Trunnion bushes not lasting

[daverclasper]

Hi. Replaced mine on Vitesse about 3 years and 9,000 ago. There is now play in both, pretty bad on nearside. Bit the bullet and ordered some Superflex ones, (about £12 more for both sides from Paddocks) as it's a bit of a faf to replace as often as this.

I think I read that Canley, don't stock Super/Poly ones for trunnions as not necessary.

Maybe I was unlucky?, though thought it might be useful info for others.

Dave 

 

  

[Pete Lewis]

Poly are not generally recomended as replacement for the hard nylons on the trunnions as there needs to be good control of the suspension upright under all the steering and braking loads

Pete

[daverclasper]

Oh dear. they are red ones, which I hope are firmer.  Well, I don't push the car at all, so maybe not the end of the world, or hopefully even a few people!.

What where the originals made from?.

Dave 

Edited November 1, 2018 by daverclasper

[dave.vitesse]

The original trunnion bushes are poly. Standard Triumph were way ahead of their time. You do need to assemble them with the rubber sealing ring between the metal cap and top of the bush to stop the road dirt from getting in.

Dave

[daverclasper]

Thanks. The Super/Poly ones I bought, I questioned with Paddocks, as they don't have the end caps/seal ring. they said they just have washers as not needed on these ones.

Could this be, because they they are softer (like wishbone bushes) and compress some if the crush tubes allow this and therefore don't ingress water between the trunnion/crush tube?. Or do I need to refit the old caps/seals.

Dave 

Edited November 1, 2018 by daverclasper

[Nick Jones]

The Superflex poly bushes I've seen have been pretty much the same hardness as the OE ones. The crush tube is stainless though, which is presumably why the sealing arrangement is considered unnecessary. Don't agree unless a stainless bolt is used too - but I wouldn't use a stainless bolt on such a critical duty in double shear.

Nick

[johny]

think the seals are only intended to protect the tube and the bolt takes its chances (presumibly its galvanised or something). So with a stainless tube no need for seals and the bolt wont be any worse off...

[KevinR]

17 minutes ago, johny said:

 So with a stainless tube no need for seals and the bolt wont be any worse off...

Except for Galvanic corrosion between the stainless steel crush tube and the bolt - which will be at a horrific rate due to the massive potential difference between steel and stainless steel, and even worse if the bolt is zinc plated because the PD between Zinc and stainless steel is 50% more than steel to stainless steel..

[daverclasper]

Bloody hell !

[johny]

yes even with SS I think the bolt will seize in the tube but at least the bushes shouldnt be damaged by rusting of the tube which finishes em off in double quick time....

[dave.vitesse]

When first introduced the bushes didn't have any seals and as a result the bushes wore out rapidly. This proved to be very embarrassing for Standard Triumph as they had stated the use of nylon for the bushes would reduce the maintenance. It was a selling point for the Herald. As it was it turned out to be the opposite. The problem was solved by the introduction the seals.

 For what it is worth I fit the original tube set-up and copper grease on the bolt to stop seizing.

Dave  

[Pete Lewis]

and the idea of these being crush tubes is very misleading  they are a solid tube which does stop you crushing the bushes

so by design they are anti crush ...the opposite of 'crush' , the tube gives you a fixed dimension for the bushes to work and rotate 

the tubes do not deform unless you get a gorilla on the bolt tightening  

the only triumph  collapsible anything , is in the later diffs when shims were evolved to a collapsible spacer,  designed to 'crush'

certainly never on any suspension bushes .

Pete

[daverclasper]

Hi and thanks.

Doing this job tom. Last time I did it, I I also to removed the trunnions to check condition of vertical links, which involved removing the hub.

Just wondering how much disassembly I need to do, to just change the bushes?, if anyone knows please.

Have manuals, but they tend to go into complete disassembly.

Cheers, Dave  

[DanMi]

really depends on how easy they come apart. In a perfect world they can be done without removing the hub, just undo the lower bolt pull apart and replace. However back in the real world you may need to cut the bolt which may be easier if dismantled further.

 

[Pete Lewis]

I never had any bush problems for the 14yrs with the Vitesse6  but do remember back in the 60s my 59 948 used to eat bushes 

as   every mot required regular replacements every year    so some things improve !!!

Pete

 

[Herald948]

3 hours ago, DanMi said:

really depends on how easy they come apart. In a perfect world they can be done without removing the hub, just undo the lower bolt pull apart and replace. However back in the real world you may need to cut the bolt which may be easier if dismantled further.

 

That's about it, although I would add that it usually helps to also loosen the bolt holding the shock/spring assembly to the lower A-arm.

As to durability of these bushings, it's hard to say what "is" or "should be"! In the 1970s, when Heralds and Spitfires and GT6s were my only cars and saw daily use adding up to sometimes 10,000-15,000 miles per year, I got to the point where I pretty much considered the front trunnion bushings to be "regular maintenance items"! It would seem that I would need to renew them typically at 24,000 mile intervals, sometimes maybe a tiny bit less often than that. As always, your mileage may vary!

[daverclasper]

Thanks.  A lot of my miles are around Bristol and the surfaces have been terrible for the past few years. Also do a lot of kerb parking (as does everyone in the street as fire engines/bin trucks etc wouldn't be able to pass). Maybe contributing?.

[johny]

I never understood why Triumph went for the bottom trunnion design as surely it wouldnt have been more expensive to have an additional ball joint at the bottom. It would have solved all the problems of wear, play and routine maintenance and is what was used by other manufacturers in later designs.....

[Colin Lindsay]

45 minutes ago, johny said:

...in later designs.....

Those are the key words! Don't forget, the Herald was designed years before it hit the roads, so we're talking mid-fifties here.

In any case, original blue trunnions and plenty of copper grease on the bolt have served me well for many years now.

[johny]

yes but they used a ball joint at the top so logic would dictate that you could use the same item at the bottom! I cant believe that a bronze casting with bushes plus machined screw thread on the upright (which needs filling with gear oil every 3000 miles) was cheaper than a ball joint and taper.....

[dougbgt6]

It is when you have a warehouse full of them that you want to shift! I've long thought drum brakes survive because somewhere there's a warehouse overstocked by several decimal points with shoes, drums, springs etc. Which is cheaper disks or drums? So why do we still have drums?

Doug

[johny]

ahhh I have a theory! On some cars disc brakes on the rear would be too powerful (the hub limits how small a disc can be fitted) so to avoid having to have a hydraulic compensator they use drums which are obviously less effective but matches the demands of the vehicle design....  

[NonMember]

4 hours ago, johny said:

yes but they used a ball joint at the top so logic would dictate

On the face of it, without any deep thought or consideration of mechanical engineering, perhaps. But the bottom trunnion holds the weight of the car in tension. Ball joints are actually not a very good design for that. You'll note the Dolomite, which does have ball joints top and bottom, also has the spring on the top wishbone, so the joint that takes the weight is in compression. Much more surface area available that way.

[NonMember]

3 hours ago, dougbgt6 said:

Which is cheaper disks or drums?

Total system cost? Almost certainly drums. Every time. Your perceptions are skewed because modern brake pad materials make the discs a consumable so they've become disproportionately cheap. The callipers are still the most expensive part of the system, though.

The main reason modern cars have rear discs is that ABS systems don't work well with mixed brake setups.

[johny]

7 minutes ago, NonMember said:

On the face of it, without any deep thought or consideration of mechanical engineering, perhaps. But the bottom trunnion holds the weight of the car in tension. Ball joints are actually not a very good design for that. You'll note the Dolomite, which does have ball joints top and bottom, also has the spring on the top wishbone, so the joint that takes the weight is in compression. Much more surface area available that way.

That sounds reasonable given that the bronze threaded trunnion was actually patented by Triumph so they must have put some serious thought into it!