Scuttle Shake

[NutmegCT]

Keith - those drums look like the ones on my M-B. Similar metal removal for balance.

Are those original to your car?

I wonder if, back in the day, people drove the cars on relatively rough roads with lots of twists and turns - and didn't really notice the vibrations.

Tom

 

[Keith_M]

Hi Tom,
As I remember, you had mismatched drums, or something like that? My drums were on the car when I got it; whether they are original to the car is another question.

I don't remember the roads being that much rougher "back in the day", but the speed limits were definitely lower. Regardless, I still find it amazing that these cars were shipped from the factory with the drums that badly balanced, but it does explain why scuttle shake is such a popular topic among Healey owners!

 

[ttrotter]

Hi Keith,

I am looking for a local machine shop to do the job but, to date, don’t seem to have found anyone that was remotely interested or had the proper equipment (according to them).

What type of Machine Shop have you found or what I should be looking for?

All the best,
Ray (64BJ8P1)

Ray, ship them by UPS to Allen Hendrix in Greensboro, NC. His specialty is all things having to do with wire wheels, tires, drums, etc and especially good at getting the shake out.
https://www.hendrixwirewheel.com/
You won't be disappointed.
Tom

 

[Keith_M]

A final update to my scuttle shake story. After balancing the rear drums (see previous posts) the shake appears to be gone. Smooth as silk all the way up to 70.

I also installed a spin-on oil filter attachment and changed the oil. A good day all around!

 

[CanberraBJ8]

Thats great news Keith. I'll be looking around for someone to balance mine then!

 

[MCS]

Good Day Gentlemen,

I having been reading this thread since post one. It really should be separated into two completely different topics.
1. Scuttle Shake
2. Harmonic imbalance

It becomes confusing when many of the posts intertwine harmonic balance with scuttle shake, the shake as we all know is a well known documented frame problem, that was produced at the factory. Our LBC's were born with it, and if you want it fixed you better buy a new uprated frame. Its that easy, not cheap but fixable. I am not bashing our cars, TR6 "s I am told suffer worse, spitfires are also bad, it is just the way it is. Please don't beat me, the only vintage car I have any interest in is a Healey, started with a sprite at 14, which I still have, 35 years later, still cant see past a Healey. Drive a Jule frame car, I bet there is one in your club, it is solid. Last time I checked Jule has manfufactured around 500 frames. If you were to bolt only one corner of the Jule car to a hydraulic hoist ,IMO the entire car would lift flat and straight, it really is that strong, nothing moves. Don't try that with an original car. We could start a 3rd thread on other LBC's with the same frame scuttle shake. I uprated the frame to a Jule chasis after doing lots of home work, Jule is the only company out there to my knowledge that makes a frame that is solid and does not shake. You can mount square wheels on it and nothing shakes, nothing needs to be balanced. Sure you would get harmonic vibration from square tires but no shake. I do understand that it may be cost prohibitive for many Healey members, or just logistically impossible to do and still enjoy the car. I do not work for Jule, I have a BJ7 with a Jule frame, not finished yet, and a BJ 8 with a Jule. Yes I am a customer and a friend, and every time I drop by his shop there is a line up of Healey frames being created. I love the business, life is to short to do everything so I go snoop and wish I had the ability to do what his fabrication shop does. My point is, there is a permeant fix, there has been for over 20 years.

The Harmonic balance issue, is a great topic of debate, in my mind if it rotates why not balance it, makes sense to me. I even balanced my dryer as it was out a bit. I like to balance everything, half the stuff I balance is probably a waste of my time. It has been said here that balancing will make make the car vibration free on a perfect road. I believe that is true but watch out for gravity, pot holes etc because frame geometry will change and now you get that scuttle shake. There are lots of frame books out there that explain in great detail what happens with many vintage cars. Harmonic balance is a huge topic that needs its own thread, the hot rodders have that down to a science. Lots of great info on there sites about wheels/brakes drive shaft pitch etc, (good info for a saggy frame). I could fill up a hundred pages on harmonic imbalance on all cars.

I am not an expert, just another Healey enthusiast that loves all Healey's , I appreciate the perfect examples of Healey's out there and yet love the Healey with a monster motor that somehow got shoe horned into the car. Part of the fun is helping others and that is my intent
Cheers Phil

 

[RAC68]

Phil,

I see it from a different perspective although I can agree with everything you have said. My interest is in diminishing Scuttle Shake to a better-than-tolerable level. To be useful, I must find a solution within my economic and skills limitations and anything outside these restrictions will be relegated to only a subject of interest only.

That being said, my conclusion is that Scuttle Shake is the effect that vibration from discrete imbalanced component/s (i.e. Brake Drums, etc.) has when exaggerated through the less than needed rigidity provided by the Healey’s original frame/substructure.

Although I appreciate that the ultimate solution would require:

1. The replacement or substantial alteration of the original frame/substructure to gain a significant improvement in structural rigidity.
2. The elimination of major vibration creators through balancing of major rotating suspension/drive-train components.

My conclusion is that, for me, the Ultimate Solution goes far beyond the economic and skills limitations mentioned prior as well as the practical objective of “diminishing Scuttle Shake to a better than tolerable level.”

So, should both Frame Rigidity and Harmonics be included in this discussion? Yes, since we are directing our focus to the cause and resolution of Scuttle Shake and both, in combination, are major contributors to this issue. No simple discussion would have exposed the complexity of the problem and allowed the extraction of an individually-selected approach to resolve the issue to the extent considered practical and appropriate by each.

All the best,
Ray (64BJ8P1)

 

[HealeyRick]

Glad the balancing worked for you, Keith. Given that just about everyone who has taken their drums off has found them out of balance, this would seem to be the first place I'd look if I was trying to cure scuttle shake.

 

[NutmegCT]

Keith - out of curiosity, did you have any "steering wheel" vibration before you started the investigations?

Thanks.
Tom

 

[Keith_M]

Hi Tom,
By calling it "steering wheel shake", I assume you're trying to distinguish if from scuttle shake or harmonic vibration, or whatever you want to call it. The answer is, yes, when I first got the car running, the steering wheel did shake at certain speeds (can't remember which ones). This turned out to be because the front wheels were not balanced completely. When I first got my brand new wire wheels balanced, I couldn't bear the the thought of putting wheel weights on the outside, so I had them balance the wheels with weights only on the inside. After rebalancing and placing weights on the inside and outside, the steering wheel shake went away leaving only the relatively minor vibration at 60 mph (which I just cured with my rear brake drums). Given how far the one drum was out of balance, I'm amazed the car didn't vibrate more than it did!

I do appreciate the distinction between "scuttle shake" and "harmonic vibration" made by Phil. The problem I cured was harmonic vibration; the scuttle shake I'll just have to live with like everyone else.

 

[Winghealey]

Interesting discussion
I had a terrible shake until I sent my 72 spoke MWS wheels and Vredestein tires to Hendrix...that got about 50% of the shake out. Alan then suggested I send him my drums for balancing.....that did the trick..very smooth now ....I'm sold on balancing anything that turns on the car ...next will be the driveshaft when I have the U-joints replaced this spring

Kerry Gauvin
1960 BT7
Victoria BC

 

[Winghealey]

I am having the ujoints replaced next week in my 1960 BT7 ....I see you had your driveshaft balanced ...was it out a fair bit ??
I may have mine balanced as well ...it is a hundred bucks more though ...worth it ?

Kerry

 

[Keith_M]

If you're already replacing the U-joints, I think it would be worth it just for the piece of mind.

 

[CanberraBJ8]

+1 for improved ride from having the drums balanced. There was still a little vibration, and I had the wheels re-balanced. This showed the wheels could do with a truing, but I will have to look around for someone here to do that... I'n the meantime the ride is now acceptable at last! The guy who balanced the drums had to add sections of steel to the rim of the drum - just drilling the heavy side wasnt enough! No wonder they rode badly!

 

[Keith_M]

+1 for improved ride from having the drums balanced. There was still a little vibration, and I had the wheels re-balanced. This showed the wheels could do with a truing, but I will have to look around for someone here to do that... I'n the meantime the ride is now acceptable at last! The guy who balanced the drums had to add sections of steel to the rim of the drum - just drilling the heavy side wasnt enough! No wonder they rode badly!

Ha! Interesting to know that mine weren't unusual in being so badly out of balance!

 

[SteveHall64Healey]

Throughout the course of this excercise, I tried several options short of welding bracework to the gearbox tunnel - as proposed by some commentors here. I did not do the bracework only because removing the engine was not an option at the time. I had the rear drums balanced, the driveshaft balanced and each wheel high-speed balanced on the car. Each of these had a moderate effect, but this past week, I replaced the wheels and tires with new 72-spoke wires and Vredstein Sprint Classics. Problem was solved immediately: no vibration or shake from 0 to 90 mph. If I'd known this from the start, I would not have wasted time and money on these other avenues.
steve