Diff whine

[sujitroy]

My Mk1 Stag's diff has a constant whine which has become annoying now. It used to whine on accelerating and decelerating, but now is constant at all speeds. Is there a DIY fix to reduce this whine? Like open it up and put some shins in? Use a different oil?

I was told replacements crown and pinons were no good. Is this not the case now.

I'm in US and am not sure if there are many people left who know how to tackle a Triumph diff.

I have a spare unknown diff. Is there a way without installing it if I can check the health of it?

Sujit

[flying farmer]

I have had quite a few diffs start quiet and get noisy over the years, some very suddenly, some over thousands of miles,depending on which bearing is failing first.

I have found on six rebuilds on various cars over the last 20 years that if I use genuine Timken bearings I can generally get away with a straight swap of the bearings and have not needed to do any re-shimming. This only works with the Timken bearings as other makes have different overall thicknesses which means re-shimming is needed and I don't have the bearing pullers needed to remove new bearings without damaging them, particularly the large pinion bearing.

Be warned though, if you only find one damaged bearing replace all six. This is because the other bearings will have been damaged by swarf from the first one, and these will in turn fail. I ended up doing my first diff three times before I learned this!

Your used spare diff will probably need oil seals, and getting the half shafts apart is the most difficult job on a diff strip.

I always mark the bearing caps with a dot punch to ensure they go back on the correct way. I have never needed the case spreading tool shown in the Haynes manual, the old diff will lever out quite easily, and can be replaced with care even with a few thou preload.

Make sure all the diff bearing surfaces are perfectly smooth, even the slightest pitting produces tremendous noise, the pinion bearings being the worse culprit as they are spinning 3.7 times faster than the output bearings. Of course, you can't actually see the inner race, but if it is starting to pit the debris will have marked the outer races.

Obviously check the teeth of the CWP for wear/damage, so far all have mine have been ok, apart from the spare I bought from an autojumble where the teeth were blue due to it having been run low on oil.

If you do end up being brave enough to try a rebuild yourself, be very careful about getting the correct bearings. Nearly all the parts suppliers list bearings for the Stag that are appropriate for the big saloon/TR/Dolomite series of cars, but the pinion bearings are in fact different on the two Stag diffs I have rebuilt, and on the first one I ruined trying!

I ruined the casing on the first one I tried to rebuild as the largest saloon pinion bearing will fit the Stag casing if you hit it hard enough, but then I found the pinion sat too high. When I knocked out the new bearing I found the old one was loose in the housing, I had stretched it and ruined it.

I was fortunate I had a spare housing, and in the end Peter of LD part managed to source me the correct largest bearing in two bits (inner and outer) from separate places.

Having replaced all the bearings I always try a little engineers blue on the teeth of the crownwheel just to make sure all is meshing correctly

I have been given a Stag Diff, in an unknown condition, by a mate clearing his garage. I intend stripping this at some point over the Winter as the 3.45 fitted to my Stag engined estate is a little too high geared for such a heavy car with 15 inch rims, but would suit one of my Stags perfectly.

Neil

[Phil S]

Even if you have to get bearings from the UK you must be able to find a classic car restorer who can rebuild a diff.
from what we see on US car programmes in th UK it appears you only have to drive down the road to have a choice of suppliers and a wealth of garages waiting to help.
I'm sure this is not quite the case but you must be able to find somebody.
failing that have a go yourself. engineering blue on the teeth is a must to correctly set the teeth mesh.
this is the cause of the noise when the bearings ware.
Phil

[sujitroy]

Thanks guys.

I was told the Triumph diff is different to most common types found in US and needs someone who knows Triumph to fix a diff. There was a nice welsh chap in San Francisco ( about 40 miles north from me) who helped me remove the flanges of my current diff. He had to apply heat to get them off. Unfortunately, he passed away.

I do have a 12 ton press. Do you think I can remove he flanges myself by applying heat?

I'm also aware, depending on the year of the diff, of the diff having a special preload washer of some type, Collapsible or something to that effect. Will this cause me issues when dismantling or during reassembly?


So, based on the constant whine, do you both say a bearing / bearing is/ are shot? Since I recall the diff only whined on de-accellerating, what a tell tell signs that the pinon and CW are worn?

I did see some YouTube videos on how to correct shim a diff.




I may put in the second diff as is and then work on my currently fitted one.

With the diff out wisdom tells me to consider getting the cone strengthened.


Sujit

[Phil S]

the bearing ware causes the teeth to move out of the correct mesh..when you apply the engineers blue to the crownwheel, you are looking for the pinion to wipe the blue off from the centre of the tooth. this should give a noise free ride, may be worth checking your spare diff before you fit.
the opinions have a collapsible tube between the 2 bearings so must be replaced when dismantled. some people advocate you can replace the front pinion seal and replace the nut as Lind as it is returned to the same spot...rather you than me...food for thought.
Phil

[flying farmer]

Bearings generally go first, CWP damage happens later if the problem is not corrected, but the noise usually causes a rebuild before then assuming the oil level has not fallen too low.

If you look carefully at the surface of the teeth on both the crown wheel and the pinion you should not see any wear, I have never seen any except on the one run low on oil, and the teeth were also blued with heat, so you should not see any of that either
it is possible to bodge a collapsible spacer, simply work your way round the bulging bit in the centre with a hammer while it is on the pinion shaft. This will lengthen the spacer slightly, and it only needs a few thou to make it re-useable.

I had to do this some years ago when new spacers were not available for a while and it worked fine, better than doing the nut up to the same place again and hoping for the best.

You should be able to remove the flanges with a 12 ton press. I have done quite a few with a 10 ton bearing puller.

!0 tons is normally no where near enough, but if I hold a big hammer on one side of the drive flange, and strike the other side sharply with a smaller hammer, the shock usually releases the taper. Sometimes it requires quite a substantial whack, and the stub shaft will normally fly quite a few yards before stopping.

I have only been defeated once and that was on some Dolomite Sprint half shafts that I had to take to my local John Deere dealership. The press got to 18 tons before the half shafts knocked a lump out of the concrete floor as they parted company from the flange!

Definately worth getting the diff extension strengthened while it is in bits.

Neil

[elvimto]

I rebuilt my diff I used Timken bearings also I did have a problem with the couplings they are on a taper and usually fitted way to far up the taper. At the time I did not have a ring and pinion but I was able to source a used diff. I made a spreader and some tooling and set it up and got the contact good but because it was an old set I could only get it so far. I have found that the blue they make today is more greasy than the old Prussian blue. Any way the diff did have a whine right around the 60 to 65 mph range and I was not happy with it. I sourced another diff and cleaned it out did some basic checks and installed it and it sounds a bit better. Since then I have a new ring and pinion and intend to install it in the first rebuild diff. I would use gear paint from GM or the likes its yellow and gives you a better indication than blue. It is doable but it is also easy to mess up the parts that are not easy to get. When you fit the hubs back on to the output shaft you can calculate the amount of pull up on the shaft to put them at. I found that they do not need the amount of pull up that they are given which makes them really hard to remove. I have a couple of extensions to strengthen which I can do at work but have been busy so I need to plan, and plan.