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Bent ARBs fitted by design


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I come for guidance, O Wise Ones.

On the Triumph Vitesse International Fb page, https://www.facebook.com/groups/355145157954928/?fref=nf it is being said that "The twist is there by design, it was introduced very early in Herald production and was maintained until the end of production."

I  disagree - an ARB should be flat on the floor - but I'll be glad for other's views.

JOhn

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to have a built in twist in an ARB is complete nuts   it would give diffent loads at each end depending which way they are twisted , 

some bright spark might pre form to suit LH or RH race tracks  as John knows , but not on road cars............ unbelievable dribble 

its likely some suspension type torsion bars have some pre determined set but how thats controlled through the heat treatment process defies any sense

true old torsion bars can develop a set due to being ..........used /worn out beyond their life cycle

Pete

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The Fb OP claims to have a collection of thirty or so ARBs, and to have seen a Service Bulletin from 1959 saying they would be all.like that from the on.

I cradled the BMIHT Archive section of they have a collection of Triumph SBs to consult.  But it's Sunday.

JOhn

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The Vitesse (all) was fitted with the same ARB as the Herald. I am not aware of any intended twist or bend in the ARB. A thicker type was fitted to the later Spits. An even thicker type was sold by Triumph Tune. It's not an uncommon mod to fit the later Spit type to the earlier cars.e.g. Vitesse.

Dave

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3 hours ago, dave.vitesse said:

The Vitesse (all) was fitted with the same ARB as the Herald. I am not aware of any intended twist or bend in the ARB. A thicker type was fitted to the later Spits. An even thicker type was sold by Triumph Tune. It's not an uncommon mod to fit the later Spit type to the earlier cars.e.g. Vitesse.

Dave

Information I have is that the only time to fit the thicker later bar to a Vitesse/Herald is if converting to swing spring as it can lead to oversteering.

Regards

Paul

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the old 5/8 bar 207093 is no longer available most suppliers offer the 7/8" bar 217033 as the only available supersession to to use across the range 

on my Vit6 i had a courier rear spring and the 7/8" ARB and its on rails , most under steers are down to bad tyre pressure balance   F &R and  initial  poor geometry setting by not following the static loading guidelines.

Pete 

 

 

Edited by Pete Lewis
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1 hour ago, 68vitesse said:

Information I have is that the only time to fit the thicker later bar to a Vitesse/Herald is if converting to swing spring as it can lead to oversteering.

Regards

Paul

If you stiffen up the rear suspension or fit a camber compensator then the thicker ARB helps keep the balance between the front and rear.

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If its specified for a 13/60 its going to be ok for all , 

The thin one bends the  thick one doesnt 

Uprating the roll parameters must aid handling ,(left the bar out as Daves propping it up)

There is a balance , we are not looking at utopian handling its a 50 year old family saloon or small sports car which has less roll to start with, the problem of orginiality is you  cant   buy the old one as a new one 

A straight 7/8 bar has to be a great improvement on  a twisted 5/8 bar

Pete

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7 hours ago, 68vitesse said:

Information I have is that the only time to fit the thicker later bar to a Vitesse/Herald is if converting to swing spring as it can lead to oversteering.

Regards

Paul

Relying on memory, perhaps not oversteer but understeer as Nick Jones post, either way not a desirable outcome.

Regards

Paul

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there maybe something in this really

as Ive seen 100,s of the thinner bars

3 on my own cars, the others on others I worked on,

plus bars that wer off

 

all the thinner ones wer bent, all about 1/2 to 3/4 inch

 

nin of the thicker ones ive seen wer bent

 

Now then, them that say its no possible, then I ask ye all to go tek yours of

and report back saying if its bent or not

 

it seems so strange that all of the bars ive seen are bent

lots of others have said there bent

lots of pictures show there bent

 

so wots causing the bend, defective metal, poor workmanship, poor tempering,the actuall mould bent,

 

look at yer front springs, O|E or aftermarket, they all got a bend in em,

that bend comes out whenst they been off for a wee while

but the ARB dont, so I dont think its metal fatigue

 

M

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3 hours ago, Nick Jones said:

Tried a thicker ARB from a swing-spring Spit on my lowered, but still fixed-spring Herald. Ruined the turn-in and made it understeer horribly. Soon swapped back.

On my herald estate, fitted with a courier (ie flat and stronger spring) plus stiff front springs, I removed the ARB altogether with very positive results. The car did a remarkable number of autosolos/autotests and 12 car rallies, so went through its paces.

 

And Marcus, that is exactly the point. I really don't think I have ever seen a "flat" thin ARB. They are always bent, and in the same way. That surely cannot be coincidence?

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