Adjustable front tie bars.

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martinclan
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Joined: Sat Aug 29, 2020 11:04 am

Adjustable front tie bars.

Post by martinclan » Tue Mar 14, 2023 9:48 am

I would like to make my front tie bars adjustable.
I realise the front suspension is not really adjustable due to the torsion bar, but I would like to maximise what adjustment there is. And I may eventually replace the torsion bar with a coil over. It's a Marlin Roadster and already uses a conventional damper rather than a lever arm jobby. For anyone interested, the lever arm is replaced with the top arm from a mini.

Imagefront suspension first fit by Robin Martin, on Flick

I understand several people have made adjustable tie bars. What is the best / simplest solution? Pictures if possible!

Cheers, Robin

david painter
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Re: Adjustable front tie bars.

Post by david painter » Tue Mar 14, 2023 1:19 pm

What Steering angle are you trying to adjust is it Camber or Castor
Dave

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MarinaCoupe
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Re: Adjustable front tie bars.

Post by MarinaCoupe » Tue Mar 14, 2023 2:37 pm

I think if I were making anything adjustable it would be the top suspension arm. This would allow you to adjust the amount of wheel/tyre negative/positive camber. A little research might turn up a Mini kit for an adjustable top arm.

Adjusting the tie bars to pull/push the lower arm backwards or forwards, will increase the stress on the lower eye bolt where it attaches to the chassis, as the centre is fixed by the torsion bar.

Given your comment about perhaps deleting the torsion bars, and the fact that you have a bare chassis, I would look at grafting in the completing front suspension from a Triumph Spitfire, GT6 or Vitesse. Alternatively, the complete front suspension from a Lotus 7 type car.

martinclan
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Re: Adjustable front tie bars.

Post by martinclan » Wed Mar 15, 2023 10:15 am

The reason for trying to make it adjustable as the Marlin chassis was not always constructed as accurately as it should be. Having some adjustment would be useful to dial out any innacuarcies in the fron suspension mounts.
Interesting remark about using a Triumph front end as Marlin did actually make some hybrid chassis with Triumph front suspension and Marina everything else. But this would be a pretty big job to do as a retrofit - and I would like to get the car finished sometime soon :-)
One of the Marlin guys came up with an answer. He has chopped off the front half of the tie bar and replaced it with a turnbuckle and rose joint. Reportedly improves the steering as well...

ImageAdjustableTieRod by Robin Martin, on Flickr

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locost_bryan
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Re: Adjustable front tie bars.

Post by locost_bryan » Wed Mar 15, 2023 7:42 pm

I wonder if you could use one of the Mini adjustable tie rod kits?
Image
Bryan
Auckland NZ

1972 Morris Marina 1750 TC Coupe "Ozzy"

martinclan
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Re: Adjustable front tie bars.

Post by martinclan » Mon Apr 03, 2023 9:38 am

So - I decided to go the adjustable tie bar route. My original tie bars are in (unusually) very good condition so I don't really want to sacrifice them. The brinneling you normally get where the bar passes through the bushes and chassis mount is non-existant.
So does anyone have any shot second hand ones? I just need the fork end and about the first 6 inches of the bar itself to be in good nick. The bar needs to be good enough to cut a 1/2" unf thread on it. See picture above.
Cheers, Robin

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