Since the bushes were in place, I ended up reaming them to the right diameter, remove 1/100th of an inch, plop.
But what a pain and waste of time…
I just completed a compete re-bush of the front of my 1985 S3 with Prothane poly pieces. One irritant I faced was a raised manufacturing seam in the ID of the steel sleeves. Had to wrap coarse emery cloth around a dowel and sand the seam down without making the general ID bigger. It worked fine and the whole bushing set fit beautifully. This may not be the same problem you are experiencing.
Dave
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When I’m done with the IRS on my YouTube channel Jag Mods, that will be my next set of videos.
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Hi Eric
Your problem lies in the fact that the original vehicle is of imperial manufacture. All fastenings and machined / manufactured parts are of imperial dimensions. The front suspension inner lower fulcrum pins are 13/16" in diameter. Any replacement parts should/must be of imperial sizes to fit correctly. The inner / lower fulcrum pins are no longer available new, and either good second hand or remanufactured pins is the only option. I have just remanufactured them for the suspension on my Cobra.
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Keith,
I am looking for those fulcrum pins for my car. Would you have made a extra pair? Are you located in the U.S.? How have they worked on your Cobra?
Thanks, Dean
The lower Fulcrum Shaft are still available, from Jaguar up to a few years ago and now being reproduced. I’ve sold several each year for decades. The original had a cotter pin hole and used a castellated nut. The last version uses a nylock and the thread on the end and the nut are Metric but the shaft is still correct.
My preference is Urethane on the lower A Arm bushes. I stock ones made by the company that made the original Lister upgrade. STOCK on the upper A Arm Bushes, which are bronze bushes running on hard chrome inner shafts. Urethane is a serious downgrade to these.
I’m a URO WD and I only sell the URO lowers when someone insists. They don’t hold up at all.
I’ve sold thousands of Jaguar parts for various Cobra replicas and they all used E-Type front suspension. I’ve seen some XJ front suspension in C-Type replicas.
I have a pair second hand in a box. I’ll take photos tomorrow and see if they are any good.
There is a lot to be said for using rubber in automotive vibration bushes.
Makers of polyurethane bushes like to tout longevity, but the harmonic absorption characteristics of rubber and polyurethane are at different ends of the scale.
Polyurethane cannot replicate rubber even if the hardness is reduced.
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yes, the difference is significant, PU has less damping which can have unintended results in a proposed upgrade. Rubber’s inherent damping is an important property - not just for noise reduction but also for positional accuracy. A bush is effectively a spring & damper system - at a broad suspension level I’d be wary of fitting a stiffer spring while reducing the damper setting.
I’m generally a bit sceptical of PU bushes - they’re claimed to have the advantage of increased stiffness over the equivalent rubber items but I’ve bought and tested many items sold for the E-type and have not seen that. Regardless of material they all seem to top out around 70 Shore A, with similar load / deflection curves.
I frequently use PU to make sample bushes and mounts for test, it’s cheap and quick, but would not translate that to a general enthusiasm for long term use on the car.
(The above comments made from a background of bench testing, not road use)
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Clive,
some years ago I overhauled my Spitfire front suspension with a quality PU kit and was - and still am - satisfied. Much of the general enthusiasm about PU bushings may be owed to two factors. First, they are never compared to good rubber bits, but inevitably to the deteriorated parts they replace (if they are ever compared to new rubber bushings it’s mostly cheap repros of poor quality). Secondly, they often come with high quality stainless sleeves making the fit a lot more precise.
Other than that I couldn’t speak bad about the rubber/metal (metalastic) bushings they used in the days.
Best
Jochen
75 XJ6L 4.2 auto (UK spec)
Well isn’t that interesting.
The two claimed benefits I want to believe is that they’re more oil resistant and offer improved handling. But I‘ll stick with rubber. Except on the XJ/XJS steering rack mounts where I think the PU bushings are miles better.
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I started looking at PU bushings with the received understanding that they would offer more precise handling through higher stiffness than available with rubber. That relies on two base assumptions:
- The PU part is stiffer.
I haven’t found many parts where this is true. E-type upper control arms are one exception, but the difference is small. - The underlying suspension geometry is good enough to be preserved and thus improved with the stiffer bushing.
I have doubts about that with the E-type. In my opinion, the front contains compromises for reasons of marketing and aesthetics, and the need to match the curious characteristics of the rear suspension, so is not certain to gain from greater control in its joints.
Those cars have the steering rack behind wheel centre line, so if the PU mounts are indeed stiffer that would tend to give oversteer (or reduced understeer) as cornering loads build up. Depending how other factors balance, that can make the steering feel more incisive or aggressive. The opposite is generally preferred for high speed precision and confidence.
I’ll defer to the man with practical experience there. In fact that’s very credible because the Spitfire has good front suspension geometry - quite pure and well suited to its purpose, so greater precision in the joints would likely be helpful.
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I can attest to that.
I replaced the old, but in good shape, steering bushings on my XJ with PU and the steering wheel behavior change was quite noticeable.
The car feels much tighter and much more precise on curvy country roads and fast maneuvering, and with a greater willingness of the steering wheel to go back to center, all very positive.
On the other hand the steering feel on highway speeds lost some of its leisurness as the steering wheel needs a lesser input and small corrections have a greater effect.
I guess it’s where variable power steering assist comes to play in today’s cars.
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This is interesting, I only had mine to around 180 kph so far but it felt very stable and confident. There is vibration from the tyres but it goes away again at higher speeds.
The original mounts are a design they were very proud of but it eats itself up and then the steering is really loose and sometimes unpredictable. The PU slide in and are more logical to me.
I hate variable power assists and I do drive fast when the road is clear.
No, it’s still very stable and very confident, just a bit more “twitchy” above 130 kph compared to before.
Personally I’ve found the the PU rack bushings in the older Jags give a good compromise between increased responsiveness and obnoxiously over sensitive.
Besides the bushing the the gear ratio of the steering rack. I think the ratio is something like 3.25-1 on the series sedans and older XJSs. Later “sportspack” XJSs had something like 2.75-1 as I recall.
I’m happy with the slower ratio.
Characteristics that seem great on a 911 or Corvette are not always pleasurable on cars designed with a bit comfort/pleasure in mind 
Cheers
DD
I understand your view, early iterations in particular could be a bit crude. I think some manufacturers felt it necessary to highlight the feature to the paying customer, so they made the transition more obvious than you might prefer. (Similar effect on some cars with switchable ride control - you can have Obviously Soft or Blatantly Hard, no reasonable midpoint).
Current systems have so much tunability that the result is largely dependent on how much time the engineer is willing (or allowed) to spend fine tuning. There are so many variables and interlinked maps to play with…road speed, engine speed, transmission, throttle position, steer angle, rate of change of all the above, etc. The first such system I worked with, the supplier engineer arrived with his laptop, it transpired that many of the maps were set to default and he wasn’t expecting to go several layers down and explore new ranges.
"Welcome to my world, come in and sit down 
It’s generally possible to get a good result out of all that flexibility, if the base system is sound and sensors are doing their job.
Very well put. The systems do need to be blended in sympathy with the desired overall character.
It could be worth looking at the bump (roll) steer. If it has toe-in on bump that will tend to make it twitchy. I’m not familiar with XJ steering detail, if it’s feasible to lower the steering rack 1 or 2mm that could add a little roll understeer and give some “sneeze factor” at high speed.
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My L322 Range Rover has variable power assist, it’s very well designed and you would never know it’s there.
Steering with one finger at standstill, very comfortable at medium speed curvy roads and rock steady at 180 kph.
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Hi,
Likewise in my 1995 456GT, it is quite stiff at load speeds, some say not enough assist, but very good feel at high speeds and twisty mountain passes.
Also although not variable I have nothing to complain about the power steering in the 1972 V12 E-type nor the 1975 XJ6C, but I do have stiffer polybushes on the steering rack mounts, normal rubber on the suspension bushes. YMMV.
Cheers!
I guess it started out with a simple solenoid that switched at say 50 kph.
Maybe it’s welcome with modern cars and their tiny bobby car steering wheels. The XJ doesn’t need it. I admit that the first car without power steering was a little revelation in the countryside.