Lower trunnion

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biomed32uk
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Lower trunnion

Post by biomed32uk »

I have done some google searching, and through the forum and I cant find a picture anywhere that shows the thust washers.

They have a chamfer on them and I am wondering which way round the should be fitted, they came off with the chamfer facing the trunnion. Just want to know it is all correct when the car goes back together, once I have stripped the other side, cleaned and painted everything etc etc.
IslipMinor
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Re: Lower trunnion

Post by IslipMinor »

Looking at the BMC Parts List and Workshop Manual, neither show the orientation of the thrust washers at all.

I have always fitted them with the chamfer facing away from the trunnion, as that gives the maximum thrust/rotating face area (less wear) between the washer and the trunnion, and makes sliding the rubber seal over the washer and trunnion register easier.
Richard


philthehill
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Re: Lower trunnion

Post by philthehill »

As above.
The fully flat face of the thrust washer should face the trunnion.
The chamfered face towards the suspension arms.
The Marina/Ital which uses the same type of lower front suspension (same size dia trunnion pin but the swivel has a larger thread) - has in the BL wksp manual AKD7555 page 60.40.02 an exploded diagram which clearly illustrates the thrust washer with the chamfer(s) towards the suspension arms.

Here is a photo of the thrust washers fitted the right way round.
You will have to excuse the multitude of grease nipples as they were fitted to determine the best position for the grease nipple(s).[frame]Image[/frame]

As an aside the original BL Marina/Ital trunnion pin and pin seals are of a much better quality than those fitted to the Minor and can be utilised in the Minor lower swivel. Unfortunately the swivel itself cannot be used on the Minor because of the larger threads but the bushes for the trunnion pin can be pressed out and utilised in the Minor lower swivel.
NOS Marina lower trunnion/swivel repair kits can usually be found on 'e' bay at reasonable prices.[frame]Image[/frame]

biomed32uk
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Re: Lower trunnion

Post by biomed32uk »

Thanks Phil, that's a useful picture. That's the way I would have put them back as I could see no good reason for a chamfer against the trunnion, does not surprise me they were on wrong.

Useful info re the bushes, the actual leg and trunnions are fine, no wear on the threads which is good, however the lower fulcrum pin has a small raised gouge mark on it, someone has forced the trunnion on with the resultant marks in the bush. It's not bad but it certainly needs a new pin. Some new bushes may just save the trunnion.

All things considered I have not found too many horrors, considering some of the other poor workmanship the car has revealed. Quite why there were two horseshoe washers behind the rear torsion bar arm I don't know. The rubber bushes are nicely perished which is the main reason I am here.

Strip the nearside off next, see what that reveals. Clean and inspect everything then, and ascertain what parts are required to build back up. In the meantime all the suspension parts get a nice coat of paint.
philthehill
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Re: Lower trunnion

Post by philthehill »

The horseshoe washers (Pt No: AAA1484) are there so the torsion bar can be withdrawn rearwards through the cross member if removal is required.
If the torsion bar needs to removed I will always remove it forwards after the suspension has been disengaged.
Strange that two horse shoe washers were fitted on the same torsion bar but I suspect that the two horseshoe washers were fitted to build out the arm on the torsion bar. Sometimes packing is required especially after a new cross member has been fitted.
Personally I ditch the horseshoe washers and fit the stepped washer (Pt No: AAA1485) either side of the cross member as it makes for a more secure fitment of the torsion bar at the its rear end.
I have found that on numerous occasions that the step in the stepped washer is not always a right angle and therefore does not fit snugly into the cross member. To overcome I have had to spin the washer in the lathe and square the angle.
Last edited by philthehill on Mon Nov 21, 2016 9:58 am, edited 1 time in total.

IslipMinor
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Re: Lower trunnion

Post by IslipMinor »

On the subject of the fitment of the torsion bar to the crossmember, the replacement crossmember that I used is slightly thinner where the torsion bar fits, and the combined depth of the steps in the two washers was very slightly greater than the material thickness of the crossmember. The nut tightened of course, but did not properly 'clamp' the crossmember, so had to face off about 0.010" from each of the washers.

I am not sure if this is a potential problem with standard Minor torsion bars or not? We have Marina van bars, and they need a slightly different rear fixing, but still using EDIT two should be one stepped washers as normal.
Last edited by IslipMinor on Mon Nov 21, 2016 10:52 pm, edited 1 time in total.
Richard


philthehill
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Re: Lower trunnion

Post by philthehill »

Richard
You quote using two stepped washers 'as normal'.
Only one stepped washer is used for the 'normal' fitment of a torsion bar into the Minor cross member and that is fitted to the rear face of the cross member.
I do not want anyone thinking they are missing/deficient a stepped washer.
Phil

biomed32uk
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Re: Lower trunnion

Post by biomed32uk »

Some interesting points there and useful tips.

I can't see any reason to pack out the rear arm from the cross member with another washer. Surely there's enough fore and aft movement at the front of the bar on the splines where it meets the lower arm to allow the bar to pull up to the cross member nice and snug.

When I took the bolt out securing the rear arm to the vernier plate the arm came away from the cross member, suggesting it was too far forward. Whether it had all rusted up on the splines when the car was rebuilt and cross member fitted, or it was just a bodge I don't know. The rear arm was certainly tight, needing some releasing oil and warmth to shift it from the splines.

Once I get it all clean I can offer everything back up for a trial fit and see what's what. I like the idea of a stepped washer either side, not bothered about being able to draw the bar rearwards.

I have a lathe on hand so it can be all engineered to fit nicely and make a proper engineering job.
philthehill
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Re: Lower trunnion

Post by philthehill »

The packing may have been done to ensure that there was sufficient spline lengths within both of the arms.
The depth that the front torsion bar splines fit into the front lower thick arm is determined by the relationship between the rear end of the torsion bar and the position of the cross member.
It may be that the torsion bar did not fit far enough into the lower thick suspension arm and a previous mechanic (sic) may have decided that the extra horseshoe washer was sufficient to give that extra little bit of spline engagement.
It is better to pack the torsion bar forward than to have insufficient spline engagement.
The rear arm can be adjusted/packed (fore and aft) to maximise the spline engagement as well.
It is all a matter of fitting and judgement.
Phil

biomed32uk
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Re: Lower trunnion

Post by biomed32uk »

What's the ideal amount of engagement for the front splines, other than as much is possible.

The way the washers were would have not altered the amount that was in the rear arm, as the whole lot was spaced forward of the cross member, so fully in the rear arm.

If I need to bring the rear arm forwards then I will turn up a custom stepped washer, that will fit properly into the recess in the rear arm and fit into the cross member.

A trial fit will reveal all I am sure.
philthehill
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Re: Lower trunnion

Post by philthehill »

The spline engagement into the front suspension should be as much as possible.
The limiting factor is the threaded stud (non removable) at the rear of the torsion bar.
The nut on those threads must be fully engaged with the torsion bar stud threads i.e. the threads should extend right through nut plus at least two threads.
I would say that the mechanic used his judgement and spaced the rear arm correctly to maximise spline engagement.
Only on a new chassis/body will everything fit together as designed.

biomed32uk
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Re: Lower trunnion

Post by biomed32uk »

There was certainly not that much thread through the nut, the threads on the end of the bar being recessed into the nut.

The extra washer was probably the one from the passenger side that was missing !, stripped that side off this evening.

At least I know what the creak was from the NS, bush completely through on one end, the pin looks to have taken the wear as the eyebolt looks OK. WD40 has kept it quiet ish for the last few months.

Both legs are OK so that's a relief.

I think it's get everything cleaned up, painted, new parts ordered up and then see how it all looks on a trial fit.

Good time to get at those hidden bits of the cross member and cover it in Dinitrol.
biomed32uk
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Re: Lower trunnion

Post by biomed32uk »

There was certainly not that much thread through the nut, the threads on the end of the bar being recessed into the nut.

The extra washer was probably the one from the passenger side that was missing !, stripped that side off this evening.

At least I know what the creak was from the NS, bush completely through on one end, the pin looks to have taken the wear as the eyebolt looks OK. WD40 has kept it quiet ish for the last few months.

Both legs are OK so that's a relief.

I think it's get everything cleaned up, painted, new parts ordered up and then see how it all looks on a trial fit.

Good time to get at those hidden bits of the cross member and cover it in Dinitrol.
biomed32uk
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Re: Lower trunnion

Post by biomed32uk »

There was certainly not that much thread through the nut, the threads on the end of the bar being recessed into the nut.

The extra washer was probably the one from the passenger side that was missing !, stripped that side off this evening.

At least I know what the creak was from the NS, bush completely through on one end, the pin looks to have taken the wear as the eyebolt looks OK. WD40 has kept it quiet ish for the last few months.

Both legs are OK so that's a relief.

I think it's get everything cleaned up, painted, new parts ordered up and then see how it all looks on a trial fit.

Good time to get at those hidden bits of the cross member and cover it in Dinitrol.
IslipMinor
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Re: Lower trunnion

Post by IslipMinor »

Phil, The Marina arrangement uses an adapter at the end of the torsion bar, and that has a step, as has the rear washer, I had memories of the 'U' washer being stepped as well, but it is not.

I have made a visible edit to the previous post to make sure that it should be ONE not the two that was in the original post.

Pity we can't use 'strikethrough' to make it clear that a change has been made - MODERATORS, can this be done please?
Richard


philthehill
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Re: Lower trunnion

Post by philthehill »

Richard
Many thanks for amending your post.
The adapters as you say do have a step.
My only comment on the Owen Burton adapters I have (pictured below) is that the rear reaction bar female splines are used 50/50 with the adapter and the rear torsion bar splines.
It is the rear reaction arm/splines that keeps it all together.
The adapters must be kept firm up against the end of the Marina torsion bar to maximise the shared splines and that can be attained by using the washers supplied with the adapters which may mean the step of the adapter may not be fitted into the cross member and the location reverts to being standard Minor type with one stepped washer.
When the number of washers required is being determined the Marina torsion bar must be driven fully home into the Minor thick lower suspension arm.
To maximise the spline contact there may be a requirement to pack the front of the torsion bar.
As I said above it is all a question of fitting and judgement and no two situations will be the same.
Phil[frame]Image[/frame]

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Re: Lower trunnion

Post by LaughingBoy »

An old thread I know but I am trying to get rid of a loud squeaking / creaking noise from the front suspension. I have pulled everything apart, re-greased the poly eye-bolt bushes and re-assembled but the noise is still there! So I have dismantled again and noticed that the chamfered thrust washers on the lower trunnion were not the correct way round i.e. the chamfered face was inwards towards the trunnion. Also noticed a curved groove on the inside of the trunnion metal bush sleeves - I assume that this is not wear but a machined groove to help lubrication. The pin itself is in good condition. So I am just wondering if the incorrect orientation of the chamfered washers could cause noise or any other problem?
Also I notice that in the photo above of the lower trunnion assembly (with 3 grease nipples!) that there seem to be several washers on the pin in addition to the thrust washer and spring washer - I just have the inside face of the wishbone arms flat against the thrust washers and spring washers & nuts on the outside on the end of the pin.

I am trying to eliminate all potential problems before re-assembling.
philthehill
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Re: Lower trunnion

Post by philthehill »

The three grease nipple bottom trunnion was a trial to see which was the best position for any additional grease nipples. The results can be found in another thread. The additional washers were just to hold the trunnion pin in place while grease was injected.
Having the chamfered washer the wrong way round (the chamfer should be away from the trunnion) would not cause the noise but it is better if it is the right way round.

Is the chassis rail cracked around the eye bolt which is a common failure point?

Have you tried the tightness of the damper mount bolts as they do come loose allowing the damper to move.

The bushes with the machined groove are correct so as to allow grease to move along the bush.

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Re: Lower trunnion

Post by LaughingBoy »

Thanks for the advice. Yes I have briefly checked the damper mountings. I disabled the lever-arm dampers a while back by removing the valves & springs and more recently flushed them through and refilled with jack oil as I was concerned the damper internals might be making the noise. Anyway I think the mountings are fine as the lock washer tabs are still folded over and I can't feel any movement. I have removed my telescopic damper to eliminate that as the source of the problem and now I can reproduce the noise by bouncing the front up and down and the noise definitely seems to be coming from under the wheel arch rather than under the bonnet - previously (with the telescopic damper in place) I had to drive over speed bumps to make the noise so it was more difficult to locate the source.

The chassis leg also looks fine but I have not scraped away the underseal. I will try to remove the eye-bolt and have a closer look.
philthehill
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Re: Lower trunnion

Post by philthehill »

Re the front damper mount bolts and lock tabs.

As the dampers have alloy bodies they are prone to squashing of the damper body in the area around the mounting bolts. Even if the bolts look tight and the locking tabs are in place and ok that does not necessarily mean that the bolts are tight. Damper mounting bolts have to be and should be checked for tightness on a regular basis.

Phil

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