Setup for upgraded torsion bars on s1 4.2 E-type

My front suspension is about 40mm too low. I appear to have upgraded torsion bars from Xk Engineering which are 23.65mm thick (about 0.93mm) Standard height is around 16 13/16" and Jag I have seen a recommended 16 1/4" but no indication of torsion bar thickness was mentioned. Can anyone suggest the correct measurement I should use on set up?

I think you’ll find that the tie rods are straight across when the ride hight is correct at least in the ball park . I’ve no experience with the heavier Tb but I’m sure the racers would know and they’ll probably chime in

Hi Paul,
Where are you taking your measurements from, as in where on the car?

Paul,
If you have the factory manual go to page JY1.

That page will show you where to measure for ride height as well as dimensions of TBs by car type.

I have seen the technical manuals and supplements mentioned
I could use the recommended settings but when there is weight on the wheels there will be less droop with stiffer TB’s and ride height will be too high, so was hoping for a suggestion as there where to start

Paul…what your after is the lenght of the setting link to use when setting ride height if useing uprated torsion bars…is this correct…Steve

I think that’s what he wants but I’ve never seen anything on it .doesn’t mean it’s not out there
It’s not a linear adjustment, trial and error is probably your best bet about three times to get what you want or close . A guess 3/8 inch off the factory setting just a guess having fooled with it
Cheers

Correct Steve. And from checking ride height the following
Checking Front Ride Height
6 cylinder E Types 107x45

The following scanned image is taken from The Official Workshop Manual for 3.8 and 4.2 E Types. Full details, including how ride height may be adjusted can be found at pages J15 and J16 of the manual.

Setting ride height on E Types is not an exact science. There are a number of factors which come into play, including the condition and specification of torsion bars and bushings.

The factory setting tool is designed to be used between the upper and lower mounting points of the front shock absorber. For standard E Types, where the torsion bars etc are in perfect condition, the manual calls for a distance of 17 13/16" between the two shock absorber mounting points. When heavy duty torsion bars are installed, the additional strength of the torsion bars means that a distance of more like 16 1/4" will result in the correct ride height.

This is where I found the shorter measurement

My TB seems to be quite thick compared to even racing versions I have seen mentioned. Perhaps this does not actually mean stiffer??

I thought I would call Xk Engineering tomorrow and speak to an advisor

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my copy paste faxed, or I did.
‘checking ride height’ came from www.classic jaguar.com

Hi Paul…i think you will find that it will be trial and error to get your desired ride height…what you posted is just speculation …i dont think anyone will be able to give you an exact measurement…you can get an adjustable reaction plate that may help but the same can be achived with a few trial and error settings of your bars…Steve

Thanks for the help Steve. Will get down to work tomorrow

From January 2020: As the car sits now decide how much you want to raise or lower each side of the front.

Disassemble per manual until you get to the point where the torsion bar is still in but unloaded. (UBJ, outer tie rod ball, & shock disconnected)

Using the shock mounts upper and lower measure the current length of the " setting link"

Add (or subtract) 0.75 times the amount you want to raise the car ( or lower) to find the new setting link length.

It’s a very linear problem. So if you want to raise your car by 40 mm, you need to increase your setting link by 30 mm from what it is now.

40 is a lot. Measure twice.

There is an exact measurement, it’s 9” from the pivot point on the lower suspension A arm, to the ground.

And it doesn’t matter that you have updated bars, the 9” is required. The heavier TB’s come into play once the suspension is moving but the ground clearance remains 9”…….unless you want to change it for some reason.

Maybe the std setting guage won’t give you that 9” but it will be a good start. As has been mentioned, and per the directions in the book, you’ll have to do some trial and error adjustments to get the 9”.

Les…the measurement being discussed is the length of the setting link…please read previous posts…Steve

Thank you Steve. My point was and still is that the only measurement he should be worrying about is the 9”. He has a std setting guage which leaves the car at the wrong height.

As has been mentioned, whatever paul does from there is guesswork with mostly trial and error. So, imo might as well forget about the new setting guage and move on by taking a careful measurement at the correct location.

Make an adjustment, carefully note/record what he changed at each end of the TB’s. Set car back on its wheels, settle the suspension and take another measure at the correct location.

Using the aforementioned process and with the information gained, paul’s next move will likely be very close to the final setting.

Btw Paul……whatever process you use it’s very likely that after a couple of hundred miles the suspension will have settled a little more and you’ll find its no longer exactly at the ground clearance (the 9”) measurement you set it at and you’ll need to go back to make the final adjustment.

Don’t be discouraged, this job I’s one of the worst jobs on the car,

Good luck.

Right. Standard link setting is about 452mm, upgraded at 413mm. We stripped and measured the existing setup which was at 410mm. Using Tom’s suggestion of 75% of the revised our height adjustment of 30mm we added 22mm to the 410 getting 432mm for the setting link. Thereafter Xk Engineering called back with the correct measurement of 432. Now to reassemble and hope all is good. Many thanks for the assistance :grin:

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Paul, That’s encouraging.

You may have read about cars settling after setting the torsion bars. Since you’re starting with a car that already settled, it should be minimal. But I would be very interested to hear if you experience settling, how much and how long does it take.

Enjoy the journey.

A quick note: Ride height is perfect first time out. Thanks for the advice :ok_hand:

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You lucky one better buy a lottery ticket :ticket:

Hmmm, wait for it
Cheers