JD43 torsion bar tensioner tool alternative

Talk about the E-Type Series 3

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Danetype3
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#1 JD43 torsion bar tensioner tool alternative

Post by Danetype3 » Sat Nov 02, 2019 5:49 pm

Hello everyone,

New to this forum. Just wanted to check if there is interest in a "JD43" tool. I have laser cut an adapter ring that fits around the 25 splines of the torsion bar and in a socket. With a breaker bar and a hydraulic jack you can rotate the socket/torsion bar 1 spline as per the manual. Tried it on my type 3 and it works great. My cheap breaker bar got bend a little though, but the spline adapter was OK and my stress levels remained very low during the operation. I could offer this cheaply in ebay soon if there is interest?

In this set up the exhaust needs to be removed because it is in the way of the breaker bar, but I could make a different version where this would not be needed. It would be more expensive especially in transport because steel is heavy and transport is so expensive...

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Fspp369
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#2 Re: JD43 torsion bar tensioner tool alternative

Post by Fspp369 » Mon Nov 11, 2019 4:49 pm

Hi, Sounds interesting and very useful...any idea of costs for the “exhaust on”one?
Peter.

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Danetype3
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#3 Re: JD43 torsion bar tensioner tool alternative

Post by Danetype3 » Mon Nov 11, 2019 7:10 pm

Hi Peter,

Thanks for the response. It would still be cheap because it can be a short piece of steel with two square 1/2" holes for the socket and breaker bar, to get the "breaker bar attach point" below the exhaust. But heavier to ship than some small adapter rings. I will have some bars made and some more rings (the first ones are a bit loose) and try on my car and take some pictures. It is an in between project for a supplier I use for work, so progress is a bit slow, but we will get there. Hope you are not in a hurry :-)

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Fspp369
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#4 Re: JD43 torsion bar tensioner tool alternative

Post by Fspp369 » Tue Nov 12, 2019 8:16 am

Thanks for the prompt reply.
Any time that you have time.
Peter.

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#5 Re: JD43 torsion bar tensioner tool alternative

Post by Danetype3 » Sun Dec 01, 2019 4:18 pm

Here are some pictures of the simple tool (with the bling bling breaker bar). Just for show because as you can see the bracket bolts are in. But I tried it on the left side with success. The adapter rings fit in the socket and around the torsion bar. They are a bit crude on the outside but that is just cosmetics. I have some thoughts on the "exhaust on" version and will post some ideas soon.

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Ole-xke1974
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#6 Re: JD43 torsion bar tensioner tool alternative

Post by Ole-xke1974 » Sun Dec 01, 2019 4:45 pm

Hej Dan,
your idea is intriguing, but as far as I remember from installing my TBs, one spline either at the front or back of the TB will result in quite a change in ride height. To get the correct ride height, you have to find the right combination of the 25 splines in the back and 24 (I believe) at the front.
Maybe I have overlooked something, and will be happily get educated.

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

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#7 Re: JD43 torsion bar tensioner tool alternative

Post by Danetype3 » Sun Dec 01, 2019 6:18 pm

Hi Ole

I am no expert, but the procedure I followed is described in the manual and it made sense. Rotate and mount the front spline such that the rear reaction bracket and mounting bracket holes align. From that point you rotate the rear bracket one spline and fix the bolts. Together with the correct fitting gauge length this is supposed to give the correct ride height. But this I can not confirm yet. I do know that without the one spline - which is how we got our car - ride height is much too low. Getting it into the garage and going downhill without brakes of any kind was a bit of a challenge :bigrin:

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#8 Re: JD43 torsion bar tensioner tool alternative

Post by angelw » Sun Dec 01, 2019 8:05 pm

Ole Wrote:
To get the correct ride height, you have to find the right combination of the 25 splines in the back and 24 (I believe) at the front.
Hello Ole,
You're absolutely correct, the one tooth variation between front and rear splines facilitates a vernier adjustment. Depending on the health of your Torsion Bars, the setting link used in place of the shock absorber will get you close, but final check is via actual measurement of the ride height. Moving the Torsion Bar by one spline at the rear, either way, may be too great.

I simply use a large Turn Buckle, instead of the setting link, mounted in place of the front shock absorbers. A reference length is marked on the Turn Buckle that equates to the length dimension of the setting link, and the Turn Buckle used to apply and release the torque of the Torsion Bars as required.

My concern with the tool being discussed is the method used to create the Internal Spline, ie Laser Cut. There is a hardening of the surface of the cut zone (even in Mild Steel as there is an introduction of carbon to the surface). Depending on the accuracy of the resulting spline, Laser not being known for extreme accuracy, there is the possibility of the spline form at the very end of the rear spline being deformed. Of course, this will not be a problem until the day when the Reaction Bracket needs to be removed from the Torsion Bar for some reason. If the Internal Spline were to be EDM Wire Cut, different matter altogether.

Regards,

Bill

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#9 Re: JD43 torsion bar tensioner tool alternative

Post by Danetype3 » Mon Dec 02, 2019 6:28 pm

Hi Bill

In my case I will not be able to put enough tension on the TB with only a turnbuckle. And the extra spline as the manual describes would rotate the turnbuckle beyond where it can be used to pull the lower arm up again to mount the shock.

Maybe my TB's are soft and require more pre tension than yours. Strange though that the manual also describes this procedure if a turnbuckle would be enough. I read some other turnbuckle posts and they also loosen the lower arm bolts to get more leverage. I did not really like that idea so that is why I made the rings.

About the tool - wire cutting would be better, but this works fine and is a lot cheaper. There is no damage on the TB.

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#10 Re: JD43 torsion bar tensioner tool alternative

Post by angelw » Mon Dec 02, 2019 8:20 pm

Dan Wrote:
In my case I will not be able to put enough tension on the TB with only a turnbuckle. And the extra spline as the manual describes would rotate the turnbuckle beyond where it can be used to pull the lower arm up again to mount the shock.

Maybe my TB's are soft and require more pre tension than yours. Strange though that the manual also describes this procedure if a turnbuckle would be enough. I read some other turnbuckle posts and they also loosen the lower arm bolts to get more leverage. I did not really like that idea so that is why I made the rings.

About the tool - wire cutting would be better, but this works fine and is a lot cheaper. There is no damage on the TB.
What do you think the original JB43 tool is, other than a variant of a Turn Buckle? It has a long threaded component (nut), threaded L and RH thread at its respective ends, into which are screwed rods that are attached to internally splined, short arms at their other ends. Mechanical advantage is achieved through the helix of the thread and the length of the internally splined arms.

A Turn Buckle of like thread helix angle, attached where the shock absorber would mount, actually has a greater mechanical advantage than an original JB43 tool due to the longer lever created by the attachment point at the lower wishbone. The only advantage the JB43 tool has over a Turn Buckle used mounted where the shock absorber mounts, is that an adjustment of the rear spline engagement is possible without unwinding the torque on the Torsion Bar. If the front spline has to be adjusted, then irrespective of the system used, the torque of the Torsion Bar has to be unwound.

I have a fully functioning CNC machine shop (including a Wire EDM) as part of an E Type restoration business (thirteen S3, four S2 and two S1 cars currently in work); accordingly, I have the facility to make any tool required. I made an exact copy of an original JB43 tool some years ago, but except for not being able to adjust the Rear Spline without unwinding the torque of the Torsion Bar, find the Turn Buckle at the front system, more convenient. The shock absorbers are be removed and replaced with a setting bar if you're following the Work Shop Manual procedure to the letter. Accordingly, substituting it with a Turn Buckle is not a step too far.

If you read the manual carefully, Jaguar only specify the use of the JB43 tool being required, when refitting the torsion bars, for cars with chassis numbers from IS50065 (RHD) and IS70413 (LHD).

The methodology specified by Jaguar is often far from being the best. For example, their method of final assembly of the Gearbox Lay Shaft sucks and I doubt there would be one person experience in rebuilding an E Type Gearbox employing the Jaguar specified method. Accordingly, just because Jaguar don't mention the use of a Turn Buckle in place of the setting link, doesn't mean it doesn't have merit.

Dan Wrote:
And the extra spline as the manual describes would rotate the turnbuckle beyond where it can be used to pull the lower arm up again to mount the shock.
Now you're talking nonsense. Neither a Turn Buckle, nor original JB43, or your tool can be used to aid the reinstatement of the shock absorber. Maybe in a very convoluted way with a tool acting on the Rear Spline with the Reaction Bracket unattached, but that is not the recommended method. You refit the shock absorber by rotating the lower wishbone about its fulcrum, using a jack, until there is no load on the setting link (or Turn Buckle in my case); it can then be replaced with the shock absorber.

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#11 Re: JD43 torsion bar tensioner tool alternative

Post by Danetype3 » Tue Dec 03, 2019 10:07 am

Hi Bill
If you read the manual carefully, Jaguar only specify the use of the JB43 tool being required, when refitting the torsion bars, for cars with chassis numbers from IS50065 (RHD) and IS70413 (LHD).
This is the kind of car I have and that is what I am doing and the tool is meant for those in a similar situation. I assumed posting it under the S3 subheading on this forum was sufficient to clear that, but it seems S1 and S2 owners are also reading this and that has caused some confusion. I was not clear that even only part of the S3 need the JD43. Thanks for reminding.
Now you're talking nonsense. Neither a Turn Buckle, nor original JB43, or your tool can be used to aid the reinstatement of the shock absorber
Well, you misunderstood me there BIll. But it was still nonsense :shock: I meant to say that in the late S3 a turnbuckle can not apply enough tension when refitting the TB because it would require the lower arm to rotate downwards more than the chassis allows. So the chassis is in the way. Hence the only place to apply the tension is at the rear spline as written in the manual. Or am I wrong here?

Anyways Bill. I am only trying to help here. if you have a way of refitting the torsion bars, for cars with chassis numbers from IS50065 (RHD) and IS70413 (LHD) without the JD43, please let me know.

I am not trying to trick people into anything. Obviously you have a lot more experience, but for my car I could not find another safe and simple solution and therefore I made it for myself, also knowing that the effort might benefit some other people as well.

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