front axle problem ?

[jackal2513]

hi guys,

quick question

picked up a 172 today

at around 70mph and above I get pretty intense shaking, up through the chassis and steering wheel. The shaking is intermittent so it comes on strong for 4 seconds or so then disappears and then cycles on and off in the same fashion.

Under acceleration I can also hear and sort of feel some grinding from the front of the car. This feels like rotational grinding and pulling away hard in 1st gear its very very noticeable with a loud creaking noise from the lower front corners of the car.

I have rocked the front wheels and the bearings seem fine. I guess this could be a combination of things including the wheels needing balancing but can anyone shed any further light ? Do the drive shafts go on the 172's and are the symptoms similar to what im describing ?

thanks in advance for any help

Rich

edite to say that the handling and suspension of the car is veyr sweet so no probs there and the engine pulls well and the gearbox functions fine with no crunching or popping out of gears etc..

 

[maynard]

The 1st gear knocking could be the rear dogbone engine mounting.

Driveshafts are fairly common to go on 172's, quite a few threads on it recently.

 

[jackal2513]

there is a strong single knocking when you accelerate sharply, esp. in 1st which does feel like a loose engine mount

is there a DIY on where to look ?


I will also take a look at the driveshafts tomorrow.. is it the CV joints that go ?

 

[maynard]

Pretty straight forward to spot the mount.

Jack up and support with axle stands.
Remove engine cover (underneath car), there's four screws holding that up.
Then you'll spot it to the rear of the engine/subframe and there will be a dogbone looking mount. It will either be straight or twisted, and due to your knocking noise especially in 1st, you'll either find it loose or the bushes pretty worn out.

 

[jackal2513]

well its not the engine mounts
bearinsg are fine as are all the bushes

it still makes a knocking sound when you plat the throttle... its actually very noticeable in 3rd and 4th if you are coating along then you stamp on the pedal... the whole drivetrain knocks as the drive is engaged and the car starts accelerating

I can also hear some grinding at certain speeds/revs and sort of feel the vibration of this grinding through the pedals.

Any ideas how i check the driveshafts ? I suspect the nearside as the noise seems to emanate from there. Shall i just pull the boots back and take a look ?

 

[Dave..]

The knocking will be engine mounts. Check the top on on the drivers side, and the upper gearbox mount under the battery tray

 

[jackal2513]

the thing is the knocking sometimes isn't just one knock

its like a stuttering noise as you accelerate, consistent with something rotating

i've rocked the engine around and it seems pretty stable to me

 

[jackal2513]

The knocking will be engine mounts. Check the top on on the drivers side, and the upper gearbox mount under the battery tray

ok thanks

been doing a bit of searching as well

i'll check under the battery and take off the upper engine mount & inspect


i'll also slide the black dogbone bracket forward and move the engine forward as well before retightening the upper engine mount

 

[_WILL_]

Might be a bit obvious but def worth a check with regards to a the vibration and grinding, but check all the wheel bolts are tight.

From what you say it does sound like engine mounts, I snapped part of mine the other day and if i pull away in any other way than like an old lady then it knocks like f**k! New k-tec one has been ordered!

Could it be the manifold on the subframe, i know its normally more a vibration noise but it could be the start of it??

 

[jackal2513]

weird ?

undid the main bolt that secures the forward end of the dogbone and lots of oil started dripping out ? is this normal ?

 

[jackal2513]

took another look

centre exhaust section + manifold had an exchaust C clamp over it which was clearly banging against the subframe (could see the marks on the subframe)

i loosened it off, rotated it for better clearance and retightened

upper Gbox mount seems ok but Top engine mount seems loose so will change that soon

the knocking does seemed to have stopped so clearly it was the exhaust bracket banging away

time to balance all the wheels tomorrow morning

thanks all for your help

 

[_WILL_]

weird ?

undid the main bolt that secures the forward end of the dogbone and lots of oil started dripping out ? is this normal ?

They tend to leak gearbox oil and from what people say its pretty normal for a Renault!! Mine leaks really badly. Apparently its from the gear selector, it may just have pooled slightly in your case and when you undid the bolt the oil has found a way out. I wouldn't worry too much about it!

Its good to here you found what was making the knocking. If your engine mount looks a bit worn then I would change it when you get a chance. I just up rated mine to a k-tec one. The old Renault one i took off looked fine when on the car (apart from the snapped buffer bit) but when i got it off and had a look it was properly fucked. The new one has transformed the way the car feels, although I am getting a fair bit of vibration, but i just need to play with it a little to reduce that.

Basically im very impressed with the new one and will be upgrading the rest of them as soon as I have the money, the extra vibration seems a small price to pay!