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TR2/3/3A TR3rear end knocking?

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I have a strange knocking sound coming from the Diff. It sounds like a u-joint banging against the tailpipe but that's not it. It's from the inside. It is loudest at a steady speed and lessens when accelerating or coasting with the clutch out. Any ideas?
 
Bill,

Sorry I did not reply earlier. There are so many things back there that could cause a knocking sound that only a thorough visual inspection may be the only true way to know. I would start with items such as the dampers and damper links to make sure they are attached to the frame, grab the driveshaft and give it a good shake for any improper movement, check springs for broken leaf, wire wheels? check splines for wear. If these prove good then your next best look should be in the rear axle. You will have to remove the rear cover. knocking noise from the axle may include splines on halfshafts or in differential gears being badly worn. Improper shimming of gears, teeth damaged, gears worn, or worse gears broken off. Based on what I hear about taking the rear axle apart it sounds like it can be a real bear of a job if you plan on doing it yourself.
 
Rear axel repair is best left to a professional. You have to use a case spreader to get the diff. gears out. All of the parts are very sensitive to proper tolerance. If you are slightly wrong they tend to make tons of bad noise. I agree that the first step is to take the cover off and give it a visual inspection with a strong light. I wouldn't drive it around if you don't have to, may just make things worse.
Good Luck, Tinkerman
 
Dave, at The Roadster Factory (814-446-4491, tech line 12:30pm till) knows a guy in Florida that is a wiz at running gear rehab, and reasonable. I actually talked with the guy once years ago and he seemed to know his stuff. Give Dave a call. Shipping something that heavy and bulky can be a real problem. Hope this is a good lead. At least Dave can give you expert tech advice, free....


Bill
 
A TR rear axle / diff job can be done by any reputable rear end expert. Check with others in your area to find a good one and take the axle assembly out the car and over to his shop to get an opinion. I had a problem and was told I needed a new crown and a new pinion gear. I bought these from TRF (made in Italy) and took it all into that shop. A few days later, it was ready and I re-installed it in my TR3A. I've had no problems since then during the 30,000 miles driven since then.
 
Bill if you do need rear end work bear in mind that the tr6 had an optional high speed ratio of 3.45 If you dont have OD this gearset will give you extra top-end cruising speed.Of course this will throw off the otherwise deadly accurate speedometer and cost a little punch of the line but might well be worth it.....
MD(mad dog
 
The problem turns out to be a broken tooth on the pinion gear which thankfully fell strait to the bottom of the case and did not get caught in anything. I keep thinking about how lucky I am. If that tooth had been caught and seized the rear end while I was driving the damage could have been much worse that the $1500 or so I project this will end up costing. I’m planning a complete rebuild while I’m there.
Does anyone have any thoughts about gear ratios? MD made a good point on the 3.45 gears. I was thinking of that even though I have an overdrive. On the other hand I don’t drive it n the highway much and some 4.10 gears would be fun.
 
Bill,

The same thing happened to my last TR3..broke a pinion tooth.

Now the good news...I bought a TRF r&p set and replaced it myself. I hadn't done much rear axle work in years except on 9" Fords but it was a simple job.

And, at least in my case, set-up was non existent. I simply removed the old ring and pinion gears, put in the new gears using the original shims in their original places, and bolted it together.

I did NOT need the elusive "spreader" tool...it came apart and re-assembled quite easily. And when I checked the tooth pattern it was spot on.

Complete rear axle overhauls require a little more work...but the ring and pinion is built to a tight tolerance...don't let this scare you...YOU can do it...
 
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