Hey guys,

Heres the story. I swapped out my worn stock lower control arms for a set of UMI tubular ones last week, easy process. Jump in the car after the install to take it for a spin and after i closed the door i was suddenly aware of a horrible knocking noise in time with the engine, which also goes up and down with the RPM's. I went round the engine bay first and couldnt hear it, its only when im in the car, and on closer inspection its loudest if i put my head to the drivers footwell near the pedals like in this video.


I checked the torque convertor bolts etc while i was under just incase it was one big coincodence but everythings fine there. I can only think that because these UMI control arms are a fraction shorter than the stock ones, and that coupled with my car being lowered its pulled the rear end forward and pushed the driveshaft further into the transmission hitting something ? does this sound like what has happened because im out of other ideas

What ive done in the mean time is put my stock lower control arms back on, the noise is still there but it wasnt as loud so now im thinking something has been damaged inside the transmission and its too late now.

 

My bet is that you dented the oil pan in somewhere , and the crankshaft is slightly hitting it .

Think about this , if this noise happens in park the driveshaft and 90% of the transmission can be ruled out because in park they aren't even moving . Sure it could be the torque converter or flexplate/ring gear , but how would changing lower control arms have affected them ? Unless you put a floor jack under the bellhousing and jacked up the car on the torque converter I can see no way the two could be related .

Check your oil pan , closely , and see if you dented it while manhandling the springs/lower arms out and then back into the chassis , it's the most logical thing that fits the problem as you describe it .....

 

Its the rear control arms i changed so cant be that as it was jacked up from the back. I probably should of said that in my original post sorry

 

throw some Lower control arm relocation brackets on there since you're lowered. it will give the lower control arms the correct angle (parallel to the ground) founders performance has a set for around $50

I'd put the back of the car on jack stands, block the front wheels, start the car, and crawl under enough to locate the sound. be very careful and make sure that the car is solid on the stands

 

If the car is in park when you rev it why do you think its the trans?

 

probably something simple. i'd jack the car up, start it and try to isolate the noise. a mechanics stethescope might help. bellhousing bolts tight?

 

Check the exhaust. Make sure it is not hitting anything.

 

Since it does it in P it's not the trans or driveshaft, it's either the converter hitting something, the crank or one of the accessories.

Might be the parking pawl in the trans if the shifter linkage moved a bit. Check the shift linkage on the trans and loosen it and see if it's all the way to the end in P. It only takes a little for it to misengage.

 

Due to the location of the noise and the sound of it, my guess is either the torque convertor or the pump in the transmission. Unbolt the convertor and push it into the trans. See if the noise is still there.

If it goes away then rotate the convertor by hand and see/feel if it turns the pump OK.

RBob.

 

I'm with this guy's answer .

When I first read your problem yes I did think you were talking front lower control arms which of course is why I suspected a ticking or rapping kind of noise would have been from the pan getting dented . Since it's the rear you were working on the now most likely thing is as bluegrassz says you've got the exhaust hitting somewhere , possibly having gotten bent slightly somehow during the work .

If you are 101% dead sure this noise did not exist before the work was done I can not see how the transmission or engine would have been affected by your replacing of the rear arms , leaving only the exhaust as the most likely suspect ....

 

Thanks for all the replies guys.

Yeah it was a set of UMI rear control arms i fitted. This knocking 100% was not there before i done this.

Its really weird as i cant hear the knocking while im under the car. I took the plastic cover off to check the torque convertor bolts and ran the engine with it off while i was looking at it but it was all fine. Pretty noisy when your lying under a car. But as soon as i put my head in the car near the floor i can hear it.

Since swapping the stock control arms back on the noise is still there but its quieter. And thats about it to be honest !

 

Other then being loud under a running car, it is strange that the tapping noise wasn't there. I did think of another possibility.

There is an exhaust leak that is striking the floor pan. Not sure how much you moved the exhaust around when doing the trailing arm swap. But never can tell, it could be a coincidence.

RBob.

 

Hmmmm I never even considered the exhaust as I didn't think it would move at all with jacking it up as normal. If its something simple like that then happy days !

 

How much of a fraction...?

Normally when a driveshaft is too long you risk the chance of damaging the thrust washers in the trans and the thrust journal on the crankshaft, but this would be a significant increase. If I were you, the first thing I would do is put the phone under the car and video it that way so we can hear it better. You may tell yourself it is louder in the car, but the phone's audio may pick it up better than you. I would also get your hands on a stethoscope, and listen to those two key areas (oil pan and trans pan), if it's in there, you will here it clearly with the stethoscope. From what I hear though, it does sound like an exhaust leak somewhere, but this is why we would need a better video from under the car...

 

A long screwdriver held to the ear works also

 

Hey guys. not had a chance to do anything lately, had an accident with a smashed plated and nearly went through the tendon in my thumb, had surgery yesterday so no messing with the car for a while its the first thing i need to get on when im able too though

 

Sounds like you dented the oil pan. I did the same damn thing when I replaced my whole suspension. They dent like really easy.

 

By installing rear control arms ?

 

I mean like anything is possible. I redid my whole front and rear suspension. I don't know when I dented mine, but i did. Only things I didn't touch were the kmember, torque arm and rear Springs.

 

Lots of things to check when i can work on it again then. Im still out of action with my hand

 

I feel ya. My right hand is broken to. Completely fractured my 3rd finger bone in palm.

 

Ouch ! Get well soon man. Ive got no grip in my left hand......and im left handed :/

 

Has anybody mentioned a cracked flexplate..

 

Exhaust leak at the manifold to y connection?
That's my 1st thought especially with the location. Hold your hand or a stiff piece of paper up there.

 

The car has been on two ramps now, the first guy thought it was the new fuel hoses i had fitted and they are vibrating right down the pipes, however im sure its not this because the knocking / tapping is too perfectly timed with the engine if you rev it etc, its definitely something catching or hitting something else.

2nd on ramp experience was at the yearly test we have here in the UK, i had to drive the car there which is about a 15-20 minute journey from my house and the car drove absolutely fine, shifts through the gears fine etc just this damn noise is constantly there, although you cant hear it about 30 because its spinning round so quick it gets drowned out by the regular noises.

It passed the test no problem and the mechanic had a listen with his stethescope while it was on the ramp running and he thinks its coming from the torque convertor area, he didnt have time to pull the cover and stuff poking and prodding as he was working on someone elses car at the time, he said he listened to the engine and the crank and it all sounded fine, the only thing he couldnt listen too was the left side of the engine as when he went near it he got lots of electrical type feedback which he said was weird ???

so anyway i drove the car home praying nothing would explode and it was fine, but whatever it is cant be good and ive got a feeling driving it there and back might of made it worse.

However, my hand is just about fine now, ive ordered some decent ramps so i can get it fairly high in the air to crawl under and try and figure this out finally. I will be going straight to the back of the engine for a listen

 

cracked flex plate....that's what it sounds like..pull the dust cover. and with a good bright light. look up at the bolts holding the flex plate in place.. look for a small crack or cracks about 2 to 3 inch long...

take a look see...or keep guessing..