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Steering

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Flinty
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Steering

Post by Flinty » Mon Apr 01, 2019 7:58 pm

I purchased an SP250 late last year and did not drive it until this year,
Having now driven it for a good few miles I am very pleased with all aspects of the car except the steering, It is fitted with a Triumph rack from a Spitfire and it seems a bit stiff with little or no self centering.

I have given it a good grease and increased tyre pressures to 30 rear and 28 front which gave a little improvement but it still seems not quite right.
Do other cars self centre or am I expecting to much.


Steve.

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John-B
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Re: Steering

Post by John-B » Mon Apr 01, 2019 9:41 pm

I don't know what tyres you have, but there was another topic a few months ago where tyre pressures were discussed. 28psi at the front would appear to be a bit low and a higher pressure would make the steering lighter. I run my tyres at 31psi all round.

Years ago I adjusted the toe-in myself and over-did it. The car certainly self-centered but danced around too. Try increasing the toe-in a little.

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JohnM
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Re: Steering

Post by JohnM » Mon Apr 01, 2019 11:10 pm

Hi Steve,
assuming the R&P conversion is one of the "known" ones, self-centering shouldn't be a problem, and the car should feel stable on the steering at all speeds. In fact, some of us prefer lower front tyre pressures because otherwise the steering can feel too light ( I run 26/28 front/rear on 165 section tyres).
As John says, check your toe-in - remember the settiing in the manual is for crossply tyres, not radials - I prefer mine set to 0deg (parallel), and check your camber angle isn't still set positive (for crossplys again) 0deg camber seems to work well.

If all that seems OK, try jacking the front up and disconnecting the track rod ends from the hubs. Do the hubs swivel freely? They should be very free to swivel, and if they're not, you need to check your vertical links/trunnions/top balljoints quickly, as they can snap if they seize. Can you move the swivel pins in the track rod ends? and the ball joints in the rack? If there's a seized one it will put real stiffness into the steering.
Does the steering wheel rotate nice & freely with the rack disconnected from the hubs? If not, maybe the rack bar is bent, or the pinion shimming is wrong.

Also, if you don't know which R&P conversion it is, a quick check is that the rack tube centre height should be close to the level of the crankshaft pulley nut, and the rack should be in front of the crankshaft pulley with only enough space to comfortably replace the fan belt. If that isn't where the rack's positioned, the steering geometry won't be correct.

Hope that might give you a few ideas, and get you towards getting even more pleasure from your SP!

Cheers, John
John M in Middlesex, NW London
1962 SP250 "B" Spec

classiclife
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Re: Steering

Post by classiclife » Tue Apr 02, 2019 12:55 pm

Hello,

Questions to both John's please, as I am unsighted on the following.

With the SP250 Triumph R&P does it also use the vertical link and trunnions from the Triumph ??

Reason I ask is that I also have a Triumph Vitesse and the trunnions MUST be lubricated with EP90 and NOT grease, as the latter does not circulate properly leading to lack of lubrication and eventual snapping.

This most often occurs when such a set-up is being manoeuvred at very slow speeds - such as in to a parking space.

EP90 negates this situation by ensuring the trunnions are fully lubricated and is specified by Standard Triumph.

It's a question out of interest really.

Many thanks.

Richard.
1968 Daimler V8-250 Saloon
DLOC East Sussex Area Representative.

Southern Classics Society Events Co-ordinator.
www.southernclassics.org.uk

Ian Slade
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Re: Steering

Post by Ian Slade » Tue Apr 02, 2019 1:35 pm

Non of the conversions I know of have used Triumph vertical links from a Vitesse or Herald, there have been some that have used the TR6 lower wishbones and vertical links but that also uses Triumph discs and calipers unless there have been modifications. Personally I use the original steering set up which can be played with to produce a reasonable lightness, the shims on the chassis end of the lower wishbones give you all the answers, you just need to play, doubt there will be many with the correct set up now.
Don't forget the Herald and Vitesse have extreme steering locks, the SP lock is nowhere near either of those two.
Owner since the 70's, Genghis is slightly to my left.

Big Col
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Re: Steering

Post by Big Col » Tue Apr 02, 2019 4:46 pm

On the Triumph racks there is a large hexagon cap which contains a spring and plunger arrangement if memory serves me correctly. It reduces play in the rack ,I think, and if it is set too tight it will restrict the steering to the extent you describe.
Colin,
I may be slow but I’m rough as well !

classiclife
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Re: Steering

Post by classiclife » Tue Apr 02, 2019 4:49 pm

Thanks Ian, that makes sense.

Regards.

Richard.
1968 Daimler V8-250 Saloon
DLOC East Sussex Area Representative.

Southern Classics Society Events Co-ordinator.
www.southernclassics.org.uk

Flinty
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Re: Steering

Post by Flinty » Tue Apr 02, 2019 8:44 pm

Thanks everyone for the suggestions, The rack installation is a Robert Grinter conversion so I think it will be properly located, I will try the other points and see if I can locate the problem and report back.

Steve.

Flinty
Posts: 38
Joined: Mon Sep 24, 2018 7:34 pm
Location: Scarborough

Re: Steering

Post by Flinty » Fri Apr 05, 2019 5:39 pm

Update.
Well I started at the hubs and checked the track rod ends then rack and then u/js on the column and all seemed Ok then I tried the steering wheel with the u/j disconnected from the rack and it was tight.
I took off the steering column and slid the outer part of the column off the steering shaft with a great deal of difficulty, The shaft was shall we say not smooth and so I polished the shaft and eased the nylon bushes with emery tape and re assembled with new grease.
The steering is transformed and I am a very happy man,
Thank you everyone for your help, and I think I must give special thanks to Tim one of our forum members who telephoned me and told me of his similar problem that was also due to a tight column.

Steve. :D

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Re: Steering

Post by grahamemmett » Fri Apr 05, 2019 6:23 pm

The knowledge displayed on this forum never ceases to amaze me
Graham Emmett
Northwich, Cheshire
Joint DB18 Registrar (with Marcel Renshaw)
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