Bolt on VS weldon shock tower

[cumminscruiser]

I'm at the point where I could either weld on or bolt on the front shock towers. Any input would be helpful. Its a sprung over toyota landcruiser.

[2008F450]

Weld them. Bolts always come loose.

[R_Lefebvre]

Unless they're tightened properly with quality hardware.

[ujoint]

Always bolt on unless you have no choice. A lot of people weld on because it's less work. Welding works in some cases, but I always try to bolt on.

If the part ever needs to be replaced, it's much easier to fix if it's bolt on.

[DenCo40]

Technically speaking mechanical fastening is your best bet. Thats why manufactures usually rivet high stress areas such as shock mounts, frames and the like. Welding if done properly is a close second. Welds have severals downfalls such as corrosion and fatigue.
How do I know this you ask? I spent too many years working on military and civilian aircraft. There are very few if any welds on them for this very reason. Instead they are riveted and fastened by all types of fasteners according to the stresses and the areas of the aircraft in which they are installed.
For trucks and cars welding is okay IF it's a good weld!

[truck mechanic]

I am getting to that same point with my IH pick up with a chevy front end converion.
I am bolting with a backing plate and grade 8 hardware.
Paul

[ntsqd]

There are a couple things that are required, IMHO, to make a bolt-on work correctly. Note that most (but not all) that are not welded on by the OE are riveted rather than bolted.

Rivets work slightly different than bolts. The action of swaging the end also causes the rivet body to expand and completely fill the hole. That's not something that a bolt can do. The best that a bolt can do is to precisely fit the hole. To do that the hole must be reamed to size and not just drilled.

Then there is the properly sized and installed requirement. To me that means using a bolt with a shoulder that is long enough to fit most of the way through the washer under the nut, using a prevailing torque, all metal lock-nut and two hardened, heavy flat washers positioned with their rounded faces against the frame and bracket. Then each bolt should be torqued to it's correct torque value. If I'm feeling excessively anal-retentive about the install I'll also put Lock-tite 271 or 620 on the bolt threads.

If the frame is a box section frame then it will also need to be sleeved for the bolts to pass completely through the frame. Which can be a can of worms by itself. The simplest way that I've found to do this is to drill one side larger than the other. Unibits are a godsend for this work. The small hole is a clearance hole for the bolt used. The large hole is the OD of the sleeve, and I make the sleeve the width of the frame rail. Which means that it stands slightly proud at the large hole side, where I can weld it in place. I choose an OD that clears the flats of the nut, say roughly the OD of the socket used on that nut and ream the ID to the bolt size. In this case only one flat washer is needed.

For the new upper damper mounts on the front of my FJ60 I am welding them on after first welding on a similar thickness doubler plate that has appropriately placed rosette holes in it. I am putting on the doublers because in using the F-250 towers there is no way to avoid a vertical, straight weld bead on the side of the frame rail. So I'm moving that bead to the doubler and have shaped the doubler to not have any straight up/down weld beads.