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BJ8 plus 55mph Front end shaking

thibault

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hello, I can not find the cause of the tremor from the front of my car and Dashboard from 55 miles per hour.

- I changed the tires ( 185R15 Vredestein Sprint Classic) , balanced the wheels (with cones)
- new drums and front discs
- new front and rear shock absorbers
- new leaf spring and bushes

but always front end shaking from 55 Mph, I need advice/help, thank you.
9522A2FA-2E3E-475F-9BE8-43FEEB5597B2.jpg

Solution page 5 : used rims because of having used them without being properly tightened
 
Last edited:

RAC68

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Hi and Welcome,

It sounds as though you have the famed Scuttle Shake most of us have experienced and some are still experiencing.

First, does your tremor start somewhere around 50 MPH or so and seem to disappear somewhere around 65 MPH or so?
Does your shake seem to change in intensity from time to time (sometimes severe and sometimes very light)?

These are some of the signs of Scuttle Shake which is often related to imbalanced brake drums. Although this tremor could be caused by a number of balance issues, the most common and overlooked is that of rear brake drum balancing. Factory and most replacements drums are not pre-balance and the Healey's rear brake drums are rather large and heavy. Since their size and weight is non-trivial, this imbalanced component transmits its issues through the springs and drive train to the car and shows up around 50 to 65 MPH. The severity of the imbalance, and resulting shake, is not constant as the left and right drum will constantly shift their relative position and counterbalancing relationship via the operation of the differential.

Since drums of this size and weight are no longer commonplace, finding a servicer to correct and balance these drums is not as easy today as years back when drums were commonly used. Look in your location for a servicer who can perform drum balancing as it requires securing weights to the drum in a secure manor that allows for heat expansion and contraction. If no one can be found, many Healey owners have gone to Hendrix Wire Wheel (hendrixwirewheel.com/drums.html) for this service.

Be aware that many local services will indicate they can cut the drums and this should solve the issue. However, cutting usually does little to resolve the problem and you need someone that is experienced in applying balancing weights to the drum.

Hope this helps,
Ray(64 BJ8 P1)
 

Patrick67BJ8

Obi Wan
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Balance Brake Drums and have tgevtires “trued”(making sure they are perfectly round. You can’t balance a out of round tire. Shocks and suspension in good shape?
 
OP
thibault

thibault

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The shake change in intensity from Time to time.
My rear drums are new (from SC PARTS.CO.UK).
Do you think a new rear drum could be unbalanced?
 

Keoke

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The shake change in intensity from Time to time.
My rear drums are new (from SC PARTS.CO.UK).
Do you think a new rear drum could be unbalanced?


YES:

Take them to a reputable machinist and have them checked.
 
Last edited:

NutmegCT

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Another thought: I had the 55mph front end shake on my 1959 TR3. New tires, tires trued and balanced, suspension/alignment trued, u-joints replaced - no improvement. Original steel wheels.

Turned out that the wheels themselves were bent, probably from hitting chuck holes and curbing in the previous 50 years. Easy to check: raise the wheel, spin and point your finger toward the rim. If the rim moves back and forth from your finger, the wheel is bent.

I bought new wheels, and the shaking completely disappeared.

TR3.jpg

Tom M.
 

RAC68

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Hi Thibault,

Normally, Healey original brake drums, or their replacements, are not ballanced from the vendor. This is something overlooked by many as full 4-wheel disk setups came into common use. I would address your vendor and ask if they know if your new drums have been balanced prior to purchase. Keep in mind that many vendors will profess the quality of their parts and suggest they have had no prior complaints … stopping short of indicating a guaranteed affirmative. Either way, I personally search out a drum balancer to validate it had been done.

As an original owner of my BJ8, for years I just assumed the drums were both truly round and balanced and were not the source of my shake. Finally, a mechanic friend and Healey enthusiast dynamically balanced each drum attached to its wheel with a fixture I created. Since both were balanced as a unit, weights were applied to the wheel making it necessary to keep the wheel and drum in the same relationship position when mounted on the car … a definite draw back for this approach.

Get your drums balanced individually to have the ability to exchange wheels and/or replace tires without affecting the drum's balance.

All the best,
Ray(64BJ8P1)
 

Patrick67BJ8

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The shake change in intensity from Time to time.
My rear drums are new (from SC PARTS.CO.UK).
Do you think a new rear drum could be unbalanced?
If you don’t see any grinding marks where metal has been ground off or added metal for increased weight, was added to the drum, IMO, I’d think that would be suspect. Have you contacted the place that you bought them from to see what they say?
 

RAC68

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Again Thibault,

Since you have 2 imbalanced rear drums connected through a differential, every time you make even a slight turn, the heavier area of one drum will change its relation to the heavier area of the other. As a result, your perceived shake will then change in intensity due to this change in relationship and vary from intense to slight. If the shake remained consistent, I would look to an imbalanced single unit such as a drive shaft, flywheel, etc.

This is not a new issue and all of us have, at one time, never expected the drums as the culprit. However, since we have all searched for the cause and found it, you can benefit from our efforts and go directly to a resolution.

All the best,
Ray(64BJ8P1)
 

gonzo

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I have at least three sets of rear drums for the BJ-7 and after trying different combinations, found a winning match. This took some time due to the nature of imbalance, but the match was tested on the road and was easy to assess...reduced shake. Taking it on step further, a set of slotted, balanced rear drums were purchased from Denis Welch Racing (U.K), installed and they also passed to road test. They're new and seem to improve braking effect - not finned as the originals, but slots make them less prone to heat-soak - and look cool behind spoke wheels. On BJ-7s the rear brake drums were painted a mat silver, but I've seen then painted black as well. GONZO
 

Bob_Spidell

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My BJ8 has always suffered 'the shake' even though I've balanced the drive shaft and the drums, balanced the wheels--72-spoke Daytons--on the car and had the wheels trued a couple times. A couple years ago I installed a new set of Vredestein Sprint Classics and the shake has all but disappeared. Note this is the fourth or fifth set of these tires I've gone through, and none made much of a difference before this set. Maybe I finally got the right combination of tires, balance, wheel condition, whatever; I'm not going to question my luck too much.
 

Healey 100

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My hundred had this problem for years. Balancing had minimal effect on it. Finally solved it with new true wire wheels and tires. Never did anything to the drums. Not likely they could cause the problem IMHO, too close to the axle and besides the BJ8 doesn't have drums on the front.
 

bob hughes

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I have not tried it yet - in fact I did not need to after fitting new tyres, but I also suffered scuttle shake at around 60MPH - for me the new tyres fixed it. We did not spin them up to balance them but statically balanced them using a cheapo machine with a balancing point and a bubble level ( Bill Rawles' bubble had broken so he had cobbled up a system with two small spirit levels- worked a treat. I had also discussed the possibility of statically balancing the hubs on the same machine should it become necessary, Rawles thought that it could be done - but as I say, it was not required so I do not know if it would be possible.

:cheers:

Bob
 

HealeyRick

Yoda
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This can be the frustrating part of chasing scuttle shake, there is no one magic bullet. One person's problems may be a bad wheel while someone else may have out of balance brake drums. By chance today when I was browsing the Denis Welch site I notice they sell rear brake drums listed as balanced for a premium over their regular drums.
 

gonzo

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10-4 on the slotted balanced rear brake drums HealeyRick. A pair of these definitely reduced shake on my BJ-7 while improving brake feel and some effectiveness. The process required years to isolate and sort out. GONZO
 

Michael Oritt

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While asking what, such as out-of-balance brake drums, might exacerbate scuttle shake the bigger question is why our cars are prone to it in the first place.

Scuttle shake/cowl shake is not unique to Healeys or even LBC's but is a potential issue in any car with a less-than-rigid frame/unibody structure and this is de facto in any vehicle lacking either a hardtop or sedan top, either of which lends rigidity. On open cars such as ours any deterioration in chassis parts' strength (read RUST) makes a potential weakness into a present issue.

For an interesting article on what one might do if balancing brake drums/wheels does not provide a solution go here: https://www.britishcarweek.org/scuttle.html
 
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