boite fait beaucoup de bruit

Bonjour,

Je suis Erik et j'ai une R5 Turbo 2 de 1985. Je pose ma question en anglais parce-que mon francais ne suffit pas pour expliquer mes problemes en francais. Vous pouves repondez en francais.

My gearbox makes a very loud rattling, almost scraping sound when I release the throttle. The sound can also be heard when accellerating in low revs but mostly when the throttle is released (no torque on the gearbox). The sound is present in all gears and can be clearly be heard inside and outside the vehicle. The noise sounds really unhealthy.

After consulting a number of specialists and other owners I concluded it must be the differential which makes the noise. With a stethoscope the sound can also be located at the position of the differential. location.

After this conclusion I had the gearbox overhauled. The differential was replaced with a new one and also some bearings were replaced. No serious damage could be seen on the replaced parts.

I have been driving the car for a week now and the sound is still there! I can assure you, this is extremely frustrating! It even appears to be louder than before but I am not exactly sure about that.

In the past I had the chance to drive two other Turbo's. One of which had the same noise, the other also but just very faintly.

As you can understand I am very desperate and dissapointed. Does anybody know this problem? What creates the noise and how can it be fixed?

Please help.

Merci beaucoup,
Erik Keizer

Bonjour erik,
Moi aussi j'aurais dit le differentiel.As tu vraiment changer TOUS les roulements ?...Les dents de la couronne du differentiel que tu as enlevé étaient usées ou pas?...
Daniel

Thank you for your response Daniel. The entire differential was replaced with a new one: Crownwheel, pinion and both exit bearings. The differential and the bearings did not show much wear, all the replaced parts still look very good. The gearbox was overhauled by an alpine dealer in Belgium.

I am now quite sure the sound is worse than before and it is also audible when the car is accellerating in low rpms.

Meanwhile I spoke to two other 5Turbo drivers. One did not have the sound in his car, the other one did. He suggested to use a sports-exhaust to camouflage the sound hahaha. I had already tried that but the sound of the Devil exhaust drove me even more crazy than the gearbox.

I will keep searching for the cause and solution to this noise.

Greetings,
Erik

Salut eriK,
Quand tu as démonté ta boite comment était ton embrayage? C'est peut être lui le coupable...
Tu as changé les roulements de sortie de pont mais comment étaient ceux sur les arbres?
Camoufler le bruit avec un échappement Devil n'est peut être pas la bonne solution.... :p
Pour écouter sa musique il ne faut pas de bruit parasites derrière...
@micalement Daniel

Allo Daniel,

I have replaced both the friction plates and the pressure bearing. The clutch parts I re-used are the diaphragm spring and the metal plate between the friction plates.

The driveshafts are both in good condition. To test if the noise is caused by the driveshafts we lifted one wheel and blocked the other. This way the lifted wheel turns at double speed. We did this on both sides. In both cases the sound was the same (and still came from the gearbox) so it is very unlikely that the driveshafts are the cause.

Someone told me that it might be the tolerance between the crownwheel and pinion. According to the man who overhauled the gearbox this tolerance was adjusted. Until now however I have not discovered how this tolerance can be adjusted. According to the manuals I have, there is no possibility to adjust the positions of either the crownwheel or the pinion (this is possible in some alpine gearboxes however)

Still searching.

Greetings,
Erik

Je ne maitrise pas du tout la langue anglaise, mais j'ai cru comprendre que le bruit est plus présent lorsque le moteur n'est pas en charge. Une cause possible et vu fréquemment c'est la bague en bronze logée en bout de vilbrequin qui usée. Le pignon d'entrainement à alors tendance à battre dans le logement. c'est une petite pièce facile à changer on ne pense pas toujours à elle.

Bon courage

Bien cordialement

I have done some experiments: I have exchanged the turbo gearbox for a Renault 25 gearbox (UN1-03). This one also rattles but very faint (I can hardly hear it). Unfortunately I am unable to keep using this one. I am now driving with a R20TX gearbox (369-14). This one rattles a little bit less than the turbo-gearbox. I am convinced that all the gearboxes have this problem. I just don't know what is causing it yet. Any more suggestions? J'ai essayé une boite d'une R25, elle fait la meme bruit mais plus doucement. Maintenant j'ai monté une boite d'une R20, elle fait presque la meme bruit.

I took the advice of 5T_six and changed the brass bearing in the flywheel. This did not help. Thanks anyway. j'ai changé la bague en bronze sans resultat, la bruit est encore la.

Dear Erik, I have driven almost more than ten r5 Turbo and all did this ratteling when geting off the throttle. Mine does it too. Some are louder and others not. You can adjust the freeplay of crownwheel and pinion from the outside of the gearbox, there where is the oilseal of the shaft (cardan) there you can turn the hole part where is the oilseal inside the same way you adjust the bearing of the differential, but adjusting on left and right side on the same time. But i think the noise will remain audible when going off the throttle. I heard that maybe using an other special gearbox oil the noise is less loud.

Regards

Thanks for your response T1. Unfortunately the procedure you describe hardly changes the freeplay of the crownwheel and pinion but only puts more or less pressure on the bearings. The reason for this is that the 369 (and UN1) gearboxes only have an adjustable nut on the right side of the gearbox. So turning two nuts at the same time as you describe is not possible because there is only one.

I also have UN-1 gearbox of a R25 which I tried on my T2. This gearbox does not rattle! I loosened the nut on that gearbox to see if this would cause the rattling. Even after loosening the nut quite a lot the gearbox did not start to rattle! Unfortunately I cannot keep using this gearbox because it has worn too much. Besides the connection for the speedometer is not there.

Thanks anyway.

Best regards,
Erik

Hello Erik,

Sorry, yes, you are right. But i think on the inside part of the side that is not adjustable you can change the thin spacers to adjust the freeplay. But for this operation you need to open the gearbox.

Best regards