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Need help on a 71 XJ6 issue: Feels like it is floating at highway speeds

XJ6 & XJ12 Series I, II & III 1968-1992

Need help on a 71 XJ6 issue: Feels like it is floating at highway speeds

 
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Old 08-30-2016, 12:20 PM
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Default Need help on a 71 XJ6 issue: Feels like it is floating at highway speeds

Hi everyone:
On my wife's 71 XJ6, with 35k miles, at highway speeds of 50mph+, the front feels like it is floating.

The tires are brand new (Yokohama Avid Touring S 205-70-15), and balanced, front end is aligned, etc... The shocks and springs are original. The rebound from bumps feels okay, there are no vibrations in the suspension or steering wheel, the car tracks straight, no weird noises, and the car does not wander.

It doesn't feel "out of control," but not tight, sort of cruising on a couch feel.

I am not sure if this would be a sway bar bushing issue or a shock issue. The shocks do not seem symptomatic, but the car is 45 years old, and was not driven for 35 years.

Is it possible that this is sidewall deflection? My car has 225/40/18 and 265/35/18, so I am used to a whole different perspective.

Should I try different air pressures over the factory spec?

Thanks in advance for any help!
Paul
 
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Old 08-30-2016, 02:23 PM
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Hello, Paul,
First of all, I Love your wife's car! Of course, BLACK is my favorite color for a car anyway so I may be a tiny bit biased.

About the floating front end; if this was my car I would replace the front shocks and maybe the rear too just for good measure. After all, they Are 45 years old and never were intended to last forever, even with only 35,000 miles. Time does a number on them.
ElinorB.
(';')
 
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Old 08-30-2016, 05:16 PM
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New shocks all round make a world of difference.
 
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Old 08-30-2016, 09:11 PM
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Agreed on shock absorbers.

A couple other thoughts:

Check your steering rack bushings.

Also, lack of caster can give a loosey-goosey sensation to the car. If you got a printout-out of the alignment settings you can see where it has been set. I always ask that caster to be set to the max allowable 'positive' amount...or as close as possible. That said, lack of caster usually also gives a wandering feel...which you say you don't have. So...?

Cheers
DD
 
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Old 08-31-2016, 10:31 AM
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Or, it may be comparing apples to oranges. The tire aspect ratio difference of the two cars is huge.


Rubber is softer and more compliant than metal. A given.


And, yes, changing tire pressure can do a lot.


But, I am with the shock absorber (dampener) comments. A fresh set
of "good" ones changes a lot, for the good.


Tis a great looking car!!!


My dear departed loved her Jaguar. Although, German born and raised, she loved all things, English??? Princess Dianna was her heroine.


Carl
 
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Old 08-31-2016, 03:44 PM
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Thanks for the replies, suggestions, and compliments!

Talked to Tire Rack and Yokohama, and both agreed to up the psi to 32 all the way around, over the 1971 factory spec. And of course, monitor treadwear patterns.

Made quite the difference!

Agreed on the shocks. The stock ones in the rear appear to konis, which I believe was an option.

Considering kyb's, unless the consensus is "no."

After upping the inflation, I took it up to 70mph, and it seemed much better, only when you turn the wheel is there a slight bit of (adjective time): wander, sponginess, etc...it almost feels like the front end lifts the corner you are turning into and pushes the opposite corner in the rear down.

I will dig out the alignment specs and post the computer printout.

The rack bushings seem tight. The sway bar bushings and end links look ok, just 1971. Thought about changing them to polyurethane just because.

Thanks again!
 
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Old 08-31-2016, 05:56 PM
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Changing to poly rack bushings is good idea (you';ll be Amazed how much improved handling you'll get), but not for the sway bar, as it makes the ride too harsh, going back to adjectives.

You want crisp and firm, but not harsh.
(';')
 
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Old 08-31-2016, 06:42 PM
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Default Agreed - rack bushings

My Series 1 did the same when the bushing went soft and gave out. Replaced with Poly bushings and it then returned to a fine handling Jaguar.
 
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Old 09-01-2016, 08:27 AM
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RSQ911:


The description of steering response is the opposite of what I would expect. "Push" aka understeer is expected of a nose heavy car. And, Jaguar's fit that description. Also manufacturers build in understeer.
to different extents. Easier for an "average' driver to handle.


So, your description is sorta akin to "loose" aka oversteer, the rear tags out. Many "skilled" drivers like that a bit.A faster path around a corner.


Added factor: Aging coil springs no longer have the original elasticity or perhaps, better stated, more. Springs play a huge part of weight transfer. it is the result of weight trans fer that one feels as one turns the wheel. Tuning weight transfer is a combination of science and art.


I still think that your cars just have different characteristics and are just fine, it is you sensing the difference.


Some time ago, I got new tires for my car. Old and stiff rubber gave way to softer new rubber and a wider wheel. Rode better, but not quite as stable in a tight turn. Not enough to bother me, still well within even my more spirited effort. Caveat, my lump is 100 pounds lighter up front. That means a lot.


Enjoy that beauty, angst not needed....


Carl
Carl
 
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Old 09-05-2016, 01:04 PM
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Hello,

You might contact sng Barrett. At one point they were supplying new rear dampers/shocks with new springs ! I found this a good way to go. Lots less hassle and lots safer if you do not have the tooling and experience in changing springs.

My experience is that you should order NEW collets if you will be changing the rear springs. Again to save the hassle and work in safety.
 
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Old 09-07-2016, 08:24 PM
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I wondered about the rear shocks with the coil overs. The fronts look like they are a straight forward job, but the rears... not so much.
 
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Old 09-07-2016, 09:16 PM
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Originally Posted by rsq911 View Post
I wondered about the rear shocks with the coil overs. The fronts look like they are a straight forward job, but the rears... not so much.

Not all that bad. This should help....

Rear Shock And Spring Replacement

Cheers
DD
 
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Old 02-04-2017, 12:30 PM
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Update on the handling.

We have replaced the shocks with KYB. The original Girling's (sp?), were still on it, and even with the low mileage, were sagging from time, and sitting.

Huge difference. The XJ6 "ride" is still there, but the ride height is up slightly, and the response/rebound time has improved in a major way.

The steering is better, but still not quite "right".

Replaced the front sway bar bushings with polyurethane. The original rubber ones were absolutely finished! Dry rotted, distorted, etc... Have not had a chance to take her out yet, but this should/will make a difference. Replacing those bushings is very different than any other car I have done. Usually one simply loosens the nuts, and the bolts are fixed, nope, not on the XJ6 LOL! For those of you that have not done this, it has a backing plate, the bushing retainer, nuts and bolts, and the bushing. Definitely helps to have two people!

Next up, as suggested, will be the steering rack bushings.

I will report back on this, and again, thanks for everyone's help!
 
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Old 02-04-2017, 05:36 PM
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Great to see persevering. It looks like a great car & I hope you get it handling like it should be.
 
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Old 02-05-2017, 03:58 PM
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We took the jag out today, and what a difference with the bushings! Definitely tightened up the feel. We are still going to do the steering rack bushings as well, but I feel a lot has to do with the sidewall size.
FYI- front sway bar size is 3/4"
thanks again to everyone for your help!
 
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Old 02-06-2017, 03:25 PM
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Great news! A car that looks that good should have the goods to match it's looks. Get out & enjoy that Jag. You've earned it!
 
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Old 02-06-2017, 03:42 PM
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+1!!
And as soon as I get central locking put back together I'll be right out there with you!
(';')
 
 
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