Trunnion bolt torque

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Roger Pennington
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Re: Trunnion bolt torque

Post by Roger Pennington » Mon Jun 19, 2017 1:51 pm

Martin North (IIRC) sourced a trunnion bush kit with stainless steel sleeves and poly (instead of nylon) top hats. There'll be a reference on here somewhere


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Re: Trunnion bolt torque

Post by Roger Pennington » Mon Jun 19, 2017 2:00 pm



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Re: Trunnion bolt torque

Post by scmarf » Wed Jun 21, 2017 12:22 am

Taggers wrote:Coming back to trunnions...

I've got to marmalise a trunnion this weekend. I have a QRG trunnion and a rebuild kit.

The kit contains 4 big (1 1/2 "ish) cup washers of thin, plated steel, and 4 thin "O" rings that seem to fit into the cup. The trunnion that's on doesn't have any of this (that I can see) and seems to have a big, thick penny washer either side, and then the nylon top hat.


Where do these bits go, please?


Chris
scmarf wrote:
scmarf wrote: .... I'll try and search it out tonight. Maybe a Slice article too as I have just done all this on a 5a so can get some photo. Watch this space.
Couldn't find the diagram but took this of the grease nipple mod.
This drawing shows the power steering setup for the SE6a. For the manual steering setup there will be no top-hat bush in the trunnion - otherwise it's identical.
trunnions.jpg
power steering trunnion setup
trunnions.jpg (91.89 KiB) Viewed 1613 times
I would include the seals even with stainless sleeves. It is never a good idea to allow dirt and water into moving suspension joints. Also, if your lubricant dries out, water could become an electrolyte and you could get galvanic corrosion between the stainless sleeve and the mild steel bolt. Why risk it?


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Re: Trunnion bolt torque

Post by Roger Pennington » Wed Jun 21, 2017 2:08 am

scmarf wrote: This drawing shows the power steering setup for the SE6a. For the manual steering setup there will be no top-hat bush in the trunnion - otherwise it's identical.
Note that only older PAS trunnions had the steel top hats, it's something that was later deleted (approximately coincident with the Se6b IIRC). Also that diagram doesn't appear to show the inner large washers?


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Re: Trunnion bolt torque

Post by scmarf » Wed Jun 21, 2017 6:13 pm

I have a feeling I could only get the nut to line up with the split pin hole in the bolt by leaving out the inner washers (hence my comment above about the sleeves damaging the trunnions/inserts) but it was a while ago. Maybe the power steering inserts were designed to not need the inner washers.


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Re: Trunnion bolt torque

Post by ScimmyMike » Wed Jun 21, 2017 9:23 pm

I can confirm that there were none fitted in the two I've replaced on my former 6b over the years


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Re: Trunnion bolt torque

Post by MikeT » Wed Jun 21, 2017 9:47 pm

scmarf wrote:I have a feeling I could only get the nut to line up with the split pin hole in the bolt by leaving out the inner washers (hence my comment above about the sleeves damaging the trunnions/inserts) but it was a while ago. Maybe the power steering inserts were designed to not need the inner washers.
I remember having a similar issue - to resolve it, i reduced the thickness of the 'brim' of the top hat bushes.

As you say though... it was a while ago ;)

Mike.


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Trunnion bolt torque

Post by Dennis Nicholas » Sun Mar 04, 2018 12:44 am

MikeT wrote:
Wed Jun 21, 2017 9:47 pm
scmarf wrote:I have a feeling I could only get the nut to line up with the split pin hole in the bolt by leaving out the inner washers (hence my comment above about the sleeves damaging the trunnions/inserts) but it was a while ago. Maybe the power steering inserts were designed to not need the inner washers.
I remember having a similar issue - to resolve it, i reduced the thickness of the 'brim' of the top hat bushes.

As you say though... it was a while ago ;)

Mike.
OR more correctly assemble all the bits correctly, and put a shim washer under the nut the right thickness to allow the nut at the correct torque to line up with the holes for the pins. The thread size (threads per inch - TPI) will tell you how far the nut moves for each turn. Where pinned nuts are used there are usually two holes spaced at a set distance that equates with the thread size. From memory the second hole is half a castellation turn from the first hole so slightly tighter or slightly backed will line hole and castellation up.
Since from the TPI you can calculate how much the nut needs to move to line hole up then you can use that thickness shim washer.
OR
A normal thickness washer can be put under the nut; torque up and see how far hole is off lining up and file down thickness of washer till holes line up. Again to save taking on and off, the distance the nut needs to move can be calculated and the washer can be filed to that size (micrometer to measure thickness)......you will be surprised how much effort filling is needed to take off a couple or so thou.
As an example using say 20 threads per inch then 1 thread = 1/20 th of an inch = one full turn of the nut; using 6 castellations then the distance the nut moves if nut turned one castellation is one sixth of a full turn = 1/20 X 1/6 =1/120 which is just over 8 thou (8.333 thou). If hole is half a castellation out then only 1/12th of a turn is required.....1/20 X 1/12 = 1/240 which is 0.004166" (just over 4 thou); If only a quarter of a castellation out then !/2 X 1/20 X 1/24 = 1/480 =0.0020833" (a tad over 2 thou) etc.

Dennis


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Trunnion bolt torque

Post by derekoss » Sun Mar 04, 2018 11:18 am

One thing I've noticed in various kits is where the spacer has been chamfered at the ends. Not just deburred. It's wrong to be like that either externally or internally.
Half the area and double the pressure. They then dig into the washer/part and become slack. I've also noticed some trunnion kits metric using metric tube. 16mm od and 14mm bore for a 12.7 bolt !
I've has to make spacers on several occasions as the replacements sent were no better. Some poly producers are worse than others.

Derek



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Trunnion bolt torque

Post by Dennis Nicholas » Fri Mar 09, 2018 5:35 pm

Ref leaving out the washers to get the nuts to line up with the holes and my reply......it has occurred to me that maybe that person meant that the nut would not go on far enough for the hole to be within the castellated area.......surly then a defect in the bolts being too short?

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