Koni Raid shocks with full air suspension

[Shingleback]

Hi all just thought I'd give some feedback on how Koni Raid shocks work with air bag suspension front and rear, as when I was searching for answers I found bugger all! I purchased the 130 already converted to air bags and it had "ultimate suspension" shocks and the ride was very harsh over small bumps and generally felt more like and old leaf spung truck than a nice plush defender. I possibly could have got them re-valved but one rear shock was stuffed anyway.

After lots of measuring I was confident I could make the koni's fit with some modifications, even though the salesman wasn't too keen! The only thing I wasn't sure on was how the valving would suit air bags, but worst case they can be re-valved at a cost and I was keen on the koni raids for their very good tough reputation.

So I bit the bullet, ordered and installed the koni's. Very briefly, to suit the airbags own internal bumpstops and max extended length I matched the shock mounts to take advantage of the full stroke of the shock while having a 30mm safety margin when sitting on the chassis bumpstops. At the rear I had to lower the bumpstops, shorten the airbag spacer and lower the top shock mount, at the front I just had to raise the lower shock mount.

End result, night and day difference to old shocks, very happy. So much smoother over bumps and heaps less body roll on the road, has transformed the vehicle, well worth the effort. If anyone want's more details of the modifications let me know.

Cheers, Andrew

[Expedition 130]

Hi Andrew,

I have Airbagman air springs and Koni Raids on the rear of my 130 and have found them to be excellent, however I have not made any modifications (hopefully photo attached). My research prior to shelling out the dollars was that the springs and shocks were compatible as was, is there a specific reason you made your modifications?

Greg

[Vern]

Any more info on the raids , as in part numbers? Open and closed lengths if you could? I have the same set up (actually i think that used to be my front housing and turrets you have there:))except coils, and I'd prefer some raids. Are they the same lengths as the old shocks?
Cheers

[130man]

Hi Taylorslandy, thanks for this timely post. I have Firestone airbags in the rear of my 130 and the shock absorbers are about due for replacement. Any further information would be welcome. Cheers, 130man.

[Fraz]

Any info about the mods is welcome! How much did you shorten the spacer, increase the bumps etc and also the shock mounts too. I will be doing this soon and already have the raids so I don't want to have to replace them :)

[isuzutoo-eh]

Yep another request for more details, and info on what valving you currently have too please. Not that I understand that stuff yet...

[Mocky]

Just a question regarding fitting Air Bags to a Isuzu County in WA
Does this modification need to be engineered to be legal.

Mocky.

[Shingleback]

OK, I'll try and answer all your questions.

Firstly, I too have the air bag man kit in the rear and you obviously can simply bolt on the koni shocks and away you go. The reason I modified the mounts etc is because I wanted to take advantage of the full stroke of the shock giving the most wheel travel. The shocks are designed for coil springs, so if the vehicle ever hits the bump stops there is still about 30mm of compression left before the shock bottoms out to allow for compression of the bump stop to protect the shock. With the airbag kit fitted and standard bump stops, if you dump air out you will notice the vehicle will be sitting on the airbags own internal bump stops and there will be a gap of about 25mm between the standard chassis bump stop and diff. This is the difference. If you don't adjust the shock mounts the shock will have a fair bit of travel that will never be used due to the airbags bump stop, and you will be opperating near the top of the shocks stroke so when a wheel drops in a hole the shock wont have much travel left before being fully extended. It is reccomended to not rely on the airbag bump stops as they are very solid, so I wanted to have the chassis bump stop contact first and allow about a 15-20mm compression before hitting the airbag BS. So, to give the 20mm safety margin the standard bump stops would have to be lowered by the 25mm (gap under BS while sitting on airbag BS) plus 20mm = 45mm. BUT! I didn't want to have my standard ride height too high and didn't want to mess around lowering the shock mount too much, SO I decided to cut about 15mm out of the airbag spacer which allowed only a 30mm spacer to be added to the bump stops giving the required compression allowance before hitting the airbag BS.
To lower the top shock mount I simply used the "other" holes in the mount which lowered it by about 16mm. I just had to grind a small flat and drill a hole in the bottom of the mount and drill one hole through the chassis, was quite easy. The end result is, with the 130 sitting on its new 30mm lowered bump stops there is still 30mm of compression before the shock bottoms out, and on full extension the airbag is near its limit.

The front has turrets from Verns old rangie and axle housing with the factory air bag range rover shock mounts. I cut the mounts off and made new ones extending them up 55mm and out a bit to clear steering arms etc as the raids are big mothers. This new shock mount position still had a 30mm safety margin sitting on the bumpstops, and when fully extended the airbags are at their limit.

The Koni shocks have a fair bit less travel than the old "Ultimate Suspension" ones when compared out of the vehicle, but after all the mods the travel in the vehicle is actually about 10mm more with the Koni's because they are set up better.

Part numbers; Front= 90 5374 for 0-50mm lift Rear= 90 5401 for 40-60mm lift.

The shocks are adjustable but I have left them as they came which I believe is the softest setting. The ride is magic compared to how it was but still not classic rangie soft, but still very good, I'm happy :)

Hope this makes sense,

Cheers, Andrew.

[rar110]

Thanks for detailed post.
Would the 90-5375 standard height Raid rear shock resulted in less modification?

[Bush65]

With the shortened spacer between the air spring and the spring perch, take care that the bellows doesn't rub against the spring perch, which is a little too narrow in that area. In service, the bellows will expand more that is when static.

I understand you don't want your "standard" ride height too high. If you raise the ride height when "off road", you will find that the extra volume of trapped air in the spring will improve the ride.

Does your control system allow different programmed height settings?

[Dougal]

Thanks for all the info. Do you know the length and stroke of those konis?

[Shingleback]

Thanks for detailed post.
Would the 90-5375 standard height Raid rear shock resulted in less modification?

You could use those shocks but because they are shorter you would have to lower the shock mount even further which would rule out the simple solution I used.

[Shingleback]

With the shortened spacer between the air spring and the spring perch, take care that the bellows doesn't rub against the spring perch, which is a little too narrow in that area. In service, the bellows will expand more that is when static.

I understand you don't want your "standard" ride height too high. If you raise the ride height when "off road", you will find that the extra volume of trapped air in the spring will improve the ride.

Does your control system allow different programmed height settings?

Yes your right about taking care the bellows wont rub, I did consider this and if you take care to center the bellow there seems to be enough clearance. And I must correct the amount I shortened the spacer, it wasn't 15mm, was more like 12mm. The standard spacers measured about 63mm +- a few mm as they wern't square, I cut them down to 52mm.

Interesting you find a raised ride height gives an improved ride, I find the ride gets firmer with more air pressure in the bags. Must admit I haven't tried the raised height with the koni's yet, will have a play.

I have the accu air e-level controller, allows 3 height settings.

[Shingleback]

Thanks for all the info. Do you know the length and stroke of those konis?

Don't have the lengths at hand but the strokes as follows;

Front = 220mm

Rear = 206mm

Funny how the fronts are for 0 - 50mm lift and rear is for a 40 - 60mm lift and the fronts have a longer stroke. I'm pretty sure the other rear shock for 0 - 40mm lift has the same stroke, is just a bit shorter in the shaft.

[rar110]

... I'm pretty sure the other rear shock for 0 - 40mm lift has the same stroke, is just a bit shorter in the shaft.

Same stroke as front shock or raised rear shock?

[rar110]

You could use those shocks but because they are shorter you would have to lower the shock mount even further which would rule out the simple solution I used.

Thanks I get it now. And the two types of rear shocks have the same travel.

[isuzurover]

This thread is timely as my rear Bilsteins are finally wearing out.

[Shingleback]

Same stroke as front shock or raised rear shock?

Same as raised rear shock. The raised rear shock has a longer shaft, not stroke or travel.

[Bush65]

...

Interesting you find a raised ride height gives an improved ride, I find the ride gets firmer with more air pressure in the bags. ...
Many people make the mistake thinking that to increase the ride height requires more air pressure.

When the ride height is within the range where the bellows is rolling on the nearly parallel section of the piston (BTW this will be around about the Firestone recommended ride height +/-), there is very little increase in pressure required to increase the ride height, and the change in ride height occurs because the volume of air trapped inside the air spring changes (increase volume to increase height).

When the ride height is lower than recommended by Firestone, and the bellows is rolling on the flared base of the piston, then the pressure will need to increase to extend the air spring because the effective area is reduced as the bellows rolls up to a smaller diameter section of the piston.

However if the load is increased the air pressure needs to increase.

Below are some figures based upon the Firestone air spring assembly W01-358-5712 with bellows 1T14C-7. This is a little different to your rear air springs, which I believe may be W01-358-5422 with a 1T14C-3 bellows, but will be close enough for the sake of this discussion (take a bit off the ride heights for the shorter bellows). One reason for using this air spring is that I have the Firestone data sheet for it. The calculations to obtain the data are based upon those given in the Firestone design manual/guide.

https://www.aulro.com/afvb/

https://www.aulro.com/afvb/

Consider first a load on the air spring of 1200 lbf (544 kg), and the following ride heights:

a) 10" ride height, 34.0 psi air pressure, 339 lbf/in spring rate
b) 11" ride height, 37.5 psi air pressure, 277 lbf/in spring rate
c) 12" ride height, 38.4 psi air pressure, 192 lbf/in spring rate
d) 13" ride height, 38.4 psi air pressure, 170 lbf/in spring rate
b) 14" ride height, 38.9 psi air pressure, 169 lbf/in spring rate

Consider first a load on the air spring of 1750 lbf (794 kg), and the following ride heights:

a) 10" ride height, 50.1 psi air pressure, 443 lbf/in spring rate
b) 11" ride height, 54.4 psi air pressure, 348 lbf/in spring rate
c) 12" ride height, 54.7 psi air pressure, 239 lbf/in spring rate
d) 13" ride height, 54.7 psi air pressure, 227 lbf/in spring rate
b) 14" ride height, 55.3 psi air pressure, 244 lbf/in spring rate

Note: I have highlighted the row for 13" as that is the recommended ride height for this particular air spring. The static ride height for a stock Defender rear coil is generally around 11" to 12".

[Shingleback]

Thanks John, very helpful, I understand it now. For a raised height you require more air volume, not pressure. Makes sense now.
Cheers, Andrew.



Many people make the mistake thinking that to increase the ride height requires more air pressure.

When the ride height is within the range where the bellows is rolling on the nearly parallel section of the piston (BTW this will be around about the Firestone recommended ride height +/-), there is very little increase in pressure required to increase the ride height, and the change in ride height occurs because the volume of air trapped inside the air spring changes (increase volume to increase height).

When the ride height is lower than recommended by Firestone, and the bellows is rolling on the flared base of the piston, then the pressure will need to increase to extend the air spring because the effective area is reduced as the bellows rolls up to a smaller diameter section of the piston.

However if the load is increased the air pressure needs to increase.

Below are some figures based upon the Firestone air spring assembly W01-358-5712 with bellows 1T14C-7. This is a little different to your rear air springs, which I believe may be W01-358-5422 with a 1T14C-3 bellows, but will be close enough for the sake of this discussion (take a bit off the ride heights for the shorter bellows). One reason for using this air spring is that I have the Firestone data sheet for it. The calculations to obtain the data are based upon those given in the Firestone design manual/guide.

http://www.aulro.com/afvb/attachments/90-110-130-defender-county/62274d1372288414-defender-airbags-v-coils-final-verdict-w01-358-5422-5426-5712.jpg

http://www.aulro.com/afvb/attachments/90-110-130-defender-county/62277d1372288511-defender-airbags-v-coils-final-verdict-1t14c-7.jpg

Consider first a load on the air spring of 1200 lbf (544 kg), and the following ride heights:

a) 10" ride height, 34.0 psi air pressure, 339 lbf/in spring rate
b) 11" ride height, 37.5 psi air pressure, 277 lbf/in spring rate
c) 12" ride height, 38.4 psi air pressure, 192 lbf/in spring rate
d) 13" ride height, 38.4 psi air pressure, 170 lbf/in spring rate
b) 14" ride height, 38.9 psi air pressure, 169 lbf/in spring rate

Consider first a load on the air spring of 1750 lbf (794 kg), and the following ride heights:

a) 10" ride height, 50.1 psi air pressure, 443 lbf/in spring rate
b) 11" ride height, 54.4 psi air pressure, 348 lbf/in spring rate
c) 12" ride height, 54.7 psi air pressure, 239 lbf/in spring rate
d) 13" ride height, 54.7 psi air pressure, 227 lbf/in spring rate
b) 14" ride height, 55.3 psi air pressure, 244 lbf/in spring rate

Note: I have highlighted the row for 13" as that is the recommended ride height for this particular air spring. The static ride height for a stock Defender rear coil is generally around 11" to 12".