08 gt rear end clunk in neutral

Hey guys I have a very subtle click while in neutral going over little bumps. I just did lower control arms, sway bar and end link bushings. So far it seems when I'm going slow in neutral over bumps. Haven't really heard it when I'm in gear. Just started out of nowhere a couple days ago.

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Upper control arm on the diff. The bushings are probably torn

X2
Since you've just done other suspension work, you might also wanna make sure that the bolts are correctly torqued down.

Dino Dino Bambino said:

X2
Since you've just done other suspension work, you might also wanna make sure that the bolts are correctly torqued down.

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I will check that. But that would only cause a clunk in neutral when going over bumps? It's like a clack...clack and then it stops.

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Are they adjustable if they are then make sure the nuts that lock it in are tight. (Lca)

They're not adjustable. I just took a closer listen today. Only clunks in neutral and mostly when turning and when the vehicle hits a bump or whatever. I think it may be time for a diff fluid change. I'm gonna do it anyway as I'm sure it's never been changed but I'll check the torque on the control arms. Does anyone know what is needed for the 08 gt as far as diff fluid and additive? I wanna make sure the information I have is correct. Also, does anyone have torque specs on hand for the lower control arms, sway bar bushings and end link bolts?

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teeje said:

They're not adjustable. I just took a closer listen today. Only clunks in neutral and mostly when turning and when the vehicle hits a bump or whatever. I think it may be time for a diff fluid change. I'm gonna do it anyway as I'm sure it's never been changed but I'll check the torque on the control arms. Does anyone know what is needed for the 08 gt as far as diff fluid and additive? I wanna make sure the information I have is correct. Also, does anyone have torque specs on hand for the lower control arms, sway bar bushings and end link bolts?

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2 qt's + 4 oz friction modifier. There is a port that you fill until it comes out of there. The fluid level should be at about half way up the axles.

Well what did you torque them to when you installed those parts? To me it sounds like a sway bar endlink or the upper control arm bushing. But it could be a lot of things. Start with what you did last with the car. 99% of the time it is something you did.

Aftermarket upper control arm used with the stock mount? That will cause clicking and banging since the holes in the mount are bigger than the bolts in most cases.

I'm goimg to use royal purple max gear I believe it's called. Had the friction modifier in it already. Should I still add some?

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So changed transmission fluid today, diff fluid and oil and torqued down everything I did everything was tight but I still have a clunk.

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rickf said:

Aftermarket upper control arm used with the stock mount? That will cause clicking and banging since the holes in the mount are bigger than the bolts in most cases.

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Good call.

Something is all kattywampus up in there. I'll put it on a lift this week and take a sneak

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I deal with noise from the rear on my '12 as well, similar to what you describe.

I've changed sway bar bushings, upper diff bushing, switch to non-adj upper arm, switched to diff. panhard bar and the sound remains.

Check the nuts on the rear shocks, they might be loose and causing a little rattle, also check panhard bar nuts and/or it's lock nut if its adjustable.

Could just be slop in the drive train? Worn tranny gears? Worn tail shaft? Looser tolerance in the pinion/ring gear? All of the above?

702GT said:

Could just be slop in the drive train? Looser tolerance in the pinion/ring gear?

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after spending countless hours underneath my car, i've attributed a lot of my rear end noise to those two factors

teeje said:

I'm goimg to use royal purple max gear I believe it's called. Had the friction modifier in it already. Should I still add some?

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I think when I ran royal purple I ended up adding half a bottle or 2 oz. of friction modifier.

07 Boss said:

I think when I ran royal purple I ended up adding half a bottle or 2 oz. of friction modifier.

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Shocks are new and yes I put royal purple In and 4oz of the modifier as per American muscle states in the facts sheet. It's not big. Only when in neutral and just happened out of nowhere. Everything is tight and torqued
Also as far as flash goes on the diff it felt.nirmal may Be less than a quarter of am inch maybe more I can't remember but it felt normal and d idnt have any abnormal play
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I test drove a '17 Ecoboost 6 spd yesterday (for shits n giggles while the car was in for inspection) and it's amazing the difference in a driveline with 0 miles on it and a driveline with 73k/mi on it LOL. Getting back in my car felt like driving a 71 F100 (if you get my big sloppy drift). I always considered my car pretty tight, pfft. I must've really forgotten what it felt like when the gears were new 'n tight. Really makes me want to rebuild my tranny and set my diff at .08 lol.

Tracked it down to the upper control arm. I ordered a new one. Any tips on getting the axle housing bushing out?

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teeje said:

Tracked it down to the upper control arm. I ordered a new one. Any tips on getting the axle housing bushing out?

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Per steeda and BMR.... use a 1.5" hole saw to get the oem rubber bushing out (this is the uca bushing at axle end, on top of differential). Then use a 1.5" wire brush to get any residual gunk out of there. The deeper the hole saw, the better. You may well have to go at it from both sides..with both the hole saw..and wire brush.

Steeda makes both a poly and and spherical bushing for the axle end. BMR makes a hd poly bushing for the axle end. Poly at both ends of the UCA is bad news, the uca can't rotate on it's axis..they will bind. Poly at axle end and spherical at front end of uca will work, but will result in some nvh.

Steeda spherical at axle end...and BMR POLY at front end is the optimum setup. At least one end has to articulate