Torsion bar adjustmen

I need to adjust the torsion bars on my e type and have some simple questions before I start.

I have read the Jag manual (pages 217 and 673)) and also looked closely at the mechanism. (Also looked at JFK history but these all seem to be about XK 120 - 150 and guess their mechanism was diffrrent)

So my e type questions are:

  1. Is it really important that the weight on the front end is correct or does the “setting gauge” make that irrelevant?
  2. The manual days " Mark position of the lever on the shaft, remove by sliding off the splines,… What is the purpose of marking the original position? Isn’t that irrelevant?
  3. Am I correct in assuming the lever slides forward on the bar? Is it difficult to move it forward?

Thanks for advice

First question would be…are the current measurements in accordance with the manual ? It sounds like you have already done this ?

Search the archives we just had a big discussion about T/B settings

The manual assumes a new car yours is 60 years old so for starters it may not want to come apart. The T/B may not twist as new sooo the manual settings are a guide. Don’t think anything is sliding off and on however it can , some would say it’s the worst job on the car but it doesn’t have to be and some of us that have done it don’t follow the manual there’s easier ways
Cheers. Jim

  1. if your plan is to set it to the factory specified spread then you could literally do it with the bonnet off. However factory spec is just kind of an average correct setting for new stock bars. It might work, or it might not. It definitely won’t work if they aren’t stock bars and likely won’t be perfect if the bars are old. So yes, tests must be done correctly laden so you know whether to increase or decrease “the spread” (the distance between upper and lower damper bolts).

  2. The only reason I’d mark the splines is if you’re expecting to return it exactly as it was prior to disassembly. Mine are marked right now because it only came apart to remove it engine. Fingers crossed it goes back together and sits at the same height.

  3. So long as the parts aren’t rusted and all tension is removed then the rear splines separate fairly easily. It’s at it’s lowest tension with the rear bolts removed and the lower arm jacked up till it points straight out to the side. That moves both ends of the bar into alignment and has the side benefit of rotating the receiver off to the side a bit so you can grasp it and wiggle it forward. If it fights you, continue raising the arm until you can remove the small locking bolt on the front splines, and then you can tap the bar rearward with a drift and the receiver will just fall forward out of the way.

Before removal however, you’d be wise to use an adjustable setting tool like a turnbuckle to get an idea what the currently “spread” is. Presumably you know whether you want the car higher or lower, so knowing what the spread is now, will give you a starting point to adjust from, increasing or decreasing depending on where you’d like it to be.

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Kind of long and wandering but it is a JL thread. Includes useful details

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.

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I assume that you are redoing these because your car is now sitting lower than you like. That is the TB’s have settled - as probably the rear springs have as well. After 50 years of E Type ownership and racing one I’ve probably done this job way more than 25 times. It is difficult but more importantly it’s very difficult to do it right, the problem being is that the old bars are essentially worn out, and on removal try to get back to their original shape, confusing the setting link, but then after re-install they sag again. I would strongly urge you to buy new bars and start from scratch. They are available from the usual’s, but also from US manufacturers for less money… If you go back over old threads you’ll see discussions about this.

Terry, isn’t there a chance, since this job difficult to do correctly, that in the car’s 50 plus years, someone did it incorrectly? I would advise doing the job right before buying new parts.

I agree Tom that there are many possibilities, some more probable than others. These may be improperly installed new bars for all we know. What I know is that when you install new bars you can use the setting gauge distance that Jaguar recommends and expect to do the job once. If you try to do it on used bars the gauge is not helpful, and the probability is very high that you will be doing it a number of times, in fact setting a used bar to the recommended distance will have the car sitting lower than when you began. Been there done that.