JD43 torsion bar tensioner tool alternative

[Danetype3]

OK, I tried to figure out for which cars the alternative tool "should" be used. But this is not as straightforward as I thought.

Anyways, I am sure you all know best yourself what works for your car. I will just have some rings made and let you know when ready.

[willotree248]

I think this is a great idea. It is exactly what I'm looking for. In fact I need it today! Please let us know when they are available. If you'd consider loaning/renting your prototype, please let me know. I sent you a PM.

Best,

Doug

[peter606]

I would love to buy one as well for my series 3 XKE
Thanks
Peter Allen
Vincenttwin@gmail.com

[Adamski]

I am lucky enough to have bought the tool some 25 years ago. It's actually made from a splined torsion bar locking plate,if they're still available?

[Pete G]

How many s3 torsion bars have you taken off/refitted to come to that conclusion? It is wrong. The job can be done without the use of JD43.

[MarekH]

I used to have one but never thought it made the job any easier so I sold it. Never had a problem doing the job without one.

kind regards
Marek

[Danetype3]

Does anyone know the difference is between the S3 before 1S70412 (no pre-tension on the bars needed) and the later S3 (pre.tension on the bars)? Were different bars used? The suspension parts look the same in the manual.

I have now finally put the car (1S74729, so with 1 spline rotation of pre-tension) on the ground but it is way too high (26cm instead of 16cm bottom of picture frame spec in manual). The weight of the car does not compress the springs, the shocks still limit the max deflection so without shocks it would be even higher. I am using the uprated torsion bars. The engine has no fluids yet, interior is empty. But my full weight of about 70kg still does not compress the springs, so I doubt it is the lack of weight of the car.

I am very confused. It looks very much like no pre tension is needed. But that does not match with the serial number...

Paul

[angelw]

Hello Paul,
The Up Rated Torsion Bars are heavier and therefore, the specification of the Setting Link for the Standard Torsion Bars doesn't apply. You will have to come up with a new set of numbers, as the Up Rated Bars will most definitely have the Front End sit much higher with the Standard Setting Link specification and you definitely won't require the use of the tensioning device.

I use a Turn Buckle instead of a fixed centre distance Setting Link, so that the amount of downward angularity of the Lower Wishbone assembly can be easily varied. To fix the problem you have with the heavier Torsion Bars, the downward angularity of the Lower Wishbone will have to be much less than that set via the standard specification Setting Link.

Regards,

Bill

[Danetype3]

Hi Bill,

I bought these at SNG and in the catalogue it says:

"UPRATED TORSION BAR PAIR. These are .88 diameter and are not handed. Setting link required to fit.19” eye to eye. Aircraft quality high alloy steel."

So even though I am inclined to agree with what you say about these being much stiffer and I have to find my own setting link length, they are specified with the usual 19" setting link?

I am also wondering about the ride quality. Did Jaguar want a softer ride after 1S70412? The later bars need a pre-tension to get the correct height, which must mean the spring stiffness is less, the ride is more comfortable. If these new bars do not need pre- tension and an even shorter setting link, would the ride not be much harder than intended?

Paul

[angelw]

Paul Wrote:

"UPRATED TORSION BAR PAIR. These are .88 diameter and are not handed. Setting link required to fit.19” eye to eye. Aircraft quality high alloy steel."

So even though I am inclined to agree with what you say about these being much stiffer and I have to find my own setting link length, they are specified with the usual 19" setting link?

I am also wondering about the ride quality. Did Jaguar want a softer ride after 1S70412? The later bars need a pre-tension to get the correct height, which must mean the spring stiffness is less, the ride is more comfortable. If these new bars do not need pre- tension and an even shorter setting link, would the ride not be much harder than intended?

Hello Paul,
19" isn't the usual Setting Link centres. The 19.563" was specified for the earlier cars and 19.25" for later cars.

The original diameter of the late series cars is 0.75". 0.13" is a significant diameter increase where =Torsion bars are concerned.

There is a different part number for the Torsion Bars used in the early and late car builds. The later cars used a 0.313" shorter CD specification Setting Link, which would have the car sit lower, but the Torsion Spring effect would be roughly the same for similar Torsion Strength bars. Pre-loading the bars would raise the ride height some. If anything, I suspect that the later car Torsion Bars may have been stiffer.

A 10cm height difference is quite considerable. and I know you stated that the engine had no fluids, and the interior is missing, but is the rest of the car in place, such as the Bonnet, Radiator, etc?. That would make a difference. As the Sherlock Holmes character said, "When you have eliminated the impossible, whatever remains, however improbable, must be the truth".

The following two pictures shows the arrangement 0f the Turnbuckle Tool I use. Once the Torsion Bars have been installed with the Turnbuckle Eyes set to the correct Centre Distance, I shorten the distance between the Eyes of the Turnbuckle so as to put the suspension in circa the position it would be if the weight of the car was applied. I leave the Turnbuckles in place until the end of the work on the car, so that the Grease Gators, particularly the top one, are not in a contorted form for a long period.









The following two pictures show the machining of the inside of the Turnbuckle Eye so as to be a close running fit on the bush shown installed in the next picture down.






Regards,

Bill

[Danetype3]

19" isn't the usual Setting Link centres. The 19.563" was specified for the earlier cars and 19.25" for later cars.

I know, but I assume that the difference in ride height due to these small link lengths differences would be smaller than can be adjusted at the torsion bar cam lever?

The original diameter of the late series cars is 0.75". 0.13" is a significant diameter increase where =Torsion bars are concerned.

Agreed, but the material might be less stiff so the diameter might not mean anything. Merketing. Bigger is better

Bonnet, Radiator, etc?.

Yes, all the major parts are there.



In the image you can see that the angle of the lower wishbone is much too steep. The shocks are still extended to their max. There is no spring action basically. Not even when I apply my own weight. It is as if the suspension is stuck somehow, but I do not see how, other than a very stiff bar with way too much pre-tension.

I have followed the manual to the letter:

1) align rear mounting and reaction bracket bolt holes by rotating the tension bar with the setting link in place. This might have been a couple of mm off in length.
2) pull back reaction bracket, rotate one spline
3) rotate torsion bar until mounting and reaction bracket holes are aligned again.

As you know it is not very likely I added one spline too much pre-tension because one step is already 14 degrees or so.

So unless you spot a major issue, I will check with SNG about the spring stiffness.

Paul

[angelw]

Paul Wrote:

Agreed, but the material might be less stiff so the diameter might not mean anything. Merketing. Bigger is better

Diameter has a dramatic effect on the torsion resistance of a torsion spring.

My opinion is that the pre torque of the Torsion bar of the later cars was to stiffen up the suspension. One tooth of the spline at the rear wouldn't have been possible to achieve the same result by using a longer setting bar, as the lower wishbone couldn't be rotated about its fulcrum a further circa 14 degrees. Do the instructions that come from SNGB say that their uprated torsion bars should be pre-loaded by one tooth of the rear spline. I would be surprised if it did, and I suspect that this is where you're going wrong. I believe that the 19" CD setting bar would be used without preloading the bar as well. The instructions in the Workshop manual don't automatically transfer when torsion bars of a different rating to the original equipment are being used. the same as the same CD setting bar doesn't.


Regards,

Bill

[MarekH]

Use some common sense and stop getting hung up about setting link lengths and the like. You'll have done it right when you have got the wishbones to settle down horizontal. That way, the bushes are all going to be set up in their "neutral" position when tightened up so remain that way when out on the road and the wishbones can rise or fall equally about their horizontal mid points.

Aftermarket parts will simply be a different strength spring to the original, so what you need to do is set it up so the end result is the same, not get hung up ábout using the old methodology of how to fit a totally different new spring to the one you had.

kind regards
Marek

[Danetype3]

Hi Bill, Marek,

My assumption was that the uprated springs were the same stiffness as the original. Why would you want to change the original jag specs because that will change the ride? Disappointing in a way. But I guess you are right. These are different springs with their own instructions. OEM can be anything. I will install without pre-tension and see what happens.

Paul

[MarekH]

The instructions in the manual assume the original same weight springs are used every time. They wouldn't have known different (non oem) springs would even be available when they wrote the manual.

Your springs are clearly much stronger. You'll need a longer setting link to tension them the same amount as the oem springs, to achieve the oem ride height, rather than no tension at all.

The ride quality will likely be different.

kind regards
Marek

[mgcjag]

Hi Paul...I'm curious as to why you fitted "uprated" torsion bars if you expected them to be the same as originals?......a lesson to learn is don't expect any non original/aftermarket E type part to be a perfect fit or work as an original part....Steve