Lower fulcrum shaft length

Technical advice Q&A

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Philippe-J.
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#1 Lower fulcrum shaft length

Post by Philippe-J. » Mon Aug 19, 2024 5:33 pm

Rebuilding my front suspensions, I noticed that the lower fulcrum shafts are not the same length on my car, by about 10 mm. As a result, I had to squeeze the LH front lower bush (bottom of the photo) dramatically so that the slotted nut could clear the split pin hole at the end of the shaft.

Image

Of course now the fulcrum block can not bet rotated by hand.

Is this situation ok? How can it be that some shafts can be shorter? Do you think that usual sellers can assess that their spare shaft will be the right length if I order one?
One solution would be to shorter the ends of the rubber bush with a knife. Would it be ok?

Thanks for your lights!
Philippe-J

1967 S1(.25) OTS ... coming together
https://renov-ots-1967.over-blog.com/

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mgcjag
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#2 Re: Lower fulcrum shaft length

Post by mgcjag » Mon Aug 19, 2024 5:45 pm

The nuts need to be lose so the wishbone can move untill you have set your ride height and after the car has been moved on its wheels a bit..then tighten the byshes..after market non original parts...you cannot rely on any part being the same as original parts....any part that you order measure against an original befor use...that includes bushes and nuts...Steve
Steve
69 S2 2+2 (sold) ..Realm C type replica, 1960 xk150fhc

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Allrand
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#3 Re: Lower fulcrum shaft length

Post by Allrand » Mon Aug 19, 2024 6:44 pm

The fulcrum points will be at a fixed distance apart determined by their mounting points in the frame.
Randall Botha
'64 3.8 fhc & '51 Mk 7 (now sold)

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mgcjag
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#4 Re: Lower fulcrum shaft length

Post by mgcjag » Mon Aug 19, 2024 8:48 pm

Randall..look at the photo the shafts are different lengths.
Steve
Steve
69 S2 2+2 (sold) ..Realm C type replica, 1960 xk150fhc

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abowie
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#5 Re: Lower fulcrum shaft length

Post by abowie » Mon Aug 19, 2024 10:31 pm

Buy new ones.

You car will not track and steer properly.
Andrew.
881824, 1E21538. 889457. 1961 4.3l Mk2. 1975 XJS. 1962 MGB. 1979 MGB.
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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Allrand
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#6 Re: Lower fulcrum shaft length

Post by Allrand » Tue Aug 20, 2024 7:07 am

mgcjag wrote:
Mon Aug 19, 2024 8:48 pm
Randall..look at the photo the shafts are different lengths.
Steve
That's my point, the short one won't fit the mounting points in the frame.
Randall Botha
'64 3.8 fhc & '51 Mk 7 (now sold)

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Philippe-J.
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#7 Re: Lower fulcrum shaft length

Post by Philippe-J. » Tue Aug 20, 2024 7:57 am

Both the wishbones fit to the frame as I found them assembled to it when I dismantled the car. The space between the blocks is the same and fits the frame both sides.
Indeed the point is the length of the thread at the front of the fulcrum shafts that is shorter on the LH:


Image

so short that I can not screw the slotted nut up to the split pin hole, and have to over squeeze the bush too.

I wonder how the PO manage to deal with it :scratchheadyellow:

I'll try and buy a new one, hoping its size will be ok. :fingerscrossed:

Thanks.
Philippe-J

1967 S1(.25) OTS ... coming together
https://renov-ots-1967.over-blog.com/

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UK Muppet
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#8 Re: Lower fulcrum shaft length

Post by UK Muppet » Tue Aug 20, 2024 9:37 am

If the only issue is the length of the threaded portion being short for the castellated nut then the easiest solution is to make the nut thinner, skim some off the clamping face in a lathe.
Its normal practice to remove material from the nut to align with a split pin hole.
Tony
69 Series 2 2+2 auto

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Philippe-J.
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#9 Re: Lower fulcrum shaft length

Post by Philippe-J. » Tue Aug 20, 2024 10:28 am

I am a bit confused about my question because I found out, and it's all my mistake!
The problem was that I was not aware of the shaft being not symetrical front vs rear. I discovered that each end has a shouldering (is that correct english?) i.e. a portion where the diameter is smaller, and that this portion doesn't have the same length rear vs front:
Image

I put the LH shaft the wrong way, with the shorter end to the rear arm, which has the larger end width :doh:

Reversing the shaft solved the issue and everything moves more freely now :thumbsup:

Edit: I just discovered a thread that deals with this issue: viewtopic.php?f=3&t=16068&p=131885&hili ... er#p131781. I should have searched better before asking...

Thanks for helping anyway.

Philippe
Philippe-J

1967 S1(.25) OTS ... coming together
https://renov-ots-1967.over-blog.com/

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