Whining sound when power is applied

[samwhite95]

Hi All,

Sadly I'm relatively new to actually driving classics as I've spent quite a few years ground-up restoring a herald project that unfortunately never got completed (other commitments) and decided now life has settled down almost 10 years later, I would get back into the hobby. So very familiar with triumph's but not so familiar for what to listen out for!

From what I can see from the engine number (starting in YC) and notes left by previous owner who installed the new gear who was 2 owners previous and passed away which separated all the history of the vehicle, I believe my vehicle is running a entire rear wheel drive Triumph 1500 drive chain from engine to diff as it has syncho 1st and some writing on a notepad included with the car says 3.89:1 Diff. 

When I apply power to the car when moving, there is a mid range (around 300-400Hz) noise that doesnt seem to come from a specific place, I can hear it from all directions in the cabin, ontop of the engine noise. If I drop the clutch at speed, the noise disappears, likewise if I take my foot off the accelerator it stops immediately. The only 'clue' I have is a small leak I spotted on the diff when I got the chance to look under the vehicle when it was on the lift at my local garage. Is this sort of noise indicative of an oil-less diff? Aside from that I cannot hear any clunky, bumpy or grinding noises in any of the stresses of driving, I've even tried to suddenly apply power in an attempt to rule out any slop at the back end.

I plan to add some oil to the diff ASAP along with some stop leak for the time being whilst I work out if I need to take it out or replace, is there a brand of oil that is recommended? Is this the best course of action, and are there any other tests I can perform to find the root cause? Or is this just a normal sound for a classic car?

Many thanks in advance!

Sam.

[Wendy Dawes]

Hi Sam GL4 Ep90 oil for the diff.  These diffs are notoriously leaky , most Triumphs drop a bit if diff oil.  If you could video the noise and post on the forum it might give us all a bit more clue what it may be, hope someone can get to the bottom of it 😊

[samwhite95]

Many thanks Wendy, I will add the oil and see if it alleviates the symptoms a little, I've also noticed the gearbox is a tad tight on the gear shift so I'll make sure it is all up to snuff! 

[Clive]

It souunds like you have a bit of noise from the diff. Power on and the crownwheel&pinion are under pressure, no power to the diff and that pressure is released.

It depends how bad it is, but once a CW&P get noisy they are VERY difficult to get silent, all a rebuild can do is reset them with shims, but it is likely to still have some noise. Even brand new diffs from reputable suppliers can scream. 

Moss sell a "special" oil for noisy diffs. It may help a little, and they are clear it doesn't fix the issue, just attempost to quieten it a bit. It is a GL5 oil, but is safe to use. I expect any other 85/140 oil would do the same job

[DVD3500]

I was going to suggest checking for a cat's tail caught on the throttle linkage but the diff seems more likely... 😄

 

[samwhite95]

Hi All, thanks for the further replies, my dad came out for a drive and commented the same. He also commented saying that some of the noise seemed to be coming from the gearbox too so we'll put all fresh oil in both and see if it does anything in toning down the noise. I'll also check the prop is secure whilst im under there and check to see if there is excessive backlash. 

W.r.t. diff oil, does it matter which grade is use from 75W/90 to 85W/140? or is the school of thought that is all works, just the more viscous oils are more appropriate with gearing that is a little looser than it should be to take up the slack?

[Rutty]

Unless the diff is howling I wouldn’t worry to much about it. The diffs can go on for thousands of miles with no problems, my Vitesse has had a whining diff at high speed for over 8 thousand miles and it’s not got any worse. Just make sure you keep it topped up with oil.

[Clive]

1 hour ago, samwhite95 said:

Hi All, thanks for the further replies, my dad came out for a drive and commented the same. He also commented saying that some of the noise seemed to be coming from the gearbox too so we'll put all fresh oil in both and see if it does anything in toning down the noise. I'll also check the prop is secure whilst im under there and check to see if there is excessive backlash. 

W.r.t. diff oil, does it matter which grade is use from 75W/90 to 85W/140? or is the school of thought that is all works, just the more viscous oils are more appropriate with gearing that is a little looser than it should be to take up the slack?

Yes, thicker oil can help a bit. 

EP80 and 90 were the original specification, but ep80/90 is a good option especially for gearboxes. They MUST have gl4 oil, yellow metal safe or not, A thicker oil in the box can make the gearchange difficult.

When checking the diff for backlash, there are 2 different ones to check for. The CW&P is VERY subtle and should be a tiny amount. As in a couple of mm rotation. The backlash most people feel is the far more obvious one, play in the differential itself which is down to worn washers and isn't a serious issue. Of course, it could be a bearing, but a stripdown is needed to find that.

Mark is correct, many (most?) diffs whine to some extent or another, so don't fret too much.

 

 

[samwhite95]

Many thanks both, I've ordered the oil which should be arriving thursday / friday and plan to take it to my Dad's and get it all filled up and sorted on Sat, will report back if there's an improvement! 

[Kevin R]

I have been following these threads with interest regarding GL4/GL5, sulphur content and yellow metal.

To throw a spanner in the works I was checking by chance for cooling system capacities in the handbook that came with my 1980 Spitfire 1500 and noticed that it specifies GL5 Hypoid for both gearbox and final drive.

So, is 1980's GL5 sulphur-free or is my late car free of yellow metal 🤔

[glang]

Does look like that's a recommendation for export cars but what was different about their transmission or the oils available in other countries (USA?) is anyones guess.....

[Clive]

The biggest problem with gearboxes is that GL5 is too slippery (too good?) for the synchros to be able to grip the hubs. Many modern gearboxes (Honda, Nissan and probably many many more) are not suited tio GL5 either.

Today, most GL5 oil is yellow metal safe, but you have to check with the manufacturer if you wish to use it in your diff.

The simple solution is to play it safe, and use GL4 oil.

Incidently, the Honda boxes are very specific. I rebuild a Jazz gearbox (just 2 bearings required) and used a "compatable" oil. Correct grade etc and the gearchange is definitely clunkier. At some point I will drain and fill with the correct Honda oil. At £15 a litre....

That oil may be good in a Triumph box, a bit thinner, and correct grade of additives.

[drofgum]

Hi,

A point that hasn't been touched upon is the difference between the gearbox and differential requirements. The differential requires EP additives because the hypoid gear set has a wiping action where the gear teeth slide over one another. The gearbox is better served with an oil that doesn't contain EP additives because it depends on the friction between the synchro rings and the cone surfaces on the gears to match their speeds. EP additives decrease that friction and can lead to slower synchro action. The modern GL4 oils meant for manual gearboxes don't have EP additives that will reduce the friction in the synchros.

Regards,

Paul