of slack. So, I'll be replacing both the CVs, which prompts my question below. The CVs have "GLO 4051" (inboard) and "GLO 3073" (outboard) written on them so it looks like these came from GLO in SA. GLO's website indicates that these CVs cross ref to an Audi 5000 - not surprising at all, the transaxle is, after all, an Audi 5000 016.

Has anyone replaced their CV axles in an 016 equipped CAV? Are the axles indeed same as Audi 5000? The axles out of my CAV are the same length - I though the Audi 5000 had different length axles. Wondering if perhaps the outboard and inboard CVs are same as spec'd for Audi 5000 but perhaps the axle shaft is a different length? In other words, a custom length for the application. Anyone have some relevant information?

Thank you.

 

[tom pritchett]

Hey Cliff,

I have broken both sides of mine and had to replace them. I had drivelines nw do them and they just changed the ends and used the same axle. It cost me about $88 each axle. If you send in the axle at the Seattle store, they will send it to Everett. They only do the cv's in Everett.

 

[Cliff Beer]

Thank you Tom. I knew there was a local place that did that kind of work, just couldn't remember the name - drivelines nw. I took some axles to them about 10 years ago and I remember they did a pretty good job for a reasonable price. I'll give them a call tomorrow - thanks again.

ps. I can imagine you could easily break axles with your (very impressive) motor. Mine is just a lowly Ford Racing 302 with about 350hp/tq so I'm probably OK with these axles....for a while at least!

Cheers.

 

[tom pritchett]

The great part of these axles are they are inexpensive. A built in fuse I guess. I would rather replace the axle than the ring and pinion in the ZF again. Now that is expensive.