simple question

[Randomrunner12]

Hey all,

Is it possible for having added traction bars to cause excess drive line noise within the cab? What Ive notice for the last year or more is what sounds like a mechanical humming noise at any speed that seems to quiet down with the clutch pushed in.

Id like to attribute this to the traction bars that I added now causing noises as there is no rubber bushing between the rear axle and frame allowing all the drive line noises to feed into the frame and basically become a tuning fork. I am thinking that if i dynomat my interior that will help a lot with the sound.

Before everyone starts chiming into replace parts... here is what has been replaced in the last month unrelated to my noise issue and still made no changes.

Truck is a 2wd so the driveshaft u joints and carrier replaced this month, clutch is now a SMF style SSD3250-GK clutch so gear rollover is to be expected and I will be running Amsoil 75w-90 manual trans fluid next month as it'll be due for a change and that can help with roll over as well.

I also have an afe raw rear diff cover and will be running another 5qts of 75w-90 sever gear amsoil as well. not sure if the aluminum is transmitting more noise as well but not likely.

 

[Jim W]

My son uses traction bars on his 2006 truck and does not complain about any driveline noise. He is like me and is tuned into any slightly different sound any of his vehicles would make.

My one question is do you have a one piece drive shaft or a two piece with a carrier bearing?

 

[Randomrunner12]

yeah I'm the same way and my wife doesnt get it. I learned the skill in the Navy working on ARS pods. If something didnt sound normal something wasnt right.

I have the 2pc with Carrier. Ive thought of maybe shimming the carrier down a 1/4" but the truck is factory 2wd right height.

 

[AEdelheit]

I have not noticed any difference in noise or vibration with mine but there alot of different setups out here. Ones with Heim joints could transmit more NVH, if they are too long and set up incorrectly, which most are, putting the suspension in a bind it would likely add more NVH as well.

 

[Randomrunner12]

Pretty sure mine might be too long. They re 72" and the brackets are from axle to frame and stop just shy of the farthest rear part of the front doors. Almost even with the front of the rear doors both sides.

I haven't noticed any real binding but I don't off road and they don't pop ever. I'm thinking it's just extra NVH

 

[AEdelheit]

Thats pretty long, being stock height helps a little since the traction bars are a flatter angle then a lifted truck but will bet there is still some binding going on there as the leafs move.

 

[Randomrunner12]

Yeah I think I'm going to pull them off and see what happens with noise

 

[Randomrunner12]

Alright, so i pulled the bars off. definitely the reason for the added road noise into the Cab. I am going to see if i can find some rubber spacers to use between the hardware. Might have to go down a bolt size as these current bolts are a 28mm socket size and grade 8 gold. They are very hefty bolts.

I am also going to see if i can find someone that sells shackle kits so i can add them on. I connected the makers of theses style and they told me with there setup shackles arent needed but I think you guys might be right that they are maybe binding some.

 

[AEdelheit]

Alright, so i pulled the bars off. definitely the reason for the added road noise into the Cab. I am going to see if i can find some rubber spacers to use between the hardware. Might have to go down a bolt size as these current bolts are a 28mm socket size and grade 8 gold. They are very hefty bolts.

I am also going to see if i can find someone that sells shackle kits so i can add them on. I connected the makers of theses style and they told me with there setup shackles arent needed but I think you guys might be right that they are maybe binding some.

Shackles are worth a try, very few companies have actually done the R&D to make the bind as minimal as possible, there will always be alittle due to the path of how leaf springs move, but that is why I run Patton fab bars. They are the correct length and geometry so even with having 13.5" of rear travel I dont notice any bind and the joints use poly races so no NVH is transmitted but they are expensive.

Be careful with such large bolts, I know someone who had a very similar setup to yours other then his truck saw a lot of hard off road use but it actually ripped the mounts right out of the frame and they were welded in well. I doubt you would have that issue just on road but if there is a bind it will find the weak spot eventually.

 

[Randomrunner12]

Yeah i've looked at those bars and they look like they would work great. I also agree that the hardware for these bars are massive. I am trying to get a picture loaded so you can hopefully see but I am pretty sure they are 3/4" thick at least.

The bars themselves weight 40-50lbs a piece easily.

 

[Randomrunner12]

 

[AEdelheit]

Ya there big!

 

[Randomrunner12]

What im debating is the following....

1. Go to my local Elliot's and try to find bushings and go with a half size smaller on the bolts to eliminate the NVH noises to the cab.
2. Sell the traction bars and save up for something different. Ill need to find another welder at that point.
3. just get rid of them all together?

trying to decide is hard cause when it comes to my truck i can never really make up my mind lol.

 

[AEdelheit]

What im debating is the following....

1. Go to my local Elliot's and try to find bushings and go with a half size smaller on the bolts to eliminate the NVH noises to the cab. - You could also look into a Poly joint like these - https://www.ballisticfabrication.co...bushings/products/forged-poly-bushing-1-75-od

2. Sell the traction bars and save up for something different. Ill need to find another welder at that point. - Probably the best long term solution but not cheap.

3. just get rid of them all together? - Depends if they make a difference, I never had alot of axle wrap or wheel hop but the rear end does feel alot more planted with the traction bars and there is zero wheel hop or axle wrap which is nice.

trying to decide is hard cause when it comes to my truck i can never really make up my mind lol.

 

[Randomrunner12]

oooohhh those arent bad. Run poly joints and not have any preload? That might actually keep the noise down and no binding either.

 

[AEdelheit]

Well there would still be some binding as the geometry is not correct but the Poly will be able to deflect and absorb the bind where the heims arent doing any of that.

 

[Randomrunner12]

oh ok. Thanks.