Hints and Tips - Nobby Helper Springs

From: David Cochrane
Sent: 19 July 2002
To: british-cars-pre-war
Subject: Nobby helper springs for Austin Sevens

Dear Austineers,

I have fitted a set of replica Nobby helper springs to the Chummy, and found they have made quite a difference to the rear suspension. The cornering has changed: the over-steer characteristics have altered so that it feels a bit more twitchy, but it goes round corners without rolling so much - I was able to squeal the tyres yesterday going round a roundabout. The main problem is that the back axle used to be able to move up by 5 inches before the top of the brake lever hit the inside bottom edge of the rear wing, whereas now there is only about 3 inches of movement before the Nobby springs become coil-bound. The result of this is that the car is now far more uncomfortable on poorly surfaced roads. Has anyone got a set of originals that they can measure for me - I feel that the coils of the spring should fit inside each other when squashed flat to give the maximum amount of deflection; this does not happen on my replicas.

Cheers,
David C


From: The Austin Seven Fanatic!
Sent: 19 July 2002
To: David Cochrane
cc: british-cars-pre-war
Subject: Re: Nobby helper springs for Austin Sevens

I have an original set on my '36 Open Road tourer.

See link on Bruce White's site: http://www.bio.flinders.edu.au/austin7/Nobby%20spring%20assistors%20-%20Barry%20Lovelock.htm

David,

will measure them and see, but judging by the picture it looks unlikely they fit inside their coils and may well restrict the axle as you've found.

Of course, the set of the rear main springs will make a big difference, the original ones having about 9 inches(!) positive and causing horrendous oversteer, which we all know and love. My '36 is a low-frame chassis of course and one might expect similar problems to occur much earlier, as the main springs are set much lower to start with. Certainly, I have not noticed it and I have exceeded the "40 Stone" limit on occasion.

Barry Lovelock.


From: The Austin Seven Fanatic!
Sent: 20 July 2002
To: David Cochrane; british-cars-pre-war
Subject: Re: Nobby helper springs for Austin Sevens
> Now for some facts on the Nobbys!

Firstly, lets state some ground rules: A7 chassis' should be parallel to the ground when set up correctly; my '36 tourer is. However, some early Chummies seem very high at the rear, your's may not be early, or high. My rear springs, with the low chassis, are almost flat with just the weight of the car on them. This means that loaded, the car should be fairly neutral until it rolls (it is). But it is best with the dreadful (too big) 4.50/17s on the back. Any self-respecting A7 owner will sell these on to a Morris 8 owner as I did and experience the normal oversteer with 4.00/17 sections! Partial cure is 28-30 psi rear, but I digress. Partner the big rears with the big fronts and the car steers like a lead balloon, but it will drift safely through corners. Let's get real here, it should oversteer, so fit the right size tyres!! Those Export cars must feel terrible!!

Now for the facts:

Without knowing what will hit first on my car (possibly the brake arm), the axle has about 5" clearance from the chassis extensions - note, extensions. The Nobby springs have about 8 coils of 1/4" diameter, so coil-bound have removed about 2" of travel, then the aluminium U-bolt bracket takes up another inch. This leaves only round about 2" of travel - similar to what you have found. Standing on the back of the running board (dangerous this even though I only weigh 12 1/2 stone), displaces the car by 3/4". Jumping up and down on the back of the running board (even more dangerous!) and the car moves 1 1/2", which only leaves about 1/2" travel left. So my car would seem to be similar to your's I suspect. The difference may be that I have chassis extensions and at least this may go some way to preventing big holes being punched in the floor I guess.

I too say take your's off, but mine have been on since before 1952 and the second owner, whom I know, so they will remain! I dare say the later spring rating is higher too.

My 1985 Vauxhall Nova had rear springs whose coils fitted into each other like a catherine wheel and Vauxhall made quite a big thing about them saving space. It might be an idea to get some made up - just a thought?

Barry.


From: David Cochrane
Sent: 22 July 2002
To: Barry Lovelock
cc: british-cars-pre-war
Subject: Re: Nobby helper springs for Austin Sevens

Dear Barry,

Thanks for the reply, and for carrying out the (dangerous!) suspension tests on your Tourer.
> ... the axle has about 5" clearance from the chassis extensions.
> The Nobby springs have about 8 coils of 1/4" diameter, so
> coil-bound have removed about 2" of travel, then the aluminium
> U-bolt bracket takes up another inch. This leaves only round about
> 2" of travel - similar to what you have found. Standing on the back
> of the running board (dangerous this even though I only weigh 12
> 1/2 stone), displaces the car by 3/4". Jumping up and down on the
> back of the running board (even more dangerous!) and the car moves
> 1 1/2", which only leaves about 1/2" travel left. So my car would
> seem to be similar to yours. The difference may be that I have
> chassis extensions and at least this may go some way to preventing
> big holes being punched in the floor.

It sounds as if your car's rear suspension movement must be similar to mine, and that the replica Nobbys must be very similar to the originals. If you can get that sort of deflection by just jumping up & down on it, it would suggest that normal travel over roughish roads must be as uncomfortable as mine now is. Big holes being punched in the floor has not been one of my worries!
> I too say take yours off, but mine have been on since before 1952 and
> the second owner, whom I know, so they will remain! I dare say the
> later spring rating is higher too

I fitted the Nobbys in preparation for a holiday on the Isle of Wight next month. The car will have to carry wife & me in the front, and two sons in the back. The oldest is 13, and two years ago the same passengers (but younger & lighter then) were causing the rear suspension to bottom quite often on the rough minor roads they have on the Island. So I think I will keep them fitted until we return to the mainland, then take them off again.

David C.


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