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whiny differential

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nick Avatar
nick nick m
Bend, OR, USA   USA
I have lived with a whiny rear end on my '79 TR7 for more than 8 years. The clock shows about 95k on the car and I suspect it is the original rear end. It is mostly audible when going down hill in the higher gears. Recently I swapped it with a newer diff I had on my '76 car. The whine went with the diff and now sounds the same as it did on the '79 car. So the question is could this whine be rear bearings or would it be from the differential? As I say, it has been in that rear end for more than 8 years. If something bad was it happen it should have by now. I hate the sound and would love to make it go away. I did check the oil level at on point and it was OK. Maybe a different type of oil would cure the problem. Any thoughts on this?



nick

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Bergie Bob Berg
Powell, Ohio, USA   USA
change the diff fluid and see if that helps...good starting point.....I'm using motul HD 80w-90...also have a flat magnet in the diff cover to catch fine metal parts...surprising what it picked up after 2 years.....


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Bergie Bob Berg
Powell, Ohio, USA   USA

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TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
My guess is the pinion bearing is whats making the noise. Pop the rear diff cover after you make sure you have a new gasket on hand, Take a look at the wear pattern on the gears. You can clean everything up with some brake cleaner and then smear white grease on the teeth. Turn the diff until the grease gets squished away and you can clearly see the contact patch. If its in the middle and there isn't excessive slop, then the gears are OK and probably not making the noise. Most likely, you can just pull it apart, install new pinion and carrier bearings, and then reassemble using the same spacers and old crush sleeve. You will need an inch pound torque wrench to make sure you torqued the crush sleeve down enough to create the correct preload on the bearings. The nut doesn't get torqued to any particular value, instead, it gets torqued down until it takes a specified amount of force to turn the pinion. Not sure what that figure is, but I'm guessing its around 18 inch pounds to turn the pinion. Before you pull everything apart, check that torque on the pinion just for giggles. If the bearing is toast, it will spin real easy. Certainly less than 18 inch pounds. Been a long time since I did a TR8 rear end. My brain is full of numbers for the 8.8 rear ends I like, but not for the stock rear ends. The numbers you will need should be in the shop manual somewhere. I know the manual says you need a case stretcher.... not true. You might need to make a narrow shoulder socket to remove the pinion nut.... or is that for the BMW diffs?? Oh well, you'll find out when you go to take it apart. Good luck. Its much easier than people would have you believe.

nick Avatar
nick nick m
Bend, OR, USA   USA
Thanks for the inputs. Todd, that's a great description of how to tear that thing down. But it sounds scary since I've never been inside a differential. I'll order a gasket and take a look in there. If nothing else I can change the oil.



nick

Charlie D Gold Member Charles Dankmeyer
Arnold, Maryland, USA   USA
Rick, I agree it sounds scary. But, nothing ventured, nothing gained. I am in the process of changing the driveshaft on my TR8 from the stock CV joint to universal joints at both ends. The flange on the rear needs to be drilled to mount the new drive shaft. The seal on my differential already leaks and needs replacement, but I am not familiar at all with crush sleeves and knowing how to make sure I have put things back properly when all I want to do is take the flange off, drill it, replace the seal and reassemble. I have been told if I don't get the crush seal just right, the rear will be whining. Shoot, I don't even know what the crush sleeve looks like yet! Guess its shade tree mechanic time--take it apart, fix it up, or do without. These cars are an adventure!

darrellwalker Darrell Walker
Vancouver, Washington, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
In reply to # 1492657 by Charlie D Rick, I agree it sounds scary. But, nothing ventured, nothing gained. I am in the process of changing the driveshaft on my TR8 from the stock CV joint to universal joints at both ends. The flange on the rear needs to be drilled to mount the new drive shaft. The seal on my differential already leaks and needs replacement, but I am not familiar at all with crush sleeves and knowing how to make sure I have put things back properly when all I want to do is take the flange off, drill it, replace the seal and reassemble. I have been told if I don't get the crush seal just right, the rear will be whining. Shoot, I don't even know what the crush sleeve looks like yet! Guess its shade tree mechanic time--take it apart, fix it up, or do without. These cars are an adventure!

Charlie,

You don't need to worry about the crush sleeve if you are only removing the flange and front cover plate. The pinion preload is set with a second nut inside.

-Darrell



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA

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Charlie D Gold Member Charles Dankmeyer
Arnold, Maryland, USA   USA
Thanks Darrell, that's good to know. I won't be surprised when I take the flange off!

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