Pumpkin/Diff Noise ... Am I making the right call?

[Ralph]

The diff has been howling since I got the car on the road in 2017, and the advice I've been getting from people way smarter than me is it may go in 2 weeks or 2 years. I have parts on order to hopefully fix it ... My practical brain says don't take the car on my 250 K trip to our summer place until the fix is done. My "damn, I've been looking forward to this drive" brain is pulling me to take the chance.
But
The warnings of "catastrophic failure" ... (seizing up one or both rear axles at 70 MPH as I'm passing that slow camper) have my practical brain in the lead...so leave the car home this time and delay the gratification.
Not really a question, but looking for encouragement that I'm making the safest call.

[spl310]

You are making the safe call. But a question, can you get it done before you get going?

[Ralph]

Nope. Leaving Friday afternoon ... If I had ordered the parts a week or so earlier (or had them air freighted for about a million dollars) I'd be golden. The good news is that the drive is one I'll be doing pretty much every second week during the summer. Kelowna BC to Christina Lake BC. An easy 3 hr drive with a stop for coffee; 2 1/2 steady with not a lot of traffic. Frenetic 2 hour with the chance of an impound for 90 days. Have a look at google maps. It's a fun drive, but lots of dead spots for cell service.

[C.Costine]

Have you looked at the oil? Presence or absence of metal could help your decision making.

[Ralph]

Have you looked at the oil? Presence or absence of metal could help your decision making.

No I haven't...but I have a differential rebuilt kit from Paul Wells. It is scheduled to go to the shop Monday evening the 11th. They will have a look. Best case is we just need to do bearings ... not sure I want the know worst case. I'll reach out once I know more.

[vinechoy]

Better safe....with plenty more drives in the future.

I once changed ring and pinion on an mg midget and got more drivetrain noise due to improper gear wear pattern

VIney

[Ralph]

The shop says they found metal in the oil ... so are recommending a new gear set (3.89). Does anyone have a source for new ones out there?... I have a used one available, so I'm not totally stuck. The shop is looking as well.

[jhayden]

Ralph,

Dave Premo et. al. have recommended switching to the 3.7 diff (which came stock in the 2L) for the 1600, so this would be an ideal time to make the change.

Jon

[Ralph]

Thing is ... I have a U20 with the 5-speed, so hopefully can keep the 3.89

[TurboRagtop]

I changed my diff from the stock 3.9 to a 3.7 when the original failed.
I like the 3.7 much better.

[jhayden]

Thing is ... I have a U20 with the 5-speed, so hopefully can keep the 3.89

Ralph,

That is also the combo recommended by the experts here. I only saw that you had an SPL, and didn't know that you had swapped out the motor+trans.

Good luck.

Jon

[Jimmers74]

No experience with Roadsters with noise in the chunk, but I can attest that just replacing the bearings is a fool's errand. There are several youtube videos about how to do it properly, and it takes some skill. My Ford truck started howling, and bearings were replaced by a well meaning mechanic, but to no avail. When I did find the skill set in a mechanic, I was told that only OEM, Spicer, or Dana parts would be used, all as an assembly. That happened, only $600 more than I was charged by the well meaning fellow, but it was worth it. Good luck with your issue.

[JT68]

Thing is ... I have a U20 with the 5-speed, so hopefully can keep the 3.89

I may have an NOS 3.89 R&P. PM if interested, be glad to check. Previous post is correct, rarely are bearings the issue.

[Linda]

Previous post is correct, rarely are bearings the issue.

You mean diff bearings? What is usually the issue?
Linda

[JT68]

No experience with Roadsters with noise in the chunk, but I can attest that just replacing the bearings is a fool's errand. There are several youtube videos about how to do it properly, and it takes some skill. My Ford truck started howling, and bearings were replaced by a well meaning mechanic, but to no avail. When I did find the skill set in a mechanic, I was told that only OEM, Spicer, or Dana parts would be used, all as an assembly. That happened, only $600 more than I was charged by the well meaning fellow, but it was worth it. Good luck with your issue.

Ring&pinion wear or incorrect mesh is what causes the howl/whine. A bad bearing simply causes a roar, just like an axle bearing.