Rebuilt 742 3rd member installed 3-4 years ago. Just now driving this car. Can't remember if it has a cone or clutch type sure grip. Added ford friction modifier with reg type gear oil. Also green bearings on axles.
No problems when cold, when it gets to temp you can really feel it and sounds awful mostly during right hand turns. I've tried adding more Ford friction modifier that didn't help. Could the clutch's just be stuck? I doesn't do it when cold so I'm thinking that's not it, but I have raised it up and when cold I could not get 1 wheel to turn while holding the other. Maybe it's setup too tight and as it gets warm and expands things are too tight?. Any suggestions?
Maybe jack it up and give a good pull on the wheel and see if there is any axle play in and out? I've not had good experiences with green bearings.... mind you this was with circle track racing. If you find any play, I'd pull the axles and investigate further...
I use Sta-lube equa torque and find a parking lot to do some figure 8s.
Tried figure 8's yesterday and again today. No better, maybe worse. Been a while since I drove this car. Remembering I had the same problem with a 3:91 gear, 489 case. Pulled that third member out and had broken spider gears and cones were worn out. Swapped out to current 3:23 gear, 742 case, did quick test drive, no problems detected then put the car away. Now I'm wanting to drive this car again and the same problem returns. So I'm wondering 2 third members in a row having the same problem or is something else causing This? This housing is shortened with after market axle bearing ends welded on with rear discs. Not sure what to do at very least I'm pulling third member. Is their anything to look for that could cause this with the housing?
Same axles and bearings with both center sections? Did you put a new sure-grip in it when you switched cases?
Same noise and clunk with 2 completely different third members. Maybe the housing isn't true and/or ends not square? Twisted tube?
I get that but I was asking if the axles and bearings are the same with both center sections? Or did you swap axles and bearings when you changed out the center?
Everything spins nice by hand. I disconnected the drive shaft and with wheels and rear rotors off. I could turn it by the pinion with ease. Also by the axle flange. Real smooth no noises. BUT Cannot hold one wheel and spin the other. Pulled axles and third member, don't see anything obvious. Will tear apart sure grip even though I haven't done this before think I'll give it a try.
Found a couple of heat marks. Don't know if what or if it's normal or not.
Some of the Sure grip clutch discs.
I am having the same problem, but it is only when I am on the throttle on a sharp turn out of a parking lot. Does it make the sounds when coasting?
No noise coasting.
Smooth easy turns no noise, but yes out of a parking lot or u turn is when I was getting the clunking sounds.
Quote from: nsmall on August 01, 2020, 11:51:13 PM
I am having the same problem, but it is only when I am on the throttle on a sharp turn out of a parking lot. Does it make the sounds when coasting?
Who's sure-grip is that? A stock one or aftermarket? If aftermarket, have you contacted the seller? I wonder what they say about it?
Suggestion. Before anyone pulls anything else apart...make sure the oil level is correct, and the right Mopar additive is in the oil, I often use a bit more of that then recommended.
Twice I was able to get a rear end quiet by making sure of the oil/additive.
https://www.doctordiff.com/8-3-4-489-case-third-member.html
"Use conventional 85 W 140, GL-5 grade gear lube. Add 1 bottle XL3 Ford Friction modifier additive when installing the clutch sure-grip differential."
I am going to try this recipe this week. We have the same problem friend.
Quote from: Burdar on August 02, 2020, 02:47:23 PM
Who's sure-grip is that? A stock one or aftermarket? If aftermarket, have you contacted the seller? I wonder what they say about it?
That's my sure grip. It had left hand threaded bolts which I am told means it's stock OEM and If they were right handed it would be after market.
There isn't any fiber discs at all. I bought this 4 maybe even 5 years ago from a swap meet vendor who was recommended. At that time he said he was quitting due to health reasons. I tried to call him about a different issue some years ago no answer.
Quote from: Kowal on August 02, 2020, 03:35:10 PM
Suggestion. Before anyone pulls anything else apart...make sure the oil level is correct, and the right Mopar additive is in the oil, I often use a bit more of that then recommended.
Twice I was able to get a rear end quiet by making sure of the oil/additive.
Yup did that before tear down
Quote from: nsmall on August 02, 2020, 09:12:12 PM
https://www.doctordiff.com/8-3-4-489-case-third-member.html
"Use conventional 85 W 140, GL-5 grade gear lube. Add 1 bottle XL3 Ford Friction modifier additive when installing the clutch sure-grip differential."
I am going to try this recipe this week. We have the same problem friend.
Oh I hope you don't. I too changed gear oil and added 2 bottles of friction modifier before I finally tore it apart.