MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGF Technical - rusty suspension knuckle bolt *lowering saga *

Hi,

now after month of doing nothing I got it today. :)

Jacked up the car and had a look for the brocken low suspension knuckle bolt.

Drained the suspension put on vacuum and removed the rusty part.
Got the aluminum piston out aswell for the second option of lowered suspension (cut piston instead using short bolt)

However, found it impossible to getting out the small pressure plate from the upper arm. I applied a load of WD40 and will get on with the works tomorrow. I have a spare upper arm and I'll swap that in if all tries to remove fail.

First images can be seen here.
http://www.mgfcar.de/suspension_knuckle/
More to follow.

OK so far.
What I need now is the measure of the _short_ bolt to find out how much to cut from the displacer aluminum piston. This cut looks easier as it will be. More on that later.

The measure marked with red arrow
http://www.mgfcar.de/suspension_knuckle/lowbolt_measure.jpg
The original long is 38.5mm
The worn still has 27mm at the highest point. Difficult to measure due to lots of rust.

I ask, cause I can't believe they cut down 11mm and sold it to us in that way.

Might that be true ?
Can anyone supply the measure from spare parts or recently bought ??

Regards
Dieter
Dieter K.

Yikes, Dieter - what a mess ! What was the car like to drive?

I suspect that there are a lot more people out there with similar problems. I can see them all checking theirs over the week-end!

Sorry I cannot answer your question regarding dimensions but my knuckles are still as standard.

Thanks for the submission to the http://www.apttony.co.uk/MGFquality/MGFquality.html datbase - I'll get that in over the week-end.

regards to Rosie
Tony
Tony

Hi Dieter,
those pictures don't look nice ! But I'm sure you'll sort that and be soon back on the road.

A difference of 11mm between "long" and "short" knuckles would result in a lowering of 40mm, due to the approx 1:4 lever ratio.
IMO, you can cut your pistons by the length that suits you, and better too little than too much !
BTW, the best and easiest solution would be to know how much Techspeed cuts ...

Cheers,
Fabrice
Fabrice

Hi Fabrice,

:) ... they are no wizards at Techspeed.
*only* technicians

Anyway, got the cut optimum without drilling deeper holes into the ally piston.

- did minus 8.5mm to the piston (will leave out the 2,5 washer between piston and rod)
This is 11mm then
- did minus 5mm to the rod end
- did minus one wind to the small coil spring, cause it went on block if fully pressed.

The piston is now 2,5mm shorter than the one from a Trophy displacer.

Nuff.

Now I need to put all back and walk over to the other rear suspension side. I'll do the same there to keep everything balanced.
Dieter K.

Dieter, are you only doing the rear spheres and leaving the lowering knuckles at the front ?
If yes, I understand better your wish to achieve *exactly* the same lowering, and yes, knowing how many mm Techspeed is sawing wouldn't help you.

Fabrice

Hi Dieter,
at work ,so short notice from me. Do NOT leave out the washer as this will give "seat" into the soft ally piston. My front was a bit high compared to the rear when I did my "short knuckles" several years ago. Thought I could lower front by leaving out those innocent washers.... A seasons drive later I found out on inspection why they are there!
BR, Carl.
Carl

I will eventually get all my lowering knuckles replaced with the std parts and get techspeed to do the proper lower by machining the spheres in the hydrogas units I beleive. I will also get the ride height adjusted to save the bottom of the car which grounds out to much specially over those stupid speed bumps.

I have had 3 brocken knuckles but luckily only one had the need for a new upper arm, lots of wd40 and a hammer saved the other 2.

Not a pretty sight and probably a mot failure if noticed.

Tom
Tom Randell

Update:
Didn't get out the rusty pressure plate
Had to replace the upper arm with a spare.
Got all parts back with some usual DIY problems.
Car is still on axle stands for final bolt works.

Carl,
will put the washer back tomorrow.

Had some more research on the reason why the damn things fail _sometimes_. (See Tom, with three of)

I'm on several options.
At first, may be installation failure. (Did it myself and who knows...)
Second is according to the upper clamp ring (green). (This side wasn't slipped off)
Third is about the rubber gaitor itself. May be the deformed thingy did lift the outer pastic ?
In any way it was _water_ letting the parts rust away ;)

Fourth is about the changed vertical working range of the suspension at lowered cars and whyever misaligned displacer centre to upper arm.
Bear in mind, the _strong_ length between lower diaphragma and upper arm gets shorter.
This means that any misalignement of the displacer center to the knuckle holder center in the suspension arm gives _more_ unwanted stress to the _loose_ contact point. ... sidewards of course. Unwanted side force to the plastic frame.

Fabrice,
no, I'll replace them all step by step. This is an easy job with an own hydragas pump :) I have an original Liquid-Lever now.
But the front later after having got experiance with the modified rear.

Anyway, got nearly insane this afternoon :)
I wanted it perfect and tried to refit the dust protection gaitor to the displacer.

*Impossible with installed displacer bracket*.
You need to get the cover off and fiddle it on the displacer lead then. Has anyone ever tried to change a RH (offside?) displacer bracket ??
;-) lovely job.
I found the LH rear change already difficult. (made 1999). But the other side beats it all.
Poor access to the upper bolts. One the left restricted by the resonator box. On the right no access with a ratchet.
OK, I got it at last, cut you should see my scratched office guy fingers... LOL

Corrected for the files:
>- did minus 8.5mm to the piston (will leave out the 2,5 washer between piston and rod)
>This is 11mm then

>- did minus one wind to the small coil spring, cause it went on block if fully pressed.

gets now:
- minus 8.5mm to the piston. WILL ADD the wascher with 2.5mm
Results in 8.5mm shorter rod.
Means max. 34mm lower. I need 30mm only, so OK.

- the coil spring may NOT need cut, cause it will fit with added 2.5mm washer.
Check each individual.

Tomorrow more of the works.

Regards
Dieter
Dieter K.


Rusty suspension knuckles indeed.

You can’t fool me; I've been to technical college!

I feel that it is my duty inform the international MG community that this thread is no more than a confusion of made up jargon and half plausible notions, intended to draw the uninitiated and innocent into foolish correspondance, wasteful and potentially hazardous endeavours with expensive consequences. This behaviour is deplorable and against every thing our proud heritage has given us and a gross abuse of this BBS.


The nurses in here have suggested to me that perhaps a very elaborate April Fools day joke is being made.

It is common knowledge throughout the Empire, that we, the British are the only people on earth with such a finely honed sense of the ridiculous to even consider perpetrating such a humourous hoax never mind expending valuable time and effort actually pressing all these buttons and chasing mice round the skirting board to enable it.

I pointed all this out to Matron, when she came with my coco and medication that this thread originated in Germany and therefore couldn’t be a joke. She smiled and agreed with me, she always does . . . . .even when I’m wrong.
D Brunton

Hmmmm - the medication is obviously working!
Tony Thompson

May I, may I not ?
I do ;)

Checked the other three sides today.

The front right hand was gone aswell. This was the one I'd seen with a *gaitor slipped off* problem in last November. I had filled it up with a load of grease to prevent from further damages. May be that was good ? Who nows, it's gone in any way.

Analysis:
Heavy rust between pressure plate and knuckle rod surface. Lost length about 2mm from rust. Water ingress was clearly through the gaitor top where the green small calmp ring had slipped off.
Surfaces look strange. I'll have a picture for you later.

Though, the upper arm is not hurt. Got all out and change back to standard knuckle rod with cut displacer piston.
Measures:
Overall pison height is 64.5mm
Cut of 8.5mm results in 56 mm

Regards
Dieter

Dieter K.

Seems to be a common problem Dieter (have you been saving up the pictures mate? Mine were sent to you years ago!! LOL :-) )

Very interesting work though, i am intrigued to know how you get on (as my replacements will probably need looking at again this / next year i reckon).

SF

P.S. Happy birthday for the 26th :-)
Scarlet Fever

Andrew,

the only problem with the stored images was to find out, which was whose ;)

Will keep you posted of course.
Anything is wrong with the knuckle kits, but what ?

Accessed the third in the meantime. The rear one on the alternator side.
It looked good from outside.

I just had put vacuum to the sytem to remove air bubbles and the rod was just free for pulling it out. So I lifted it with a screwdriver carefully and pulled it out.

Lots of brown-black sludge in the suspension arm dropping (spelling?) when I pulled out the knuckle.
No evidence for water tracks. Not on top of the gaitor, and not at the lower surround. Plastik frame unhurt, O-Ring in place.

No rust visible direct from outside until I removed the lower pressure plate from the plastic clip.
But inside:
- cambered roll surfcae: scarred surface from rust
- (former) plain rod roll surface: the same grain and already with worn track

I can't get what's going on there. I have three now in total different stages.
The last gets changed tomorrow.

Why do this parts fail, and why don't the original parts fail ??

Could it be the grease they used with the aftermarket parts ???
Dieter K.

Not having seen these replacement knuckles, let alone replaced, changed or modified any, I might be getting the wrong impression, but looking at Dieter's photos, especially http://www.mgfcar.de/suspension_knuckle/compare_dsc04996.jpg , I am asking if the shortened knuckles are standard ones that have had the bottom face machined off, and then maybe, or maybe not,( ? ) an attempt has been made to reharden them.

If this is the case, I would be very cautious of using them. In a lot of cases, hardening, if not done properly, can only be skin deep. Certainly, 'hardening' treatment is very specialised and these photos seem to suggest that it is not being done very well, if at all.

Tony
Tony Thompson

Hi all,
due to this thread and the horror pictures, I had a quick look at my own knuckles yesterday (!)(Is this really correct English?)
Well, my pampered "Green Frog" from-97 with home-made lowering knuckles shows no sign of rust or wear.
For grease between the steel bits I use Molycote (black stuff) that is clearly branded "EP"= extreme pressure.
The rubber boots is then filled up with white Lithium grease. This is also an EP grease BUT has outstanding properities in fresh or salt water. Really when looking into the rubber it was a mixture of both giving a grey substance... It is important to secure the rubber both on the lower and upper part. I discarded the flimsy expansion rings and used thin SS wire (as used in avionics to secure bolts etc.) to be sure it would stay fit.
The car hardly ever sees rain and defenatly no salty roads , so this can of course be the reason for "as new" condition....
Could it be possible to implement 4 additional nipples to this area in order to re-fill with grease?
I think a nipple with 6mm winding could be attached to the bottom of the arm ? Suggestions ?
BR, Carl.
Carl

Dieter, as you have these suspension-parts totally apart. Is it meant to be any "grease-channel" from the greased bearings into the arms seat for the suspension ? If not it might be good to drill a 2-3mm channel into the portion where the lower part of the knuckle seats.... In this way the grease spreads into this area as well ! Or a separate greas-nipple might be even better. In your pictures it seems possible to attach one in the "pothole" in the suspension-arm.
BR, Carl.
Carl

Hi,

Tony, they are machined from new and the surface is hardened. German *Nitriert*, skin hardened only.
I'll see for other material details later and get back on the matter. Thought on contact corrosion already, according to different sorts of material.

Carl, I considered in adding a additional grease nipple already. No problem at all, but where should the grease go or drain out when it's all filled up ? :)
I think the proper preperation with best grease will be OK.
You have found no rust !!

The only difference between _yours_ and our is the steel used and obviously the grease.

OK, I go out now and do the remaining.

CU
Dieter
Dieter K.

This thread was discussed between 30/03/2005 and 02/04/2005

MG MGF Technical index

This thread is from the archives. Join the live MG MGF Technical BBS now