7 replies to this topic

[MontpellierVanMan]

My 1380 transmits more vibration than I would like, at low revs, into the body of my 1978 Van.

 

If this is the price to pay for having reduced considerably the noise everywhere else in the usage-envelope, especially high-speed cruising, then it's a swap I'm moire than happy with.

 

Whilst so much of the car is modified and prevents any intelligent comparisons with other Minis, and even less with Saloons, I thought I would appeal for any informed suggestions ?!

 

Balanced crank, SW5, HiF44, motor pretty well set-up I think ; it was the same when 1275 ; once the car gets going it's much quieter.

 

Standard top-steady, standard lower front steady, from memory all standard sub-frame and engine bushes/mountings, from Somerford

 

A lot of the vibration can be felt through the steering column, to the extent that I wondered if I hadn't got some contact between the rack and the sub-frame, or hadn't even got a tool or bolt trapped in a gap somewhere, but searched to no avail.

 

My top column mount is different (wheel lower, seats much further back etc) and much stiffer, which probably doesn't help,

 

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my top engine-tie has a reinforced mounting on the bulkhead, following the usual repairs, which won't help either,

 

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and my roll-cage is tied into the shell all over the place, which helps massively at high speed (no more drumming) but may be the origin of the problem at low-revs.

 

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Is there anything clever I've missed regarding the top subframe turret mounting rubbers, for example, I'm all ears - the bushes under the big turret bolts are correct, I can't remember what I used under the traverse and on top of the turrets, are these parts super-critical ?

 

[tiger99]

Why are you not using a FULL set of solid subframe mounts? (I assume you have a FULL set of rubbers, never mix or fatigue cracking is guaranteed as you may be aware.) That would stiffen the entire front end and possibly cure your problem at the expense of marginally more noise.

The standard non-Issigonis rubbers may be making it worse in your particular configuration, with an unusual degree of stiffness in strange but not particularly helpful places because of the cage.

Anyway it will definitely handle better with solid mounts. They should be the first mod on any Mini. Don't forget toe board reinforcing plates.

[tiger99]

Oh, and there is nothing untoward about your steady bar attachment repair that should worsen things.

[mk1leg]

well the older subframes were metal to metal which will transfer noise that's why rubber mounts were introduced with single top mount sunframes

[MontpellierVanMan]

My priority is reducing the noise before improving the handling.

 

Would have thought solid-mountings might just be handling before noise ?

 

This plate, seated on rubber strip and carrying sound-proofing material behind, made a massive difference to inlet noise, for example.

 

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Yes, changing an instrument bulb does involve removing the carb !

 

Which of the various tie-rod rubbers available are recognised as being the better ones for noise ?

 

Is it worth modifying the rear exhaust brackets to the oval-rubber-hanger type from the later cars ? The original Metalastic bobbins do feel very stiff.

 

 

 

 

 

 

[ChopperHarris]

Could your exhaust be touching the tunnel or remote?

[MontpellierVanMan]

It would be nice, but no chance ; I've got a 2-post lift and the car is super-accessible.

Acres of room all around the exhaust system.

 

[MontpellierVanMan]

Duplicate.

Edited by MontpellierVanMan, 30 May 2016 - 07:53 PM.