Chasing that "frt end clunk"

[Eyespyautomotive]

Sway bar and links are brand new. When I put my rebuilt shocks back in with brand new bushings, there was basically zero clearance between the lower control arm and the shock bushing on the sides, there was no room to put anything else in there. I checked because someone else mentioned a shim and i was going to do it if i could.

I totally understand what you're saying about the clearance, that's why I was paying attention to it when I took it apart to do my shocks.

I might revisit this after checking some other things, but I really don't think that the bottom bushing is loose at 420 lb/ft on the bottom bolt. On mine anyway.

I would love to see someone torque the lower bolt in a removed LCA with no shock and take before and after measurements of the lower eyelet area to see if the LCA compresses or not. Anyone have a spare LCA to try this?

And yes, definitely gets worse in cold weather.

 

[Eyespyautomotive]

I tried something last night and had some success.

I revisited the lower shock bolt (same side as prior post of shock eyelet with no clearance) and when I removed the nut I could see how all the bolt to hole tolerance was pushed down (because of shock pressure) with a big gap above the bolt in the hole. What this does is make the shock sit lower in the LCA pocket and closer to bumping the LCA. So what I did was use a small jack and a socket to push up on the shock bottom (with it loose) to push all the tolerances back up and then I tightened up the lower nut. Watching closely when i released the jack, the shock stayed up, this kind of proves the LCA can compress and hold the shock.

I did both sides.

Taking the truck for a ride I noticed a much quieter front end and a more "soft" feeling ride, like a new truck would feel. Driving to work today hitting all the same roads i do every day, i can say it is way better, much better. tolerable.

So today I cut sections in CAD of the Raptor LCA and lower shock mount as designed to investigate, it shows 5-6mm of clearance around the lower eyelet, as I suspected it should have. I have nowhere near that on either side, It almost touches, and i have new bushings. I firmly believe due to part tolerances there is not enough clearance to the LCA below the shock eyelet. Add some bushing wear and push it all down and you get a knock between the shock bottom and the LCA when the bushing flexes.

The lower bolt tightening procedure kind of makes this happen. It says to tighten it with the truck on the ground, under pressure. My thought is to do the opposite. Tighten it in the full extended unsprung position so the shock is in its design location.

So when I get a free day, I plan to pull the shocks back out and go after the LCA pocket with a die grinder to buy some room below the shock to hopefully alleviate the problem for good. I also believe a fully shanked bolt like forged sells would keep the shock more correctly positioned. And I would bet the spherical lower bushing would eliminate all movement maybe solving the problem.

Something else to consider, in manufacturing, parts tend to change over their lifespan due to wear on dies, and molds and equipment. maybe these later parts are not to spec as good as earlier ones? because i can tell my lowers look sloppily molded and do not look like the CAD data shows. Add all this up and your 5mm design gap goes away.

 

[BenBB]

Nice, I'll have a look at mine when I rotate tires this weekend.

 

[stewwalker]

I tried something last night and had some success.

I revisited the lower shock bolt (same side as prior post of shock eyelet with no clearance) and when I removed the nut I could see how all the bolt to hole tolerance was pushed down (because of shock pressure) with a big gap above the bolt in the hole. What this does is make the shock sit lower in the LCA pocket and closer to bumping the LCA. So what I did was use a small jack and a socket to push up on the shock bottom (with it loose) to push all the tolerances back up and then I tightened up the lower nut. Watching closely when i released the jack, the shock stayed up, this kind of proves the LCA can compress and hold the shock.

I did both sides.

Taking the truck for a ride I noticed a much quieter front end and a more "soft" feeling ride, like a new truck would feel. Driving to work today hitting all the same roads i do every day, i can say it is way better, much better. tolerable.

So today I cut sections in CAD of the Raptor LCA and lower shock mount as designed to investigate, it shows 5-6mm of clearance around the lower eyelet, as I suspected it should have. I have nowhere near that on either side, It almost touches, and i have new bushings. I firmly believe due to part tolerances there is not enough clearance to the LCA below the shock eyelet. Add some bushing wear and push it all down and you get a knock between the shock bottom and the LCA when the bushing flexes.

The lower bolt tightening procedure kind of makes this happen. It says to tighten it with the truck on the ground, under pressure. My thought is to do the opposite. Tighten it in the full extended unsprung position so the shock is in its design location.

So when I get a free day, I plan to pull the shocks back out and go after the LCA pocket with a die grinder to buy some room below the shock to hopefully alleviate the problem for good. I also believe a fully shanked bolt like forged sells would keep the shock more correctly positioned. And I would bet the spherical lower bushing would eliminate all movement maybe solving the problem.

Something else to consider, in manufacturing, parts tend to change over their lifespan due to wear on dies, and molds and equipment. maybe these later parts are not to spec as good as earlier ones? because i can tell my lowers look sloppily molded and do not look like the CAD data shows. Add all this up and your 5mm design gap goes away.

You may have already found this out, but just because you have "new" lower shock bushings, does not mean they are still good. I had some OEM bushing laying around in the garage for a year and finally decided to install them instead of the hemispherical bushings I had in the truck already. Install was easy, but the passenger side clunked right out of the driveway. My theory is the heat and cold that deteriorates the factory bushings. If you take one apart, there is 3 different types of rubber / plastic in the assembly and they all expand and contract at different rates. When the bushings were sitting on my shelf (not installed) they went through extreme hot and extreme cold, much like an installed bushing would. I think bushings that sit on the shelf look and feel fine but deteriorate and as soon as you install them, the weight of the truck kills them immediately.

At least that's my .02. I've been chasing noises around trucks for years... I feel your pain.

 

[Eyespyautomotive]

My new lower bushings were bought brand new, but maybe they are old?, unsure, they look fine, feel tight. I dont know about this noise, driving the truck yesterday I still feel it, really feels like crap, its like there is major play in something, but everything checks out. I really dont want to start throwing parts at it. But man id throw a grand at it if someone/something would solve it. Everyone has a different opinion of what it is but nothing seems to solve it.

I might try doing more vids underneath and see if I can figure it out. Pretty frustrated.

 

[EricM]

Have you driven any other Raptors to compare with yours? I get a "boomy" type sound from the shocks over small bumps in the road, but nothing that feels loose or sounds like it's loose.

 

[Eyespyautomotive]

I havent, but it seems like a lot of people have complaints about noises in the front of these trucks.

 

[Canuck714]

I'll have to look at the clearance between the lower shock and A-Arm on mine, but I really think the thud comes from control arm bushing.
When I upgraded to 3.0's I also swapped to the shanked bolts from Forged, disconnected the sway bar and the thud was still there.. You can almost feel it in your feet.
When I got my alignment done, I had requested the shop push my lower control arms as far forward (staying in alignment as best they can) to gain the most clearance I could for the 37's. The thud was temporarily gone until first off road trip. That's why I think its in the control arm bushing

 

[Hasty]

Limited seat time in the truck lately but I’ve noticed the clunk is back and seemed to be getting worse. Checked all the usual suspects (lower shock bolt, ball joints, a-arm bolts, sway bar end-links, tie rods). When I rebuilt the shocks I did put in the Forged shraeders, so I checked nitrogen pressure and the pass side dropped from 200 to 90. Went ahead and refilled, (still yet to determine leak but I’m suspect of the threads and locktite used to seal) clunk is significantly better but slightly there on rebound. The truck has scene a decent amount of off road so I expect some character. Current rate, this is livable. Still have to check the driver side, I assume that is leaking too. The Forged shraeders I purchased came without o-rings, I see Kartek sells them with, may go that route now.


Sent from my iPhone using Tapatalk

 

[Eyespyautomotive]

Im not sure what to do next other than start replacing parts and hope I get it. Im a little leery of the UCA ball joint, so i will probably throw a set of UCA's on it and see what that does. I think I will revisit the rack too. The noise in the rack video back on the prior page sounds exactly like the noise i feel/hear in the cab by my feet.

Gonna keep looking, but man Im sick of working on and laying under this thing...

Really wish I could get this thing on the road simulator at work and run a test. I thinik id find it then..