Front Suspension Ride Height V12 E-Type

[jfjharry]

I've just gone thru the steps in the maintenance manual to measure the ride height with the bracket made up to insert in the damper position. This measurement was pretty close to spot on. The problem is the front end of the Jaguar is 2" lower than it should be. I am now at a loss to explain the low height. I expected the torsion bar to have lost its tension and the measurement to be 2" low, the wheels are standard size and I would appreciate any help to explain this. The actual ground clearance at the front is 3" and I need a minimum of 4" to get passed the road worthiness check and get it registered. At the back I have 4" clearance. The cam adjustment was already set at the highest ground clearance setting, when I dropped this right back I lost close to another 1/2".

[vipergts]

This is exactly what happened to mine.

I measured and made a distance rule and bolted in place with complete accuracey only to find my car sat far too low and I too wound up the cam to max.....still no good

I took it all apart again and moved the torsion bars around one more notch and now it sits too high with the cams off.

I know there is a method whereby there is micro adjustment using a combo of notches on the torsion bar. (there are differing notches on the spline front to back)

I'm at a loss having followed the procedure accurately.

This is how mine is today and it irritates the life out of me to the extent that I have lost interest in the poor old girl.

Let me know how you get on.



:(

[jfjharry]

Vipergts
Thanks for the information re ride height I've decided to go ahead and remove the torsion bar and shift it a notch or a portion thereof. I assume you shifted it one notch at the front, could you give us an estimate of the increase that you gained...this would be a big help as if it is too much I will have to work out the combination of the front to back spline's. If anyone else knows this information I would be pleased to hear from them.

No-way could I remove the torsion bar while on the car I have now removed the complete unit and it looks like a trip to a workshop with a press after soaking for a day or two.

[e-bygum]

I've just gone thru the steps in the maintenance manual to measure the ride height with the bracket made up to insert in the damper position. This measurement was pretty close to spot on. The problem is the front end of the Jaguar is 2" lower than it should be. I am now at a loss to explain the low height. I expected the torsion bar to have lost its tension and the measurement to be 2" low, the wheels are standard size and I would appreciate any help to explain this. The actual ground clearance at the front is 3" and I need a minimum of 4" to get passed the road worthiness check and get it registered. At the back I have 4" clearance. The cam adjustment was already set at the highest ground clearance setting, when I dropped this right back I lost close to another 1/2".

Harry
I don't understand. What maintenance manual are you using?
You don't measure the ride height with any brackets fitted. How can the front end be 2" low if the ride height measurement is pretty close to spot on? Where are you measuring front ground clearance.? The ride height should be 6.25" +/- .25 between the bottom edge of the picture frame and the ground.
There are two very different procedures for removing/refitting/adjusting torsion bars depending on the chassis number of the car. These are both detailed in the ROM. Each uses a different length setting gauge and the method for later chassis numbers requires a special tool to release/apply pre-load to the torsion bars.

More info. needed to give half decent suggestions.

[vipergts]

The original manual I used did state a different setting for late cars.

It suggested drilling a length of metal top and bottom at a distance quoted. This is then mounted on the top shock location and the bottom shock point. (The length is greater than that of the shock itself. Removal of the hub/disc assembly is required.

In order to get mine sitting as it is now (too high) I ended up with a much much greater distance between the two points. I would say the car sits 2" higher that the first time I tried.

[jfjharry]

Pete
Thanks for your reply, sorry about the confusion about the clearances but I will stick to the book and your measurement of 6.25" - my measurement is 4". The maintenance book I have is REPAIR OPERATION MANUAL for JAGUAR SERIES III V.12 'E' TYPE published by Jaguar Cars.
My chassis number is the later 74599 therefore in the manual I went by remove and refit torsion bar section 60.20.42.
The point that you brought up, and where I may be confused, is that I understood the setting bar 19.25" was also the measuring bar i.e. the right length for when the bottom torsion bar is under no tension. I wondered why mine was so easy to get out with no tool to remove the tension.
Is it the case that this bar should be under extension tension all the time? If this is the case that is the problem with mine as it has been set with NO tension. Going by other peoples experience I think that one notch on the torsion bar should give me 2" more height and in that case I may need the tool to get it back together again.
Can you comment on the above and let me know whether you think I am correct or not and point me in the right direction........
It is interesting to note that I have come across 2 other people with the same problem.

[vipergts]

It stands to reason that you don't need to tension the torsion bar if the bottom arm is able to travel lower than its normal setting. My torsion bar slipped into place easily too using the quoted measurement.

When I refitted the hub etc it was necessary to force the bottom suspension arm up using a jack etc to get it in place. I guess you could call this tension.

something clearly not right :?

[Doddsy333]

I have the same problem with incorrect ride height. It does appear to be a common issue. Any advice would be much appreciated.

Some background.

The ride height on my car also measures 4" from the ground to the picture frame on both sides of the car. I have followed the ROM using a metal bar to position the Lower wishbone with length 19.25" between centres of two holes. The torsion bars on both sides were assembled without tension. My car is an early car. Even with the cam adjuster at its highest position the clearance is at most 4 1/4".

My tyres have a diameter of 640mm so I can understand that there will be a reduction due to these having a lower profile but not 2".

Do torsion bars become less stiff with age?These are still the original ones.
I cannot see a RH or LH mark on the torsion bars and so they could be installed swapped but would this cause both sides to be 4"?
Is a solution to make the setting bar longer so the balance position is lower?

The rear height is within specification. The proliferation of speed bumps where I live and a new stainless steel exhaust means that I do want to have this resolved before I venture forth in my car.

[MarekH]

Dear Lee,

If you have measured the difference in the ride height before and after adjustment, then it ought to be possible to make a calculation as to what adjustment is needed.

For example if the bar end you adjusted has 24 notches and you adjusted one notch, i.e. 1/24 of 360 degrees and gain 3 inches (15 degrees = 3inches), then to gain 1 inch instead, you should 1/3 of 1/24 of 360 degrees, i.e. 5 degrees.

If the other end adjusts on 25 notches, then that's 14.4 degrees per notch, so to add just 5 degrees, add 8 notches front AND rear, you gain 8 x (15-14.4) = 8 x .6 = 4.8 degrees = almost one inch height.

Put another way, the vernier works by what you add on one with 1 @15degrees, you partially back out with 1 @14.4 degrees per notch. It may appear to the naked eye as though no adjustment is being made as you can't see 24 or 25 splines difference, but the bar is moving round 0.6 degrees each time. e.g. add 10 notches to both = 6 degrees; add 15 notches to both = 9 degrees.

Adding 25 notches to both is the same as moving one end around 360 degrees at the 25 notch end, but moving the 24 notch end around 360+15 degrees - which is where you came in.

You'll need the Dremel some marks (or use paint spots) onto the bar ends to keep track of adjustment.

The reason you need to jack the lower suspension to refit is that the bars are old and have taken on a "set". At some point, it'll be time for new bars as it is too hard to twist them around and line up the front suspension mounting screws.

kind regards
Marek

[miltonk]

Ok this info helped me a bunch this weekend.
I too followed the instructions in the repair manual and set the distance at 19.25"
I was using the old torsion bars, The result was as many others here, the ride height was about 3.5" before adjusting the Cam. the cam did not make up the 3 odd inches i still needed to get the suggested 6.25" +-.
So after reading all this i marked the Rear Spline position and leaving the front as is, i removed the rear reaction plate (2 bolts) changed the Distance from 19.25" to about 20.5" + or - this allowed me to move the rear reaction plate 1 tooth and still align the bolts and refit.

Once i did the Ride height was 5.75" before adjusting the Cam. Today I will adjust the cam bolts and Hope to get the ride height in the manual. 6.25".

Thanks for all the suggestions.

Note using this method i did not have to remove the Front Spline at all.
This is the third time i have done this job, but the first time with all the LOAD needed.
This is not a hobby for the faint of heart.
I'll try to post some pics.

Milton