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Gigglepin extended rear arms


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Ive used jonny joints for several years now and with no pronblem they do make it a bit harsher as the bushing is not rubber but the ball is greese able and they dont where as much as rubber and give full travel they are good if your making up 3/4 point links as leaste they have bushing unlike heim joints if yo ubuy from currie then i wouldnt get the greese able bolts and dont get the joints with the thread attatched as they are imperial we ended cutting them all off and rewelding metric fine threads back on

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So, who has them and what are they like in action?

I'm not familiar with these "johnny joints" either - if anyone could enlighten me i'd be appreciative :)

Hi,

'Jonny joints' are an american joint first introduced by Currie Enterprises I believe, there used extensively on rock rigs etc. Have a look on some of the US rock crawling websites for them, great in dry (Moab) climates.

Cheers,

Andy

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Thanks for the info on the joints :)

So - anyone know how the extended arms themselves perform?

I wouldn't bother...

I had a look at some last time I was at Chris' (Exact Fabrication - were on a customers car) and wasn't really that impressed, you wouldn't gain anything over running Rose Jointed standard length rear arms IMHO (apart from slightly less axle movement/walk)... and with standard length arms you wouldn't have to modify the chassis.

Another option would be to run Disco 2 rear arms... I know Dan (DirtyDiesel) has used these on a few of his truck with good results - they have the benefit of the front bush being mounted longitudinally and aren't that expensive to buy.

But thats just my opinion....

Ian

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Thanks for the info on the joints :)

So - anyone know how the extended arms themselves perform?

Hi,

We have used these arms for over two years now with great results.

We use a 'Johnny joint' as rose style joints wear very fast and any movement (wear) in the joint is felt through the drive line as a 'knock'.

The other resean for using these joint is that they tend to keep mud and grit at bay far better than a standard rose style joint, and they react like a bush, rather than giving the hard 'feel of a joint.

The advantages of these arms are huge.

Firstly we do away with the rear radius arm mounting bracket on the chassis, thus removing the large obstruction that normally hangs in the way.

We then fit a 'Bolt-on' chassis bracket that is removable even with a side mounted fuel tank.

These brackets are supplied with all the correct tubing to be welded into the chasis thus strengthening the chassis.

The arms themselves are designed to take heavy impacts againist rocks etc... and due to there design will not fold-up or become weakened if damaged.

The fact the arms are longer stops the axle from 'walking forward' when under extreme articulation, this means the car is far more stable platform with which to work.

The fact that these joints do not hinder downward travel also means that articulation is a fast process that is not dependant on waiting for bushes to compress before stability is realised, this gives sure footed handling when driving at speed in hazardous conditions.

The final advantage of these arm is the way that the drive is now placed to the chassis.

All that use our arms always comment on the fact that they find the hill climbing ability of their car is improved, this because the arms are transfering the power in a flatter plain so that the axle is pushing rather than trying to drive 'up-under' the vehicle.

But once again, we believe that proof is in the pudding, we have never had an arm failure (Although one has been damaged) and arms are fitted to trucks that win..........Nuff said

Porny,

the vehicle you saw at Exact Fabrication belongs to Nick Langley, He raced using these early last year (Yes Chris has had is car that long :rolleyes: ) He won first time out (Scorp chall @ West Harptree) and kindly suggested that the arms helped.

The other event he took fastest time on the rock stage at 7 sisters before retiring (Personal matters), again he attributed the vehicles improved performance to the arms and rates them as the, and i quote

"The best money i have spent on this vehicle"

I hope that helps to unravel some the mystery surrounding these arms, and there use.

Jim :)

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Afternoon all :D

Jim

The cars been in for a long time as bespoke work tends to evolve as the clients design and requirements change, presently the car weighs in (on calibrated corner scales) at over 200kgs lighter than the "claimed" lightest truck from a specialist 4x4 garage, Anyway thanks for clearing up the mystery surrounding the arms Jim - very helpful :)

Chris

P.S Congrats on the baby spose now Kaz has two kids to look after ;)

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Porny,

the vehicle you saw at Exact Fabrication belongs to Nick Langley, He raced using these early last year (Yes Chris has had is car that long :rolleyes: ) He won first time out (Scorp chall @ West Harptree) and kindly suggested that the arms helped.

The other event he took fastest time on the rock stage at 7 sisters before retiring (Personal matters), again he attributed the vehicles improved performance to the arms and rates them as the, and i quote

"The best money i have spent on this vehicle"

I hope that helps to unravel some the mystery surrounding these arms, and there use.

Jim :)

Don't know whose car it was, but was towards the end of last year...

The gigglepin arms had been blasted to be re-coated, and in all honesty I wasn't that impressed with what I saw. Though I freely admit this was from a purely asthetical point of view... I'm not exactly qualified to state whats good and bad welding - might have just been a bad day though - probably still strong enough, and one of the arms was dented from what I remember. In all honesty the chassis brackets didn't look the best either.... but that's just my view.

The ideal is borrowed from what a lot of the US were doing, but in all honesty I doubt it actually gains that much... unless you start having silly amounts of suspension travel.

If axle walk is such a serious issue with a standard length arms, then LR would have changed the design... they spend millions/billions of pounds doing Design and Development work (not that I'd know.. I only work for Jaguar/Land Rover Development).

I know that standard arms are designed to work with standard suspension travel so a slightly different kettle of fish, but under climbing the suspension would be partly compressed, so working within the confides of a standard LR suspension set up... in this case if Land Rover felt the need for longer arms, they would have been used, or at least trialed... which to my knowledge they never have been.

It must be said that the work being carried out by Chris (including the cage) was spot on ... but that's neither here or there with regards to this thread.

Ian

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I have to agree with Mark there - the "Land Rover spend millions developing it so it must be the Best" argument is ridiculous. They hardly develop the cars for long term offroad usage. They have very different constraints to work to than people preapring vehicles for mainly offroad competition use, but why am i telling you this? - you used to work there so surely you already know :rolleyes:

I too work for Land Rover, at their design facility (maybe we know the same people?) and so can say with confidence that Land Rover does not produce components that are perfect - far from it - they build cars to make profit and comply with regulations, and as such these factors come a long way on the prioritories list before suitablility for use :)

Not meant to be taken as having a go at you Porny, I'm just surprised at your opinions

Lewis ;)

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So everything on a LR as it leaves the factory is the best it could ever be?

If the arm design works so well why was something different tried on the DiscoII?

For most applications, usually as a compromise, most stuff usually isn't that bad.... I'm not saying that it's perfect, but at the same time LR have to consider to all possible uses/markets and try and make a product that suits everybody.

As to why LR changed the design for Disco2, I really don't know... but it wasn't the only thing they changed. They also went for a watts linkage etc etc. But in all honesty, the Disco was always aimed at a more road biased market... hence why it also has ACE etc, and radius type arms front and rear, rather than a trailing arm with just one bush at either end.

But if the Defender design is so bad, they would have changed it... after all the design came from the RR which remained unchanged from the late 1960's to 1994/5... and then carried over into the Ninety and OneTen.

Ian

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No one was saying it's a bad design, just that it could be improved on. You seemed to be saying that it could not be improved on otherwise LR would have done it had.

I think LR carrying things over to 'new' models as as much to do with cost (re-tooling, etc) as anything else. If it works ok and it's cheap enough then they'll use it. Very litt;e was truely new on the first 90/110, it was mainly an amalgamation of the existing models, RR and SIII.

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Porny,

Landrover standard suspension only has 7 inches of travel.....

So you are quite correct that the arms used by Landrover are fine for this application.

However if you intend to use more travel than this then i would recommend perhaps a different approach, depending on your needs.

Jim :)

Ps: Chris, Baby and Kaz are well Thank you, I look forward to seeing Nick's truck soon, i'm sure that the fabrication as always, will be something talk about :)

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I think you're right there Jim - Having seen Chris's fab first hand I know who I would want glueing steel together for me - he is a TIG god, not a wannabe engineer by any stretch, not often you get that high a quality of finish these days :)

we've only dabbled with a bit of flex and found that slighty re-jigging the stock geometry worked ok, mind you we are only playing with ideas at the moment ;)

TwistedPetalatKims.JPG

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Re:-"The cars been in for a long time as bespoke work tends to evolve as the clients design and requirements change, presently the car weighs in (on calibrated corner scales) at over 200kgs lighter than the "claimed" lightest truck from a specialist 4x4 garage, Anyway thanks for clearing up the mystery surrounding the arms Jim - very helpful

Wow 200kgs lighter, what did you have to do to achieve that?

John

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Hope the "wow" was,nt sarcasm John :blink::huh: There has been ALOT of work put into above truck and YES you are right Jim over a good few months!!!

BUT as you all may know or not know i have had major probs over the last 8 months with staff and the quality of thier work ( with the excetion of DAN a real diamond),well i had to make a decsion what to do,wethere to turn out sub standard work like alot of other people or not employ anyone and do it all myself?????That has been one of the hardest things to do ever :unsure:

So now it is me and ONLY me that lays hands on a clients car purly so i can produce 100% 1st class work,so was does this mean well i can only work as fast as i can,for the last 12 months if i have had 5 days out of the workshop at the most, that means working EVERY day NOT 5 days per week,that includes working the weekends that my 3 year old daughter comes to stay and see me if any of you have kids you will know how much that it means to you when you get to spend time with them or in my case not spending time with them it kind of put the whole slaging each other off on here into perspective do you not think?

So if people want to throw B_LLS__T around about me then fine carry on just rember i know who you are,were you are and what goes around will certainly come around but i can honestly say i am giving it my best,and from the feedback i get from the people that understand and let me get on with thier jobs they love what i do.

With being so busy i havnt been on the forum,but the prob with that certain people put it around that i have gone bust and trying to cause hassle making things up when they dont know :o well i am afaid to say that simply is,nt going to happen as my name says in it NORTHERN i dont and will not go down with out a fight,Yes it is hard, Yes workin 24/7 and not taking a penny out of the place and still trying to enjoy it makes it even harder.There are always people going to try and knock me and that i am affaid is life.

Chris

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Sorry NorthernChris but SouthernChris is drifting back on-topic for a few minutes... ;)

I have been looking at the extended arms on Jim's website and at the Johnny joints in particular - and at the pics on my link above of the joint in pieces. I have a question; How much rotational movement is there in these joints? What I mean is, obviously they are able to rotate right round to allow the axle to drop but what about when the axle articulates? I guess that these joints have to allow for that rotational movement in much the same way as the A-frame ball joint? Is there sufficient rotation in there to allow for this?

Chris

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I'm sure Jim, Paul and other people using longer arms have done the same calculation, but I thought I would plot the locus of the movement of the axle over a range of compression & droop. The triangle is a rough representation of the diff with the point being the centre of rotation of the prop UJ.

Traditionally, the reason (I thought) for longer arms was to reduce the flex in the chassis bush for a given axle droop. This is obviously not a requirement if one is using jonny (or similar) joints which do not have this restriction. So, I wondered if it improved the angles on the A frame ball joint or the misalignment of the prop shaft or even the spring hangers.

Without any bias, here is what I found:

AxleLocus.jpg

I didn't know which way it would go - it's hard to visualise in ones mind - even for me!

Anyway, it seems that increasing the length of the arms actually increases the misalignment on the prop, spring hangers and A frame ball joint. The longer the arm,the worse it gets.

On the diagram, the red image is a rise of 10 degrees on the A frame, Black is normal running for 2" lift, Blue is about the limit of travel for most 90's and green is a droop of 30 degrees on the A frame - which is more in either case than any A frame ball joint will give.

It seems that in this case, Land Rover have done their homework - the angles change surprisingly little. I was surprised anyway.

Longer arms may, if anything decrease articulation!

On the plus side, as Jim says, the new hangers do not hang down as far and this may more than compensate for the angles.

If anyone wants a copy of the original drawing - it is open to scrutiny. Just mail me and I'll send a copy (tell me the preferred format too!)

Si

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Eerrrrrrr??

And?

How much articluation are you after....?

Any more than we currently use is pointless, we want good axle movement not large droop.

However, we also agree with the you about the rlationship between the radius arms and the 'A' frame which is why our new trucks use longer 'A' frames to compenstate for this :D

On a recent visit to Paul Wightmans place we played with his new rolling chassis where it is quite clear what you explain above.

However the bueaty of our arms is that being adjustable you can raise the differental pinion hieght to compensate for this when using the standard 'A' frame, and due to the fact that most vehicles will only at best have 11' of square downward travel this rules out any of the problems forseen by the calculation.

Most also are restricted by the 'a'frame ball joint that also only allows limited downward travel

Nice to see it on the screen, we had already taken this into consideration some three years ago when first we looked into posibility of this solution, and nice to see that we were right.

Thank God for 30 degree propshafts...... :lol:

Longer 'A' frames will soon be available from oursleves mid feb :) (Not a sales pitch, just fact)

Thank you Simon for the diagrams, very pretty and imformative :)

Kind regards

Jim :)

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