Help! Torsion Bar Quandry

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Sdinse
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#1 Help! Torsion Bar Quandry

Post by Sdinse » Sun Jan 13, 2019 9:49 pm

Has anyone else run into this? I am refitting my uprated torsion bars since they have taken on a set that leaves the front end a bit too low. They were installed new when the car underwent restoration some years ago. I'm not sure how they did it, but I am trying to follow the manual. I have the shock bolt centers set to 19.25" per the manual and the adjustment ramps at their lowest. When I try to fit the torsion bar to the front, it comes into contact with the rear lower control arm support before I can get it to align with the front fitting. The bars are specified at 0.900 and came with a rather thick powder coat that had to be sanded down to allow the reaction brackets to rotate when pushed past the splines.

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Am I doing something wrong? What did I miss? Probably something obvious, maybe I've been at this too long. :scratchheadyellow:
Steve
1971 SIII E Type 2+2

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Sdinse
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#2 Re: Help! Torsion Bar Quandry

Post by Sdinse » Sun Jan 13, 2019 10:30 pm

Does anyone know what dimension setting tool should be used for uprated torsion bars? Surely, I can’t be the first to fit these.
Steve
1971 SIII E Type 2+2

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AussieEtype
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#3 Re: Help! Torsion Bar Quandry

Post by AussieEtype » Sun Jan 13, 2019 10:42 pm

I cannot really help as mine have been in and out a number of times but many years ago - all I can say is that mine went in relatively simply and there were no obstructions and mine did not touch the wishbone. All I can suggest is that you need to look again at how you are installing these as the OEM bars fit easily.

Hopefully someone will come along and can see an obvious mistake or provide better advice than I can provide.

Good luck

Garry
1971 Series 3 E-type OTS

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lowact
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#4 Re: Help! Torsion Bar Quandry

Post by lowact » Sun Jan 13, 2019 11:31 pm

You need to feed the bar into the spline BEFORE you set the shock absorber spacing. Once the bar is in the spline it moves with the arm, can never contact. Here is a pic of my supper sophisticated shock absorber spacing tool, with notches as required to clear stuff. The 3 holes at the bottom end is because it took me three goes to achieve a level that I was happy with.
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Regards,
ColinL
'72 OTS manual V12

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Sdinse
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#5 Re: Help! Torsion Bar Quandry

Post by Sdinse » Mon Jan 14, 2019 6:51 pm

Update!

Just for the record, I had to close up the setting tool dimension to 17.5 inches before I was able to insert the torsion bars on both sides. Once they were in and indexed, I set the preload to 1 spline using the JD43 tool as directed in the procedure. Trial and error here so I'll know if this works out once I get it back down off the jackstands.
Steve
1971 SIII E Type 2+2

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lowact
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#6 Re: Help! Torsion Bar Quandry

Post by lowact » Mon Jan 14, 2019 9:49 pm

Setting tool? JD43? Golly gosh… Curiously my otherwise reliable workshop manual specifies a 49.69 cm (19.563 inch) shock bolt setting, this was too much. What I ultimately adopted was 487 mm, i.e near as dammit yr 19.25 inches but without any preload. I was then able to adjust to specified ground clearance using the cams. I am assuming I have standard (OEM) stiffness torsion bars …
Regards,
ColinL
'72 OTS manual V12

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Ole-xke1974
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#7 Re: Help! Torsion Bar Quandry

Post by Ole-xke1974 » Tue Jan 15, 2019 3:28 am

Sdinse wrote:
Sun Jan 13, 2019 10:30 pm
Does anyone know what dimension setting tool should be used for uprated torsion bars? Surely, I can’t be the first to fit these.
I did the same as you a few years ago and ended up taking the uprated TBs off the car again to reset them.
I did some drawing on paper and came up with a new distance which puts your ride height at the specified 6.25" clearance.
Based on the ride height I achieved with the originally specified length of the setting tool, I drew some circles with different setting tool lengths and found the one which is just under 19" to give me the drop of about 1", which the car sat too high.
The minimum ride height is just about 6" on my car, which I still find optically too high and If I had the time and inclination, I'd set the TBs with an other .25" shorter setting tool.
I hope this helps ........ Ole

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1974 SIII E-Type w. XJ S2 4sp w. O/D

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angelw
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#8 Re: Help! Torsion Bar Quandry

Post by angelw » Tue Jan 15, 2019 11:19 am

Colin Wrote:
Here is a pic of my supper sophisticated shock absorber spacing tool, with notches as required to clear stuff. The 3 holes at the bottom end is because it took me three goes to achieve a level that I was happy with.


Hello Colin,
I use Turn Buckles and they work well. For the units I use, I've determined a constant, that when the separation between the ends of the Left and Right Hand thread is added, gives the distance between the shock absorber mount bolts.

Best regards,

Bill

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Sdinse
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#9 Re: Help! Torsion Bar Quandry

Post by Sdinse » Tue Feb 12, 2019 1:15 am

Update!

After getting the car off the jack stands and on to the street I have found that even with about 10 miles of driving with the adjustment cams at their lowest setting, the front height is about an inch too high.

I'm thinking that the jacking points I used at the time may have had something to do with the interference issue. I was supporting the front at the jacking points and I noticed that in the manual they specify placing the jack stand under the "lower wishbone fulcrum support bracket". If there is any amount of body/frame flex, that difference may account for the torsion bar hitting the lower wishbone mount bolt at such a low shock setting dimension.

I also have come to the conclusion that all the different dimensions I've heard for the setting tool (18, 18.5, 19) were all set without using the JD43 tool to preload the torsion bars by 1 spline.

Mathematics says that 1 spline SHOULD account for a 2 inch difference in ride height. So if I took out the preload, I should be about 1 inch too low with the adjustment cams at their current low setting. If the adjustment cams can give me 1 inch up at the highest setting I should be OK without having to actually remove the torsion bars again. We'll see! If not, then I am definitely changing how I support the front end when I have to do it all over again to get it right!
Steve
1971 SIII E Type 2+2

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lowact
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#10 Re: Help! Torsion Bar Quandry

Post by lowact » Tue Feb 12, 2019 12:26 pm

There are different number of teeth on the front spline and on the back spline. This enables you to make fraction-of-a-spline adjustments. E.g. Front CW 3 and rear ACW 2 is different to Front CW 2 and rear ACW 1.

There are different instructions for earlier and later cars. Cars earlier than 1S70413 (LHD) DON'T use the JD.43 tool and DON'T have the one-tooth pre-load. You are US, 1971 so number is earlier than 1S70413?

I imagine, because yr bars are stiffer than OEM, the setting distances in the manual would not be applicable. trial and error may be the only way.

With OEM bars and earlier than 1S70413, without the tensioning tool and preload, it is super easy, I found I didn't even need to undo the ball joint.
Regards,
ColinL
'72 OTS manual V12

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Sdinse
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#11 Re: Help! Torsion Bar Quandry

Post by Sdinse » Tue Feb 19, 2019 6:21 pm

Final Update!

As I mentioned in a previous post, where the jackstands are placed DOES have an effect on the clearance issue that was the initial problem. Simply relieving the 1 spline preload on the torsion bars installed at 17.5 inches left the ride height too low. Looking at Ole's drawing and doing some math I came to the conclusion that 18.5 inches on the setting tool(turnbuckles in my case) should put it all in a reasonable range.

With the jackstands directly under the rear lower wishbone at the crossbar mounting I was able to get set the shock bolt centers at just over 18.5 inches before there was interference, so 18.5 was the setting I used. With the cams at their highest setting and the car back on the ground, the ride height measured around 7 inches after running the car back and forth on the driveway a half a dozen times then back into the garage. Setting the cams back down to the lowest setting resulted in 5.75 inches. WAHOO! :bouncyyellow: A normal ride height was within range. After 3 tries at fine tuning the adjustment cams positions I was able to get the ride height spot on.

Moral of the story: follow the manual PRECISELY!

Thanks to all for the many suggestions!
Steve
1971 SIII E Type 2+2

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Ole-xke1974
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#12 Re: Help! Torsion Bar Quandry

Post by Ole-xke1974 » Tue Feb 19, 2019 11:07 pm

Thanks for the update Steve, and congratulations on your success.
1974 SIII E-Type w. XJ S2 4sp w. O/D

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