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A tip for XJ owners and others

Last week I had a thumping noise coming from under my 88 XJ and thought the weird (and expensive ... if you can find one) transmission mount for the BA10/5 transmission had finally bit the dust.

Rather, I found the metric crossmember-to-unibody bolts for the driver's side were stripped! Some idiot that shouldn't be on the same planet as tools had overtightened them at some point (impact wrench????) before I bought the vehicle and a chuckhole caused them to loosen a bit, making the noise everytime I applied my brakes.

A few minutes with a jack, drill bit, 13/32", drill, 7/16-20 tap 7/16-20 X 1

1/2" machine screw (Grade 5), 7/16" lock and flat washers and I had it fixed. I was able to give the new bolts full torque (55 ft/lb dry, 40 ft/lb oiled) and now that side is stronger than the passenger side.

Judging from the ease of tapping, the metal used for the hidden nuts is fairly soft, so anything over grade 5 is a waste of money.

The other side will have to wait till spring.

Reply to
Budd Cochran
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Question: how the heck did you keep the captive nuts from spinning as you tapped them? I finally had to tack weld the crimp on mine to get them tapped but that a tad drastic if there is another way....

Reply to
Will Honea

I really don't know why they didn't spin, but I used WD-40 to lube the tap and flush the chips. Normally I use either congealed bacon drippings or sulphated cutting oil.

I only cut a quarter turn at a time, backed out enough to snap the chips loose and then went again ... very slow and careful. No hard twisting, nice and easy.

Every full turn or turn and a half, I backed out enough to break chips then I shot the WD in to flush and re-lube things.

On my XJ there's no, zero, nada, access to the captive nuts (frame welded to body) so I couldn't have even welded them if they had spun and that's why I went so slow. Plus I didn't want to drop the crossmember if I didn't have to, so I drilled and tapped right up through it.

Looking back, I understated the time required ... I was laying on a cold driveway for an hour at least.

My apologies on that.

And you can go 1/32" bigger on the drill if you have to and not lose much thread strength. That will make tapping easier also.

Reply to
Budd Cochran

Translation: I got lucky ;-)

The captive nuts I'm most familiar with are the ones with a small section that fits thru the frame with the end of the thru-section rolled over to crimp the whole mess. I usually tack weld the exposed rolled part but the one I remember best was the one that simply pushed back into the frame - old Jeeps and rust have this affinity... Anyway, the was a larger hole fairly near to the spot where the thing popped out so I was able to fish a nut over the hole and get a long bolt started into it. That held it long enough to weld the nut to the side of the hole but it was a fight.

Another trick with a turning nut I was shown was to thread a stud into it then use a thin halfnut to cinch it down while I worked. Still a PITA on a

22 year old vehicle!
Reply to
Will Honea

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