Weird Noise Under Car

[canbeam]

I am getting a weird intermittent noise from underneath my Tiger. It is hard to explain, in that sometimes it sounds to me like something is loose and sort of grinds, or rubs roughly once in a while. It's not like a noisy bearing or U-Joint vibration or grind, which I have experienced on other cars I have owned. I took the Tiger into a local speed shop that I use on occasion, and they checked underneath everywhere, testing all bolts, and looking for cracks, for anything they thought it could have been, and it still makes this noise. I have the Dan Walters Torque Arm set up, but it checked out fine. The noise is intermittent, only while I am moving. It doesn’t seem to make a difference if the road is bumpy or smooth, I’m going around a corner, the speed I am going or accelerating or decelerating. I’m starting to wonder more and more if something is happening in my transmission or the rear end. It could have something to do with the positraction, so I’m going to put the car on axle stands on Friday, and change fluids in both, to see if that helps. My rear axle and/or transmission seems to whine a bit more at 60 mph, but that could be my imagination. Maybe it as simple as low fluid. My car doesn't leak much though.

I have been researching on the internet, and there are a lot of opinions as to what fluids to use, so will be studying that more this evening. For the tranny, David Kee says on his web site to use 75W-90 gear lubricant, or 80W-140 gear lubricant for more aggressive driving. With respect to rear end, I have seen people who say use GL-5 lubricants with built in friction modifiers for LSD, but there are different opinions on whether to use 75W90, 75W110 or 75W140. I assume this has something to do with the heat and heavy usage. I wonder though how the different viscosity effects the performance of the LSD

Any suggestions or thoughts on this would be appreciated.

Ron

[Warren]

Piece of Sunbeam makes a real aggravating little brake noise till the pads warm up in the rear but they're Fiat x19 brakes.

A professional Cobra guy and Paradise Wheels owner, who recently bought a local member Tiger, suggested using Brad Penn 80 to 90 gear oil as it's best for the brass in the top loader.
From the label of the product... Will not harm yellow brass bronze copper another soft Metals used in synchronizers bushings thrust washers and other components typically found in classic manual transmissions and transaxles contains no friction modifiers .

[canbeam]

Thanks Warren. I'll see if I can track it down at a retailer in Canada. I can order it on the internet, but I only have tomorrow to work on the car before attending a British Car Show on Saturday, a couple of hours away form my home.

Ron

[canbeam]

Forgot to mention I have Willwood disc brakes all around with 15" Panasport wheels that have been on the car for probably about 5 years. The car is lowered but while all spaces are tight, there doesn't seem to be any rubbing due to suspension movement or wheel turning. Unless I am getting fooled by echoes, I would swear the noise is inboard and under the rear half of the car. Drives me nuts.....

[Mlerne]

I had the exact same thing happen not too long ago on my 66 Mustang and it also drove me round the bend. I was convinced it was either a faulty pilot bearing or something else in the transmission but the intermittent noise did not seem to be reactive to clutch depression. Turned out it was an exhaust pipe that the every now and then would rattle close to the tranny. Sometimes the stupidest answer is the right one!

[canbeam]

I'm going to have another look underneath to see if there are any wear marks anywhere. My exhaust does rattle in the frame sometimes as I have big pipes, but that is a totally different rattle noise. But still worth checking.

I live in a small Town, and all I could find for the rear end is Royal Purple 75w-90 Synthetic gear lube. From what I have read, and what Warren said about the yellow metal corrosion, I wouldn't want to put this in my tranny because of the sulphur, but has anyone used this lube in their rear end with LSD. It says on the label it has the friction modifier in it, and I don't think there is any yellow metal to worry about in the rear axle.

[Warren]

Conley is the Cobra restorer and pro top loader rebuilder. We have another thread that discusses the sulphur issue. Now I know a guy who's really cheap and put the stinky sulphur stuff in his Tiger . He also put a shiny brass key in the oil on the bench for nearly a year. Now that was not a scientific test as it didn't get hot ever.
I , I mean he Didn't use the stuff on a new transmission or rear end.

When I googled the Brad Penn I got some hits from Amazon and Walmart. I'll add a picture of the bar code on the bottle.

As for the little noises maybe turn up the tunes it makes my header rub go away mostly...

[65beam]

Warren,
The sulfur-phosphorus compound used for the extreme pressure additive is why you never want to add a conventional gear oil to a transmission that has parts made of yellow metals. This starts a corrosion of parts such as syncros that can't be stopped. If you don't know if the gear oil has sulfur-phosphorus in it just smell it real good. The smell of sulfur is hard to miss.

[Warren]

Bob, I recall the earlier thread. There's also more than the mere mortal needs to know on the WWW.

Also claimed is that they do something​ to the sulphur oils to make them not attack the soft metals, believe it or not. For a few bucks more and given the Federal case it is to R&R a Tiger trans, it's a no brainier.

I have a fresh wide ratio transmission for the new Brad Penn oil. I won't ignore the advice of a builder like Craig.

[65beam]

Originally Posted by Warren

Bob, I recall the earlier thread. There's also more than the mere mortal needs to know on the WWW.

Also claimed is that they do something​ to the sulphur oils to make them not attack the soft metals, believe it or not. For a few bucks more and given the Federal case it is to R&R a Tiger trans, it's a no brainier.

I have a fresh wide ratio transmission for the new Brad Penn oil. I won't ignore the advice of a builder like Craig.

Warren,
We're talking different things here. I'm well aware of the Brad Penn product since we are a master distributor for them. I have no problem with their product since I sell their product. The sulfur-phosphorus is an extreme pressure compound added to conventional gear oils. This is what makes the gear oil stink so bad. The purpose of this additive is that it prevents sliding metal surfaces from seizing under conditions of extreme pressure by chemically combining with the metal to form a surface film to prevent what could be called welding or seizing of the two metal surfaces. FYI, there are a couple types of crude oil, Naphthenic and Paraffinic with Paraffinic being the most widely used for lubes due to the high viscosity index. Naphthenic has a high solvency property.