Jupiter front torsion bar

[garthwright]

Any advice on following puzzle welcome. Drivers side front torsion bar on my Jupiter has always been at max adjustment - right up to diagonal chassis member - in order to just about obtain ride height. I have some time ago replaced all spring arm bushes and checked all chassis straightness and chassis mounts/welds at adjuster ends and adjuster arms seem firm in the mounting (believe there is rubber bush in here but can't find drawing/section so not sure how to change it anyway?) All seems fine but on refitment of torsion bar - no difference on the drivers side - still needed max adjustment. I obtained another torsion bar which appeared in good non rusty condition and fitted this - still no difference. Each refitting I have removed the rubber buffer under the spring arm and allowed the spring arm to drop to lowest possible position which it feely does. I have made up a tool/clamp to pull the adjuster arm right out to the chassis against rubbery resistance of the internal bush and the torsion bar then just about lines up to tap in in both ends - hence all seems to be correctly alligned.(Same both sides).
Adjusting up the drivers side bar from this assembly position it takes almost twice the turns as the other side, hence up against the diagonal to support the car weight.
Obvious first conclusion was weak torsion bars - but is this likely with two different bars?
Any other ideas welcome before I try another!
I would ideally like it a bit higher and to see some daylight at the end of the adjuster......

[Keith Clements]

You are probably 1/8th turn out.
When initially fitting the bar you should find a bit of twist on the bar allows you to get it into the next position around. Essentially you would be preloading it.
It is possible to fit the wrong way around. The end with the threaded hole must be at the adjuster end. Obviously, if it is not, the locating plate (50323) that should fit into it will not be there!
Regarding the 'rubbers' (or dampening ring (52908), the one at the adjuster end) has been found to be similar to the VW which is made out of nylon. Details from Scott and James in CA.

It is possible the adjustment was done with load on the car which may have strained something.
Also make sure the adjustment pad is in place (53540).

[garthwright]

Thanks for this - most points mentioned had been checked - I cannot envisage getting another 22.5 deg on assembly as everything was already as far down/over as possible with then adj arm touching the chassis - needed a crowbar on the adj arm to ease the pad back in! Only area I'm not clear of is the 'VW bush' in the adjuster end. Was this a bonded rubber insert initially? It still feels like it with no obvious play and everything looks central - would degradation make adjustment so different. Looks like a job from hell to change it - does the big hex on the other end of the housing unscrew to get the adj arm out?
I think I will have to find somewhere with a full lift and get under it properly - getting too old for heaving torsion bars lying on my back on the concrete!

[Keith Clements]

It is also possible the bars have become handed as they do rotate in opposite directions. If the bars were swapped from side to side that might give more lift, BUT this is not recommended as they may then shear.
I have many spare torsion bars so I could look and see if there is any discernable difference in the relative position of the flats.

[Drummond Black]

Garth,
You are not the only one with this problem. I have had it since the car was rebuilt. I had tried many , many things to attempt rectification to no avail. I must have had about 6 different Torsion bars in this side over the years. I even swapped the two from one side to the other to no avail. A slight grind to remove metal to allow it to move closer to the angled chassis member made a fraction of difference but not solved the issue. Even tried moving the Torsion bar along the spring arm to locate on a fresh mounting area but to no avail. I have even changed the Spring Arm but no change.
I thought that this issue only pertained to my car until recently I received a call from Geoff Wills who is currently rebuilding his Jupiter asking advice on exactly the same issue. Thoughts are that there is , on some cars, a slight irregularity on the frame position, maybe not enough to notice, OR the rear bush is handed. It was probably the only item that was not removed during the rebuild.
My car rides at the correct height with the drivers side on MAX adjustment and the passengers side half way along the bolt.
I have parked the issue as over the winter I intend to totally rebuild the Front Suspension and Steering so more in-depth investigation will take place then. Once identified it should not be a major issue to rectify it. I have even considered a " Cut and re-weld of the Rear Arm as a last resort.

I wonder how many other Jupiter's have a similar problem. ??

Over to you Garth.

Drummond

[garthwright]

Hi Drummond and it is re-assuring that the issue has cropped up elsewhere if only to suggest I may not have got it wrong on this one. Have done other Jup/Jav torsion bars without any problem!
Fortunately the ride height is just about ok as now with max adjust on drivers side - am tempted to await any more news on others with the same problem and how maybe it can be solved on rebuild - can't quite get my head around the geometric possibilities! Perhaps get another bar or two handy just in case there is subtle difference between them to help in case I need something to do some time!
Don't suppose re-tempering torsion bars is a possibility to increase spring rate?!

thanks

Garth

[garthwright]

Keith - thanks for your thoughts - would be interested to know if there is any 'set' in any bars!

regards

Garth

[Drummond Black]

Garth
I genuinely do not think the issue is torsion bar related. I think the answer lies in the orientation of the rear bush. Like you, I have been under the car , luckily on a 4 post lift , trying to puzzle out the geometry. My recent thoughts came when under another Jupiter and noticed that there was plenty spare adjustment to spare. I now plan to reexamine this car in detail looking for variations. This time taking my camera with me. Hope to do this very soon as we may require to drop the fuel tank for cleaning. Will advise.
Drummond

[Forumadmin]

I have a vague recollection that I put the bar back without the spacer. Then screwed the adjuster up, wedged the arm, loosened the adjuster, inserted the spacer, adjusted up and then removed the wedge.

[garthwright]

The query in my mind re geometry is that to get to the next flat on the torsion bar for assembly it would actually take a total of 45 deg ( not 22.5 as my earlier post?) further angle between the spring arm at its lowest without the runner stop, and the adjuster - and I cannot quite envisage how to get this much.
I have made a tool/long bar with lugs to fit in the adjuster arm holes which allows me to pull the adjuster arm preloaded enough to get the pad in (also to ensure the adjuster is right back touching the chassis for assembly position).
Hence kept coming back to the bar stiffness, but to be sure finding the issue the same with a random different torsion bar fitted points against this being the issue.
Let me know if you find anything else on this in due course !!