Cracked sheet metal above radiator body bushings

Its truck doing truck things. You ever seen a Unimog or Zetros offroading? Those almost have life-like organic movement.

 

The bushings do move a ton... and think about the cantilevered effect between the front cab and the radiator core, where movement between the front to rear cab bushings is amplified on how much the radiator needs to move in order for metal to not absorb the flexing. That is what I've been saying all along. People with poly bushings are for sure forcing more flex to happen in the sheet metal, and one could argue many other issues with comfort and durability.

 

Now I'm going to have to go down a strange rabbit hole of youtube videos...

 

radiator mounts seem almost equidistant from aft cab as well, given the engine bay isn’t a fully enclosed shape/construction like the cab is im sure the radiator support and related structures are subject to more stress.

 

agreed. Cab is a very solid enclosed box with much less flex, when it moves, it can impart a lot of force and movement up by the radiator, that all has to be absorbed somewhere. Either bushings, or the metal. Flexing metal is work hardening itself, like bending a paper clip a bunch of times, eventually the point of bending gets hard and cracks instead of continually flexing like a spring.

 

My kidneys hurt thinking about those factory bumpstops smashing into the frame.

 

Installed new OEM bushings and patched up the cracks with some 22ga sheet metal. I used 3M DP420 epoxy to adhere the patches instead of welding given what I’ve read about other people’s luck with welding on that. Those are epoxy drips by the way, my quick spray paint job isn’t THAT bad

I also took a closer look at those body mount bushings. There is a lot more engineering than I had considered before. It seems they are specifically tuned for a certain amount of compliance given the different diameters, asymmetric lengths, and different durometer materials.

 

Do you have the part number for oem bushings

 

Yeah here you go: https://www.tacomaworld.com/threads...or-body-bushings.636828/page-17#post-27838354

 

Thanks now to find them on the web

 

https://parts.toyota.com/

 

Anyone here with an Access cab? I feel like it may be subject to less cantilever forces.

 

https://www.tacomaworld.com/threads/so-you-push-your-1st-gen-offroad-what-cracks-next.631359/

1st gen crackin’ thread if anyones interested

 

I'm confused. There is no cantilever / overhang here. The forward and rear mounts are at the extents of the cab. For the AC and DC, the distance between the front and middle mounts is the same.

The distance between the middle and rear is more, but the DC also has an actual B pillar that the AC does not.

 

Just feel like AC’s would see less movement in general in addition to less weight. I also haven’t seen any in these discussions. Not to say correlation is causation though, just curious.

 

Seeing how much the suspension uncompressed when I jacked half the cab up to swap the mounts was pretty telling. I think the difference is only about 200lb with all of that in the back of the cab.

I'm not saying that you are in left field, but I just don't see a connection at the moment.

 

Wanted to add my experience with poly mounts. I bought the energy second gen full body mount kit for the core support bushings (think they have a 3G kit now, but they didn't then). I had no core support tears at that time, but I had gone through 2 sets of rubber bushings. I have a 24f AGM in the stock location, CBI hidden winch mount with a Warm 9.5XP-S, and 6112's at about 1" of lift with super bumps. 265/75R16 tires.

I just had did 6500 miles in a month, a lot on dirt roads, fire roads, and forest service roads out west, and was really pushing the suspension at speeds up to 70 on long dirt roads with good lines of sight, and 30-40 on forest service roads. I guestimate my curb weight to be around 5600. I still don't have any cracks.

Understanding that stock trucks are getting tears, maybe the following are some mitigating factors?

-Correct (non-universal) bushings. I have read they may be a different hardness (softer) then the universal ones. They appear to be the correct thickness as well, where the universals are not.

-Hudden winch mount. It mounts very securely with plates that run down the sides of the frame rails, better then a few full bumpers I have seen, and as good as the best bumpers I have seen. Maybe it provides a reduction in twisting between the front of the frame rails without significant weight.

-Suspension. The 6112's and super bumps provide a pretty cushy bottom out. The super bumps are probably 4x taller then stock bump stops and are involved in the compression cycle much more progressively.

It seems like no one knows for sure what is causing tears in the core supports, but I wanted to throw my experience out there for consideration.

Edit to add-i would not say I "wheel hard," I'm not putting a tire in the air very often. I did mosquito pass in CO and that was probably the most difficult trail I have done. I don't like the very slow stuff much. I guess my truck doesn't see the full length twisting forces of that kind of driving very often, but it gets hit hard at speed.

 

Nope, even with an access cab it will still end up tearing.

 

I think that's just a result of the "rarity" of AC's and the common place of DC's.

 

the frames flex a lot on these trucks so imagine the cab mounts need enough give to compensate for the flex. if you put stiffer bushings in, then those forces are going to the weakest link which is the sheet metal.