Turn in oversteer

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tony g
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Re: Turn in oversteer

#31 Post by tony g »

Thanks Ronald, I just measure my rears and I am also running 490mm from arch to lower rim. I have had the car lower but speed bump put me off that idea more than handling. Im actually 10mm higher on the from at the mo so may I'll try the reversed tyre pressures first then adjust the front height down 10mm to match the rear.

Cheers

Tony
TahitiSPRINT wrote: Thu Jul 26, 2018 2:14 pm Hi Tony, pressures 30 front / 28 rear for me too on 185/60 Yoko's.

Another thing to note is that if your car is lowered too much at the rear, this will cause some adverse characteristics as I 've found out on my Sprint.

I'm led to believe that the lower trailing arm on the outer side (if in a bend) will be under such a negative angle that the outer wheel tends to tuck-in even more than the normal weight transfer would induce, causing a very nervous feel at the steering wheel.

I've since adjusted the rear height to 490 mm measured between the underside of the wheel rim and the wheel arch as suggested by LJColeman on his NAB 755T Dolly and the handling is much more secure, without the nervous twitch.

If you have adjustable suspension platforms, I suggest you experiment what settings suits you best. Of the ca. 23,000 Sprints build, maybe only 100 have the thicker ARB so I'm not convinced that 22,900 Sprints have bad handling ;-)

Also I can recommend the shorter/adjustable front tie-bars as supplied by Rob of sprintspeed.co.uk . These give a better turn-in and straight line stability without noticeable heavier steering.


Good luck experimenting :D
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tony g
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Re: Turn in oversteer

#32 Post by tony g »

Do you know the diameter Paul? (an open ended spanner is a quick way to check) It would be interesting to try 2 types for comparison on the same car.

Cheers

Tony
PaulB wrote: Tue Jul 24, 2018 8:25 pm Very early Sprint definitely had a thicker rear ARB, VA6 has one. I don't think there were many, but couldn't say when it changed to the thinner one.
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sprint95m
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Okay........

#33 Post by sprint95m »

TahitiSPRINT wrote: Thu Jul 26, 2018 2:14 pm Of the ca. 23,000 Sprints build, maybe only 100 have the thicker ARB so I'm not convinced that 22,900 Sprints have bad handling ;-)
The basis for suspension is hard front/soft back with the front's track width being greater.
Fitting a thicker ARB to the back compromises this, so if anything the 100 Sprints has "bad handling".



Having rebuilt a Sprint suspension using all standard parts (save for fitting solid in place of void bushes to the back lower arms)
I confirm that the Sprint has predictable neutral steering, being very controllable on the throttle.




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Re: Turn in oversteer

#34 Post by Carledo »

I've been messing about with Dolomite suspension for a good many years now, trying this, trying that, in search of the holy grail, the perfect settings that suit my much modified car and my particular driving style.

But I have also driven a large number of Dolomite type cars from bone stock Toledos to track spec Sprints and if there IS problem with handling, there is usually a cause which can be defined. As a general rule, Dolomites handle pretty well, it's a competent suspension setup with very few intrinsic faults. So, rather than looking to use tuning refinements to cure this, I think we should be looking for something that is wrong or worn! It's not inconcievable, in my experience, to find that a looseness or twitchy behaviour of the rear end has it's root cause at the front end. In particular, wear in the inner track control arm bushes (and the associated "variable tracking" it produces) can make the car very nervous during sudden direction changes like roundabouts.

However, "feel" is extremely subjective and very difficult to define in words, so I do feel a bit sorry for Tony who is trying to do just that! It would be so much easier if I could drive the car and "feel" the problem myself!

Steve
'73 2 door Toledo with Vauxhall Carlton 2.0 8v engine (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine (The Dolomega)
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tony g
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Re: Turn in oversteer

#35 Post by tony g »

Yes Steve it is hard to describe completely. The rear bush changed has made a positive effect but it still slightly does it. In my experience of driving and road testing (as you do), front end stuff is normally "felt" a lot earlier (to me at least). Ill check the front inners though just to be sure.
Just to be clear this is not a snap oversteer event, its a very smooth but definite happening that only needs the steering "opening" up slightly to counter it. At track speeds it may be much more of an issue but I havent done that yet :)

Cheers

Tony
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Re: Turn in oversteer

#36 Post by new to this »

Tony

Finally remembered to measure the anti role bar front 21mm rear 16mm

Dave
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Re: Turn in oversteer

#37 Post by tony g »

Cheers Dave :thumbsup:

Tony
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