Trailing Arm bolt sizes

[95GS]

One trailing arm bolt is giving stubborn resistance. I've read the threads.

If it takes a cut-off, I'll need a new bolt. 

Are these bolts 12mm & 16mm diameter?

I took a new Dorman trailing arm to the hardware store.

12mm is a little loose, a little wiggle room.

Checked with the old arm & original bolt - also a little wiggle.

 

Is that right?

Didn't think there would be any noticeable tolerance between bolt and bushing sleeve.

Wouldn't that introduce minute slop into the suspension, and worse yet, excess wear?

[Imp558]

You also need a bolt the correct hardness.

[95GS]

Thanks for that Imp. It's the correct diameter that had me concerned.

[Imp558]

If you can see any markings on the head of it they will tell you hardness. As for size, I'd cut the old one out and use that as a sample. Alternatively you could clean the threads a bunch and use lots of penetrating oil and try to save the existing bolt for re-use. I'm a fan of your plan to replace it though.

[RobertISaar]

a little loose isn't going to be a tire killer.... if we're talking a millimeter or two, bushings alone can be that far off-center and it would never be noticed.

[95GS]

If you can see any markings on the head of it they will tell you hardness. As for size, I'd cut the old one out and use that as a sample. Alternatively you could clean the threads a bunch and use lots of penetrating oil and try to save the existing bolt for re-use. I'm a fan of your plan to replace it though.

Thanks Imp.

The originals are 10.9 - I found new replacements, same hardness, thread & diameter (12 mm). Nuts are interchangeable.

I'll cut out the stubborn one tomorrow.

Fortunately the trailing arm mounting platforms on the body seem to be in reasonable condition. 

Though rusty, they are not frail, just greasy.

When I bought the car in 2009, a mechanic told me this was a known weak spot. He had welded in new mounts on another W-body.

Since then I've been spraying them with oil several times a year.

[95GS]

a little loose isn't going to be a tire killer.... if we're talking a millimeter or two, bushings alone can be that far off-center and it would never be noticed.

Thanks Robert, you're right. I'm not rebuilding the Space Shuttle.

[Imp558]

95GS, do you remember what the length of the bolts was? I'm going to get the bolts for both sides of mine before I tear into anything as a pre-emptive strike. (10.9 hardness, 12mm X ? Length.)

[95GS]

95GS, do you remember what the length of the bolts was? I'm going to get the bolts for both sides of mine before I tear into anything as a pre-emptive strike. (10.9 hardness, 12mm X ? Length.)

 

Imp, just noticed your question. I can check the new bolt boxes in a couple of days (they're not here).

But I have a surviving bolt from one forward (body) mount.

10.9, 12mm. The bolt shaft length is 3 - 3/8", overall bolt length including head is 3 - 13/16".

(I can't remember if the new ones were sold as 3.5 or 4 inches)

 

I wrapped some teflon tape on mine to discourage a rust bond with the bushing inserts.

& LPS-3 in the bushing.