Author Topic: S1 A-arms  (Read 260 times)

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Offline My S1

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S1 A-arms
« on: Sunday,June 08, 2025, 02:50:45 PM »
Well sure enough my upper and lower A-arms are thrashed to beat the band.  Did our Hethel mates modify the Triumph arms in any way?  That is to question, can I buy the Triumph arms from any of the usual British car parts outlets or do I need to pay top dollar to our trusted Europa sources for replacements?  Are they still made in England or are they all coming from the East?

Offline BDA

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Re: S1 A-arms
« Reply #1 on: Sunday,June 08, 2025, 03:59:42 PM »
I'm pretty sure that the A-arms are not copied from Spitfires or any other car. Also, they changed during the S1 and S2. arms are different from the TC and TCS. SJ Sportscars sells them (https://www.sjsportscars.com).

Offline GavinT

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Re: S1 A-arms
« Reply #2 on: Sunday,June 08, 2025, 06:19:01 PM »
They are exclusively Lotus parts. I think I'm correct in saying the A-arms changed between the Type 54 and the Type 65.

However, the geometry is common across all models though to install the later arms, you'd need some spacers due to the top trailing arm being located aft of the T section.
And I seem to recall the S1 having some peculiarity concerning that aft mount point.

Offline My S1

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Re: S1 A-arms
« Reply #3 on: Monday,June 09, 2025, 07:50:06 AM »
Thank you for the education.

Offline jbcollier

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Re: S1 A-arms
« Reply #4 on: Monday,June 09, 2025, 08:18:12 AM »
You would have to modify the body to fit later upper a-arms to an S1.  They are available new/used on ebay.  Kelvedon makes reproductions.  They are fabricated rather than stamped.

When buying used there are three types out there:

1) no reinforcing at bush, ball joint holes are inline with the arm.  These can be used on either side.  The ball joint may bind at full droop.

2) no reinforcing at bush, ball joint holes are "tilted" in comparison to the arm.  Now handed and marked LH/RH.

3)  reinforced at the bush, ball joint holes are "tilted" in comparison to the arm.  Now handed and marked LH/RH.  These are the best choice.

Any lower a-arm can be used as they are all dimensionally the same even though the have different shapes.

Offline My S1

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Re: S1 A-arms
« Reply #5 on: Monday,June 09, 2025, 02:58:55 PM »
Thank you John for the head's up.  I'll have to think this through more closely.