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Should Upper Trunions be Replaced?

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dschwartz1957 David Schwartz
Framingham, MA, USA   USA
1950 Morris Minor "Moyshe"
1968 Morris Mini Traveller "The Tardis"
2000 Mazda MX-5
A few weeks ago during a discussion about replacing the front brakes in my 1950 Tourer, someone suggested inspecting the trunions (link pivot). Since the back plates are off this seemed like a good time for a thorough cleaning and inspection. I am also installing a set of rebuilt front dampers, so everything needed to come apart.

Attached are some photos of the upper trunion and related parts. They are worn and do not match the parts listed in the original BMC shop manual part diagram (page K.2). These do not use rubber bushes and instead have a brash bushing. I had a very difficult time removing the damper from the trunion. At a minimum, the seals, rubber band rings and locktab washers need to be replaced. Could a previous owner have installed parts from a different car? These don't match the lower pins and links either, though the lower do use the rubber band sealing rings.

Should I replace the trunions and upper links? If so, which parts should I use? ESM has a full kit which is less expensive than ordering all the individual parts:

Trunnion Kit-Top R/H (Made in UK) WITH UPPER PIVOT PIN & RUBBER BUSHES. SUS137
http://www.morrisminorspares.com/front-suspension-c47/front-suspension-all-models-c71/trunnion-kit-top-r-h-made-in-uk-with-upper-pivot-pin-rubber-bushes-p830544

Trunnion Kit-Top L/H (Made in UK) WITH UPPER PIVOT PIN & RUBBER BUSHES SUS138 - photo appear to be the lower kit
http://www.morrisminorspares.com/front-suspension-c47/front-suspension-all-models-c71/trunnion-kit-top-l-h-made-in-uk-with-upper-pivot-pin-rubber-bushes-p830545

Thanks again,

David Schwartz



Edited 2 time(s). Last edit at 2017-09-11 08:00 PM by dschwartz1957.

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pixelsmithusa Avatar
The fulcrum pin does not look correct, and appears at least to be improvised/compromised in some way. I would replace complete upper and lower if it were me. In my mind, a bad sign of a repair like that puts all of it in question. You'll want to make sure that the Acme threads at the top and bottom have not been compromised. Worn or corroded threads at the top or especially the bottom can lead the the trunnion separating from the king pin, leading to collapse of the front end. I've actually seen this happen on a couple occasions.



Gerard

http://gerardsgarage.com/

0123 Mike D
Biddulp, Staffs, UK   GBR
In reply to # 26032 by dschwartz1957 A few weeks ago during a discussion about replacing the front brakes in my 1950 Tourer, someone suggested inspecting the trunions (link pivot). Since the back plates are off this seemed like a good time for a thorough cleaning and inspection. I am also installing a set of rebuilt front dampers, so everything needed to come apart.

Attached are some photos of the upper trunion and related parts. They are worn and do not match the parts listed in the original BMC shop manual part diagram (page K.2). These do not use rubber bushes and instead have a brash bushing. I had a very difficult time removing the damper from the trunion. At a minimum, the seals, rubber band rings and locktab washers need to be replaced. Could a previous owner have installed parts from a different car? These don't match the lower pins and links either, though the lower do use the rubber band sealing rings.

Should I replace the trunions and upper links?
Yes smiling smiley
If so, which parts should I use?
ESM's kit unless Gerard or
Steve can give you a better price.

ESM has a full kit which is less expensive than ordering all the individual parts:

Trunnion Kit-Top R/H (Made in UK) WITH UPPER PIVOT PIN & RUBBER BUSHES. SUS137
http://www.morrisminorspares.com/front-suspension-c47/front-suspension-all-models-c71/trunnion-kit-top-r-h-made-in-uk-with-upper-pivot-pin-rubber-bushes-p830544

Trunnion Kit-Top L/H (Made in UK) WITH UPPER PIVOT PIN & RUBBER BUSHES SUS138 - photo appear to be the lower kit
http://www.morrisminorspares.com/front-suspension-c47/front-suspension-all-models-c71/trunnion-kit-top-l-h-made-in-uk-with-upper-pivot-pin-rubber-bushes-p830545

Thanks again,

David Schwartz

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emjay Jim English
Marietta, PA, USA   USA
It appears that you still have the first style of upper link. Replacement was recommended in the workshop manual. If you do update to the rubber design, the bump stop needs to be moved due to the different offset of the top trunnion.

0123 Mike D
Biddulp, Staffs, UK   GBR


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usmh3 Avatar
usmh3 Rob Thomas
Cardiff, Wales, UK   GBR
Keep those parts for historical purposes. The bronze top links and plain steel pin are only used on very early cars. Isn't John Voelker (?) on here rebuilding a very early car? He might need them!

I'd buy the kit from ESM and remember to move the bumpstop, as above, and add a 3mm+ shim between the eyebolt and the chassis rail, as per the manual.



Edited 1 time(s). Last edit at 2017-09-12 08:44 AM by usmh3.

dschwartz1957 David Schwartz
Framingham, MA, USA   USA
1950 Morris Minor "Moyshe"
1968 Morris Mini Traveller "The Tardis"
2000 Mazda MX-5
If I fit the improved top links and pins, moving the rubber bump stop looks to be straight forward. However, the instructions in the manual for modifying the lower suspension to maintain the correct steering geometry are rather confusing (see page K.11 in the original Workshop Manual). This is beyond simply fitting a 3mm shim washer.

Since the bronze top links are original to the early Minors, I am inclined to use them in the short term. It would be really nice to get my car back on the road before snow and road salt season.

David

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0123 Mike D
Biddulp, Staffs, UK   GBR
Good thinking David thumbs up

emjay Jim English
Marietta, PA, USA   USA
I'll look into it later but was the workshop manual stating that the upper link pin at one time was threaded in the link? It seems that the first attempt to eliminate movement of the pin in the upper link (rattle) was to use a threaded pin to prevent axial movement. If you jump over this modification and go straight to the later design with rubber bushings you don't need to do all the associated mods. But the upper link does widen the tack.

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dschwartz1957 David Schwartz
Framingham, MA, USA   USA
1950 Morris Minor "Moyshe"
1968 Morris Mini Traveller "The Tardis"
2000 Mazda MX-5
Attached are two pages from the September 1954 Workshop Manual, Issue 4. These describe the various links and pins. Figure K.12 shows the modifications to the lower suspension arm that are needed if you install the links and pins that accept rubber bushes. I find the figure and instructions lacking sufficient details for me to do this job ;-) Then there is cutting the inner wing support to move the bump-rubber (figure K.13).

Simply installing the later links and pins look simple.

David



Edited 1 time(s). Last edit at 2017-09-27 09:21 PM by dschwartz1957.


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JohnV Avatar
JohnV John V
Woodstock, New York, USA   USA
I will be fascinated to find out what you decide, David.

I've not had my 1949 Tourer apart (and it won't be for a couple of years), but as Rob T and Jim E note, the brass bushings are original to the early cars.

If you do decide to do the conversion, indeed, I'd be happy to get the older brass bushings. My Tourer needs ... well, essentially everything.

0123 Mike D
Biddulp, Staffs, UK   GBR
In reply to # 26294 by JohnV I will be fascinated to find out what you decide, David.

I've not had my 1949 Tourer apart (and it won't be for a couple of years), but as Rob T and Jim E note, the brass bushings are original to the early cars.

If you do decide to do the conversion, indeed, I'd be happy to get the older brass bushings.
Have you considered plastic bushings?
My Tourer needs ... well, essentially everything.

dschwartz1957 David Schwartz
Framingham, MA, USA   USA
1950 Morris Minor "Moyshe"
1968 Morris Mini Traveller "The Tardis"
2000 Mazda MX-5
At this point I plan to reinstall the early links and pivot pins. The conversion to the later parts is more than I want to take on right now.

RE: Have you considered plastic bushings?

The brass bushings have a smaller outside diameter from the rubber (or poly) bushings. The poly bushing does fit on the pivot pin, but there is no way it would fit in the link if I removed the brash bushing. Plus, the later pivot pins use large washers to hold the bushings in place.

http://www.morrisminorspares.com/front-suspension-c47/front-suspension-all-models-c71/trunnion-kit-top-r-h-made-in-uk-with-upper-pivot-pin-rubber-bushes-p830544

0123 Mike D
Biddulp, Staffs, UK   GBR
If it can be made in brass
it can be made in plastic Matethumbs up

Polypenco acetal if you prefer thumbs up

emjay Jim English
Marietta, PA, USA   USA
The upper link doesn't have nearly the load on it that the lower link does which is still a metallic bushing. However, looseness in the bushing will be apparent sooner since the lower one maintains contact better due to the higher loads and the upper one can easily rattle when there is clearance. Keeping it well grease will help. Another non-metallic material can be used, but most likely will need to be machined to fit, so in either case a machining resource is required. However, if you go with something that is not compatible with the grease that will be on the threads of the swivel, the bushing needs to be isolated as originally, one grease fitting did both areas.

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