Lotus Elan

Trunnions. Angles and greasing

PostPost by: snowyelan » Mon Jun 28, 2021 8:46 pm

The balljoint isn't required if a different method of aligning the trunnion can be used. The elan (and all trunion style suspension by design) has parallel inner pivot axis' so the amount of bind doesn't change when articulated. All that needs to be accomplished is that the trunnion axis needs to intersect the upper balljoint centerpoint.
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PostPost by: Vali » Tue Jun 29, 2021 5:27 am

Fitting a spherical rose joint in the trunnion instead of the bushes would help, right?
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PostPost by: snowyelan » Tue Jun 29, 2021 11:55 am

Vali,
It would work if it replaced the bushings. Fitting it in with the upright thread so close could be an issue.
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PostPost by: 661 » Tue Jun 29, 2021 12:27 pm

snowyelan wrote:The balljoint isn't required if a different method of aligning the trunnion can be used. The elan (and all trunion style suspension by design) has parallel inner pivot axis' so the amount of bind doesn't change when articulated. All that needs to be accomplished is that the trunnion axis needs to intersect the upper balljoint centerpoint.

This what I have done with a re engineered , offset trunnion polybush.
The shock on a 26r has a spherical bearing at its lower end so no extra stresses there.
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PostPost by: Vali » Tue Jun 29, 2021 7:58 pm

It would work if it replaced the bushings. Fitting it in with the upright thread so close could be an issue.


So the bore of the trunnion is 3/4".
OD around 28.5mm.
But smallest spherical rose joint (then with 1/2" bore for bolt) is 7/8" = 22.2mm.
For fitting this size the trunnion bore would need to be bored out from 3/4" to 7/8"
That would leave a wall thickness of around 3.1mm ... not much for brass.
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PostPost by: snowyelan » Wed Jun 30, 2021 1:22 am

If you have access to a lathe and mill I suppose you could re-bore the trunnion slightly bigger with an angular offset, reface the ends, then turn up custom bushings to suit the larger bore and slightly shorter trunnion bore (thicker tophat rim). As my old drafting teacher would say, lots of ways to skin a cat.
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PostPost by: Vali » Wed Jun 30, 2021 7:52 am

https://www.limora.com/en/suspension-li ... 18041.html

This might be a solution, too. Available in 3 degrees, too.
Bore out to 3/4" and press the Elan bushes in.
I will look into this. Might work out.
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PostPost by: 661 » Wed Jun 30, 2021 9:16 am

Vali wrote:https://www.limora.com/en/suspension-link-trunnion-1-118041.html

This might be a solution, too. Available in 3 degrees, too.
Bore out to 3/4" and press the Elan bushes in.
I will look into this. Might work out.


Good spot. Why not just use the TR4A polybushes? The bolt may be smaller but if it's big enough for the heavier car it's probably OK for an Elan. I reinforced the holes in the wishbones anyway so a smaller hole could be made in them if needed.
I assume the 2 deg 40 mins would be added to the 3 deg the chassis should have, which would be about right.
I looked at the TR4A king pins and I assumed the threa into the trunnion would be the same as in the Elan?

How much depth was there in the botton plate of the trunnion for you to thread your grease nipple into and did you have to cut down the other side of the nipple to avoid touching the bottom of the king pin?
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PostPost by: Mike+2 » Wed Jun 30, 2021 8:00 pm

I'm not sure if this has been discussed, but I am of the opinion that you do not use a typical grease gun with grease to lube the trunnions. Regular grease is too heavy - thick to do any good in a trunnion. If you have removed a used trunnion before, and have had to use a small blade screwdriver to work out the goo between threads on the upright, you know what I'm trying to describe here. Cleaning the inside of the trunnion is a whole different exercise.

What I would like to bring forward is to use a more fluid gear lube. This requires a different type of 'grease gun' to inject via the grease nipple, but I've used it on my Triumphs for nearly 20 years now and have had no failures or binding. I submit the picture below for consideration.
Attachments
Gear Lube Gun for Trunnions.jpg and
Gear Lube Gun for Trunnions
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PostPost by: Vali » Wed Jun 30, 2021 9:05 pm

661 wrote:How much depth was there in the botton plate of the trunnion for you to thread your grease nipple into and did you have to cut down the other side of the nipple to avoid touching the bottom of the king pin?


I measured the plate with 2mm.
And I tried to cut down the nipple thread but then the spring inside just popped out. Cutting down the nipple thread is not recommended then.
Nipple thread is 4mm long so it sticks out in inner trunnion 2mm.
King pin had a space of 6mm I believe, thats enough space.

If possible use a rivnut or similar like Triumph must have let done to theirs.
https://rimmerbros.com/Item--i-133839
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PostPost by: rgh0 » Thu Jul 01, 2021 1:26 am

Mike+2 wrote:I'm not sure if this has been discussed, but I am of the opinion that you do not use a typical grease gun with grease to lube the trunnions. Regular grease is too heavy - thick to do any good in a trunnion. If you have removed a used trunnion before, and have had to use a small blade screwdriver to work out the goo between threads on the upright, you know what I'm trying to describe here. Cleaning the inside of the trunnion is a whole different exercise.

What I would like to bring forward is to use a more fluid gear lube. This requires a different type of 'grease gun' to inject via the grease nipple, but I've used it on my Triumphs for nearly 20 years now and have had no failures or binding. I submit the picture below for consideration.


This has been discussed many times - oil, semifluid grease , normal grease. They all work.... some better than others in differing conditions. I wont repeat myself except to say normal modern grease is probably best IMHO despite what Triumph said originally 60 years ago... time and technology moves on.

cheers
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PostPost by: ChrisD » Mon Jul 05, 2021 7:11 am

I agree with Rohan, modern grease is it.
I wanted it strong, so I took solid uprights.
But how to grease then?
I spot welded and soldered nuts to the trunnion bottom for grease nipples.
Works fine.
But propably my future project could be some Caterham uprights and home made lower adapters for spherical joints.

Regards, Christian
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