Solid Body Mount Bushings

[Inv4drZm]

I figure I'll start a preliminary thread on this potential mod. I'm wanting to install solid delrin blocks in place of the soft rubber body mount bushings. I was considering polyurethane bushings, which might be a good compromise between solid and rubber, and energy suspension makes a poly kit for the 3rd gen but not the 4th gens. I can weld in more crossmembers to the frame, shock tower braces, and the like in order to increase chassis rigidity, but I might save that for phase 2.

I think it may solve a couple of my problems:

My 4x4 labs rear bumper is rubbing my body pretty good at a couple different places due to what I assume is body/frame flex and rubber bushing deflection. Increasing my 1.5" body lift will help a little but is more of a bandaid.

Doing some internet research, muscle car guys have reported reduced sway on turns and better overall handling with solid mounts.

What I'm concerned about:

More vibrations/noise transmitted to the body. I have full sound deadening and plan on installing suspension seats.

Body flex. With the solid mounts the body will become more load-bearing and will flex more with the frame. This could lead to cracking of the body around the body mounts. The muscle car guys that swap to solid mounts stay onroad and don't offroad like us.

What is the consensus? Will I shatter all the windows on my truck when I flex out or will it handle like a dream? I have access to a lathe at work and have already bought the delrin rods so I might as well try it at this point.

 

[WhiteBoomer04]

If I was any good at posting video Id show you some footage I took over the weekend using my go-pro on my driver door and also from the roof, while offroading. The amount of movement between the bumper (solid mounted to frame) and the body (OEM bushings) is quite amazing. Some serious flex - maybe 1.5". I would never imaging solid body mounts a viable thing!

 

[Inv4drZm]

If I was any good at posting video Id show you some footage I took over the weekend using my go-pro on my driver door and also from the roof, while offroading. The amount of movement between the bumper (solid mounted to frame) and the body (OEM bushings) is quite amazing. Some serious flex - maybe 1.5". I would never imaging solid body mounts a viable thing!

Maybe I should focus on the frame rigidity aspect first. If I can increase the frame rigidity enough to not have any rear bumper on body rubbing, I can likely get away with using solid body mounts if I wanted to try and decrease body roll.

 

[T4R2014]

I think you will have a lot of metal fatigue issues on the horizon. Bad idea. I already worry that poly mounts will cause it. I can't imagine what delrin could do.

 

[2016 4Runner SR5]

I was going to say the same thing. I see lots of ripped sheet metal in your future not to mention an incredibly still and noisy ride due to transfer into the body. I would not do this if I was you.

 

[fourwd1]

OK, you have a 1.5 in BL. What's it made of ? Hou havs the original rubber mounts as well ? If so, what not just remove them ?
Or go to a 2 in BL, much easier.

 

[Inv4drZm]

OK, you have a 1.5 in BL. What's it made of ? Hou havs the original rubber mounts as well ? If so, what not just remove them ?
Or go to a 2 in BL, much easier.

The BL is UHMW plastic, and is stacked on top of the original rubber mounts. Remove which ones? The solid 'bushings' I wanted to make would replace both the factory rubber and UHMW body lift blocks.

The body is already moving an inch in some places, and I like the fit of the bumpers and sliders how they are now.

I think I'll strengthen the frame first, and if it still rubs, then increase the body lift by 1/4" or so.

I'm just surprised it seems like I'm the only one with rubbing issues with an aftermarket rear bumper when I see other 4x4labs rear bumpers mounted super close to bodies on other rigs.

 

[cloud]

The BL is UHMW plastic, and is stacked on top of the original rubber mounts. Remove which ones? The solid 'bushings' I wanted to make would replace both the factory rubber and UHMW body lift blocks.

The body is already moving an inch in some places, and I like the fit of the bumpers and sliders how they are now.

I think I'll strengthen the frame first, and if it still rubs, then increase the body lift by 1/4" or so.

I'm just surprised it seems like I'm the only one with rubbing issues with an aftermarket rear bumper when I see other 4x4labs rear bumpers mounted super close to bodies on other rigs.

I don't have the rear bumper yet, but I'm extremely interested in the negatives of solid mounts. I think it will cause the body to act similar to sway bars and as others have said, will stress the sheet metal too much.

I'm interested in adding a roll cage to my truck and I wouldn't mind going external to increase the roof rack capacity. So the amount of movement of the body is my main concern.

I would like to mount tubing from my bull bars to my sliders to protect the quarter panels. I need to know how far the body will flex to prevent one from damaging the other.

Sent from my XT1710-02 using Tapatalk

 

[Terminator03]

As others have pointed out there will be way too much flex induced into the sheet metal. What I would suggest if going the solid mount route, would be to first build a “backbone”/full cage to control frame twist. Your options are very limited for what you can do underneath for bracing, since you don’t want to lose valuable clearance, and the cage would add more rigidity anyway. In order to make it most effective though, you will lose some street comfort by having to truss the door openings to tie everything together like a race car chassis. Not sure this is practical for something you still want/need to use for street driving though.

 

[Drunner97]

The BL is UHMW plastic, and is stacked on top of the original rubber mounts. Remove which ones? The solid 'bushings' I wanted to make would replace both the factory rubber and UHMW body lift blocks.

The body is already moving an inch in some places, and I like the fit of the bumpers and sliders how they are now.

I think I'll strengthen the frame first, and if it still rubs, then increase the body lift by 1/4" or so.

I'm just surprised it seems like I'm the only one with rubbing issues with an aftermarket rear bumper when I see other 4x4labs rear bumpers mounted super close to bodies on other rigs.

You're not the only one. Mine is rubbing but I'm still working out fitment issues since it was a one off bumper. I actually dented the corners of my hatch at some point in the last 3 runs. I do need to solid mount (weld) my bumper to the frame though because I have a ton of play in it with the way the mounting legs were designed.

 

[truckhigh]

I've been replacing them with the febest brand and they have been working out great. Its much cheaper then going oem those are the pn# just add febest and there sold on ebay too

 

[nevada]

Maybe I should focus on the frame rigidity aspect first. If I can increase the frame rigidity enough to not have any rear bumper on body rubbing, I can likely get away with using solid body mounts if I wanted to try and decrease body roll.

the frame has been designed to flex. that is all built in. I don't think it would be a good idea to mess with that just to make an aftermarket accessory work.

I would be looking at changing the bumper...

 

[Inv4drZm]

the frame has been designed to flex. that is all built in. I don't think it would be a good idea to mess with that just to make an aftermarket accessory work.

I would be looking at changing the bumper...

In an ideal world the frame wouldn't flex at all, the suspension would be doing all the cushioning.

You're right I could space the bumper down with a 1/4" sheet or two somewhat easily. Maybe one sheet in the back, two on the front to square it up.

So everybody knows what I'm talking about I might as well post some pics:

Slider tube level:​

Slider tube is a little unlevel after painting and reinstalling for some reason​

Yes, the kit had tabs in place to help locate these vertical plates, IMO way too close to the hatch but I should have realized that before I welded it. Spacing it won't help this rub.

 

[nevada]

In an ideal world the frame wouldn't flex at all, the suspension would be doing all the cushioning.

You're right I could space the bumper down with a 1/4" sheet or two somewhat easily. Maybe one sheet in the back, two on the front to square it up.

maybe, I have no idea. I don't design frames, I just know that frame flex is designed in.

I really think adjusting the bumper would be the way to go.

 

[blackoutt]

I've been replacing them with the febest brand and they have been working out great. Its much cheaper then going oem those are the pn# just add febest and there sold on ebay too

I replaced the upper part (part the weight sits on) of my front most two body mounts with febest when installed the body lift to replace the compressed stock ones. About a year later I noticed one of the febest mounts had split at the parting line. I replaced it back with OEM. The other side febest mount is still fine so maybe fluke but just a watch out.

 

[duffdog]

The problem is just the rear bumper design. Every other company who builds these things knows that you are supposed to have 1" clearance from any sheetmetal part on the truck on all sides. That would be the front, rear, doors, sliders, grille, everything.

If the bumper had been correctly designed to begin with you would not have even made this post at all...

Now were talking about modifying the structural integrity of the FRAME to stop this weird bumper from breaking your truck? Or worse yet, changing the mounts on the body to make them inflexible, which might be fatal in an accident when they all break simultaneously? No thanks...

 

[Inv4drZm]

The problem is just the rear bumper design. Every other company who builds these things knows that you are supposed to have 1" clearance from any sheetmetal part on the truck on all sides. That would be the front, rear, doors, sliders, grille, everything.

If the bumper had been correctly designed to begin with you would not have even made this post at all...

Now were talking about modifying the structural integrity of the FRAME to stop this weird bumper from breaking your truck? Or worse yet, changing the mounts on the body to make them inflexible, which might be fatal in an accident when they all break simultaneously? No thanks...

If you look at online pics, the majority of rear bumpers on our trucks are mounted very close to the body, along the sides anyway.

Increasing the structural integrity of the frame.

Like I have said I can space the bumper down relatively easy, or increase the body lift 1/4" a little less easily. But if I can reduce frame flex/bushing flex without issue that would be the ideal fix.

 

[truckhigh]

I replaced the upper part (part the weight sits on) of my front most two body mounts with febest when installed the body lift to replace the compressed stock ones. About a year later I noticed one of the febest mounts had split at the parting line. I replaced it back with OEM. The other side febest mount is still fine so maybe fluke but just a watch out.

I pretty much did the same thing I related the lower one cause i got lazy doing the BMC mod. So i replaced just the lower one cause i scorched it a little. i noticed it wasn't even contacting the frame cause the upper was to compressed. i think because the spindle between them doesn't let you really torque them down. I replaced all of them and a lot of my squeaks went away and body roll. these trucks are over 10 years old. the febest is a lot stiffer then the oem ones.

 

[duffdog]

If you look at online pics, the majority of rear bumpers on our trucks are mounted very close to the body, along the sides anyway.

Increasing the structural integrity of the frame.

Like I have said I can space the bumper down relatively easy, or increase the body lift 1/4" a little less easily. But if I can reduce frame flex/bushing flex without issue that would be the ideal fix.

Yes, you are right. I disagree with the design of all of the commercially available rear bumpers, far too much "barn door" engineering for me. Which is why I had a shop custom make my rear bumper to my specifications. Not only is it stronger and lighter than the commercially available units, but it has a hidden winch mount and has survived a 70mph rear end accident with no damage to it. FWIW, I had the frame rails braced on the inside with 3/8" plate and then connected together (where the factory rear frame crossbrace goes) with 4"x4" .250 wall steel to resist flexing.

You seem to be on the right track, but it might be really hard to brace the frame after the fact.

 

[NinjaOne]

RE: solid bushings

Came across a thread yesterday about cracked fenders as a result of stiffer body mounts. Largely on the 120 platform overseas where there was for a limited time stiffer body mount bushings available. I think those were discontinued? So potentially reinforcing the body in combination with the stiffer body mount material. Think I saw it on Toyota120

After your reduce your frame flex