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Click/knock on initial acceleration

Recently for absolutely no reason I get a click/knock from the rear, sounds like from the very middle of the car when I initially accelerate from a stop and then through the first few gears. I can also hear it when I allow the car to slow down to about 1k rpm and then begin speeding back up. anyone have an idea of what it could be?
 
Senderofan said:
Any suspension mods? If not...might be the trusty two piece driveshaft?? It's known to make noise.

Wayne

Everything in the rear is whiteline except the sway bar which is stock, it sounds similar to the clunk heard after installing a UCA from the gear lash but it happens at the same time or sometimes independent of the gear lash.
 

Senderofan

Having more fun than should be allowed..in my Boss
What bushing style does your UCA have? Reason I ask that....I started with a Hotchkis that had a Heim joint. It functioned well...but it transmitted noise like you're describing. I swapped it out a month ago for an adjustable UCA with Poly bushings and an aftermarket mounting bracket. It's really been a huge improvement...but still have a little noise, on occasion, from the backlash and/or two piece driveshaft.

I know it's a bit frustrating....trying to figure out what is exactly going on. I've re-torqued everything three or four times....I've also re-greased the fitting a few times.

Hopefully you'll find the culprit soon.

Wayne

Do you have a catch can for your rear diff.? I had a Shelby version....that would have contact once in a while...with the UCA mount on the rear diff. I could replicate the squeak-clunk backing out of my driveway....there's a small lip...and when the rear dropped the noise happened at that time as well. I've removed that as well...Went with the Ford Turkey Baster.
 
I am thinking the poly bushing on either the UCA that I have or the rubber bushing of the axle could be binding. Also may be the sway bar end links in the back, I have had issues with them in the past, also I am thinking the OTA's could be to blame.
 

Grant 302

basic and well known psychic
Brandon302 said:
I am thinking the poly bushing on either the UCA that I have or the rubber bushing of the axle could be binding. Also may be the sway bar end links in the back, I have had issues with them in the past, also I am thinking the OTA's could be to blame.

I doubt it's the rubber bushing. I'd go check the UCA ploy bushing. Well, go check everything...but definitely look there too.

The bind caused by the UCA bushing ultimately causes the bushing to fail. Poly can't take the repeated twisting and hammering.
 
Grant 302 said:
I doubt it's the rubber bushing. I'd go check the UCA ploy bushing. Well, go check everything...but definitely look there too.

The bind caused by the UCA bushing ultimately causes the bushing to fail. Poly can't take the repeated twisting and hammering.

I'm thinking your right, either the UCA or the LCA's it's just odd that up and down motion doesn't cause it but acceleration does.
 

Grant 302

basic and well known psychic
Brandon302 said:
I'm thinking your right, either the UCA or the LCA's it's just odd that up and down motion doesn't cause it but acceleration does.

My money's on the UCA. In theory it does very little under axle up and down motion. It's only controlling the angle and a bit of location of the diff/axle. Under accel/decel it becomes 1 of 3 members creating the IC and depending on the geometry can be taking about half the load while the LCAs split the other half. Add the same/similar forces under any roll conditions and the lateral angle of the UCA is the most changed of any of the arms, and depending on the rear geometry, the front is the worst. This is why it's such a BIG bushing stock...and also why the 'rubber pencil' example posted on SVTP is so wrong for a car that is doing anything but drag racing.

Right or wrong it'll be interesting to see what the problem is.
 
Grant 302 said:
My money's on the UCA. In theory it does very little under axle up and down motion. It's only controlling the angle and a bit of location of the diff/axle. Under accel/decel it becomes 1 of 3 members creating the IC and depending on the geometry can be taking about half the load while the LCAs split the other half. Add the same/similar forces under any roll conditions and the lateral angle of the UCA is the most changed of any of the arms, and depending on the rear geometry, the front is the worst. This is why it's such a BIG bushing stock...and also why the 'rubber pencil' example posted on SVTP is so wrong for a car that is doing anything but drag racing.

Right or wrong it'll be interesting to see what the problem is.

I almost want the UCA to be broken and I will send it back to whiteline and have them refund my money, if that is the case.
 
Retorqued/checked the torque on everything in the rear. I also loosened and retorqued the UCA where it attaches to the diff since I didn't do this while the axle was loaded, or I don't think I did. Few things were loose and I have yet to get the same noise, however it has only happened 3 times in the 20k+ miles that the rear suspension has been on 7k or so being with the UCA.
 
I also the same kind of noise under the same conditions. Noticed it recently, but my car is stock. I'm thinking it may have something to do with a few high speed shifting lock-outs. Need to find time to take it in soon to be checked out.
 
Shaun12 said:
I also the same kind of noise under the same conditions. Noticed it recently, but my car is stock. I'm thinking it may have something to do with a few high speed shifting lock-outs. Need to find time to take it in soon to be checked out.
I ended up torquing everything back down in the rear, a few things weren't tightened to spec anymore so that may have resolved it, just not sure what it was that I tightened that got rid of the noise.
 

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