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Front trunnion bolt


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Way back in the mid 50s, my James Cadet motor cycle rear swing arm was 'similar'? to this set yup. It seized up. My journeyman (I was an apprentice. dismantled it, cursed with comments like crap design etc, took it to his workshop, drilled down from both ends and then cross drilled into the drill hole, fitted grease nipples each end and re-assembled after filling with grease. Pump some in every few months 'boy' and it will never seize again. If you ever see TRP849  (I think) check the swing arm. Just a thought for trunnion bolts?

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4 hours ago, Roger K said:

The real world, with traffic jams, weather extremes, 12 months between services etc. is a far harsher environment than any race track

 

3 hours ago, Peter Truman said:

he Herald/Spit front upright was also used by Brabham in his Formulea 1 cars,

If my memory serves me well my Lotus Europa utilised Spitfire uprights and trunnions; those bits did not fail and that was running from Rosyth Dockyard to London the weekends not at sea.  At the rear the stub axles were courtesy of the Hillman Imp.  LOTUS - Lots Of Trouble Usually expensive was frequently voiced by others.

Dick

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Pete is right about drilling. The bolt must be tight but my thought was that if the grease came through onto the nylon bushes, then they would be a lot easier to remove as usually the bolt rusts up and grips the top hats and makes it nigh on impossible to just push or drift the bolt out. I regularly (yearly) remove bolt, clean any rust off surface, re-grease and replace, all part of running an older car. I HAVE, in the past, had great fun removing a reticent bolt!

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3 hours ago, Pete Lewis said:

the bolt greasing only helps remove a rusty one , the bolt must be tight this locks the  bush crush tube and the bushes rotate around the tube the bolt and tube should not rotate .

drilling to grease the bush  on its tube could be fun 

Pete

I'm going to have to redo my rear trunnion block.  The steel tube sits about 3mm in from the ends of the nylon pieces and is too short.  I've got a poly set now with a correct length stainless tube, and none of the washers or seals.  I'm not convinced they achieve anything anyway.

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Im sure they dont recommend poly on the front trunnion as if too squidgy you have less  control of the stub axle 

not such a problem with the rears but these bushes do have to take all road load deflections 

you might punch a poly to bits where as the solid might seize but wont get squidged to bits 

Pete

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7 minutes ago, Pete Lewis said:

Im sure they dont recommend poly on the front trunnion as if too squidgy you have less  control of the stub axle 

If they're red poly they'll be solid enough; far more so than the blues. I'm interested in giving them a try on the convertible which certainly won't be raced or rallied. 

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Brief update:  I bolted up the trunnionless 'trunnion' to the lower wishbone, then attached the shock absorber mount to ensure fit was correct and placed the 'trunnion' in position so the flat sides were parallel to the lower wishbone.  I then ran a weld along each side at the top, and a couple on the underside.  I'll have the bolt in there as well, but I think this'll do the job neatly.  Photo, in etch primer.

 

 

IMG_9918.jpg

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Hi Roger,

I am very impressed with your welding. I wish I could do such things.

As the item has only one bolt securing it is it OK for it to be welded in a fixed position?

I do not know the structure so just asking.

Roger

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19 minutes ago, RogerH said:

Hi Roger,

I am very impressed with your welding. I wish I could do such things.

As the item has only one bolt securing it is it OK for it to be welded in a fixed position?

I do not know the structure so just asking.

Roger

It should be, as far as I can see.  The bolt is designed to hold the structure together, not to pivot.  The spherical bearing allows full range of movement of the vertical link - I've checked with a mock-up.

Thanks for the comments!  I've been doing it a long time...

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1 hour ago, RogerH said:

Hi Roger,

I am very impressed with your welding. I wish I could do such things.

As the item has only one bolt securing it is it OK for it to be welded in a fixed position?

I do not know the structure so just asking.

Roger

It is a nice weld. 

I have seen that done before, although in practice the bearing housing does not seem to move. I certainly can't see any witness mark on mine. Equally, there is no downside, unless a wishbone gets damaged. But then it is just a case of a new housing or 20 mins with the grinder. I am tempted to follow suit....

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17 hours ago, Roger K said:

Brief update:  I bolted up the trunnionless 'trunnion' to the lower wishbone, then attached the shock absorber mount to ensure fit was correct and placed the 'trunnion' in position so the flat sides were parallel to the lower wishbone.  I then ran a weld along each side at the top, and a couple on the underside.  I'll have the bolt in there as well, but I think this'll do the job neatly. 

Definitely impressive! But: you're sure the movement that would be provided by the lower trunnion pivoting on the original bush and bolt setup isn't required?

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no, its a rose joint with pivoting ball that connects to the new upright under that piece of masking paper in the photo and that allows all the movement required for full suspension travel. Really its just converting to a ball joint at the bottom like moderns...

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