tightening torques on front suspension assemblies

[michel geny]

in the owners workshop manual I found torque wrench settings for rear axle bolts but nothing for front supsension fixations
I will change ball joints and all rubber parts on front suspension and I would be secured to find the tightening torques of all fixations
Can anybody help me to find this ?

Michel

[abowie]

There aren't really any torque values in the Manual.

In this situation your best bet is to go to a generic torque table for the specific bolt (grade 5 5/16" UNF for the ball joints, for example) and tighten it to that spec.

[Series1 Stu]

Most quoted figures are for clean (new) joints. You need to make allowance for things such as rust. Preferably, don't lubricate the joint before assembly but if you do then you need to reduce the torque applied quite significantly. Sometimes by as much as 40%.

Regards

[michel geny]

hello

thanks a lot for quick reply
14 ft-lbs is 18.4 Nm (I weigh 11 stones )
Seems to be a low value for a joint ball nut
Modern cars are tightened with higher values :



Here for this example : 42Nm

I should put exactly Jaguar's original specs

[rfs1957]

Some grasp of the physics is necessary to keep this reasoning on the rails.

You need to take into account the diameter of the bolt AND also the PITCH.

Your example of a lower ball joint with a single nut will more likely correspond to 7/16” or 1/2” (circa 11 ou 12mm) which in Andrew’s table require respectively about 3 times and 5 times the torque of his 5/16 bolt, comfortably exceeding your 42 Nm.

The title PLATED refers to a “plaquage” in French, such as cadmium or zinc plating, and these are “greasy”metals which effectively lubricate the ramp, which is why the torque figures are shown as lower in this context.

Interestingly, this is why stainless bolts are dangerous because the galling that occurs between male and female threads makes for highly unpredictable effective stretch of the fastener.

I never use stainless nut/bolt combinations in any context where they really need to be tight, irrespective of whether they are particularly load-bearing, and even then I always assemble them greased.

They work best, on our cars, I find, when ONE of the components is NOT stainless - stainless nuts seem to work fine, and predictably, when used with (greased) zinc plated bolts, for example.

Having been an avid stainless devotee in my earlier years, I now think they are highly overrated as fasteners, and need to be used with great care.

[Series1 Stu]

Clearly, this isn't an E Type suspension assembly.

What Rory has said is correct, you really need to know the thread diameter, pitch and strength grade before you can decide on the torque to use. In the case of a ball joint, you are unlikely to be able to find out the material and temper used in it's manufacture so you would be guessing. It may be possible to find the factory spec for another application of a similar ball joint and use those figures. Alternatively, find the manufacturer of the ball joint and see whether they quote torque figures.

Regards

[michel geny]

thanks a lot everybody for your advices (I am new in this forum and I appreciate very much your enthousiasm)

working for a car manufacturer in Product Planning dpt I am used to have very precise specs for car assemblies

I checked the diameters of ball joints I received from Barratt and for track road end the diameter is 12.7mm (1/2 inches). Torque will be 64ft-lbs because of plating (86,4 Nm) that seems to be close to values I am used to