C4 Differential - knocking
07-04-2015, 08:04 AM
#1
C4 Differential - knocking
Hi, have a bad knocking noise that feels like the diff is trying to engage when moving. It is not consistent but happens often enough if you move the car 20 yards. I am not prepared to drive it further to see what happens. I have the 4wd drive warning system light on. That started off as intermittent then stayed on more consistently. Have only done probably 15-20 miles since lights stayed on. Parked it for a bout 4 weeks and then when I went to drive it I moved 20 ft and then noticed this noise. I am going to get it trailered to my Indy but anyone have thoughts on what could be causing this? It sounds expensive. Sometimes a knock but occasionally its a grinding noise. The knock makes the car shudder. Any thoughts would be appreciated.
07-04-2015, 06:18 PM
#4
Race Car
C4 Differential - knocking
Planet gears should take you over the 5k mark. I won't say how far over. But be prepared for more...in fact, sometimes it's best just to source a used or rebuilt transmission.
Outside that, apart from the abs light being on, I had rear cv joints get over worn and they clanged. So small chance it's only those, but with the shudder, the clanging and the abs light, sounds planetary.
Outside that, apart from the abs light being on, I had rear cv joints get over worn and they clanged. So small chance it's only those, but with the shudder, the clanging and the abs light, sounds planetary.
07-06-2015, 08:52 AM
#6
Yes thanks, 1990 and its done 106K miles. I have not tracked the car mainly fast weekend driving. The previous owner only did one or 2 track days I believe. I plan to use the car for track days though when all the issues have been resolved.
07-06-2015, 08:56 AM
#7
Planet gears should take you over the 5k mark. I won't say how far over. But be prepared for more...in fact, sometimes it's best just to source a used or rebuilt transmission.
Outside that, apart from the abs light being on, I had rear cv joints get over worn and they clanged. So small chance it's only those, but with the shudder, the clanging and the abs light, sounds planetary.
Outside that, apart from the abs light being on, I had rear cv joints get over worn and they clanged. So small chance it's only those, but with the shudder, the clanging and the abs light, sounds planetary.
Trending Topics
07-06-2015, 10:02 AM
#8
Planet gears should take you over the 5k mark. I won't say how far over. But be prepared for more...in fact, sometimes it's best just to source a used or rebuilt transmission.
Outside that, apart from the abs light being on, I had rear cv joints get over worn and they clanged. So small chance it's only those, but with the shudder, the clanging and the abs light, sounds planetary.
Outside that, apart from the abs light being on, I had rear cv joints get over worn and they clanged. So small chance it's only those, but with the shudder, the clanging and the abs light, sounds planetary.
07-08-2015, 06:11 PM
#9
Racer
Join Date: Jun 2008
Location: Sawbridgeworth, Herts, UK
Posts: 252
Likes: 0
Received 2 Likes
on
2 Posts
Hi Rabs just wondering how you are getting on with this. I had to get my mech to teardown the gearbox to see what had happened, not sure how else you could check.
I hope you've been lucky and it's something else but if you have joined those of us unlucky enough to experience this failure don't lose faith, I had both the awd clutches replaced and all the syncros renewed. It cost a fair amount and as the engine was out I had it resealed and top end rebuilt too.
The way the prices have gone up in the years since I have more than covered the cost and I have a rock solid car that feels like mine. Good luck and please keep us informed, the help and support of this forum is invaluable.
Keith
I hope you've been lucky and it's something else but if you have joined those of us unlucky enough to experience this failure don't lose faith, I had both the awd clutches replaced and all the syncros renewed. It cost a fair amount and as the engine was out I had it resealed and top end rebuilt too.
The way the prices have gone up in the years since I have more than covered the cost and I have a rock solid car that feels like mine. Good luck and please keep us informed, the help and support of this forum is invaluable.
Keith
07-09-2015, 02:33 AM
#10
C4 Differential - knocking
Keith, really appreciate the message. I am getting the car towed to Steve Bull Specialist Cars in Devizes today. They are recommended to be the best local specialist for 964 by a few guys I have met. I am hoping it's something else but time will tell. The car has 106,000 miles and leaks quite bad so it might be time to bite the bullet and go all in as you did. The engine pulls great though so until now I could live with the oil leaks. I will keep you updated. Have been looking at second hand gearboxes but prices of all spares have increased inline with car values I feel. Hopefully I've caught it before any more damage has happened. Do you know the part number for planetary gear? I have been looking in PET but have struggled to identify it. I believe it's part of the transfer unit on the gearbox?
07-09-2015, 05:20 AM
#11
[QUOTE=Rabs;12417835 Do you know the part number for planetary gear? I have been looking in PET but have struggled to identify it. I believe it's part of the transfer unit on the gearbox?[/QUOTE]
Looks like PET .pdf Page 131 Item 27 - good luck!
Looks like PET .pdf Page 131 Item 27 - good luck!
07-09-2015, 07:17 AM
#12
Burning Brakes
C4 Differential - knocking
Definitely sounds like planetary to me. If it hasn't completely fallen apart and caused further damage (sounds like it hasn't yet) you may get away with a straight replacement second hand part. I would recommend getting the pins welded in before reassembly. I sourced a second hand bits from cogscogs.com in the US. Great guy to deal with too. Good luck.
07-10-2015, 04:33 AM
#15
Racer
Join Date: Jun 2008
Location: Sawbridgeworth, Herts, UK
Posts: 252
Likes: 0
Received 2 Likes
on
2 Posts
Gents, just to chime in... I am definitely not an expert on any of this but I was advised not to weld the thing and to have the holes peened. Something to do with the materials involved. Having said that the photos in your kiwi thread look very impressive. Maybe someone with more knowledge could give us some qualified guidance here...