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Citroen Specials Club

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Modified Front Arms, Advice needed

I recently had my front arms modified by Phil Gregory (Pemberton) and had them fitted along with new King Pins by a 2CV specialist. This mod improves the steering, making it much lighter. The problem that I have is that the steering is now very stiff.The steering stays on the lock and will only return when I straighten the steering wheel.With everything disconnected and jacked up, the rack is free, and the king pins seem free, connect everthing up as normal and holding the front wheel, I have great difficulty in moving from lock to lock. Phil thinks the problem is in the K Pins. I would like to know if any other member has experienced this problem, or any remedies to cure it. thanks, Ian

Membership No. 1805

Re: Modified Front Arms, Advice needed

The pembleton runs at a given chassis height to put the king pins in the same caster angle as the 2cv was originally...to give the one finger steering feel...
If yours is different, might that show up as harder steering ?
sump drain plug to ground=127mm [5" in old money]
[rear chassis member 240mm-but thats a pembleton chassis...]
I find it much easier to cut a piece of wood to that length...if it fits its good, if not its either 2 high or 2 low... saves struggling, torch in mouth and tape in the hands...
as soon as you "grumble" the torch falls out !!!
Give the king pins a really good greasing both up on a jack and if someone can turn the wheel to give full coverage -all the better....

Re: Modified Front Arms, Advice needed

Thanks David, Phil G told me that the arms on the Pembleton are virtually parallel to the ground, mine slope downwards, other Lomaxes have had this conversion done, how are the arms on those ? Next job check the ride height, I did'nt know where to take the measurement from, so thanks for that.

Membership No. 1805

Re: Modified Front Arms, Advice needed

Reducing the caster angle should make the steering less self centring and not more so. I have driven brand new 2CVs (one as recently as February of this year)and whilst the steering is not heavy for a non-power assisted set up, it has never been one finger light.

I would agree with Phil that there is some problem with the kingpins. If he had increased the caster angle then you would get an extreme self centre effect that would make the steering feel stiff. The only way that could happen is some sort of major mistake when putting the arms in the jig. Unlikely as Phil has done many successful mods of this type. If it had happened then the kingpin would be more laid back than a standard one. The aim with this mod is to get it more vertical.

Is he offering to have a look and sort it out?

Re: Modified Front Arms, Advice needed

A pembleton only weighs around 320kg-at least the one I built did.with 4 spoked wheels and adaptors included.
They really are fingerlight to steer.they don't need anti roll bars as- yes the arms are almost horizontal.
2cv Ride height does affect caster angle which is why unmodified lomax are heavy to steer- but easy on the straight.-also a 3 point turn is impossible when the wheels flop over and reduce lock...4 or 5 point ...
Give the king pins a good greasing and a few miles to ease off...

Re: Modified Front Arms, Advice needed

ps, in the hints and tips papers- of which I have an emailable copy of the king pin modification, there are 3 ride heights settings to weld to with body/ chassis height mentioned.
Phil will have done his in the pembleton jig..for pembleton..which might not be the same as lomax...
but you can adjust this to comply by adjusting the suspension rods to give a correct caster angle-as long as it is not neutral...

Re: Modified Front Arms, Advice needed

As none of the above posts have mentioned it, I'm probably wrong. But - when the ride height has been adjusted, doesn't the tracking need resetting also? If this is true, and the ride height is now lower than before, I don't know what the effect would be, apart from tyre wear!
Lowered ride height is, I thought, a reason for changing the track adjusters for longer ones and thus maintaining a safe engagement length with the track rod ends.

Membership No. 1865

Re: Modified Front Arms, Advice needed

You're turning end of the arm to get lighter steering and not necessarily lowering the car.

Re: Modified Front Arms, Advice needed

If you mod the castor angle on the front arms and don't lower the car, you'll have negative castor angle - and that's not very desirable (think shopping trolley!).

Most people mod the arms because they are lowering the car. modifying the arms restores the original castor angle (15 degrees?).

Obviously, by owering the front, the tracking will be affected slightly.

Rgrds
C

Re: Modified Front Arms, Advice needed

Ian,
I've tested the effect of lowering (or increasing) the ride height on the steering alignment, using long pointers attached to the front wheels.
With the suspension tie rods disconnected and the front of the car supported on a jack, it could be moved between 'full bump' and 'full droop' with very little effect on the wheel alignment.

As regards the need for lengthened tracking adjusters, this only arises whenever the arms have been 'turned' to lighten the steering with lowered suspension.

If you examine the relative positions of the steering arm ball and the attachment of the track rod to the rack, it should be easy to see how 'turning' increases the included angle between the track rod and the front axle.

Might be worth bearing in mind that the racers run at 40mm ground clearance compared to 180mm as standard, so their need for turned arms was understandable.

Also, it's possible to overdo the amount of correction and end up with little or no self-centreing effect, so the degree of 'turning' should be related to the amount of lowering...

Ken.


Ian Hutchins
As none of the above posts have mentioned it, I'm probably wrong. But - when the ride height has been adjusted, doesn't the tracking need resetting also? If this is true, and the ride height is now lower than before, I don't know what the effect would be, apart from tyre wear!
Lowered ride height is, I thought, a reason for changing the track adjusters for longer ones and thus maintaining a safe engagement length with the track rod ends.

Membership No. 724

Re: Modified Front Arms, Advice needed

Ian,
have you checked that the track rod end housings are correctly centred on the steering balls when the car is resting on the ground, also that the 'adjustment' of the track rod ends isn't too tight?

If the hub carriers move easily on the kingpins when disconnected and the rack itself isn't stiff, those are some other items which could cause the symptoms you've described.

Ken



Ian Avery
I recently had my front arms modified by Phil Gregory (Pemberton) and had them fitted along with new King Pins by a 2CV specialist. This mod improves the steering, making it much lighter. The problem that I have is that the steering is now very stiff.The steering stays on the lock and will only return when I straighten the steering wheel.With everything disconnected and jacked up, the rack is free, and the king pins seem free, connect everthing up as normal and holding the front wheel, I have great difficulty in moving from lock to lock. Phil thinks the problem is in the K Pins. I would like to know if any other member has experienced this problem, or any remedies to cure it. thanks, Ian

Membership No. 724

Re: Modified Front Arms, Advice needed

To achieve the 15 degree caster angle with a lomax ride height/ground clearance of 125mm = 5", the cut arm needs to be turned from the datum point 5mm.[forwards...]
for a ground clearance of 100mm or 4" it is 6.5mm..
so there is a crucial difference.maybe pembleton arm modification is different to these lomax ones...?
It is necessary to mark..scribe these datum points before cutting the arms-just past the original weld but not through the insert of the king pin which revolves inside the arm.
careful not to loose the camber angle...
yes- it increases the wheelbase by 1" as it follows the arc so track rods need adjustment..and it suggests a collar or welding up the centre part.[or fit stainless adjusters..]
I can email the 2 page info on this if anyone wants a copy...

Re: Modified Front Arms, Advice needed

David,
do those figures take any account of the depth of the chassis/space frame or the diameter of wheel/tyre being used?

( Some Lomaxes have Citroen original style chassis which are 108mm deep, others have a Lomax chassis which is shallower and the Pembleton frame is even shallower. )

If they don't, maybe take them with a pinch of salt, because the two measurements which determine the true 'angle of dangle' of the front arms are the heights of the centrelines of the front axle and wheel hub above the ground at whatever ride height the individual builder decides to use.

'Ground clearance' or 'height of sump plug' are just a shade too vague, given the variables mentioned above...

Ken

Membership No. 724

Re: Modified Front Arms, Advice needed

Hi,

What steering arms and cups are you using?

There was a firm who sold reputedly new cups which were so rough that they chewed up the steering arms and made the steering very stiff to turn.

The finish of the concave surface of the cups should be mirror smooth. The duff ones were so rough that you could file your finger nails with them.

Hope you solve your problems soon.

John

Membership No. 301

Re: Modified Front Arms, Advice needed

I can only presume the lomax measures are for an original 2cv chassis.
Working out the difference in lomax chassis you would get similar settings.
The pembleton measure from the sump is the one in the build manual-specific for pembletons-which also have a plate to bolt the steering tube to that cants the rack back to lower the steering column related to the frame.

Re: Modified Front Arms, Advice needed

ps,,,I did try to explain this in my first post as it is only relevant to pembletons

Re: Modified Front Arms, Advice needed

John Plaister
Hi,

What steering arms and cups are you using?

There was a firm who sold reputedly new cups which were so rough that they chewed up the steering arms and made the steering very stiff to turn.

The finish of the concave surface of the cups should be mirror smooth. The duff ones were so rough that you could file your finger nails with them.

Hope you solve your problems soon.

John


One of the reasons I had mine made in phosphor bronze.

Re: Modified Front Arms, Advice needed

Hello David.
Please could I take you up on your kind offer of the information about the angles of the dangles involved in modifying the front arms? If so I would be most grateful.

Respectfully yours Rob A. Wednesday the 11th of July 1012.

Membership No. 1400J

Re: Modified Front Arms, Advice needed

The best thread for quite a while. When I modified my suspension arms, Alan from Silly CVs lent me a jig. This got one side done but wouldn't work for the opposite arm. I measured the staggered scribe marks and found an 8mm difference so this is what I altered the other arm by.

Membership No. 1906