Easy subframe bushings replacement

[Ameer Antar]

Those bolts are s'posed to be stretch bolts, that's why the directions in the Bentley say to turn to a very low torque and then tighten a certain number of degree's. I'm fairly certain that a regular 8.8 bolt is different from the OE stretch bolts. You really should buy the OE bolts and for now tighten the bolts to the proper torque for their size. I think the normal torque for class 8.8 is like this:
M6 - 7 ft/lbs
M8 - 15 ft/lbs
M10 - 33 ft/lbs
M12 - 66 ft/lbs

not sure about other sizes, but you could look it up in a metric torque chart. I have a chart if you need one.

Also just keep in mind that grade 8.8 is not the same as class 8.8. It's confusing since the numbers are the same, but the term 'class' is for metric only and 'grade' is for SAE only. Class 8.8 is around a grade 5 fastener as someone already mentioned. 

No need for loctite if the shop manual doesn't mention it. I think that's what those stretch bolts are all about. I know they ain't cheap, but I think your safety is worth it. Not that regular bolts are dangerous, but they just weren't designed for that suspension, and you already had problems finding the proper torque. bite the bullet... I think I got 4 of 'em for $12 at the dealer. good luck.

-Ameer

----Original Message----
Date: Wed, 20 Oct 2004 16:26:29 -0400
From: Louis-Alain_Richard at computerhorizons.com
Subject: Easy subframe bushings replacement
To: urq at audifans.com, quattro at audifans.com
Message-ID:
	<OFB203CCFA.E53EAB15-ON85256F33.006D9C23-85256F33.007049E5 at computerhorizons.com>
	
Content-Type: text/plain; charset="US-ASCII"

Hi there,

I just installed the 4 OEM bushings on the rear subframe, and the job was 
even easier than last week's (front subframe).
Why?
Because I followed one listers suggestions: put the rubber bushings in the 
freezer for an hour. Installation was nearly effortless... but I can't say 
if it's more the freezer or because I am now a semi-pro of bushings 
installation (I have done the 16 on my car...)!
Nonetheless, the harder the rubber, the easier it will slip in place, with 
less deformation of the "bulge". 


However, I have some questions regarding the bolts and their torquing.

Since all the subframes bolts must be replaced (per Bentley), and my 
dealer doesn't stock them, I went to my FLAPS and bought some M10X85 
bolts. 

Now, can somebody tell me if these bolts (grade 8.8) are correct for this 
application ? 
What is the difference with the 8.9 grade we more usually see ?
Are the OEM bolts (N 905 569 02) special high strenght bolts ?

For the torquing:
Bentley says torque to 25 ft-lbs and then add a quarter turn more. I did 
just that.
But even after that, I still feel that the bolts are "under torqued"... It 
was real easy to add that quarter turn. More, there is no provision for 
securing the bolts in place (no Loctite, no lock washers, nothing...). 

Am I paranoid ? Should I leave this all alone and don't worry about it 
anymore?

Thanks in advance,

Louis-Alain
1983 Quattro, gliding over bumps now...


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