So, I have had a rubbing noise that happened intermittently on deceleration. It would instantly go away if I touched the clutch or the throttle. Looked at all the brakes and drive shafts sprocket and the diff. Regressed the diff with no effect. Nothing obviously stood out. Now that I'm doing my winter maintenance, I could hear a light rubbing noise when turning the left side with the hub and the right axle was removed. A little more investigation revealed the reverse hub had some run out. So out came the diff. Measuring the runout at about .040". This is with the reverse hub fully seated in the forward position. So further apart it came.
First remove the 5 bolts, they are very tight with red loctite, so an impact gun is required.
with the outer cover off you can see the torque sensing part if the Quaife QBA7R diff.
Then lift out the reverse planetary gear assembly
down inside where the engagement dogs go, was a small piece of a metal dowel, (I removed it before the photo, it's the piece in the following photo)
This piece was preventing the reverse hub from fully engaging the drive dogs.
It came from one of the axles for the planitary gears, so I fished out the rest of the axle. It was broken in three pieces.
So I checked the rest of them and found two more broken, but they had not fallen out. The pins are held in with a large singe snap ring on the inside lip.
here is a photo of all the parts. The socket head screws are just place holders for the broken axles. They would be flush like the other 5 remaining ones.
now if I can get replacement parts, this will be simple.
Also good to note, that the reverse cavity is separate from the diff cavity. So just greasing the outer fittings will have no effect on the ATB section. You will have to remove the bearings and use the grease fittings on the ends.
Great post! Wow! You are really lucky that you didn’t have more damage. What kept the planetary gears from getting out of place and jamming when the axles broke? I assume you are replacing all of the axles, not just the broken ones... correct?
Charley
Lucky I never used reverse! I always pushed the car by hand to turn it around in the garage. The planetary gears where held in by the remnants of the axles and grease. As long as reverse is not selected, the whole assembly stays in one place. As for replacing them all, will a new part not fail? Maybe the proven ones are better? No real way to know.
Wow, that is lucky. If that part got into the wrong area it could have been bad. How many hours does the unit have on it? Was it past it’s recommended overhaul interval? If it were me I would replace them all. All of those axles have likely seen similar stresses so without testing you really don’t know how close the others are to failing. Seems like cheap insurance.
But, I come from a very risk averse aerospace background so I am pretty conservitive. Never wanted to have a conversation with NASA about... yeah, we saw that three of the 8 pieces failed but the others didn’t break so they are probably good... you should be fine to fly the Space Shuttle. 😉
Charley
I agree on the conservative approach, as I am the director of maintenance for a group of private jets. But if the root cause is say the positioning of the 3 gears that failed, then a new part will fail prematurely. If the the problem is the production of the axles, or the design of the whole system, then new parts could still fail. If it was a bad batch of axles, then replacing them all would make sense.
The real question is can I get replacements? This is an assembly that was jointly developed by Quife and Radical, with Radical holding all responsibility for its support.
The car & diff have about 2400 miles, with diff having a 8000k recommended rebuild interval. So mine is about 50% there.
I believe Forum member “XNR Racing” (Josh) has been rebuilding SR3 Quaifes, so you might want to contact him to see how he is getting the parts.
Charley
I have seen this before with these diff's, its one of the few things that goes wrong with them.
As you say if you you don't use reverse they stay in place and you don't have problems, in general we do not use reverse with the chain drive diff to avoid this! If you do they normally fall out and then you cannot completely engage forward gear again.
Parts might be an issue, Radical will sell you the parts to refresh an SR3 drive unit but I have never heard of it with the chain drive diff. Everyone has been back to Quaife to be repaired via Radical.
I am a little worried that parts might be an issue.
Worst case I could have a machine shop make some from hardened tool steel.
I would reach out to Mark Quesada, the Service manager at Spring mountain and see what he can do for you.
Charley
Update, parts have been ordered. There is a newer style pin/axle that will need to be welded in place. I should have the parts before the end of the month. Then just put it back together.
Great. Where did you get the parts?
Charley
Ordered them through Chris at Spring Mountain. Normal stock order. The factory supplied the part numbers.
Great!
The new pins/axles are installed. I had them tig welded in place. That way, if they do break, the won't fall out. Apparently the new version of the diff has them pinned by a roll pin at the top. But the welding was their intermediate solution. I replaced the one end bearing because you have to pull across the balls to remove it. It had to come from the U.K. To get a quality part.
also there are 3 small balls and spring that are between the sliding part and the center, FYI.
Now to just reassemble and reinstall!
Finally track tested, no more noise!
