Track adjustment

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Track adjustment

Postby jvasabra » Wed May 03, 2017 11:39 pm

Hello all,
I am looking for correct info about the track adjustment on a Sabra (4), flailing arms suspensoion. The Sabra shop manual says : toe in 0,218" ( = 5,5 mm ) , but other info says 1/16" = 1,5 mm.

Can anyone confirm either of the two info's or tell me how the track is put on his car , if running and behaving satisfactory.

PS Book says it must be adjusted with the load of two persons in it.

Thanks already now,
Jacques Vandevelde
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Re: Track adjustment

Postby CNHSS1 » Thu May 04, 2017 12:58 am

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Re: Track adjustment

Postby heathsabre » Thu May 04, 2017 2:48 pm

I have had a conversation with Nigel Newth-Gibbs about toe-in for “flailing arm” Sabres and Sabras. He is very interested in this subject as he will have to address it as part of the restoration of 6EUE. Nigel thinks it is a grey area and he does not have a definitive answer, suggesting that it is a case of “adjust to taste”. Particularly with this front suspension type, toe-in will change with ride height. More toe-in will improve directional stability, but directional stability will also, for sure, be affected by play in the steering linkage. Of all the “flailing arm” cars I have checked in this respect, 1.5cm free play at the steering wheel is as good as it gets. Less toe-in or negative toe-in might improve turn-in. We had our competition Coupé set up with negative toe-in which did improve turn in on the track but made the car seem unstable on motorways. Whatever is done I think that the suspension and steering on our Sabras and Sabre Fours will always be heavy and relatively poor in feel.

The views and opinions of others would be welcome and interesting.
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Tony & Jaki Heath
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Re: Track adjustment

Postby Old and Slow » Thu May 04, 2017 5:08 pm

A very interesting topic, Tony.
I've always been led to believe that toe-out (or negative toe-in?) was not encouraged (except on front-wheel drive cars) because it has inbuilt instability, each wheel in turn wanting to align the car, thus causing wandering, which becomes impossible to correct manually using the steering wheel when travelling at high speed. You'll also notice the car "dives"into corners (feels like instant oversteer) if you have toe-out - I had this problem with a kit car once, until I shortened the track rod ends enough to allow them to be screwed in further.
At the other extreme I believe you can feel excessive toe-in because the "fierce" feel when steering wheel wants to centre itself.
Changes in toe with suspension travel will result in bump steer; I would imagine that with the Ballamy design the steering rack end pivot has to be aligned with the flailing arm chassis pivot when set for straight-ahead to minimise bump steer.
Fred Puhn's book lists (mostly American) manufacturer's toe-in data:Some UK figures:
One-sixteenth for '67-69 Sprites, '71 XKE and XJ6;
Three-thirty-tooths for '67 Healey 3000, '68-70 XKE, '71-72 MGB
(thirty-secondths? Thirty-twoths?)
One-eighth for '71-72 Midgets
Do you think 0.218" might be a typo, seems a bit too big to me, although the '80 Mustang is listed as wanting 5/16 toe-in. Could be 9/32 (0.281") which is specified for a number of Fiats and the Toyota Corona Mk 2.
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Re: Track adjustment

Postby jvasabra » Mon May 08, 2017 10:15 pm

Hello,
Thanks all for the comments. Always interesting.
I finally succeeded to stop the car from wandering on the road and stay in the right lane.
Checked all "play" in steering links. All ok, only play was at the streering box ( and so on the steering wheel). Checked toe in , and yes the car has toe in. Measurement showed it was 2,2 mm ( 3/32") , so It wasn't changed.
Finally I adjusted ( took away all "play" ) the steering box and the car stayed nicely on his track with no wandering. wiggling / wobbling , but the steering was too heavy. So I gave it some play ( 0.5 cm at the steerinfg wheel). Now steering wheel comes back to centre, but still heavy steering and the car has to be kept on track with a minimum of effort. that's the compromise for the moment.I can live with that.
2.2 mm or 3/32 is in the grey zone ,as someone called it, between a min of 1/16 (1.5mm) and a max of 7/32 ( 5.5 mm). Both appear in Sabra publications.
Bye for now and thanks again. Jacques
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