Thread: Longer rear trailing arms on a defender.

I stole this from LR4x4 forum: the attachment was from the same post and ought to be read with the text below. Brings confusion and clarity to my dilemma.

"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!"

And the response from Gigglepin

"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

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......

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

The rest of the post is here: Gigglepin extended rear arms - International Forum - LR4x4 - The Land Rover Forum

The characters got a little heated but it's an interesting read.

MLD

That increased misalignment is what I was talking about earlier.

What the modelling doesnt include though is the pinion realignment when you do the long arms because the ride height is 3" different to standard so the end result wont be as severe as that.

I'm going enliven this post. Fast forward 2 years and i'm still in the same position and back in the market for a solution (I'm still eating Superpro bushes). I was out with a truck with the TF johnny jointed arms on the weekend and much of what i expressed below was visually evident in the angles of the trailing arm. To my mind the arm is way past providing any resistance to axle walk and must be contributing to upward drive to the chassis unloading the suspension. Having said that, short of going all custom there is still no easy solution for a longer arm in a 130.

IMG_2110 - Version 2.jpg

Would my thinking be correct: if locked in the rear at full drop the effect of axle walk is minimised because the passenger rear wheel can't advance relative to the drivers rear wheel (noting that the torque vectors hit the passenger rear more so than the driver's rear by the direction of rotation of the driveline). What i described doesn't address the upward forces. Just trying to work out which evil is the lesser (the compromise).

2 years down the track, any feedback on the Superior Engineering trailing arms. Anyone using them?

@MLD

Ill throw my 2 cents in ... a word of caution = my username.

Im not quite sure what you are getting at in your last post. But there is NOTING positive about that pic or what you describe, the 2 evils are just evil.

I had a quick read through of the link to the LR4x4 forum.... head shaking... I do wonder how the poms of all people are the most behind when it comes to LR sometimes.

The comment was made that long arms came about to address bush wear. What a load of BS!!! Long arms came from the comp scene, and cant say for sure but probably originated in the USA for a few reasons. Not talking LR here just 4x4 in general.

Bush wear comes from a few things. Geometry, bush design and job requirement. All in all the LR set up isnt too bad stock for a stock vehicle as a compromise for a working rig - road and offroad.

Thats where it ends. Lift it, bush wear increases, work it hard off road at full or extended flex, bush wear increases.

The main reasons for long arm is to reduce anti-squat (smoothly transmit forward acceleration forces rather than walk under and jack up) and to reduce axle roll axis - axle oversteer/understeer.

The relationship between the uppers/A frame and lowers is set as not equal length so during droop, as anti-squat rises, the rate at which it rises lowers. It still rises, but less so as the uppers and lowers swing different arcs and become more parallel to each other. LR got this right at approx 75% of the lower length. Pinion change is handled by the uni joint.

Yes it would be desirable to increase the length of the Aframe the same % as the long arm lowers.... but thats another fab-tastic job to resolve. Long arms can and have been made to work with the stock A frame. Yes the pinion angle change through bump/droop will increase and youd have to look at the operating angle of the ball joint at A frame....but can be done.

As for the superior arms, it sounds and seems like they are a really good HD stock replacment arm. The other option if not changing the length is to get a HD arm that is pre bent, so the chassis bush isnt half bound at ride height.

This thread got a bit derailled by me:

Superior Engineering Trailing Arms

would have liked to hear more of ricks thoughts....

Thanks Uninformed.

I recently replaced the A frame joint (worn) with a Maxi extended wide angle A frame joint and OEM chassis upper bushes. The extended A frame joint ought to correct in a small way the exaggeration of relative difference between upper A frame and lower trailing arm on long travel suspension.

I found that post after i raised this post. It did take a left turn quite quickly. Still an interesting read.

In an ideal world i'd like to see a long arm kit that retains the bush design of the defender but rotated to align with trailing arm pin. A johnny joint or rose joint will be harsh for ordinary road use. I suspect fabricating a chassis mount to accommodate the LR bush design will be challenging when you take the outrigger location into account.