AHC Suspension overhaul

[Ken Brenton]

I am planning to overhaul the AHC suspension on my return to UK (currently in Jakarta on contract) later this year prior to some European touring, hopefully some trails included in Portugal or somewhere similar.
I need some advise on what I should just change out.
I will go and see Pleiades to check out and recondition the AHC systems but at the same time was thinking of fitting new rear springs and air helpers.I have already received rough quotations which seem reasonable to recondition the AHC system and fit springs and adjust torsion bars at the same time.
Anyone any advice as to what products to use or if I should first inspect before just replacing the springs.
Are the springs OEM only or can other suppliers meet the requirements? Anything else I should consider replacing whilst at it?
The vehicle is a 2001 100 series VX with 4.7 petrol engine and has done 135000 miles. I fitted LPG when I first bought the vehicle with a 90L tank replacing the spare wheel and will be adding a rear wheel carrier and some rear storage ready for touring/camping. So a bit heavier in the rear than originally.
The suspension seems to be working fine at the moment and all the height and sport controls also working. I would just feel more comfortable, given the age and mileage of the vehicle, to be safe rather than stuck in crawl mode in the middle of nowhere or am I being over-cautious after reading about AHC mishaps?

Thanks

 

[Dark Dude]

Ken

If it ain't broke don't fix it! Nowt wrong with taking your truck to the guys a Pleiades (as I swear by these dudes) but I wouldn't be opening a can of worms which I couldn't close. My car is the same age as yours (as well as being LPG) and when I had my AHC system checked all of the original parts (apart from the front and rear spheres) passed with flying colours. That was almost three years ago and my car's AHC suspension hasn't missed a beat, not once. Next year I'm going to replace the rear springs and adjust the torsion bar and that's it. Keep it nice n simple and don't be spending money that you don't need to.....

 

[Ken Brenton]

Dark Dude
Thanks. That is pretty much what I intended to do, let Pleiades check it out and swap spheres if necessary but at the same time change rear springs and add air lifter bags and get them to check the torsion bar. Their quote for this work was very reasonable and it seems sensible to do the lot one time for peace of mind.
My question is, where to source standard rear springs, is it OEM only and also what air bags to use?

 

[uHu]

Your rear coils will certainly have weakened over the years, so don't expect it to have the full carrying capacity. Seems to be normal that after only 5 years, the rear pressure goes above specs.

When carrying an extra tank and adding a spare wheel carrier and a drawer system, you will have a permanent weight which is higher than the standard. That means that without modifying the rear springs, you will not be able to carry much cargo or back seat meat.

The standard springs come in 2 flavours, pink and purple, where the purple can carry a bit more than the pink. I think the purple is standard for the cars with the 50 l sub-tank, but many people have changed their old springs with new purple ones.

Harder springs (than standard for ahc) would be those for conventional suspension, but they would give you no damping at all with an empty car, as the gas spring wouldn't get any of the weight. I haven't seen any data on the standard AHC-springs, other than length, and haven't heard of any 3rd party springs that would fit for e.g. 200 kg extra on an ahc-vehicle.

Air bag helper springs seems to be the easiest way to go, and there are a few 100s around with that setup. Gives good handling both with loaded and empty car.

There are other parts that should be checked as well, like sensors, sensor links and pump, although spheres and rear coils seem to be the first to go.

 

[Ken Brenton]

Uhu
Thanks for the comprehensive and informative advice, just what I was looking for. Seems I was on the right track

 

[Dark Dude]

For mew the jury is still out on the subject of air lifter bags but anything that can improve on-road handling can't be a bad thing. Alas I drive my truck well within it's limits......

 

[uHu]

Just updating this old thread with more info on ahc coil springs, p## & spring heights:

EU market LC100 w ahc:
48231-6A750 W(ACTIVE HEIGHT CONTROL); H=455, PINK PAINTED
48231-6A770 W(ACTIVE HEIGHT CONTROL); H=485, PURPLE PAINTED
These are the ones used for both UZJ and HDJ in the EU market, right and left, and on both rhd and lhd. The pink is the standard, and the purple 30 mm longer, for a few pounds extra fat. It would have made sense to have a longer/stronger one on the left tho' as that's the heavier side.

In the N.A. market, the numbers are different:
48231-6A770 W(ACTIVE HEIGHT CONTROL); H=485, PURPLE PAINTED, RH
48231-6A780 W(ACTIVE HEIGHT CONTROL); H=500, BROWN PAINTED, LH
(Comment: Also for the non-AHC version, there's a longer spring on the LH side, which there isn't on the EU version.)
Comment2: One reason for the difference is that in EU, the trailer tounge weight is never over 75 kg (150 lb), while in the US, I understand that 10 % is common, giving nearly 300 kg ekstra with a heavy trailer.

Australian market:
48231-6A770 SPRING, COIL, REAR RH, H=485, PURPLE PAINTED - $130.46
48231-6B010 SPRING, COIL, REAR RH, H=515.5 - $317.30
48231-6A770 SPRING, COIL, REAR LH, H=485, PURPLE PAINTED - $130.46
48231-6B010 SPRING, COIL, REAR LH, H=515.5 - $317.30
Are the 515 mm long ones for those with the sub fuel tank?
In Australia you also have the King Springs KTRS-79, designed for permanently added weight. Not longer, but beefier.

link to mud-thread:http://forum.ih8mud.com/threads/coil-sp ... hc.871848/

 

[arnonmg]

I use the KTRS -79 at rear and they are shorter then original
I didn't like it and I don't know if there's down side ...
nowadays looking for beefier torsion bars - any idea?


2006 TLC 100 IL

 

[uHu]

arnon, do you know the length of the ktrs-79 springs?

 

[arnonmg]

No - I didn't check back then but when I had them side by side with the original ones they where shorter
I can check the box or pull one of them out when I replace the rear shocks - one is bleeding
I fly tonight for tow week - will get back to you when I have the info


2006 TLC 100 IL

 

[t1pper]

Hi,
I brought mine with 150,000 miles, I have replaced the link rods and arms on the sensors and swaped the oil, I belive the oil is Toyota only but Milners have stock at a lower price, the oil seems to be rarely swaped and mine was bad!
I checked my spheres by counting the markers on the AHC oil tank iirc 7 marks plus from low to hi ride height means the spheres are fine, after that its visual inspection for me.
My car is standard but I tow a fair amount, never felt a need to increase the springs.
Hope this helps