A couple of questions on subframe mounts

Post by **amblerman** » 01 Jun 2018, 07:18

Hi Folks,

I'm preparing to replace my subframe mounts as part of a subframe swap on my 1999 s70 and I have a couple of questions.

I got access to the official instructions and two things came up that confused me.

1) One of the mounts is apparently unique. According to the instructions one of the mounts has a oval mounting hole.
According to the instructions it say "The hole in the center of the bushing is oval. The oval must be positioned lengthways to the car, as illustrated."
However, I've also read in posts that people have used identical round hole mounts in all 4 positions.
Does anyone know what the current story is with respect to what mounts to use? I have seen some pictures of the unique oval mount but they seem more difficult to find on different parts sites.

Also, if I do use an oval holed mount, what does "... must be positioned lengthways to the car..." mean?
I believe it mean the long axis of the oval is orientated front to back. The picture in the instructions isn't all that helpful.

2) With respect to the subframe mount bolts the official instructions say "Install the four screws in the sub-frame together with the sub-frame brackets. Use new screws . Lubricate the screws" (empahsis mine)

The instructions do not say what to lubricate the screws with. I also know the new mount screws come with loctite on them and than with respect to applying the proper torque, I thought lubrication was a no-no.

Does anyone have any suggestions on what to do with the "lubricate the screws" part of the instructions?

Thanks
Andy

Post by **amblerman** » 01 Jun 2018, 07:50

I think I have answered my own question.

I believe Volvo did away with the oval design and I can use 4 round hole subframe mounts.

Andy

Post by **oragex** » 01 Jun 2018, 07:54

In all situations, never use oil/grease on any bolts that I remember. Smallest amount of grease on the threads (even just a smear from a hand that has some grease on it) will reduce the 'torque' force to the point of stretching and even breaking the bolt when tightening it down - it will feel like the bolt never gets 'tight'

It's the friction at the thread surface that creates the 'tight' feeling of a bolt. Grease on the threads will reduce the friction coefficient by a factor as grease is specifically a lubricant.

Post by **amblerman** » 01 Jun 2018, 09:07

Thanks.. that's what I thought as well. I was surprised to see "Lubricate the screws" in the official Volvo instructions.

-A

Post by **FLXC90** » 01 Jun 2018, 14:33

you may consider a dab of anti-seize on the shanks of the bolts to prevent them galling in the sleeve of the bushing. Applied just off of the threads, so that inserting them smears it "up" the bolt.