Do torque specs apply when fastening lock nuts?[sm=bs.gif]

 

Hello VolvoDriver,

Yes, in general torque specs apply to lock nuts. For Volvos, there are a number of luck nuts used on suspension and other components, and they have to be torqued with a torque wrench, and some lock nuts even have to be tightened further with an angle gauge, which is an angle indicating instrument that attaches to a 1/2" (3/8" adapter may be used) drive breaker bar. The only time I ignore torque specs on lock nuts is when I'm working on radios or othernon-safety related items in cabin. Also, the angle gauge I bought for $10 at AutoZone didn't work very good, so I eye-balled my nuts and then marked all nuts with a correction fluid. So, during brake or suspension inspections at certain intervals, themarks I put show if a nut has loosened and in such case I would definitely replace it with a new nut.

As a general rule, lock nuts must be replaced with new ones whenever they are disturbed (loosened); however I recycled a few nuts on my 850's suspension and the reason I decided to do this was because the nuts were only a few weeks old and there was still a good amount of resistance felt even with a ratchet handle, as well as the unique oblong-shaped thread hole keeping their original shape.

I hope this helps your question.


JPN

P.S: I'll attach a sample pic & URL for Snap-on's of angle gauge. Note, that Snap-on tools are the most expensive tools on the planet, and home-mechanics, or even professional technicians, can do away with less expensive tools as long as they are name-brand (Craftsman, etc...).

http://buy1.snapon.com/catalog/tools...e=snapon-store

[IMG]local://upfiles/6892/9A8A5BB955384E639771348D465D8A47.jpg[/IMG]

 

most excellant, thank you JPN.
I really need to invest in a torque wrench, I replaced the swaybar grommets, I reused the nuts on the endlinks. no torque spec., seemed useless. I did not use a torque wrench when fastening the bolt at the control arm when replacing the bushings there. I'm actually a stickler for strick maintenance for my Volvo.

I ask this question in regards to exhaust manifold studs and nuts. I'll be replacing these, specifically. So, then a torque wrench is an absolutemust?

 

>I ask this question in regards to exhaust manifold studs and nuts. I'll be replacing these, specifically. So, then a torque wrench is an absolutemust?

If it were my car, I would definitely use a torque wrench. If under-torqued, it won't be gas-tight and cause problems. If over-torqued, something terriblemay happen (breaking studs, cracking something, etc...).

In general, a 1/2" drive torque wrench covers most torque ranges you need. I have 2 (both are Snap-on):

1. 1/4" drive, range: 40in-lbs to 200in-lbs (3.3ft lbs to 16.7ft-lbs)
2. 3/8" drive, range: 200in-lbs to 1,000in-lbs (16.7ft-lbs to 83.3ft-lbs).
http://www.onlineconversion.com/torque.htm

The above 2 wrenches covered everything I did on my 850, except the 36mm front wheel hub axle nut which required more than 83.3ft-lbs. When I have saved up a $200, I'll buy the 1/2" drive unit too.

There are a number of mfg's & types for torque wrench, and I suggest that you get one or two, made by awell-known mfg. Snap-on's are ok, I don't like their heads (they're thesame heads as general ratchet handle) and bleak "click". Yes, I would get the "click" type and forget the deflecting-beam type. If you're not too fussy, I would recommend a Craftsman Digitork; this one covers a great range of torque but I didn't like the "click". http://www.craftsman.com/toolsequipment.html

Here's my personal view on torque wrenches:
Deflection-Beam Type: Simple & durable, but not accurate and inconvenient to use.
Micrometer ("click") Type: The most popular type but must be handled with care.
Precision Dial Indicator Type: The most accurate & expensive, used at aircraft manufacturers, turbine (jet) engine servicing shops, etc...

A decent torque wrench costs about $100 to $200. You won't need a fancy one, just make sure that it is of name-brand and is made in the USA. Or, you can rent one at AutoZone for free (their tools are usually made in Taiwan, though).

>I reused the nuts on the end-links. no torque spec., seemed useless. I did not use a torque wrench when fastening the bolt at the control arm when replacing the bushings there.

As for the end-links, I would get the new nuts and replace them. The torque specs should be in a service manual, such as Haynes. As for the control arm bolts, the bolts are reusable (though I replaced mine, as the car had 140,000 miles and was 12 years old) but the nuts should be replaced. When you torque suspension nuts & bolts, it is ideal that you apply 1G of force onto the suspension; you can do this by leaving the car on jack stands and use a floor jack and jack up the suspension for about 2-3 inches at robust points, such as the knuckle. But this may not be necessary, it is only an accepted practice in Japan and I didn't apply 1G when I did my suspensions and did not have a problem.

>I'm actually a stickler for strict maintenance for my Volvo.
Same here!

I hope this is ofsome reference to you.


JPN