RSAErick

My worst fears have been realized:

It was while tightening one of the 4 top nuts to the threaded posts of a USED coil over unit. Using a torque wrench set to exactly 27 ft-lb, the post snapped off while tightening the nut! H&R specifies 27 ft-lbs.

Note: this is not a bolt that can simply be removed and replaced. The threaded post is attached to the top of the coil over unit!

So now what?!?!

My initial feeling is that this is a product defect that H&R should be responsible for replacing, but I may be overreacting. I can't believe that these posts would be so weak considering the consequences if they break!

Any advice on what I should do? Can someone replace a post like this? Should I ask H&R to do the post-replacement?

FYI, I decided to continue with the other side coil over install. Would you believe that one of the posts stripped during the same process?!?! What is going on here? My torque setting are exactly what H&R specifies! This makes the coil overs impossible to install correctly. What is someone supposed to do?

Thanks for any advice...

Erick

Kevin

Erick;

I just checked the manual and spec are 24ft lbs. Aren't the bolts pressed in from the backside of the plate? Have H&R send you new ones. Bolts stretch and maybe they have been cycled to many times and need to be replaced.

914und993

The other thing to consider is your torque wrench's calibration - it may be well off what it reads. Even new ones can be innaccurate.

It should not be hard to find someone in your area who checks and calibrates torque wrenches. It isn't expensive, and considering what has happened to you it would be cheap insurance!

Chip

Adrian

Dear Erick,
You will never get warranty on used units. You will need to get the unit repaired. Pkus as recommended get your torque wrench calibrated.
Just for info the Porsche/boge upper strut mount torque is 17 ft lbs according to the workshop manual. I cannot imagine why H&R would say 27 ft lbs.
Ciao,
Adrian
911C4

Cupcar

Call H&R's importer in Washington state, they can sell you new studs. They press out easily you can press a new one in, it's no big deal. I used a hydraulic press but you might get away with a big vise as a press. Adrian has a good point it should be 17 lb-ft for an 8 mm stud.

I would replace all of them if I were you, they have probably been abused. <img border="0" alt="[typing]" title="" src="graemlins/yltype.gif" /> <img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />

Kevin

Erick

In section 40-02 the 964 manual list 17ft-lbs for the 8mm stock fastner, however, in the RS specs listed for the M 8 fastner it is printed as 33Nm with 24 ft-lbs. I would have to assume that you are using the H&R coil over setup with mono-blocks... If you are not using mono-blocks but the stock rubber mount, refer to Adrian's post.

Cupcar

I used 24 lb-ft on my monobal front RS mounts ala factory spec.....and stripped one. My first experience with pressing studs out. <img border="0" alt="[typing]" title="" src="graemlins/yltype.gif" />

Adrian

Dear Kevin,
I did not see any reference in the original post to the RS monoball system. Now this is possible but one has to assume it was not mentioned for a reason. This is why I often ask for accuracy in posts because we are often called to assume. At least with 17 ft lbs you can torque it up in segments. Over torque is much harder to undo the damage.
Maybe Erick can explain exactly the system he is installing.
One tip when torquing is to do it in stages. Finger tight, then a pre-torque (approx 50%) then a final torque to the correct amount. One also has to make sure the threads are dry. Wet torquing or greasing threads before torquing requires a conversion factor downwards. One should also use new nuts when a torque is required. This helps avoids stripping them.
Ciao,
Adrian
911C4

RSAErick

Okay gang, thanks for making me realize that this isn't the end of the world.

For clarification, these are the matched H&R coil overs with the stock rubber mounts. The 27 ft-lb specification that I used came from Jeff Curtis' write-up in <a href="http://www.porsche964.co.uk/" target="_blank">John's 964 website</a> . If the actual spec is 24 ft-lbs, then I'm still disappointed to find that 27 ft-lbs stripped one stud and broke another! <img border="0" alt="[grrrrrrr]" title="" src="graemlins/cussing.gif" /> Unless my torque wrench is seriously out of calibration.

Well, I've pulled the front coil overs and will press the threaded studs out. Hopefully I can find some higher quality threaded studs to press back in there. I'll call H&R, but does anyone have any recommendations for grade of stud? Fortunately, a friend has a press, and familiarity with this process.

Thanks for the help.
Erick

Cupcar

Just to clarify, the studs I referred to in my post above are the ones that press into the H&R monobal mounts made of billet alloy or the stock cast alloy European RS monobal mounts. The studs will press out of these and H&R can supply the stud for their mount. I had to get the 8mm X 24mm press in stud from the racing parts program (part # 999.080.021.09) for the RS mount,as it is not a normal dealer item.

If you have the stock rubber mounts made of pressed steel, then I have no experience. Sorry for the confusion, I thought you had the H&R made stuff. <img border="0" alt="[ouch]" title="" src="graemlins/c.gif" />

Adrian

Dear Erick,
The workshop manual says 17 ft lbs for stock mounts,
Ciao,
Adrian
911C4

Jeff Curtis

Erik, like others have stated...no big deal on the stud replacement, and I do concur that there has apparently been some abuse with overtightening of the studs prior to your ownership.

I'm assuming that the hats (the part that the studs are pressed into) came with the Bilstein shocks?? If not, then they are YOUR originals??

Either way, I'm sure they are good 'ol factory springs hats for a C2...in that case, the 17lb torque factor is what you use.

Also, just to add my two cents, there would be virtually NO difference between 24 and 27lbs when torquing!!

...not enough to warrant damage to the studs anyway.

Press your new studs in, and go with the 17lb torque setting, I may have made an error in my procedure on John's site...I'll check it out. <img border="0" title="" alt="[Eek!]" src="eek.gif" />

Good luck on your new install...I told you that there was NO way you could wait!!

Cupcar

I just got out my manuals to check the shock top hat mounting torques for the rear of a 964.

The 8mm fronts studs are 17 pound-feet but don't make my mistake and misread manual and do 23 pound-feet as this number is for is NEWTON-METERS!! I stripped one at 23 lbs-ft, so a few pound feet hurt in my inept case. <img border="0" alt="[ouch]" title="" src="graemlins/c.gif" />

The rear mount was modified for MY'91 and on the rear, for 1991 and later, the torque is 27 pound-feet(pre-1991 car is 15 pound-feet).

When using 27 pound-feet you MUST use special nuts which are shouldered locking nuts (I replace them with new). Due to the locking design, these nuts have increased internal friction, hence a higher torque is safe. The nuts are part # 900.380.006.02 and they must be used with a special 3.1mm thick washer 999.025.125.02 <img border="0" alt="[typing]" title="" src="graemlins/yltype.gif" />

RSAErick

Adrian and Jeff, yes, they are stock rubber "hats" that came with these coil overs. I'll use 17 lb-ft when I re-install. I'm still disappointed that 27 lb-ft resulted in a stripped and broken stud, though!

Cupcar,
Thanks for the input. I was hoping on getting some better/stronger threaded studs from somewhere. Would the monoball studs possibly press into the stock hats?

Jeff,
You were right. My enthusiasm for track driving has forced me to spend money that I have no right spending. Understand that this setup is a compromise street/track setup. With unlimited resources, this would be a devoted racecar.

RSAErick

It looks like Porsche does NOT sell the treaded studs separately for the stock top bearing/hat. The dealership suggested I remove one of them and take it to a local fastener/screw company for matching. Is this recommended?

If anyone knows of a place to source these, I would appreciate your input. Also, does anyone know the specifications for this threaded stud?

Thanks much.
Erick