Are rear upper shock mount bolts a weak link?

[oilbrnr]

Back in January I put in some new Dobinsons MMR’s on Sexy Lexey, re-using the original four upper fasteners, which appeared fine. Torqued to spec 37fl/lb.

Now, I do 2.75 miles one way from my house to pavement every day that consists of woops, washes and plenty of washboard here in NE Scottsdale, AZ. So ~5 miles of dirt a day, say 345 days a year = ~1,700 miles. (road condition varies on rainstorms and those of us with tractors to drag the road. So it is generally s***ty.)

Need less to say, the inboard bolt broke the other night coming home over some of the worse washboard. Looks like I’ll be able to extract the bolt with some vise grips and screw it on in and out, but should I use the new OEM bolts or a higher grade? Of course these would mean the next fuse is the captive nut…

I tried searching the topic here and via Google, but didn’t see anything in particular, and I don’t recall seeing this as being a common failure over the years… Is it?

 

[greentruck]

Depending on how often those bolts have been in and out, probably a good idea to replace with OEM. The real issue is the corrosion issue. The bolt itself is adequate. It's the stress of getting it back out when needed that creates issues. Standard recommended practice here is to juice them up for a week or so prior to removal. Folks do get inpatient and you can still get them out, but repeat and reuse enough and BINGO, problems will crop up.

 

[BILT4ME]

Back in January I put in some new Dobinsons MMR’s on Sexy Lexey, re-using the original four upper fasteners, which appeared fine. Torqued to spec 37fl/lb.

Now, I do 2.75 miles one way from my house to pavement every day that consists of woops, washes and plenty of washboard here in NE Scottsdale, AZ. So ~5 miles of dirt a day, say 345 days a year = ~1,700 miles. (road condition varies on rainstorms and those of us with tractors to drag the road. So it is generally s***ty.)

Need less to say, the inboard bolt broke the other night coming home over some of the worse washboard. Looks like I’ll be able to extract the bolt with some vise grips and screw it on in and out, but should I use the new OEM bolts or a higher grade? Of course these would mean the next fuse is the captive nut…

I tried searching the topic here and via Google, but didn’t see anything in particular, and I don’t recall seeing this as being a common failure over the years… Is it?

I agree with @greentruck .

The other thing that comes into play is the PO. Did they install the bolts with an impact wrench and over torque them? The bolts could have been over stressed and cause an early failure particularly when subjected to abuse such as driving with stiffer shocks than designed over washboards at speed.

Replace all the bolts with OEM.

This is the same reason I am replacing all of the wheel studs on my truck. I have 361K miles and they have never been changed. It's a matter of time before failure.

 

[oilbrnr]

I picked up my order of bolts at lunch today from my friendly Lexus parts dude. They are more substantial than I had mentally remembered. Thanks for the input. Agree on the studs.

 

[Mark W]

I tried searching the topic here and via Google, but didn’t see anything in particular, and I don’t recall seeing this as being a common failure over the years… Is it?

No.

Mark...