Top suspension trunnion brackets bending

[Morris]

I know some of you read the owners club forum but if you don't it's well worth you checking out 'DIY-SI' orange XI build.

He's driven his car 60 odd miles resulting in both top trunnion suspension brackets bending forwards!

It could have occurred during the IVA brake test but as yet the cause is not clear.

It's worth checking out yours just in case as it looks bad!

Here is a link to the post:

https://forum.wscc.co.uk/forum/topic/14 ... nt-1578416

Cheers.

Morris.

[jonclancy]

Hi Morris,

Thanks for the heads up. I’ll check mine when I’m next under the bonnet. This sort of distortion is rather obvious…. And worrying.

Cheers

Jon

[jonclancy]

Looks like the same gauge of metal. Mine is slightly compressed due to the tightness of the fasteners versus the width of the bush.

Maybe the other car is over-braked for the top mounting? Dunno - not thought too deeply about it. This part would probably be better made from billet, I think.

Cheers

Jon

[Morris]

Yes, mine look like yours in that they are compressed in by the bolts (although cleaner due to not being in a serviceable car yet!).

This appears to be an isolated case and rather bizarre.

If the trunnion bolt wasn't tightened sufficiently then that might apply a bending moment to the bracket under a braking force?

Pure speculation though...

[Westfield 129]

I find this curious. I have about 55,000 miles on my car, and no such bending has taken place, nor has this taken place on any of the 6 cars that I have been directly involved with, or built personally. This is an area that I am often involved with, as all of the cars that I have seen needed front suspension alignment. I had to physically remove the upper trunion and adjust the "fork".

Braking could not cause such distortion, but a misalignment of the upper and lower control arms might. The arms are Left and right for the lowers, as I recall. Putting the arms in the wrong location, or upside down (also possible) would put a bending moment on the upper mount and force it forwards.

I would take a good look at the installation of the upper and lower control arms for proper up/down alignment. You can also do a caster check to see if the correct amount of caster is present. Very light steering or jumpy, imprecise steering response can be caused by both the caster and toe being way off.
The only way that caster can be off would be to install the lower arms incorrectly. Correctly installed arms should have the king pins slightly angled aft of the lower mounting point at the top. This may be hard to discern, so it may be necessary to measure the camber to ascertain the caster number, which, as I recall, is around 4.5º. Incorrect toe (always toe out, due to setting toe without the driver installed, and not cutting the steering arms short enough) is a common problem that I have seen in EVERY W11 I have worked on, save the ones I built myself, and the very first one I purchased, my own #129.

The upper mount will distort somewhat if overtightened. The tube inside the bushing should just contact the inside of the mount when tightened. I like to run the pivot point bolts a bit looser than recommended, to keep the suspension supple. I am also using urethane top bushings as well. These last longer, and don't crack. If you run the 5~10 lb.ft. I recommend, check the free movement of the suspension and the tightness of the bolts on a regular basis. I have not found any problems in the decade or so that I have been doing this, but it is always a good idea to check. You can also drill your suspension bolts and cotter pin a castle nut in place. I have not done this yet, but I did do this to another car with success using Aircraft AN fasteners.

My experience is that the kits are pretty well constructed, and quite rugged, considering the relatively light weight. My early car alloy floor car weighs 1070 lbs. The suspension seems to hold its alignment well. I have not had to make any adjustments to mine in, um... years...

[Morris]

Many thanks for the full reply Jan. I've passed this to the chap who's car this occurred to.

Btw, you haven't posted here for a while so great to hear from you.

[Westfield 129]

'Been busy restoring a barn find R5turbo, and another R5Turbo that set a record price on Bring a Trailer here in the US. Then, there were the bikes... The poor W11 had to sit, as it couldn't be moved from its slot in the garage with the R5s in the way ('cause they were mainly bare chassis that I had fully disassembled). Well, the current R5 does run, and is in the process of getting a full California emissions certification, and the W11 has been taking my now 8 year old daughter to school, and running errands. Still a bit rough looking , but mechanically superb. The kids in school love it...

And then, there is the early narrow track Morgan +8, which is my own personal project. It blew the clutch carbon (yes, a carbon release bearing, on a V8 Morgan with a Moss box. Engine out (gearbox, too) job, The more things change, the more they stay the same.

Anyway, it is getting an engine refresh when the parts that I want become available. I already have the new clutch and a lightened flywheel. Now, I need adjustable roller rockers (not until February) and a roller cam (no blanks available to grind one), along with a set of vastly improved heads (that have to go to a specialist to be properly flowed and ported). While I wait, I am installing the correct rod mount rear view mirror, an original type ignition/steering lock and a proper throttle cable setup for the 4bbl Edelbrock/Weber, now paired with an original, NOS Buick Factory IHRA/NHRA race intake, which looks just like a stock Buick intake on top, but is a bit different underheath. I did get the headers installed with a really nice side exhaust setup of my own design just before the carbon disintegrated. Anyway, maybe 250 HP, which is up 70 HP on the original power output if I do this properly. 'Should be quick enough (it weighs 2000 lbs spot on with me in it). There is also a negative camber front end and a tube damper rear setup on the shelf, waiting. I also covered the ugly wood instrument panel (in cheap black vinyl as it was originally). The doors have to come off to rebuild the hinges and the mounting points (wood screws changed to machine screws into metal inserts), and hopefully, repaint the wings black to go with the yellow tub.

Meantime, I have been hanging out at The Morgan Experience, disrupting their site.

Once the Morgan is done I can finally refinish the 11s frame and repaint the primer blotched coachwork. But, the engine is sharp, strong and the gearbox quick, while the LSD is just tight enough. No 15" wheels and Dunlops...yet. First thing will be to replace the spindles with the Huffaker improved ones, otherwise, the chassis is pretty good. Then, the Dunlops on the 15" wheels. I have a plan for an improved cooling system much like the one that I did on the RHD car. It never ends...