Poly bushes - Fitment and thoughts - X200

[Lazlo Woodbine]

So I fitted some Powerflex Black Series polyurethane bushes to the lower front arms of my S-type the other week. Mine is the early type suspension so 2002.5 onwards cars will be different but I should think the same differences in ride/handling would apply.

It all started with a noisy wheel bearing.. I already had a spare upright which I took the bearing and ball-joint out of back in June as covered by another thread. So I refurbished that ready to go on but I knew the big bushes at the front of the lower arms were poor and couldn't bring myself to fit new void bushes in their place. I have used poly bushes on various cars in the past and although I don't agree that they are better or even equal to rubber in all situations they should in theory be just fine in this application.

Here are the arms. Ignore the one nearest as it's upside down. The one further away is as it would sit on the car, as you can see the little bush sits level with the wheel hub. The big one sits some way in front, about level with the tyre.

 

Apparently these big bushes "never fail". I beg to differ. The rubber was even more degraded than shows in the picture.

 

They still took some effort to remove though. The central rubber part pushed out with the hydraulic press quite easily but the aluminium outer shells had to be cut out.

 

Cutting these shells out is really just slotting them so that they can be shrunk in diameter so they let go of the register. It requires accurate cutting but isn't difficult. As you can see in the two pictures above I've made two cuts and removed the bit between them. This can be necessary when the shell is thicker to give room for it to contract. It's best to make each cut a little at a time so that one isn't too much deeper than the other, this helps avoid pinching the saw blade.

 

This is what the big bush was made of.

 

The small bush was awkward. It's a two part bush but the central tube is flared at either end which doesn't make sense to me. I burned and cut the flange off one end so I could push the tube and hopefully the other half of the bush out, it worked.

After cleaning up the registers I was ready to put the new bushes in. The big ones actually have the central hole off centre and it's important to get them properly aligned. To do this I marked the register and the smallest part of the bush with a Sharpie so I could keep it lined up as they went in.rim

 

Pushing the new bushes in was uneventful. Just make sure you have all of the old one out. On the small bush I didn't, there was an aluminium shell still in the arm that looked for all the world like part of the arm.

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[Lazlo Woodbine]

Having fitted the arms and done a complete alignment adjustment the car it is now driving beautifully. Cornering is more stable and predictable with none of the wandering or bump steer like tendencies from before. The ride is a little coarser but it really is only on the sorts of slow country lanes where is doesn't matter much anyway. I would say that on the open road at decent speeds the ride is overall far better as the car feels far better planted on the road and doesn't wallow as much. I would even say that there is some feeling through the steering wheel, something the S-type seems to usually do a good job of preventing.. Not only is there more feel for what's going on with the tyres and road surface but the slight knock or judder that I would sometimes get through the wheel when changing direction on rougher roads is gone.

Overall I'm very happy with them. None of the improvements I feel could really be judged scientifically as it's all just sensation but it feels better and that's good enough for me.

[Claws]

thanks for sharing this Ralph

very, very informative, i'm sure some members will find it extremely helpful

regards

Steve

[Beulahjag]

This is Great stuff to share Ralph. I take it that your press to remove wasn't appropriate?

Also, swould you mind me asking where you got these bushes from? Im after a full set of poly-bushes but struggling to find anyone that'll do them.

[Lazlo Woodbine]

The press was great for some parts but when it comes to the thin outer shells of the bushes cutting them is far easier. To get a purchase on them with the press would require very precisely sized mandrels which would have taken too long to make to be worthwhile.

I bought the bushes from https://www.spring-loaded.co.uk/   as they're local to me. There are lots of people who supply them but Spring Loaded were no more expensive than any of them. There was some lead time from Powerflex as apparently they're not a common part which I can believe as I doubt many people want to make there S-types stiffer. Part numbers were PFF27-601BLK and PFF27-602BLK. That's front and rear bushes for the lower front arms on an X200. There is also a slightly softer compound option, they're purple in colour.

Personally I wouldn't fit poly on the inner and rear outer registers on lower arms of the S-type. Their standard bushes are known as "pillow ball bushes" and the way they work is like a ball-joint. So unless they're worn out there is zero radial play but the central tube of the bush is free to move in and out of alignment with the outer shell. This misalignment is necessary for the lower rear arms of the S-type to move through their arcs properly. This is because the mounting points on the chassis do not all align with each other by design for complicated geometry reasons. Polyurethane bushes could have either of the original bushes abilities but not both as making them soft enough to replicate the misalignment would allow radial play and hard enough for no radial play would make the arms bind as they moved through their arcs. That all seems very confusing written down doesn't it? The third bush of the lower arms is the front one and that is a great big bonded metal and rubber jobby. Now that one I would consider polyurethane for but I knew I couldn't afford them when I did my lower rear arms so didn't really look too far into it.

The upper arms both front and rear would be good candidates for polyurethane. But do note that they have integral ball-joints so fitting new bushes to old arms may not be worthwhile. The bushes can of course be re-used in another arm though.

I fitted Polybush front ARB bushes 6 months ago and am happy with them. I shall also fit poly to the rear ARB at some point as they're looking pretty rough, that's a hell of a job apparently..

[Beulahjag]

Thank you Ill take a look at that. 

[Suppedraken]

17 hours ago, Lazlo Woodbine said:

That all seems very confusing written down doesn't it?

It did so we'll have to trust you. Which we do.

[Russ68]

Excellent work Laz, you obviously have a talent for this 

[Mercury57]

Hi Guys, Just had some grim news from my local Jag specialist. Took in my 2.7 XS (2007) after some creaking from N/S/R. I expected it would be bushes but didn't expect the advice to replace the wishbones rather than re-bush. I can see their reasoning why it may be better but the costs involved are ridiculous. Kind of like replacing an alloy wheel 'cos the tyre's below the limit.

Looking at the forums (Lazlo's) great post for instance, seems replacing the bushes on the lower wishbone at least is (relatively) straight forward. I don't have the knowledge, time, space  or bottle to attempt this job myself but what's the general opinion on this ? I trust the specialists advice to a point but the costs are painful to say the least.

Any advice would be greatly appreciated.

[Russ68]

Hey Tony, I did complete wishbones on my X200, what were you quoted?

[Lazlo Woodbine]

I believe Russ bought after-market arm complete with bushes for a good price, so yes speak to him.

Just changing the lower rear arms is actually quite simple. There's no alignment involved as all the points are fixed and it's only five bolts a side. If the few tools required are available then it's definitely doable by someone competent, or any garage for (I should hope) just a couple of hours labour. Some may understandably not be happy about using customer-supplied parts so it's better to speak to them first. It would also be worth checking for wear in the upper arms, ARB bushes and drop links before hand as it's annoying/expensive to have to take it apart again afterwards.

[Mercury57]

Hi, Sorry about delay in replying  Russ68 & Lazlo. Eventually had the job done by local specialist; Front hockey-stick bushes + rear upper & lower wishbones replaced.Cost a grand including labour & the dreaded VAT. 3 hrs labour wasn't bad, it's the silly cost of the parts or more accurately that the arms need replacing at all. You wouldn't replace the alloys 'cos the tyres are shot ! Anyway thanks guys.

BTW. I was considering replacing the front windscreen & upgrading to the auto-dim mirror. Seems the wiring is a concern but after some investigative work I've discovered at least one, maybe two taped-up connectors attached to the loom in the roof void...There's so little free movement it was just luck I spotted them at all. Being a late model I'm guessing all the wiring is present and I would assume there's supply for a sunroof and autodim mirrors. Would you know if that's likely correct ? Also I'm not bothered about the rain-sensing feature so would that have bearing on which mirror I obtain ? As always, any advice would be appreciated.

 

[Suppedraken]

On 28.8.2017 at 12:27 AM, Lazlo Woodbine said:

I have used poly bushes on various cars in the past and although I don't agree that they are better or even equal to rubber in all situations they should in theory be just fine in this application.

This may be a silly question and you may already have explained this somewhere else, but please forgive me for asking. If they're not better or equal, why use them?

[Lazlo Woodbine]

Tony; I don't know about the mirror, I have a feeling that Joe dot com may be the man for that, a new thread with a descriptive title may be the best way to find out. Yes the arms are expensive that's why I changed the bushes only, although the upper rears are a different matter what with the built in ball-joint (nonsense). Three hours sounds reasonable, I trust they set the toe, camber and caster to spec?

Knut Are; It's only for certain situations that I think polyurethane is not worthwhile, I'll try to explain myself.

The bushes on the front arms of early S-type have to only absorb radial loads, that is that in normal suspension movement they simply pivot around a bolt and for the most part are only asked to absorb the vibrations and radial forces from the arm which they're fitted into. It's the same with the ARB bushes as they only locate a bar that rotates within them. For these applications I think polyurethane is just fine and in fact suit my requirements better than rubber. I don't like a car to shake me to bits just for the sake of it but I do like them to handle predictably. So although the rubber bushes that it had in the arms absorbed a lot of "chatter" and small bumps that the poly bushes don't they also allowed the suspension geometry to change in an instant which is not predictable and so created unpredictable handling especially over the fast, rough A and B roads around here. The poly bushes are much, much harder than the rubber which ensures that the arms are better located to prevent the geometry changes. For me the trade off was absolutely worth it although I'd be equally happy with the slightly softer poly bushes which are available, all suspension is a compromise.

On the other hand, in my experience, poly bushes which are designed to flex and hence deform as part of the normal movement of the suspension tend to permanently deform in use and end up unable to locate the components properly. A good example of this that I can give first hand knowledge of would be the front wishbones on most 80's VWs, in this case an A2 platform (Golf mk2 and Corrado). If you look at the picture below you can see that the front bush works like both the ones on early S-type arms as it simply rotates. The rear on however has to flex as its pivot is at 90 degrees to the arm, hence the voids in the rubber bush. In use I have found polyurethane rear bushes to permanently deform at the central hole allowing the bush, and so the arm, to move around the bolt that goes though it. This defeats the object of the bush as a location point and lets the caster and toe values vary wildly and uncontrollably. This obviously makes the car handle badly. For VWs with arms like this I fit solid rubber in the back and poly in the front.

This is only what I have concluded from modifying and tuning suspension on a fairly limited variety of cars. I may be wrong and I certainly don't know geometry or materials theory but I think my reasoning is sound.

I didn't fit poly bushes to the rear lower arms of my S-type because I think there is just no way they could have out performed the standard pillow-ball bushes, but that's for slightly different reasons, see my third post.

[Russ68]

You know you’re bushes Laz, thanks for the detailed explanation! 

I thought the £1k sounded expensive Tony, but that’s a lot of work and parts 

 

[Suppedraken]

4 hours ago, Lazlo Woodbine said:

I'll try to explain myself.

Which you did brilliantly.

[Russ68]

Just checked my records, I Paid £136 per side for the lower rear arms, with bushes, good ones though from Berkshire Jag Spares, this in £326.40 in the VAT, ouch! At the time it was easier to get the MOT garage to do it than fitting them myself, so I agreed £100 for this. Making it, I think the most expensive job I've had on her to date...

[Mercury57]

Wow Laz,  I'd like to know how you have accumulated this amount of detail on the finer points of bushing. Sounds like a lifetimes' work. Just a shame I can't find anyone out there with the same degree of knowledge when I need stuff replacing. Great read though.

I'll start a new thread about the mirror. Thanks.

Russ 68,  With regards to the costs, yeah I suppose if you do some digging and have faith you might be able to save some £ by buying off t'internet but when someone else is going to fit the parts, I'd live in fear of the dreaded phonecall that it's the wrong part no. Then it's the hassle trying to sort it out whilst the car's on a ramp in bits. Mind you that's nothing compared to telling the wife that the car's not going to be fixed by the end of the day !

[Russ68]

I didn't buy off the internet for those BTW Tony, I went to Berkshire Jag Spares, who know their stuff and offer a quality product. I use them for nearly all mechanical and service items and they haven't let me down or sent a wrong part yet, long may that last! 

In this instance the price did ramp up, I had one completely shot and another questionable joint on the one side and decided to replace both arms. Costing the best part of £500 inc VAT and labour, ouch! But know what you mean, saving a few £ is nothing to being stuck without a car, or being supplied the wrong or a poor quality part!

Bet Laz did it much cheaper with his hands on approach, what did the lower arms add up to Laz?

[JOE-DOT-COM]

Hi Laz

in this picture

which bush is this

also it looks eccentric, how do you know where to position the bush, as I assume it could effect the geometry

cheers

Joe

[Mercury57]

Hi Russ,  I used Berkshire Jag for some cosmetic bits some time ago and they were very good. Always useful to know if someone has had good service somewhere.

[Lazlo Woodbine]

17 hours ago, JOE-DOT-COM said:

Hi Laz

in this picture

.....

which bush is this

also it looks eccentric, how do you know where to position the bush, as I assume it could effect the geometry

cheers

Joe

 

That's the front bush. Adjusting that end of the arm in the subframe changes the castor, the other end of the arm does camber.

Yes it is offset by quite a lot so putting it in wrong could push the geometry right out. Fortunately the hole goes closest to the arm-side of the register so it's not too difficult to get right. If you look back through the pictures you can see I used a pair of callipers to determine the narrowest part of the bush and marked up it and the register with a pen. It would have been nice if they'd had a mark moulded into them to be honest, I have seen that on other round but eccentric bushes.

I would assume these big bushes were made thicker on the inside edge to allow the wheels to move backwards ever so slightly to help absorb the jolts of hitting square edged bumps. You can certainly feel patches and missing bits of tarmac more with the new bushes.

On 10/24/2017 at 8:58 PM, Mercury57 said:

Wow Laz,  I'd like to know how you have accumulated this amount of detail on the finer points of bushing. Sounds like a lifetimes' work. Just a shame I can't find anyone out there with the same degree of knowledge when I need stuff replacing. Great read though.

I'll start a new thread about the mirror. Thanks.

Russ 68,  With regards to the costs, yeah I suppose if you do some digging and have faith you might be able to save some £ by buying off t'internet but when someone else is going to fit the parts, I'd live in fear of the dreaded phonecall that it's the wrong part no. Then it's the hassle trying to sort it out whilst the car's on a ramp in bits. Mind you that's nothing compared to telling the wife that the car's not going to be fixed by the end of the day !

Well as I say it's only my conclusions but thank you. I suppose I do have a bit of a suspension obsession generally. I've ridden off road on two wheels for most of my life which certainly make you appreciate traction!  Then as an adult I had some fast cars which didn't grip or handle well enough to use the power. Struggling to enjoy driving them fast I realised that I prefer corners to straights and haven't really tuned an engine in years but concentrate on suspension instead. Bushes and geometry tweaking is fairly cheap compared to dampers and springs or some of the more radical changes you can make and it's probably going to be as far as I go with the Jag. Russ has heard me whining on about wanting a set of Bilstein dampers for months now, but they're £600!  That's over half what my car's cost me with all the work I've done to it. One day maybe..

 

[Suppedraken]

9 hours ago, Lazlo Woodbine said:

Then as an adult I had some fast cars which didn't grip or handle well enough to use the power. Struggling to enjoy driving them fast I realised that I prefer corners to straights and haven't really tuned an engine in years but concentrate on suspension instead. Bushes and geometry tweaking is fairly cheap compared to dampers and springs or some of the more radical changes you can make and it's probably going to be as far as I go with the Jag.

Carroll Shelby explained: “There are two theories: build a real stiff chassis and have a brilliant guy do your suspension work, or you can take a flimsy chassis that bends so the wheels stay on the ground anyway. We just kept putting wider tires on it – there was nothing sophisticated about it. If it hadn’t been so flimsy, we’d never have made it work.”

[JOE-DOT-COM]

Hi  Laz

cheers for the reply

£600 for a set of Bilsteins in good value

A standard set of the adaptive CATS dampers, also made by Bilstein are £1200 for S-type R

what set you looking the B6 bilsteins

cheers

Joe

[Lazlo Woodbine]

On 10/26/2017 at 10:13 PM, Suppedraken said:

Carroll Shelby explained: “There are two theories: build a real stiff chassis and have a brilliant guy do your suspension work, or you can take a flimsy chassis that bends so the wheels stay on the ground anyway. We just kept putting wider tires on it – there was nothing sophisticated about it. If it hadn’t been so flimsy, we’d never have made it work.”

I like that. I bet Colin Chapman would've been disgusted!

 

Joe; No worries.

Yes it's the B6 I'd want. I'm sure they're much better value than cheap stuff but it's a lot of money regardless of what I got for it. Still, £1200 does make me feel a little better!