Rear spring arm

Tim Neville · Post by **Tim Neville** » Sun Jul 26, 2009 6:13 pm

I've just loaded a few pics into the Bodywork section of my Gallery album, showing the rear spring arm on which the top edge weld and all the spot welds have corroded and broken. I can easily M.I.G. plug weld (usually a lot stronger than the average spot) where the spots were and re-weld the top edge, but has anyone any input or ideas as to a better way of joining the two halves together. One thinks of :-

a. Weld all along top and bottom edges. And seal exposed join where the two halves spread apart.
b. As above plus plug welds.

It seems to me important that no water/muck etc., can get between the leaves and cause corrosion.

Drummond Black · Post by **Drummond Black** » Sun Jul 26, 2009 9:23 pm

Tim, The spring arms on my Jupiter were welded all round when the car was put back on the road in 1994. I used an Austinetic welding rod ( Chrome -Nickel make up ) Due to the arm material do not use a mild steel rod, a stainless rod will work better, They have shown no sign of any problem.

Drummond

David Morris · Post by **David Morris** » Mon Jul 27, 2009 4:52 pm

Hi Tim,

I completely agree with Drummond. The rear spring arms really need to be welded all round, as otherwise the two plates get water between them, with horrible results in terms of corrosion. On a Javelin, the same applies to the lower links, from the chassis to the axle. These are eliptical in section and need welding along the top and bottom seams.

One small point you might like to consider. We found that the spring arms are 'handed' and mine had been put on the 'wrong way round'. This had the result of lowering the rear suspension on our Javelin, to the extent that she 'bottomed' when fully loaded. She was a good 3" lower than normal and was brought up to the proper height when we put them on the right way round.

I suspect this was a dodge by the previous owner, Ken Lees, who had been the JCC Competition Secretary in the 1960's and the aim then was to 'improve' the handling by lowering the suspension.

If you have problems getting hold of some stainless steel welding rods, I can let you have some.

All the best,

David

Tim Neville · Post by **Tim Neville** » Mon Jul 27, 2009 6:33 pm

Thanks for the info chaps.
Iam intrigued about the s/s welding, and in my usual fashion am going to inquire further!
The spring arm halves appear to be made from steel with a bit more carbon than normal mild but they are not much harder. The existing main welds on the join to the boss piece are not stainless (unless Iam much mistaken), the old spots of course were not stainless, so whilst I bow to superior knowledge, I would like to know a bit more why it is considered necessary to use an austenitic rod/wire, and which grade?
I have vague memories from my stainless steel T.I.G. welding past of stress cracking occuring on welds with austenitic steel and dissimilar metals.
You mention horrible corrosion David, some of which I already have. It is of course well nigh impossible to get to the inner faces to clean them properly; so I thought;
a. Clean as much as possible and then not worry about it as it will be all sealed.
b. Clean as above, introduce oil after having welded one edge, then let the oil burn off as the other edge is welded and then soft seal the short edge at the splay.
c. Cut one leaf off, properly clean the faces and then weld it all back. A bit drastic I think!

paul wilks · Post by **paul wilks** » Tue Jul 28, 2009 9:07 am

For what it's worth - Re those lower links eliptical in section from the chassis to the axle on the Javelin, to which David refers.
I had mine replaced by new ones from Roy Braddock many years ago and he suggested that I drill two small holes on either side of the tube nearest the chassis. I should use one to fill the tube with oil the other acts as an air outlet. I should then seal with self tapping screws. I followed his instructions and to date these have remained solid. Just a thought.

Paul

TedAllen · Post by **TedAllen** » Tue Jul 28, 2009 4:08 pm

Paul, Some ( many! ) years ago I acquired two lower link arms which are square in section and fully welded. They look very strong but I haven't needed to fit them up to date.
I shall keep them for an emergency and pass them on to the next of kin eventually !

Hope all is well with you and the family.
I was interested in David's post regarding the upper links being handed. My car rides very low at the back and I wonder if this is the cause. Anyone know how to identify this ' mis-fitting ' ?

Ted

David Morris · Post by **David Morris** » Tue Jul 28, 2009 11:53 pm

Hi Tim,

You asked about the corrosion inside the faces of the upper arms. All I suggest is that you take a leaf from Paul's post and weld up as much as possible and then drill two small holes on either side of the assembly. Oil could then be poured in, perhaps with a pump-type oil can, and the holes then sealed with self-tappig screws.

Trying to get at the inner faces would mean full dismantling and probably getting some oil inside the assembly means that they will last for a good few years anyway.

Ted asked about the ride heights at the rear. Low heights at the rear can be caused by worn rubber bushes on the ends of the torsion bars, although this only seems to cause an inch or two 'drop'. I have seen upper arms cut and welded to restore the correct height and this is what we were going to do on our Javelin, until we realised they were handed. As for identifying which side goes where, sorry, I don't have a clue. It was 'trial and error' with us! I guess you could tell by measurement but you would need to have one off the car and I don't have a spare arm to hand.

I purchased some spare lower links from JCS some years ago for our other Javelin and these were round section and look locally fabricated.

On the subject of stainless welding rods, the advice from my welding lecturer was that these are the 'bees knees' and you cannot get much better. Apparently, they are used for fabricated high pressure systems, where weld integrity is vital.

All the best,

David

TedAllen · Post by **TedAllen** » Wed Jul 29, 2009 9:54 pm

Interesting topic. I, too , cut and welded a couple of top spring arms to give a higher ride height. I never fitted them and now can't find them.

The rear torsion bar is octagonal at the ends and I wondered if pulling the arm off and re-fitting it a 'flat ' or two further round, in the right direction, would raise the car. I have torsion bar in the workshop ( makes a great leverage bar for all sorts of jobs ) and I guess it would be easy to hold it in the vice and measure the different heights of the arm when moved. Trouble is, I don't have a spare arm. ( any offers for a loan ? )

Can the arm be pulled off the bar, with a two leg puller, perhaps, without taking the wing off ? I've only removed them a couple of times, and they were on cars which were scrap...many years ago, I hasten to add.

My car is fairly high on 4 axle stands at the moment, and it would seem a good time to try.

Any thoughts out there ?

Ted

Tim Neville · Post by **Tim Neville** » Thu Jul 30, 2009 11:49 am

David's comments re. 'handing' of the rear arms prompted me to investigate and these are the results from my Jav.

If you place the two arms one on top of the other carefully aligned with the octagonal boss to the right, the flats of the offside arm will be seen to be slightly further rotated clockwise.This is to compensate for the torsion bar height difference of appx. 12mm between n/s and o/s.

All ride heights unloaded.

The o/s arm gives a higher ride height of appx. 60mm. if incorrectly fitted.

To 'wrong hand' a set would give an uneven ride height.

To use all n/s arms would give a lower and uneven ride height.

To use all o/s arms would give a higher and uneven ride height.

The difference between all o/s and all n/s ride heights is only about 22mm.

The 'uneveness' factor is appx. 60mm.

For your info Ted, to rotate the arm by one flat produces a ride height difference of 275mm.(nearly 11")! Not on I think!

TedAllen · Post by **TedAllen** » Thu Jul 30, 2009 4:17 pm

Indeed, Tim.
Realised after I posted that to move 2 flats round ( out of 8 ) would move the arm 90 degrees...1 flat ..45 degrees.
A quick test with the torsion bar and a piece of flat tube clamped on, 13 1/2 long, about the length between the arm pivot points, gave me a rough measure of 9" difference moving I flat !
That would make her sit up !
Your measurement will be nearer the mark than mine.

I had a look at my spare lower arms today, the square ones.
They look as though they are factory made.....I wonder if Jowett ever made any modified ones, perhaps after a spate of broken ones.

So, it might be all arms off and swapped over later in the year.

Ted

Post by **Forumadmin** » Fri Jul 31, 2009 8:40 pm

The very first bars had splines rather than octagonal flats. On early road tests these failed, hence the change.

Bars do gradually sag , more quickly if the surface is damaged in any way, including rust. They will gain an orientation , so should be replaced the same way around.

TedAllen · Post by **TedAllen** » Fri Feb 26, 2010 7:13 pm

I have a spare upper arm, kindly supplied by JCS this week. ( the cheque's in the post, lads )
Clamping my torsion bar in the vice and putting a bar through the bush holes, I find a 3 inch difference at the axle end when turning the arm over and using the same ' flat ' on the bar.
I don't know if my arms have ever been off but it may account for the low ride if they have.
Does anyone know if the arms can be pulled off the torsion bars with the wings still on and if so, what puller will do the job ?
If it's a case of removing the wings then I might not bother.
I don't see any way of checking if they're wrong other than trial and error with them off.......Another purchase of Tippex might be required !

Ted

David Morris · Post by **David Morris** » Sat Feb 27, 2010 10:03 am

Hi Ted,

Yes, the rear spring arms can be taken off without removing the wings. Dennis Sparrow did this for me a couple of years back, when we discovered this was the reason she was sitting so low at the back! We were just about to cut and re-weld the arms to correct this but realised that they were 'handed' and swapping them over sorted out the problem. I didn't see what he used as a puller, but I guess a two leg puller pulling on the outer flanges of the spring arm and bearing on the centre of the torsion bar should do the trick? Perhaps a phone call to Dennis might give you the answer?

You might have to replace the aluminium covers though, as these get pretty corroded. I believe the club have re-manufactured ones in stock?

I suspect though that many Javelins are getting a bit low at the rear, as the rods age? We all tend to carry too many spares in the boot, and you see Javelins at rallies that look pretty 'soggy' at the rear!

Hope this helps?

David

Post by **Forumadmin** » Sat Feb 27, 2010 12:08 pm

From memory the bars have a threaded hole which can be used to apply some suction using a puller. But you are likely to need to supplement this with a large hammer in the appropriate place. Copper hammer is best.

Make sure you put Copperease on the hex when replacing; just in case you need to take it out again!

TedAllen · Post by **TedAllen** » Sat Feb 27, 2010 1:10 pm

The old copper hammer ! A cure for most things.
I shall source a small puller and have a go when it's a bit warmer.
Thumbs don't like this weather !
My alloy casting are OK but I'll fit new rubber bits if they're available at JCS.
Thanks for the replies.

Ted

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