The scuttle shake mod- I can't decide

[57_BN4]

Hi Guys,

I need some help deciding whether a BN4 should have the scuttle shake mod done or not. The PO has welded a panel in but I'm tempted to remove it as it makes getting at the throttle shaft brackets impossible among other things.

Has anyone driven an earlier car without the mod done and found it different than a later car because of it? I'm not looking to race the car but am planning on putting quite a few miles on it. It already has a Kilmartin chassis with reinforced main rails etc.

[pics stolen off Andrea's site]: top is BN4 without mod, below later car with factory fitted strengthening panel

Andy.

 

[John Turney]

I have a 57 Longbridge BN4 without the mod. I also have everything balanced (tires, wheels, disc brakes, driveshaft, engine) and scuttle shake isn't a problem. With the engine in place it's still hard to get to the throttle shaft brackets.

 

[dougie]

I have a 57 Longbridge BN4 without the mod. I also have everything balanced (tires, wheels, disc brakes, driveshaft, engine) and scuttle shake isn't a problem. With the engine in place it's still hard to get to the throttle shaft brackets.

I agree with John. My Longbridge BN4 vintage racer has the original frame and none of the "scuttle shake mods" because I don't have any scuttle shake. I've always believed the "shake" is due more to the improper balance of the items John mentioned.

 

[57_BN4]

Thanks guys for your input.

I also have balanced the drums plus all engine components and will balance the wheels when they arrive. Off now to the garage to find a grinder.

Andy.

 

[red57]

Mine is also a '57 BN4 with no 'scuttle shake mods' and since I went to rear discs I have no shake either. I did with the drums, but I had never had the drums balanced so I think the drums are one of the keys besides the wheels/tires.

 

[andrea]

Hi Andy
I also have one original 100/6 Longbridge frame, without any modification -If you have Kilmartin chassis you sure haven't
probability to experiment shuttle
Cheers Andrea
https://picasaweb.google.com/lh/photo/5V6KANOF9Sd-lWvQZwjRTdMTjNZETYmyPJy0liipFm0?feat=directlink

 

[Frameman]

In my 30 years of rebuilding Healeys, I have never experienced an original Healey that did not have scuttle shake.
Scuttle shake is a result of torsional loading throughout the chassis. The steering geometry is effected, rapid toe in and toe out of the wheels. This is very evident when you go over railroad tracks or pot holes. Most race cars have hard tops and roll cages which will reduce torsional loading.
Balancing drums, wheels and drive shafts are good things to do for your car but have little effect on scuttle shake but will positively effect drive train smoothness.Certainly a poorly balanced wheel will cause a car to shake but I would not label that scuttle shake.
The chassis should be rigid and the suspension controls the ride of the car.
A non-rigid chassis becomes a flexi-flyer.
Welding a strip of steel down the main rails will assist in the static loading of the chassis which is when the car is stationary but once the car is put into motion the loading becomes torsional and the strip of steel has little effect.
The reinforcement panel installed in the later models showed little effect in reducing scuttle shake although it is an improvement on the original design.

 

[57_BN4]

Scuttle shake mod panel is now no longer...

Unfortunately the heater box has a bit of acne from the welding so I have some more work to get it flat again.

Frameman- I'm not so concerned with whether the car has scuttle shake or not, more whether there is a significant difference with/without the panel. After driving a Triumph Vitesse for a number of years I am quite used to the bhlamalamalama sound when putting a front wheel in a pothole and the whole body wobbles around on the chassis which I think is a recycled hospital bed frame underneath the Triumph.

Andy.