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Does anyone have under bonnet insulation to combat vibration noise. If so any recommendations.

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Your better off insulating the firewall and gearbox cover, any underbonnet insulation is 1 difficult to fix properly and 2 often looks rubbish. Unlike moderns where they have specially shaped sections buttoned up to the underbonnet

Stuart.

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Hi Stuart

I was just looking for ideas, It is the sound resonance on the bonnet which was troubling me, particularly on tick over. I thought it was a daft question, Some things I have to put up with or do away with it all together, No way.

Thanks, I agree, don’t want anything ugly under the bonnet.

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The engine area is best dealt with from inside the car- closed-cell foam is very effective when fitted to the bulkhead - its adhesive on one side and available in various thicknesses- I used around 12mm thick. Its quite a job as wiring, piping and all sorts get in the way but worth it after a massive fiddly job. Try:- 

https://www.deadening.co.uk/collections/ccf-closed-cell-foam

The same team sell sound damping pads for floor, metal panels etc. Dynamat is one brand.

James

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Make sure the 2 cone shaped rubber pieces that fit into the 'dimples' at the 2 corners of the bonnet at the windscreen end of the bonnet are correctly located and adjusted so they touch the bonnet. Up and down adjustment is achieved by the screw that connects them to the car. You can put washers as spacers to get the correct height. Once you have the height correct then with the nut slack, close the bonnet and open again. The cones should now have moved in line with the dimples in the bonnet. Tighten the nuts and then they should stop that end of the bonnet vibrating/squeaking.

There are also rubber wedges along the drain channels that can be adjusted to fit.

On mine there is also something best described as wadding that is between the bracer and the bonnet underside roughly beneath where the Triumph letters fit.

Keith

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16 hours ago, keith1948 said:

Make sure the 2 cone shaped rubber pieces that fit into the 'dimples' at the 2 corners of the bonnet at the windscreen end of the bonnet are correctly located and adjusted so they touch the bonnet. Up and down adjustment is achieved by the screw that connects them to the car. You can put washers as spacers to get the correct height. Once you have the height correct then with the nut slack, close the bonnet and open again. The cones should now have moved in line with the dimples in the bonnet. Tighten the nuts and then they should stop that end of the bonnet vibrating/squeaking.

There are also rubber wedges along the drain channels that can be adjusted to fit.

On mine there is also something best described as wadding that is between the bracer and the bonnet underside roughly beneath where the Triumph letters fit.

Keith

TR4 didnt have the pointed cones at the rear of the bonnet they only had flat topped bump rubbers though accurate adjustment of them plus replacement of the side wedges do help.

Stuart.

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My early 4a (mar 65 - 52373) had flat bump stops and no bonnet dimples, both believed originals

Rgds

David

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  • 1 month later...

Following above advice, checked bump stops and remember when I rebuilt the car 35 years ago I cut the tops off the cone stops leaving them flat, I have adjusted them and cancelled all vibration. Ahhhh silence, can now hear the delightful exhaust. Thanks all 

Vic

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