Poly body mounts. Road noise?

[snowman7]

So I have an 81 2WD CCLB Towpig that I'm about to start converting to 4wd.

I'll be adding 63" duramax rear leaves, but that requires removing the saddle tanks.
I have a 91 3/4 ton burb for parts, so i'll use the burb fuel tank.

To facilitate all this I'm going to start all this off by installing a 1" body lift, and since I'm there, might as well replace the 34 year old body mount bushings.

Everything I can find about poly bushings say they increase road noise. I really don't want that. I'll probably be boxing the frame, so I don't care about flex, they'll be lubed so I'm not worried about squeaking, but I really don't want any additional road noise(that kinda defeats the purpose of body bushings, Does it not?!)

I also don't want to(CAN'T) spend $200+ on a set of rubber bushings from LMC, which is the only place I have actually found them in a kit. Their kit comes with bolts and washers, which I'd just chuck as I'll have longer bolts for the BL. Elsewhere I have found single mounts, for $30 EACH!? 30x8=$240?! When a poly kit can be had for $100 or less???

This rig will be getting a Cummins, and spend the vast majority of the time cruising down the road. My goal is to make it as smooth and quiet as possible doing that.

I've searched quite a bit, but the only discussion I can find is whether or not poly bushings squeak...

Who has before/after data on road noise?

I've also seen some topics about installing the 2010+ Hydraulic cab mounts in older GMT800/400 rigs. And I've seen lists that show body mounts applicable to 81-2000 trucks.... Maybe these Hydraulic mounts are an option? Not cheap, I know, as the mounts are like $50 each, but for a 2010....maybe swipe em from a boneyard truck for less?

 

[454Sub]

Any road noise you may get will pale to the Cummins noise you will be adding. I would bed line the piss out of the floors, and that would quiet it down when combined with carpet or rubber.

 

[bp71k5]

I couldn't tell any difference in road noise after using poly body mounts. It has so many other noises though so I've no idea on actual noise difference.

 

[snowman7]

Any road noise you may get will pale to the Cummins noise you will be adding. I would bed line the piss out of the floors, and that would quiet it down when combined with carpet or rubber.

Yeah, I plan to raptor line the inside of the cab, pretty much everywhere I can, underside of the cab, as well as the entire engine bay. And then use dynamat or something similar on as much of the interior as I can.

I'm just concerned with the poly transmitting more noise/vibration from the frame/suspension than rubber mounts would.

 

[Stomis]

Sometimes I think people are paranoid because they change something and hear "O it can have this negative side effect", except that noise or squeak or click or rattle was always there. Now you're just deliberately listening for it...

 

[454Sub]

I dumped a gallon of bed liner in my truck and just mushed it around. With that and new carpet, I can talk going down the road with open headers pretty well. Vibes were cut down significantly as well, and I have poly mounted everything.

 

[dyeager535]

I'm just concerned with the poly transmitting more noise/vibration from the frame/suspension than rubber mounts would.

I went from rubber to poly on my K5, did not change ANYTHING else about the truck. I didn't grease them, and there is no difference in road noise.

I then went to poly engine and trans mounts, and noticed no downside. I *did* notice that under torque the t-case shifter didn't move around like it used to.

All of those tend to have "horror stories" online about how they were either noisier or induced vibration. I found neither to be true. The truck was loud and rattle-y before and after, IMO that has nothing to do with those components, and everything to do with flimsy frames, solid axles, improper drive line angles, and worn out suspension components.

The trucks are probably less affected by poly body mounts than a k5 because the frame isn't tied to the body the same way. A boxed frame in any case is going to remove some of the work the body mounts are asked to do, which will act to transmit more load to the body when the material is less forgiving, like poly.

I did separate the A pillar weld in the K5, and I can't blame or rule out the poly as being the cause.

 

[snowman7]

Thanks Dyeager! That's the kind of info I was looking for. Maybe I will give poly bushings a try.

 

[prolinews]

Single best thing I have done to mine period! I didn't grease them just bolted them in with the 1" pucks. I have not heard the first squeak.

 

[mckustomfab]

So I have an 81 2WD CCLB Towpig that I'm about to start converting to 4wd.

I'll be adding 63" duramax rear leaves, but that requires removing the saddle tanks.
I have a 91 3/4 ton burb for parts, so i'll use the burb fuel tank.

One small thing on this note, if it is a 40gal tank you will need to relocate the shocks. The passenger side shock will interfere with the tank, I ended up going outboard with my shocks and mounted them both forward facing (similar to a F**d Raptor).

 

[snowman7]

One small thing on this note, if it is a 40gal tank you will need to relocate the shocks. The passenger side shock will interfere with the tank, I ended up going outboard with my shocks and mounted them both forward facing (similar to a F**d Raptor).

Yeah I planned on that. My goal is to relocate both shocks. Outboard of frame, to the rear of the axle. And build traction bars to control any wheelhop/axle wrap.

 

[82355]

If you have any rust issues at all, buy the rubber kit from LMC. Worth every bit of the $200 to get ALL new hardware.

Martin

 

[snowman7]

If you have any rust issues at all, buy the rubber kit from LMC. Worth every bit of the $200 to get ALL new hardware.

Martin

I've considered that. I haven't pulled mine apart yet, but from rolling underneath and looking, the bottom washers don't look too bad. And it's kind of a waste for me on the bolts, as they are charging $4 a piece for some of the bolts, when I won't even use them, and can get longer, better bolts for less than $1 each...

 

[prolinews]

I spent around 200 for the bushings and pucks from ORD and it came with new hardware.

 

[snowman7]

So, went ahead and bought a set of Energy Suspension 3.4121G Body Cab Mounts off ebay. $73 bucks shipped. As well as a set of 2" poly lift blocks for $50. Buying aluminum pucks from anywhere was going to be at least $70 for 1" pucks. I'll probably put these in and see how it looks/feels and then I can cut them down later. I'll pull a body bolt out and just go to the hardware store and get longer bolts there. Also snagged a windstar fan for $25 off craigslist here. I'll work on that the next couple days before the body mount stuff gets here.

Still need to run down to the scrap yard and see if I can buy scraps. Try to find some 1"(or2) X 2/3/4" tubing to cut for spacers for the bed.

Hopefully I can get all that done in the next week or two, before I go get my donor suburban and really get this project rolling.

 

[bp71k5]

Careful if you buy bolts from a hardware store as they are usually grade 2 at best. The bolts on a pre-72 are grade 5 but not sure if the later models used the same or not.

 

[snowman7]

Careful if you buy bolts from a hardware store as they are usually grade 2 at best. The bolts on a pre-72 are grade 5 but not sure if the later models used the same or not.

By hardware store I meant Fastenal. If Gr 8's aren't much more expensive I'll look for those.

 

[bp71k5]

By hardware store I meant Fastenal. If Gr 8's aren't much more expensive I'll look for those.

It's the carriage bolt style that's hard to find high grade bolts. If you change to regular bolts, it's not an issue, except holding the bolts while you tighten the nut underneath.

 

[snowman7]

It's the carriage bolt style that's hard to find high grade bolts. If you change to regular bolts, it's not an issue, except holding the bolts while you tighten the nut underneath.

Yeah, I may end up trying to weld the bolt, or nut to the bed to make it easier. But the BL should give a little more room to get a wrench in there also.

Also, the BL pucks got here yesterday...2" seems outrageously huge...I'm pretty much already decided to cut them in half. I'll have to make up a jig for my miter saw to cut them down without cutting my fingers off...

 

[snowman7]

Poly bushings got here today...WOW they are hard, compared to the rubber ones.... Starting to rethink this poly stuff. I've got family stuff to do this afternoon, but hopefully I can get them put in tonight.