MTFCA Forum

Im on the Spokane tour (it's beautiful here) but I'm dealing with a noisy rear end. I promise it's nothing I ate....

A little history.

I have 1921 Touring, the Ruckstell was rebuilt 3 yrs ago with all the good stuff. New Pinion gear installed then and the ring gear was perfect. We set the r&p lash per standard specs. After the rebuild, there was a MAJOR NOISEY R&P but after 1000 or so miles, it settled down to a nice, acceptable whir. No noisier then than any of your cars.

Fast forward to 4 months ago, and I had Micky and his partner down in Bakersfield build me a Laycock drivetrain - actually it took him over a year (but whose counting) and I finally installed it 4 months ago. Their work is regarded as the best in the business and the end result is a literal work of art. It works great and shifts flawlessly. I installed it with the same spool and fun projects bearing I had with the original drive shaft. I also used the same number of paper gasket spacers between the spool and ruckstell housing as I had previously.

However, now there is a new whirring/grinding noise coming from the drivetrain I can't identify. It ONLY happens on acceleration under load. At cruising speed, the noise is gone. The pitch/frequency of the noise under acceleration is the same no matter what gear I'm in, low Ruckstell, hi Ford, over drive, direct drive. To me, this eliminates the entire input section to the Laycock. So it has to be either the output of the Laycock or the ring & pinion. After several hundred miles, the noise hasn't really changed or gotten worse, its persistent, again only under load and always the same pitch regardless of what gear I'm in . This leads me to think it's the R&P again, just manifested in a different way as the sound is different from the first time I rebuilt the Ruckstell and rear end.

If it Is the r&p, is it too tight or too loose? I suppose it could be coming from the Laycock, but I'm not familiar with the inner workings other than I know there are several bearings of different types in that unit.

These noises are so hard to diagnose as they travel thru the drivetrain and resonate in odd ways making you think it's coming from one area when in reality it's coming from a totally different place.

Anyway, thoughts and educated opinions welcome.

AdminJeff

Ps, yes, I finally finished my move to Idaho a month ago (what a nightmare, I can't find half my crap) and I'm slowly getting the shop back together. I'll be spinning up the starter/generator rebuilding biz again once things settle down in a few months. Thanks for all the inquiries, but this move has been brutal. The shop move alone was over 30,000 pounds.

I would suspect the ring/pinion. It may be a matter worn parts rather than of adjustment. It may or may not improve with some run time. Used gears with an established wear pattern may not run their quietest when set to spec. I'd be inclined to replace both the ring and pinion with new parts if the noise can be isolated to them and if it persists at an unacceptable level or if it gets any louder. As you pointed out, it can be difficult to be certain of where a noise is coming from. Sometimes an exhaust system can make sounds that mimic gear noise. So can tires. If you continue to run it, it would be a good idea to check all the drive train lubricant reservoirs frequently for excessive free metal. I'd do so immediately after a run when the lube is warm and stirred up.

...what a nightmare, I can't find half my crap...

I moved here in 1985. There are things I know I have, but I have no idea where they are.

We moved here six years ago and there's still stuff in boxes that contain stuff that we will never use but is far too valuable to throw away. Someone else will get rid of the junk when I cash in my chips.

TXGOAT2 wrote: ↑

Sun Jul 11, 2021 10:22 am

If you continue to run it, it would be a good idea to check all the drive train lubricant reservoirs frequently for excessive free metal. I'd do so immediately after a run when the lube is warm and stirred up.

those was the first things I checked... and I've ruled out exhaust. its definitely a drivetrain noise. I'll update this thread if/when I learn more.

" We set the r&p lash per standard specs."

The lash is almost unimportant. Set ring & pinion mesh for an even contact pattern on the gear teeth and for smooth rotation. If you do those things first, the lash will take care of itself. In other words, don't set the lash, set the mesh. You can end up with excellent lash numbers and horrible mesh if you only care about lash. (Why your R&P sounded bad when you first set it up.) Yes, I know, that runs counter to all the published procedures and I sometimes get told I don't know what I'm talking about. Oh well...

I'm not a Laycock expert, but doesn't it use a separate sump for lubricant ? If so, you might learn something by taking one oil analysis sample from the Laycock and another sample from the differential, then send both in for a lab analysis. When the results come back you should have a pretty good idea which one is shedding metal.

I know, that won't help you right now on the tour. But I'm betting no amount of educated guessing will give you an absolute answer right now either. About the only "right now" analysis you could do would be to check the temperatures of the overdrive and the differential immediately after driving. Is either one excessively warm ?

It may not be shedding any metal, but it's something I'd look for.

It's a long shot, but your tires, or any one of them, could be causing the sound. A good way to check for tires "singing" is to run the car over pavement that has different textures at the speed where the sound is most noticeable. Higher pitch tire sounds usually occur on very smooth pavement. Coarser textured pavement usually either masks tire noise or prevents it from happening.

If you can get the rear end up. Run it in gear & go hunting. You should be able to pin point the origin. Use your ear & hand.

Jerry Van has echoed my thoughts on setting crownwheel and pinion mesh. It is the rolling fit of straight cut gears which needs setting, not the lash. As he said, the lash will take care of itself when the fit is correct, and it may be way off that specified in the books on rear axle assembly.

Perusal of Ted Aschman's 'Tinkerin' tips' volume two explains this and sets out how to do it.

Allan from down under.

The Laycock provides overdrive through a planetary gearset. A planetary set may "whirr" especially under load or acceleration and with no noise or vibration isolation (rubber mounts or insulators) in a Model T, the whirr possibly could be heard through the driveline. However, when the Laycock is "off" it is direct drive and shouldn't make any gear noise.

What kind of tires do you have? The tread on my Riversides sing as I go down the road, but this noise doesn't change under load.

I'm also on tour here and rode with Jeff on Thursday night - it's not the tires ! It sure sounds as though it's in the "drive train" area coming from the torque tube - hard to distinguish front or back due to the sound projection.

We're headed out of here in about an hour - should be a good run - been a bit warm !