[944 163hp] banging when starting off

[zoilgust]

Hi all,

I'm french and I'm the owner of a 944 from 85, 163 hp.

I'm disturbed by a noise at the rear of my car and I often find this forum through my searchs.

It's the reason why I suscribed to this one.

I recently change my motor because the original one had conrod fail because of very old oil in engine (fault of the old owner)
I changed transaxle and all mounts (motor and gearbox) because of vibrations under acceleration.

but now I have a new problem, when I'm starting off I heard one loud "bang" from the rear, maybe 2 or 3 second after release the clutch.
It moves the gear shift, I can feel it

my disque clutch (rubber) was ok, not torn, was ok.

I changed only one CV joint, the right one, because it has clearance, le left one too but it will be changed soon. with the new right CV the problem is always there.

If I'm starting off very slowly it's sometimes ok, I don't heard the noise, but it appear sometime when accelerate juste after turned.

My question is : is some of you already had this case and how did you fix it ?
Because i'm not confident about new CV joint and i'm a little bit scared about a gear box problem (I will ask after about that for causes)

The problem is that I found several thread about this problem but users never came back to their thread to say if their problem was solved and how ...

I found 2 things that can confirm my problem.

in first that :
CV JOINT Welcome to Rennlist

and finaly this found on this forum :
http://forums.pelicanparts.com/uploads17/Shock+noise1279837448.jpg

what could I check to find this noise ?

it's not a clicking sound usualy heard on CV's, it's one loud bang ... which move the gear shift ....

thanks in advance !!

[Nigel Haslock]

Sounds to me like the rubber clutch disk is failing. The symptoms match what happened to me.

[zoilgust]

Thanks for reply.

I tested the flector by turning the transaxle shaft, and had no clearance ...

I forgett this, a video I made to try to find the area of this noise.

listen at 50 seconds, I do 2 starting off and we can heard the "bang"

bruit au demarrage 944 - YouTube

[JivenJim]

Just by chance in case...
Is the parking braking on, or Dragging hard?
Jack rear, out of gear, and try to rotate wheel by hand easily..

[zoilgust]

Originally Posted by JivenJim

Just by chance in case...
Is the parking braking on, or Dragging hard?
Jack rear, out of gear, and try to rotate wheel by hand easily..

Yes, I suspected parking break in first, but it's not the case ....

I just tested to lift the left-rear of the car and try to reproduce the noise but I didn't manage to ...

I only have the "bang" on acceleration when torque is applied on 1st and 2nd gear only (maybe in 3rd but don't heard), but never during deceleration ...

@nigel
I made this video, have a look from 50 seconds, I did 2 starting off and you can heard a little "clic"
http://www.youtube.com/watch?v=3oghFax8rYs

I just tested again if the rubber clutch is broken and seems not, I didn't manage to turn the transaxle with my hand, it's totally without clearance

I read several threads about and I think that it's not my case
my rubber clutch has been inspected maybe 2 month ago before installed my new engine and it was ok

No noise in the clutch area when clutch pedal is pressed or not.
my noise is not a metallic "clac", it's difficult to explain (especially in english) but I feel that something is under stress and the "bang" relieve this stress

Here is my clutch disc :


thanks for your help

[Nigel Haslock]

OK, I thinking it was a much louder noise. I hpe someone else has a better idea.

[zoilgust]

arf, maybe the same case like him :
differential problem

any experiences ?

[ibtisam.jawad]

It's difficult to tell from the last video ... but if it were clutch related you would hear a clunk sound as you shifted from one gear to the next e.g. 1st to 2nd, or 2nd to 3rd. Is that something that happens to your car? Also, the clunk sound would come as soon as you let go of the pedal after putting the car in the next gear. The sound would NOT come if you matched revs when shifting, or just waited a bit with the clutch depressed and let go of it smoothly.

The other thing could be your transmission mounts. You said that you changed them but make sure that you put them on correctly ... I don't know how that's done though. I had a similar problem with another car and the transmission mount turned out to be the culprit. On this one, the clunk was more pronounced when driving the car from stop. It was also more pronounced when reversing.

People here are very helpful so I'm sure someone can point you in the right direction.

[JivenJim]

I heard that click once on your video around 48.
Sound like something is shifting under acelleration.
I would try to take car to parking lot where you can drive at good speed in few circles Right, then left. If the sound pulses on and off then I would think CV Bearings on outside wheel.

Check try pushing around the Transmission and exhaust (while cold!) to check for loose mounts and visually check the torque tube mounting bolts are tight.

Then maybe check for loose rear wheel bearing. Jack car and pull/push on wheel at 3 and 9 o'clock positions. In case wheel bearing is going bad.

just some ideas to try.

[zoilgust]

@jivenjim
yes, around 48 it's when I engage the first gear

this morning I tried to turn and to test, the noise is more present when I turn right.
to be more precise, I shifting down near the corner, i'm in 2nd gear for exemple, I turn and just when I accelerate I heard the noise, but not in left corners.

I will try to move wheel as you described


@ibtisam
to describe a lot more, if I put the 1st gear then I release the clutch pedal, the car starting off and don't have noise. I put a little bit torque by accelerating then I have the "bang" ...
in second gear I have sometime this bang, but the noise is very low.

This morning I observe that in first 10 minutes I almost no heard this "bang".
but after these 10 minutes it was more present.

EDIT
I think that I found something
look at the video below I made today, at 1:04 the "bang" moves the left-rear wheel, it's very visible ....

http://www.youtube.com/watch?v=tQfdC0hvQ18&feature=youtu.be

I checked as recommended for rear wheel bearing, maybe I can heard a "cloc cloc" when I'm moving it, but not sure
the thing that i'm sure that's the right cv joint is very old and have play .... maybe a consequence ?

I hope so ....

[zoilgust]

problem solved !!!!!

I changed my left cv joint today and the old one was very bad, it has good clearance on gearbox side.

with the new one no bang, no vibrations, so the rennlist "banging when starting off" is real, a cv joint can cause that

hope it will help other owners with this problem

thanks for your help !!!!

[JivenJim]

Well done zoilgust. You serve as an excellent example of how to use this site well.
You are very good problem solver.

I will add you to my list of French contributions:
1) Civil War Supporter of US
2) Statue of Liberty
3) Edith Piaf
4) French Wine
5) zoilgust - English writing, Frenchman; driving and fixing German 944 (with Passion:+)

[zoilgust]

a big thanks to you jivenjim !!

[ludo944]

Hi Zoilgust,

finding your post when looking for a solution to my problem: when engaging 1st gear, my 944 S2 vibrates, especially if I do start while on curve, or road up.
if starting with low torque gently and straight, vibrations are not there.
by driving up hill at minimum speed, I can sometimes hear like a 'clang', higher pace than wheel turns, coming along with those vibrations.
the cutch and gear box are smooth, and at medium to high speed, I do not have such vibes...
I do not know if the clutch has been changed in the past, the car sums up 156000KM
I did elevate teh car both sides: wheels are turning well balanced, no specific 'slack' .

what is the CV joint you changed to fix the problem 3 years ago ? (en Français ça m'aiderait, je suis aussi du pays des baguettes)

Thanks all,
Greetings from France

[zoilgust]

que de souvenirs !

en fait c'était les cardans que j'ai changé ... c'est vicieux comme symptômes

j'ai vendu ma 944 mais redis moi un peu tes symptômes en français et je te dirais si ça peut être les cardans

[jhowell371]

Tres Bien

[CHICKS]

Mine makes the same noise and I suspect a bad CV as my clutch disc is new and the CV's are rebuilt Cardones.