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 Post subject: Turn in oversteer
PostPosted: Wed Jul 18, 2018 7:58 am 
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Hi on my Sprint when I turn in to a roundabout or similar bend the initial turn in is very precise but after the turn is made the rear feels to step slightly out giving oversteer. Getting on the power while this happens makes it a bit worse. This is not at speeds that lose traction and no protesting from the tyres.
I had it on the ramp yesterday and put a bar between the rear arm bushes and nothing felt odd. Obviously there was movement but not a failed bush type of movement. The bushes are old except the top arm ones that I poly bushed (axle end). Could this oversteer feeling be caused by the rest of the bushes being as bit soft? I do have a set of rear arms ready to go with new stock type bushes so I could swap them but if the Sprint is prone to this oversteer feeling maybe its a waste of time changing the arms.
I'd like to get opinions on this if you would please :) Shocks are in good condition (Gaz fully adjustable with near stock ride height)
Cheers

Tony

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 Post subject: Re: Turn in oversteer
PostPosted: Wed Jul 18, 2018 8:09 am 
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I remember over the winter there were a couple of points where my old MX5 would have the most hilarious oversteer at a couple of roundabouts. I thought there was something wrong but turned out some fuel had been spilt about 2 weeks previously and the road remained slippery.

Your problem would to me indicate a loose rear end somewhere but I'm at a loss to say what as you seem to have looked at everything.

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 Post subject: Re: Turn in oversteer
PostPosted: Wed Jul 18, 2018 8:13 am 
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Yes its not tyre slip for sure. Just a kind of looseness without any clonks or definate axle shift feeling (like the big triumphs get)

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Tony

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 Post subject: Yes,....
PostPosted: Wed Jul 18, 2018 8:43 am 
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Based on my experience I would concur with your thoughts that the bushes are likely culprits.


When I put my (first) Sprint on the road in 1990 it did what you described.
Since it already had new lower arms I replaced all the upper arms bushes and
this effected a cure.



Ian.

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 Post subject: Re: Turn in oversteer
PostPosted: Wed Jul 18, 2018 9:11 am 
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Thanks Ian, I may swap all 4 arms this evening and report back.. :)

Tony

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PostPosted: Thu Jul 19, 2018 7:26 am 
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Well, I swapped the 2 lower arms last night which are fitted with new Rover bagged bushes. Put it all back together and thought something looked odd.... ah yes I fitted the anti roll bar backwards :lol: . Quick change around and I was ready to go :). Drive home in traffic didnt tell me much -except it felt a lot firmer (even harsh) just going over bumps etc. So something changed. This mornings run in (early) to my favourite left/right flick on the roundabout was taken at about 55mph and a VAST improvement is felt. There is a slight turn in oversteer still there but much like how I remember from first driving the car. Almost as if when the weight transfers onto the front it has a bit of an effect. I'll do a full geometry check next week when I can so if there are any preferred settings other than factory that you know of let me know and I'll try them. :)

Cheers

Tony

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 Post subject: Re: Turn in oversteer
PostPosted: Fri Jul 20, 2018 8:37 am 
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A weak anti roll bar can cause horrible oversteer. Does anyone do an uprated one for the Dolomite ? Graham


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 Post subject: Re: Turn in oversteer
PostPosted: Fri Jul 20, 2018 8:58 am 
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A weak anti roll bar can cause horrible oversteer. Does anyone do an uprated one for the Dolomite ? Graham
The Factory race cars had a rear ARB made of something closely resembling piano wire. Homologation rules said there had to be one, but the drivers preferred it without so the "fake" one was adopted.

But the presence (or absence) of an LSD makes a big difference to the Dolomite's handling! An LSD equipped car tends much more to oversteer, so it can be a good idea on such cars to actually ditch the rear bar. And fit a stiffer front one! (earliest Sprint ones were thicker)

Does your car HAVE an LSD, Tony?

Steve

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 Post subject: Re: Turn in oversteer
PostPosted: Fri Jul 20, 2018 2:19 pm 
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Tony ,what tyre pressures are you using ?


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 Post subject: Re: Turn in oversteer
PostPosted: Fri Jul 20, 2018 6:25 pm 
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No lsd in mine.(Id like one though) Pressures are 30 rear 28 front. Turns in lovely and plenty of grip. Modern tyres obviously. The roll bar delete on race cars had got me confused but my gut feeling was a stiffer bar may help my oversteer and a mate said a better bar would transform the car (he wasnt aware of the race car delete). Does anyone know the 2 diameters of early and late bars? I have a 78 car so assume late? If I have the thinner bar I would like to try a thicker one.

Cheers

Tony

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 Post subject: Re: Turn in oversteer
PostPosted: Fri Jul 20, 2018 9:47 pm 
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Tony

mines a 74 i can measure the anti role bar tomorrow

Dave

p.s just a thought have you got the same make of tyres all round or at least front to back


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 Post subject: Re: Turn in oversteer
PostPosted: Fri Jul 20, 2018 10:31 pm 
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Thanks Dave that would be great. Yes same tyres all round :)

Cheers

Tony
Quote:
Tony

mines a 74 i can measure the anti role bar tomorrow

Dave

p.s just a thought have you got the same make of tyres all round or at least front to back

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 Post subject: Re: Turn in oversteer
PostPosted: Sat Jul 21, 2018 9:28 am 
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Pressures are 30 rear 28 front.
Recall Trackerjack saying in a thread to try swapping that around and play with having more pressure in the rear than the front. Seen as we no longer can get the correct tyres and Triumph are in no position to give advice it can't hurt to experiment!

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 Post subject: Re: Turn in oversteer
PostPosted: Sat Jul 21, 2018 3:01 pm 
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As far as I know, it was only the very early Sprints that had the thicker front bar, may have been the original 2000 cars or thereabouts.
I have VA 2245 AND VA 10224 ( both series 1 cars) in my yard ATM so will measure them and compare them to the Carledo's bar which came from an '80 model Sprint (Series 4 car) and my own '78 series 3 Sprint's bar (VA 26140)

In the meantime, you could try removing the rear bar and see what effect it has, it's only a few minutes work after all and softening the rear has the same effect as stiffening the front, but costs nothing!

If you have adjustable shox, you could also try softening the rear settings a bit and see what that does. I know it goes against the grain to suggest SOFTENING the ride, but, as I found out, it's all about balance!

On tyre pressures, I have no opinion, not having had a stock Sprint on the road long enough to form one and there are too many variables anyway, make, compound, age, driving style, all affect the optimum, so this is something best sorted by experiment. FWIW, I reckon running the rears a tad softer than the fronts, suits me best......but that's me and is purely subjective!

I COULD regale you all at length about the trials and tribulations I had with getting the Carldeo's handling balance set right, but it would be pretty pointless, since the car has different overall weight, CofG, axle weights, spring rates, shock settings etc et boring cetera to a conventional Sprint powered 4 door, so any data i've gathered and settings i've used are not really relevant to anyone elses car!

Steve

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2 door '73 Toledo with Vauxhall Carlton 2.0 8v engine OWF 797M (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine EGP 247T (The Dolomega)
'91 Cavalier 2ltr 8v auto
'95 Cavalier 2ltr 16v auto
Spectrum Auto Services, Servicing, Repairs, MOT prep. Apprentice served Triumph Specialist for 45 years and home of Maverick Triumph.PM for more info or quotes.


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 Post subject: Re: Turn in oversteer
PostPosted: Sat Jul 21, 2018 4:01 pm 
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Ah was it only front bars that were thin or thick?. Removing the rear and trying that is an option and I had thought about softening the rear damping also :). Maybe they need a thicker front bar after all?

Cheers

Tony

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