A strange shimmy

[4banger87]

Hey guys/gals, a newbie here.

So I purchased a 1997 cobra it's got 113k on it and it runs really good. It's got the famous "thump" when taking off, from searching on here I'm thinking it's probably due new control arm bushings but I'll probably go ahead and upgrade them.

Now the strange thing that I'm hoping y'all can help me out with is the weird shimmy. So to get home I make a right hand turn up a hill which flexes the suspension probably to the max cuz the hill is pretty steep. When I make the turn I get a thump from the rear and once I've straighten up the car does a weird side to side shimmy, at the same time it also feels like it's surging front to back. This turn to get home is the only time I've noticed the shimmy or the surging. I'm climbing the hill in 1st gear if that matters. By the time I get to the top of the hill the shimmy has stopped and shortly after the surging back and forth feeling has stopped. I dunno if this is the axle getting realigned after some weird flexing or what..

Today when I leave and come back I'm gonna swing wide and try to hit the hill more head on and see if that helps. Other than this the car seems to runs very good and has plenty of power.

Thanks for taking the time to read my post and I look forward to making some friends here!

 

[4banger87]

So I jacked the car up today (gotta get a new jack) to make sure nothing was super loose and about to fall apart lol.

Questions

How much play should the control arms have in them?? I stuck my 18" pry bar in them and they twist with little force. The side I can see still appears to have the bushing in it.

Also while I had it on jack stands I repeatedly put it in gear in 1st and reverse and let off the clutch it didn't thump not one time...

Also I'm assuming this is normal but when I turn the wheel with my hand you can hear sort of a metallic scrub very briefly, I'm assuming this is the LSD engaging because it stops once the other tire begins to spin. Or maybe my rear end is about to explode.

As for the shimmy if I swing wide and hit the hill straight on, I don't get the shimmy or surging feeling just the "thump".

Everything appears tight so I'm hoping the thump I hear on take off is just the UCA & LCA bushings. I've already ordered a aftermarket set.

Any help is appreciated. Thanks.

 

[jgt58]

Sounds like your gears might be missing a tooth

Sent from my LG-H900 using the svtperformance.com mobile app

 

[4banger87]

Sounds like your gears might be missing a tooth

Sent from my LG-H900 using the svtperformance.com mobile app

If thats the case would it not thump or make some sort of noise when going from 1st to reverse with the wheels off the ground? Once it makes the initial thump it doesn't do it again until I stop completely and take off again. Letting off the throttle and hitting it again doesn't cause it , nor does shifting gears. It only does it when taking off or getting back on the throttle after slowing down to make a sharp turn. Is there any other signs of broken teeth without pulling the diff cover?

 

[jgt58]

U joints wearing out?

Sent from my LG-H900 using the svtperformance.com mobile app

 

[4banger87]

I suppose thats possible, it does have 113k on it. I gotta get a better jack, mine doesn't go high enough to really get under there and check everything out as good as I'd like.

 

[4banger87]

If I'm VERY gentle I can actually get into 2nd hear before the thump happens. Also it fluctuates. Sometimes it sounds on the passenger side and sometimes the driver's lol.... I should just get a custom tag that says thumper!