Scuttle shake finally sorted

Wooo hooo After much prevarication, hair pulling and anything else that you could think of I have finally got rid of the scuttle shake.

A new set of chrome wheels, hubs, spinners and Vredestein Classic Sprint tyres and there you have it - job done

And - as a bonus, there is no dreaded clunk as you apply the brakes as the new wheels are a great fit on the new hubs

That is the trouble when you do a rolling restoration - in what order do you tackle things - I picked the floor, suspension, soft top brakes and engine as priorities and I still have the boot floor to do - ( trunk).



Bob

Congratulations!

Bob,
Thank you for posting the followup! It's helpful to know how your efforts resolved the problem.

Did You have the drums balanced too?

Yes, thanks for posting. That will be my next challenge in the rolling restoration of my 100. I'll would also be interested to hear if you balanced the drums. Also, did you have the new tires and wheels balanced on or off the car?
Cheers!

Hi Guys

In short - no, the drums were not balanced.

When I bought the car back in 2002, through a Healey restorer acting as an agent, the price included £500 to get it on the road! As far as I can remember, this included brand new rear drums, MOT and other things long forgotten. The wheels were the old 48 spokers and the tyres were very old then. Being of short in arm and long in pocket other things came first. It was long suspected that the tyres were the main problem, though I did research potential businesses who specialised in balancing things just in case I needed their expertise.

I bought the chrome wheels last year by chance when at a coffee morning at Bill Rawles' place, they were not new but very nearly new and at a price I could not ignore. The tyres came brand new via Ebay, direct from the Netherlands, again at a price I could not ignore and Bill fitted them onto the wheels using a static balancer. I must say, I was a bit sceptical but Bill assured me that he had no complaints. Discussing the scuttle shake with Charlie - Bill's son, whilst the tyres were being mounted, he suggested using the static balancer on the drums if the shake persisted after installing the wheels on the car, so I was prepared to give it a go, but as things turned out I did not need to.
The MOT was up last Thursday so I put the rear hub splines on as they were easy, put the new wheels on all round and added the spinners, strangely the new spinners would not fit the old splined front hubs so I had to refit the old ones and got the car to the MOT testing station where I am pleased to say that it passed with flying colours.



Bob

Bob,
What pressure are you running your tyres at? I have the same on my BN4 and run them at 30psi but not sure if this is correct. Thanks.

Mine are currently what has been put in at the shop some time ago it must be said - around 26, but when I bought the car I was told to shove in 30 all round, so I may top this up when I have finished installing the front hubs.



Bob

First time out today this year, glorious day could not be missed, recent winter work included having the rear springs re tempered, installing new Michelin XAS tyres, front wheel alignment and other general 'maintainance'. Took her up to a steady 70mph (sorry officer it was a dual carriageway!) and bingo noo scuttle shake zero zilch what a result. I am sure it's the tyres that made the difference as the rear drums were replaced last year with no effect. Did notice the front end was a little 'lighter' on steering could this be because the rear end was a little higher? Or due to going a little strong on the toe in.

4tecdog said:

(sorry officer it was a dual carriageway!)in.

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For those of you on this side of the pond as an ex Brit I will translate .
Dual Carriageway = divided highway or interstate . Usually two lanes each way .

Healey Nut said:

For those of you on this side of the pond as an ex Brit I will translate .
Dual Carriageway = divided highway or interstate . Usually two lanes each way .

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AKA freeway.

John Turney said:

AKA freeway.

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Nope.

Thats a motorway.

While doing some research on the Rolls-Healey I learned that one of the improvements made to the 3000 chassis was replacing the fiberglass transmission tunnel with a solid steel tunnel to combat scuttle shake. Obviously a bit extreme for our cars, but I think it points out that a certain degree of scuttle shake was inherent in the design, particularly on the convertibles that carried the extra weight of the larger windshield. Tracking down the source of scuttle shake is made more difficult by the fact that it can be due to various sources and which is why owners can spend a bunch hunting it down. Worn front suspension, out of balance wheels, out of round tires, out of balance rear brake drums are all suspects. I finally beat it with new wheels and tires, shaved for roundness along with balanced rear drums, all done by Hendrix Wire Wheels and doing the scuttle shake mod while my motor was out: https://www.britishcarweek.org/scuttle.html. The car track true and with my V8 and 5 speed turning 2200 rpm at 70 mph, it's a true joy on highway runs. My point is not to pat myself on the back, but to let people know that although the chase to find the cause of the shake can be a long one, the end result is really worth it and the car is transformed after that annoying shake is gone right at the driving sweet spot.

That sweet spot on our Welsh roads is normally 45 to 60 mph and she used to shake a little about mid that point could drive out of it but that was too quick. Will do the tunnel modification when the power plant comes out but hey what a joy to drive now with the new correctly balanced tyres thanks to longstone tyres.

I had Hendrix wire wheel do my drums last fall and it made a tremendous difference.

Hi All,

It is amazing how often over the years I had the wheels and tires balanced but never thought of balancing the drums. I had always thought the drums were balanced at the factory when manufactured as was the practice of American cars at the time and never thought this was not the case for my Healey...especially since the drums are so large and heavy. A while back, when statically balancing my drums, I found in excess of 5 or more ounces out of balance which is quite a bit.

As I see it, the underlying issue is a design fault in the Healey substructure that seems to amplify and transmit rear wheel (wheels, tires, drums, etc.) balancing imperfections and aggravatingly appears between the commonly driven speeds of 45 and 60 mph. To add to the issue is the fact that the amplitude of this imbalance is not consistent and seems to be determined by the relationship of left and right wheel imbalances as varied by the differential. Although I have no specific clue where to modify the underlying design to eliminate the potential of scuttle shake, it is apparent that many have had success when truing and balancing wheels, tires, and drums. Since these balancing elements also vary, it is not that unheard of to find some drums to be close enough to balance not to be a contributing cause of scuttle shake. However, finding servicers that have the expertise, understanding, and equipment to address these balancing issues are quickly disappearing.

Just my thoughts,
Ray(64BJ8P1)

My dad was a factory rep for Ford when the Mustang came out. He said the Mustang convertibles had similar vibration issues, and that Ford never fully resolved them, though some extra bracing in the undercarriage helped. 'Shake' is pretty much endemic to droptops; even though they usually weigh a few hundred pounds more than hardtop versions due to additional chassis reinforcement. I have no data, but suspect the effect is exacerbated by most cars being monocoque--aka 'unibody'--design (presumably, with body-on-frame the shake could be damped with shock-absorbing mounts).

I'd like to hear from owners who have managed to eliminate scuttle shake though careful balancing of rotating parts how long the 'fix' works since tires, at least, are subject to uneven wear no matter how often they're rotated.

Rear discs will also likely do the trick.

My tricarbs' shuttle shake it caused by potholes and RR crossings. Not driveline vibration.
Where can I learn more about reinforcement of the transmission opening in the firewall?
Thanks.
Douglas

dcarlg said:

My tricarbs' shuttle shake it caused by potholes and RR crossings. Not driveline vibration.
Where can I learn more about reinforcement of the transmission opening in the firewall?
Thanks.
Douglas

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https://www.britishcarweek.org/scuttle.html