Hi all,

I've just fitted the polybushes into my wishbones and unlike what seems to be the norm, mine didn't require the usual massive effort to fit. Now, I'm no Swartzennegger, but I managed to push them in by hand, quite hard but do-able. As for the steel anti crush bushes I have had to employ a G clamp to press those in ( I have as couple which actually slide in quite easily..no play though)
Is the megga tightness an issue? or do you think my reasonable interference fit will be ok (0.2- 0.3mm diference between bush od and wishbone id)

I suspect once everything is bolted together, it will be solid, but your comments would be appreciated.

Thanks

Dave

Hi Dave,

Have you silicon lubed the inserts and bushes? They will need this to move freely.

Kind regards,

Darren

Hi Darren, Thanks for the reply

Yes, although I have used copper grease.

I'm still wondering if my bushes are tight enough. I think to achieve the sort of press in fit that seems to be the norm, the difference between the poly bush od and the wish bone id has to be around 0.5mm (in engineering terms thats hell of a lot)mine are 0.2-0.3mm. Of course the tighter the fit the more the bush bore is reduced ( squeezed in) making the steel liner incredibly tight to fit.

Anyone like to comment on this observation?
Is it really necessary to have them vice tight?.

Maybe making an oversize bush and pressing that in would achieve the same effect should your bushes be too easy a fit.

Many thanks.

Dave

Hi m8

I had a similar problem last year (search thread if you want) where my crush tubes were too tight inside the poly. This meant my suspension didn't want to move when everything tightened up. I got hold of a 16mm reemer as my crush tubes were 15.98mm OD and this cured the problem.
I would say your bore on poly bushes is incorrect, or bushes are incorrect. You cant leave it like that.
Hope this helps.

Thanks Hornet, that is a help. Glad to know I'm not alone on this. I'll check the free movement once everything is bolted up and take it from there.

All the best

Dave.

almost answered my problem, what size bolt are you using with your bushes? have measured up the steel tubes and they have a i.d. of just under 13.75mm. I can't get hold of 13mm bolts and was wondering if you just drill em out to 14mm.

cheers

I am using 12mm bolts as my crush tube has 12.5mm bore (made on lathe) however, in my opinion, once you tighten the bolts onto the crush tube, you would not have a problem with 12mm bolts. What size of hole do you have in your brackets? this is more important.

Hornets spot on, you must consider the holes in your brackets. It's quite a size jump , make sure you don't weaken the brackets (no doubt there is plenty of meat to spare)
Another thing, if you open up everything to 14mm and don't leave sufficient clearance for the bolt, then unless you've been super accurate with your brackets, you may find you have fun and games lining everything up.

Been there , done it etc

Just a thought

All the best

Dave

addition to the above:

The above is only relevent of course if you up the bolt size to 14mm.

I'm using 12mm bolts with 12.3mm tube id

If it was me, I think I would look to replace the crush tubes if you can't use 14mm bolts, there is alot of movement potential in 1.75mm clearance should anything become loose.

Cheers

Dave.

Hi Dave

Your bush should be a tight fit in your wishbones otherwise they will turn in the w/b instead of turning on the crush tube. I made my w/b's in stainless and used 25mm o/d bushes. Bored the bush tubes to 25 which shrank when I welded them (.05mm). Fitted them with the aid of the vice. This as you say shrinks the i/d of the bush, which I then reamed on the lathe to ensure perfect alignment with each other. When fitted to the chassis they just need light pressure (one hand) to move them.
The crush tube i/d / bolt size isn't an issue IMHO as when the bolt is tightened nothing can move except the bush on the crush tube.

Paul G

Poly bushes don't compress when you fit them into the bush tubes, the rubber Triumph ones do. You could loctite them into the bush tubes if you are worried about them turning there instead of on the crush tube.

yours, Pete.

bit of a puzzle that as the crush tube's are the one's supplied by mk. As to the size of the brackets the current holes are 12mm, so I think I will be making some new crush tubes, are they just mild steel?

Cheers guys
chris

[Edited on 7/1/04 by flyingkiwi]

Most are mild steel m8, but if you can get something better then go for it, for example a ground finish would be best.. it is after all a bearing surface you are gona create. for what its worth, mine are mild steel and polished .

Cheers.

how far out of the ends of the bush do the crush tubes protrude? anyone got any pics, i think my crush tubes may be a bit short when inserted.

Col.. mine stick out by 0.5mm each end.

Thanks paul G your info was very helpful.

My crush bushes are harder to push in, but the poly bushes seem to be turning on them rather than the wishbone tube. I have applied some copper grease to stop the creaking.

Chris, my tubes are mild steel and polished on the od.

Setting the lathe speed to 750+rpm and having the feed rate as fine as possible, that together with a good tool (preferably carbide tip as you will not need coolant)
Should give you a decent enough finish.
If you want to make them really smooth, give em a light rub over with worn emery with the lathe rpm at 1000+ negligable material will be removed.

Col
My steel bushes are a combination of sticking out about 0.1mm or flush with the outer face of the poly bushes.
I figure that should there be a slight compression of the poly bush faces when bolting down hard onto the crush bushes, then this wouldn't be a bad thing (I'll probably change my mind later when everything locks up solid)

Thanks all for the replies, certainly helps to keep the old stress levels to a minimum.

All the best Dave.

Yes good info in this thread, helps you get the basics right so you cancentrate on the more "interesting" bits of the build, i will mesure mine tonight but i think they may be recesses into the bush a bit.

they are not my own fabricated bones and the bushes were already in when i got them. if the tube is not protruding i guess its eithr because the bush was not pushed home fully or the tube on the end of the bone that the bush slides into it slightly too long to alow both halves of the bush to meet in the middle.

Anyone any advice on removing bushes without destroying them? and advice on how to identify what bushes i need to replace it with if it is destroyed as i have no idea where they came from.

Hi Col

There is about a 8mm gap between my bushes when pressed in. I managed to tap mine out from the centre by using a piece of plastic rod with the end slightly radiused (is that a word??) so as to not damage the bushes. By tapping evenly from side to side, mine came out ok. The bushes are quite forgiving.
Fortunately I have access to a lathe so I was able to modify the polybushes by turning a small amount off the inside face of the bush flange thus allowing my crush tubes to protrude.
If you dont have a lathe and lets face it not many of us do, then how about finding some steel washers that will sit just inside the poly bush bore to take up the gap and drill them out to suit your bolts. This will allow your crush tubes to be clamped solid against the washer/s, you probably would only need one on one side. This would also eliminate the need to take out your bushes.

I also applaud the good folks out there who take the trouble to explain some pretty basic stuff, but to us new to this game, its the " almost too embarrassed to ask" topics that cause us the most grief.

Anyway hope this helps.

Thanks again guys.


Dave

Cheers Dave,

I will have a closer look at mine and see how they go together and think it may be the washer option as i dont have access to a lathe

Having had a closer examination of the BLACK bushes that are in my wishbones that have 4.25 moulded on to the widest part of the bush (the bit that stops it going all the way into the tube)

Anyone any idea what that is? possibly a rating for hardness/softness?

Hi col

Not really sure on that one, but the thickness of the poly bush shoulders on mine is approx 4.2mm, could the figure thats moulded into yours possibly be the thickness ? My bushes don't have any numbers on them.

perhaps give the supplier a bell and see if they can shed some light on it.

Cheers

Dave

Thats half the problem, i cant find any contact details for Triton

I bought the chassis second hand complete with wishbones etc.

still puzzled as to why my crush tubes have such a large i.d. Has anyone out there got a crush tube from mk loafing about and wouldn't mind checking the dimensions for me

It's not easy finding 1m or so of steel tubing around Yeovil, anyone got any suppliers they know off?

Cheers
Chris

Hi Col.

This might seem daft but ask Darren @ GTS Tuning, if you get my drift (Pardon the Pun)!!

Cheers. Ken.

Cheers Ken, will do that.

I wasn't going to bother posting on this thread, as the topic has been covered in great depth on previous occasions, but certain inaccuracies in this thread couldn't be ignored.
The crush tube lengths should be the exact internal width of the suspension bracket on the chassis.
The total assembled length of the PU bushes should be 0.5 mm longer than the crush tube.
Yes, I know that makes them wider than the bracket internal width and makes them hard to mount to the chassis, but it's the correct way of loading the PU bushes. The PU bushes require a degree of loading in all contact areas.
Don't use WD40, Coppaslip or just any old grease to lubricate PU, use Molybdenum Disulphide grease, or silicone grease as second best.
Try searching for the other PU bush thread(s).

BTW, stainless steel is the best material for crush tubes, as there is absolutely no way it will rust and become adjoined to the bolt. Don't be conned by pretty-looking plated mild steel crushtubes. The plating will get worn off by the moving PU within a few miles and will rust, even in that greasy environment.

Rorty me old Chicken, that has thrown a right spanner in the works, im sure im not the only one but i am well confused now.

Questions! :

A) Should the wishbone and bush be one complete unit, i.e the bush will not turn in the wishbone tube, meaning that the crush tube is held fast between the mounting brackets and the bush and wishbone will rotate about the crush tube?

B)If so how come the ends of the bush do not bind on the insides of the mounting brackets as they will be hard up againt them in order to squash them in enough for the crush tube to be flush.

Regards
One confused suspension assembler!

Now this is interesting.

I mounted my wishbones at the weekend.
My crush bushes are either flush or slightly less in length than the polybushes.
On the rear (IRS) suspension they are a tight fit in the welded brackets, needing a decent push to get them in. When alls bolted up the suspension is very tight, so all is correct.

The front suspension is a different kettle of fish. The welded brackets are much wider than the poly bush/ wishbone assembly by almost a centimetre.

Luego instructions are to use spacers to the internal front and rear faces of the bracket to take up the gap.
My guess is that they have done this to allow precise alignment of the front suspension wishbones and adjustment of the upper and lower wishbone offset to the correct castor angle. ( I know this is supposed to be fixed with the position of the welded brackets, but mine are way out)
I have emailed Luego about this and hope to get an answer soon.

A couple of comments on Rorty's observations, and many thanks for taking the trouble to join our debate.

Having the poly bushes slightly wider than the mating brackets wouldn't cause everything to lock up because unless your bushes are made of acetal, then polyethelene is quite soft and will compress sufficiently. Mine did not lock up and although very stiff, everything rotates as it should.

My understanding is by reading various other posts on this subject, that we should be locking down on the crush tubes. You want the largest bearing surface for the wishbones to rotate on, logically the crush tube od to polybush id.
If you didn't bolt the crush tube hard to the bracket, then the tube and bolt would rotate around the bracket bolt holes. This to my mind would be the worst possible outcome and very poor engineering.
Curiously, Luego suggest backing off the bolts until they just turn, I have asked them about this as it seems to contradict the general consensus of opinion. I have read somewhere however that the final tightening of the wishbones should happen when the car is on its wheels.maybe this is what they are alluding to.
I have again asked them the question.

I'll let you know what they say Col when they reply to me.


The grease has two functions:

1) Help with assembly
2)Stop the creaking of the suspension which would eventually drive you mad.

Plastics are widely used for bearings and bushes etc in all sorts of fields where using lubrication would be a problem.

Rorty's correct about the stainless steel. In an ideal world I think we would like everything to be stainless, however sadly I will have to make do with copious amounts of grease around my bolts and hope the sun always shines

Aplogies about the length of this post, I guess too much info is better than none, just pick out the bits that make sense.

Cheers

Dave.

Very informative Dave, well worth the time to read it all.

I guess i will have to take a propper look at mine again and make some notes - take some measurements and see how things add up.

thanks again - i may be back for more info.

You're welcome

Cheers

Dave

yip, this post has sorted out my problems, just fitted the wishbones to the car and went on a treat.

Double checked the messurements of the crush tube and the richard cranium at the shop must have buggered up as a 12mm bolt fitted perfectly.

Now just to buy the shocks! thats if teh missus will let me

cheers for everyone's help!
chris

quote:

---

Originally posted by Rorty

The total assembled length of the PU bushes should be 0.5 mm longer than the crush tube.

---

I disagree with that. Surely the crush tube must be longer. Otherwise when you bolt everything up, you would be locking the suspension in a set position.
The poly bushes need to rotate on the crush tube and also for lateral movement.. move on the bracket sides.

If I'm wrong.. then I'm wrong... but my crush tubes are staying longer

Hi Hornet,

If you haven't got any sideways movement when everythings up an bolted, then I wouldn't worry too much.
Like I said in my tome above, mine are flush or slightly below the poly bushes. Its all nice and tight with everything swivelling where it should.

So thats all right then.

This really has opened a can of worms.

Cheers

Dave.

excuse my ignorance, but what is the material used to make the poly bushes, so I can order the correct grade of material

Chris

Hi Chris,

They are made of polyurethane.

You might find this informative:

http://www.superflex.co.uk/

Cheers

Dave

I must say that what Hornet is saying seems FAR more logical...

If the bearing surface is between the crush tube and the bush, with the crush tube effectively locked in position and the bush not rotating within the wishbone, then surely the last thing you want is to lock the bush against the suspension mount.....

Or maybe I'm missing something as usual?

Dave

I agree, it kind of goes against my logic to do it the "correct" way.

from a previous big argument between rorty and syd, I remember the following.

The bushes and crush tubes DONT ROTATE AT ALL.

The idea is that the 'rotation' is actually compliance within the bush. Its the bush that 'rotates' by distorting.

the crush tube stays put as does the outer circumference of the poly bush. rotational movement is within the bush material itself.

syds counter argument is that the bush rotates on the crush tube.

you are supposed to tighten the bolts that hold the crush tube at normal ride height. this allows a degree of 'bush flex' in the bump and rebound positions.

f you look at old style bonded rubber bushes, the crush tube and bush outer are all bonded - there is no rotational movement. All movement occurs in the rubber itself distorting.

atb

steve

ps - i have rod ends

Stick ur rod end up ur ass!

I have rod ends on the outer end of the rear bones but bushes at the inner end.

I can agree with this theory as the trailing arms on my F27 have the rubber bushes with the metal outer thet are presses into the tube and the crush tube is locked up tight too so the flex is in the bush its self

Oh bleep it i shall bang it all together and see what happens!

[Edited on 13/1/04 by colmaccoll]

Poly bushes rotate around the crush tube.

Rubber bushes dont rotate, they distort as gusters said.

Thats all I'm saying, cos anything beyond that and I've no idea!

I think the concern is that the bolt and crush tube are not meant to be pivot surfaces, but apart from that I cant see any disasters - but im only relaying what I heard, not what I experienced.

Apart from when you take production car suspension apart, it never flops, and seems to stay 'elastically' in place held by the bushes.

Thik I will leave my rod ends where they are thanks

atb

steve

[Edited on 13/1/04 by stephen_gusterson]

I used spherical bearings(rose type joints)on the axle end of my trailing arms and poly bushes on the chassis end. The bracket locks onto the crush tube to hold it in place so the bush rotates on it. My bushes were flush with my crush tubes and they work o.k. so that's the method I'm using next time on all the suspension.

yours, Pete.

i have just downloaded and printed the Pdf file on GTS website for the 36 piece polybush set.

http://www.cougarracing.fsnet.co.uk/polybush.pdf


Im having trouble working a few things out, it says all dimensions are in mm unless stated, the tube side required is 1.25 (i guess thats inches) is that ID or OD?

It also doesnt give any info on the OD of the part of the bush that goes into the tube.


Am i missing something on the drawing?

Also can anyone confirm the thickness of 18swg?

18 swg is 1.2mm thick, but there is a bit of doubt in that!

Nope it is 1.2mm, or so Mr Zues Table tells me

[Edited on 14/1/04 by flyingkiwi]

Appologies for not rejoining earlier to answer the questions directed at me.
PU (poly ) bushes are made from polyurethane, and come in various degrees of hardness (shore) 70 being the typical grade for wishbone bushes.
The crush tube must be a tight fit in the chassis bracket, and the assembled PU bushes must be a fraction longer than the crush tube. The PU has a certain degree of compliance, and will squash into the bracket and still rotate in use. They will appear really tight when you try to wiggle the fitted wishbone up and down though.
The crush tube must be tightly gripped in the chassis bracket and must not rotate on the bolt.
The PU bushes are pressed dry into the wishbone, where they should remain...motionless!
The bores and outer faces of the PU bushes should be greased with Molybdenum Disulphide grease (usually pencil-lead-black, but Redline do a red version). Do not use Copaslip or any ordinary grease.
The PU bushes are designed to rotate on the outer surface of the crush tube, and against the inner faces of the chassis bracket, and do not have sufficient compliance to distort with suspension movement. The earlier rubber/metal "Metalastic" bushes were designed to work in that fashion....you just tightened up the bolt through the centre, and the rubber squished around, thereby affording the wishbone some up-and-down movement.

If you were to use acetal (self lubricating, hard wearing plastic) for the bushes, then they would have to be an exact fit in all respects, as acetal has zero give

Gusters, it's not like you to get the wrong end of the stick and mis-quote people! You totally cocked up that one!

Hornet, if your PU bushes aren't longer than the crush tubes, there won't be any preload on the bushes,and they'll move backwards and forwards under normal motoring, and will give the impression of sloppy suspension, even though they may seem tight in their brackets.

Rorty, your argument sounds the best yet to me, tell me, my wishbones tubes have been made from a different batch of tube from my trailing arms, the crush tubes slide easily into my trailing arms with no play but really have to be pressed into the wishbones, which is correct, should I ream out the bushes once fitted into the wishbones to let the crush tubes slide

thanks

[Edited on 25/7/04 by planetester]

I would suggest you don't ream out the bushes, just press them in using a vice, G clamp or similar (besides, even the sharpest of reamers tends to chew the poly rather than cut it). use a smear of vacuum grease on the bushes etc or they will creak when in use. The bushes do need to be tight.
Hope this helps.

Dave

quote:

---

Originally posted by Syd Bridge
And you can still use Y419's rotating on a greased bolt. ie. Not tightened to compress the inner metal tube. No different to a metal/metal rodend. SVA man I spoke to said he would prefer to see this than 'metallastic' type installations. Fewer stresses in the wishbones and no torsional/rotational forces and stresses in the chassis/bush brackets.

Oh, and by the way, he is a chartered engineer as well!

Take your choice.

Syd Bridge.
C.Eng., M.I.Mech. Eng., MRINA, SNAME, dah dah dah.......

---

I would agree with Syd on that, there are bushes and bushes and all the poly bushes Ive seen from Locost parts suppliers have practically zero flex, so the crush tube must be longer than the assembled bush.
To clamp up onto the assembled bush and not the crush tube would be a recipe for disaster, with all the load going into the thin walled chassis tube or wishbone whichever gave way first.
Metalastic and flexible PU bushes fair enough use the flex in the PU,but even so with such thin walled tubing even then I'd think twice,it would be interesting to know what type of bush earlier threads with bent wishbones used.
Cheers,
Bob

My concern with the loose tube is that the grease would likely work out through the gaps between crush tubes and brackets, while road dirt could enter the joints.

[Edited for gratuitous flippancy]

[Edited on 30/7/04 by pbura]

as a kid I had a soapbox cart that used a single bolt as the main steering axis.

It was fine.

The biggest problem was the 'mechanical backlash' in the rope that formed the steering system.

In the 2 -3 miles of so it covered in its lifetime there was no problem with the bolt.

atb

steve




ps - which goes to show that APPLICATIONS count. What might be OK in one case, may not be in another.

[Edited on 29/7/04 by stephen_gusterson]

All my front suspension and inboard shock rockers on bronze oiltite bushings on ground shoulder bolts. Just have to make shure that the brackets are a perfect fit--make the arms up and attatch the brackets to the arms and then weld the brackets to the frame and they line up nicely.
Very cheap and easily replaced when they where out.

Dale

Syd, I can only disagree with you.

I challenge you to show me some industrial machines that use a small bearing surface, steel-on-steel interface with the sort of cyclical loading we're putting on a suspension joint.

Your conecting rod analogy is amusing -- even given its much larger bearing surface -- try running your engine without the lovely film of high pressure lubricant for a few minutes and see what happens.

The joint interface in our case has two substantial stress raisers when installed with the bolt not properly tightened. The pivot points become the holes in the tabs - the bearing surface of each pivot is roughly 1/8 of a square inch, which gets less with wear or if, god forbid, you're pivoting on the threads. Any lubricant present will be forced out immediately, because of the joint's tiny bearing surface, and the bolt will gall on the holes in the tabs.

One of two things will occur, the bolt will saw its way through the mild steel mounting tab or the scarred alloy-steel bolt will shear off in a fatigue failure.

Seems a huge risk to expose yourself to when the alternative is to install the same components "as designed".

Cheers, Ted

Why not weld a nut to one side of the bracket.Run a correct part treathed bolt through the polybushes and lock the bolt with a counter nut against the welded nut.No more crush tube to worry about-no more metal on metal rubbing.

quote:

---

Originally posted by Cita
Why not weld a nut to one side of the bracket.Run a correct part treathed bolt through the polybushes and lock the bolt with a counter nut against the welded nut.No more crush tube to worry about-no more metal on metal rubbing.

---

I only wanted a yes or no,my experience is that you dont let the metal to metal work unless you put grease nipples to force lubrication in, you wont remember morris 1000 front pivots falling off thro lack of it, any way, I think the crush tube should be locked solid in the chassis bracket & the poly bush should rotate on it, I just want someone with experience to tell me how easily it should rotate, at the moment I have pressed the crush tubes in with grease & when mounted to the chassis they are very stiff

thanks all

quote:

---

Originally posted by Dale
All my front suspension and inboard shock rockers on bronze oiltite bushings on ground shoulder bolts. Just have to make shure that the brackets are a perfect fit--make the arms up and attatch the brackets to the arms and then weld the brackets to the frame and they line up nicely.
Very cheap and easily replaced when they where out.

Dale

---

Ted,if you use a reamer to get the perfect fit for the bold and it is tightened with the locknut how could that bold be fretting?
I dont know if a loose bold is worse than a bolt which is used as a spring as would be the case with the welded nut and a to large bracket hole on the bolt head side.That "fretting" bolt will snap all of a sudden while a loose bolt wil start to rattle and shake more than enough to warn you.
All IMHO offcourse.

Cita: The bolt as captured by the welded in nut arragement you mentioned would have no troubles at the nut-end, at the head-end it's still free to rub on the bracket -- worst case, the head might break away and you'd still be left with a stud.

Your idea is far more workable and (in the unlikely occurence that it did fail) fails more gracefully and safely than Syd's loose bolt.

Syd: I am eternally grateful that I am separated by an entire ocean from you and any vehicles you can touch or otherwise bodge.

Everybody Else: The plastic bushed joint with a crush tube works, and works well, as designed. Any problems experienced will go down to ill fitting or improperly installed parts. If they don't fit properly send them back for replacement or dress them to size with a file or reamer -- re-engineering a part to solve a fitment issue is silly.

-Assemble with Moly grease.
-The crush tube should fit tightly between the brackets and be locked in place by the bolt & nut.
-The ID of the crush tube and the holes in the brackets should be a tight fit on the bolt.
-The bolt's shank should be unthreaded where it passes through the crush tube and chassis brackets. You should have a flat washer at the outside of each end and use a Nylock or other self locking nut.
-The bushes should be a tight fit in the suspension arm and should swivel freely about the crush tube with no slop.
-If you "preload" the bushes as Rorty suggests (the thrust surface "brims" of the tophats being slightly too big to be a slip fit between the mounting brackets so that they are compressed a little bit during installation) make certain that once assembled the joint swivels freely (light hand pressure) about the crush tube.

Once fitted they should be entirely trouble free. I would check the bolts for tightness and perhaps disassemble and regrease occasionally.

Cheers, Ted

[Edited on 30/7/04 by andkilde]

Thanks for the explanation Ted and as far as i understand it now:by tightening up the crushtube inbetween the bracket you prevent the bolt from any movement at all,am i correct?
So if we could develop a method of keeping that bolt from any movement we would not need a crushtube?
Forgive me my ignorance but i'm willing to learn.

all gather in the playground lads, looks like we are gonna have fight.

I will look out for teacher



atb

steve
Rescued attachment mud.gif

No crush tube would be nessesary if you use an apropriate shoulderbolt with a thrust washer at each side of the bushing. Although a locking mechanism to keep the bolt from turning under stress would help as well (flat edged washer with a placement pin maybe)
Dale

yeah

I nearly mentioned (on the oceans apart thing) that you had a boat



atb

steve

great. we all agree on so much! all anyone disagrees on is whether the crush tube should be slightly shorter, longer or the same as the bush! by less than a mm either way! and even that wasnt a clear cut disagreement, cos rorty never said it should be tight enough to lock up...

if you follow most of the advice on here, you cant go much wrong really. i think this one has been hammered to a conclusion...

Until next time?


Grim avatar

Ted you have my support. Syd is barking up the wrong tree. Sure there are metal on metal soints in all sorts of industries but they are all exactly toleranced and made from suitable material. A metalastic bush has only got a bit of ERW tube up the inside of it and at best would be a loose fit on a bolt.
Syd argues a bolt is a shaft. Well unless it is a aircraft (such as AN) quallity it will not even be round. Again unless the bolt is AN it will probably have threads exposed inside the assembly which everyone knows is a disaster waiting to happen.
I spoke to a class 1 scrutineer (just below F1 standard) and described Syds theory. He laughed and asked if Syd was still at school.

quote:

---

Originally posted by Syd Bridge


Just to ponder the problem further, What is the difference between a ground,(or precision) bolt, fixed from rotation, with the tube rotating on it; and a 'crush' tube with the poly bush rotating on it; and a metal-metal rodend. All used in the same application, say on a racecar.???? Answers of more than three words fail to grasp the basic engineering principles.

[Edited on 6/8/04 by Syd Bridge]

---