Shocks to suit Gen 3 bags

[Pete38]

Hi All. I happily made a purchase off Paul (Paul38A) of some arnott gen 3 bags. I like the ride and the fact they have the potential of more height and articulation.

But as the stock shocks are the limit now for downwards travel the EAS values can't be put up much without popping wheels off the ground. I'm at a height in High mode where I am happy and the sensors did not need to be extended surprisingly. But it does tend to lift wheels a little easier than I would have liked.

Now I know Hardrange sell a good kit that includes spacers, brake line extensions, spacers and shocks etc... But I was hoping to keep the highway and standard modes at normal heights (rather than all up 2 inches permanently) cause I wouldn't say I'm a devoted rock climber and spend most of the time on the tarmac but have put the P38 through its paces and got minor battle scars to prove

So what I am after is some shocks to complement the "Gen 3" 2-3 inch extra extension without the need of extended bump stops that reduce some articulation. A good look on the internet doesn't return much luck without going down the custom path as is shown here Custom Bilstein shocks for ARNOTT GEN III P38

I had thought about putting front to back and adding an extra 1 inch on the bump stops to stop the shocks bottoming out on the rear. This would give an extra 79.5mm downwards travel (53mm times 1.5 due to geometry of rear axle) which is a touch under the 3.5 inches arnott claim. But the upwards travel would be 40mm less (27mm times 1.5) so the articulation would definitely be increased somewhat.

Not so sure what to put in the front????? Guess they could be 1 inch longer when closed as the rear already would have 1 inch more bump stops so all heights would already be up 1 inch anyway.

This approach would be good as I only have to buy 2 shocks seeing the front goes to the back.

But ideally I would prefer to put longer stroke shocks with the same closed length in front and back, with 30mm and 50mm extra in extension respectively.

Anyone gone down the path of longer stroke shocks for gen 3 bags with no extension of the bump stops and without using spacers? Guess not seeing there is not much to be found on the internet.

[Pete38]

Just throwing these out there, so still well and truly open for suggestions or comments.

Maybe these shown below? I guess the front extension is not multiplied by 1.5 as the shocks are vertical huh? So the 3.3" extension should be OK with the claimed 3.5" extra of gen 3 on the rear. But I would need to increase the bump stops by an inch on the front to stop the shock bottoming out.

The rear can have the bump stops extended by 1 inch and throw the front to the rear.

10" Reservoir Shock - Short Body (8 Inch) 150/50
Part #:
AK7110SB01
Shaft Diameter:
14mm
Extended Length:
24.29"
Collapsed Length:
14.06"

Edit: These would need the top mounts modified from the eye ring to fit the P38 style stud mount though. Not sure what that mount is called though.

[PaulP38a]

Convention for shock length measurement is from the centre of the eye at top to the collar of the pin at bottom.

Standard shocks are approx:
front - 534mm open, 337mm closed (21", 13.2")
rear - 475mm open, 311mm closed (18.7", 12.2")

I would be concerned that the shocks you mention may allow over-extension at the front, and doubt that Arnotts would cover that under warranty.

[Pete38]

Hi Paul. Oh yeh my mistake. Thanks for pointing that out.

For some reason I was thinking the front had 3.5 inch more travel but that's for the rears. So I guess i need the fronts to be extended length of 23" (2" extra on stock) or less huh? I'm assuming that with the shocks vertical in the front and them being further out from the diff the bags will extend a little less than 2" when the shocks is extended 2"???

The last thing I want is to over extend the bags. The warranty is one part, but I also don't want to risk having to change the bags often in the bush.

A good rule of thumb for the rear is a maximum of 1.5 times the travel at the bag compared to the shocks isn't it? This being due to the angle and geometry of the shock mounts on the rear? So the 2.3" extra travel in the rear shocks (using front shocks) will give less than 3.45 inches more extension of the bags in the rear?

[Pete38]

Just clarifying.

So maximum ideal lengths would be (obviously not going to get these exactly, but these are the limits);

Extended shocks are approx:
front - 584mm open, 337mm closed (23", 13.2")
rear - 534mm open, 311mm closed (21", 12.2")

And leave bump stops the same.

Likely need to modify the height sensors not to increase the ride height, but more so the sensors don't get over extended when a wheel comes off the ground???

[PaulP38a]

You are correct to try to keep the closed shock length the same as original. If you increase closed length you will need extended bumps and may actually lose articulation.

Front shocks are near enough to vertical so +50mm on the open length should work ok with Gen III's, but I would suggest a safety margin of 25mm to not max them out.

I think your comment about rear shocks and may be reversed... If we treat the shock as the hypotenuse of the triangle, the air spring as the adjacent and assume that 45deg is the nominal angle, then the open shock length can be about 1.4 times the extended length of the air spring. The calculation in your subsequent post look about right though.

Good luck finding such shocks. Be sure to share with us if you do.

[Keithy P38]

Paul, you sound very "fresh outta school"! What your real age haha!

[mtb_gary]

pbrown,

Ronron, a p38 lover from Sweden went through exactly what you are trying to achieve see link Range Rover P38 On-Off-road project he finished up with Bilstein 7100 long travel. But watch out for your height sensors!

Gary

[Pete38]

You are correct to try to keep the closed shock length the same as original. If you increase closed length you will need extended bumps and may actually lose articulation.

Front shocks are near enough to vertical so +50mm on the open length should work ok with Gen III's, but I would suggest a safety margin of 25mm to not max them out.

I think your comment about rear shocks and may be reversed... If we treat the shock as the hypotenuse of the triangle, the air spring as the adjacent and assume that 45deg is the nominal angle, then the open shock length can be about 1.4 times the extended length of the air spring. The calculation in your subsequent post look about right though.

Good luck finding such shocks. Be sure to share with us if you do.

Hi Paul,

Thanks again for your informative post. I'll take a lot from that.

That was my initial thoughts with the shocks but it's about how much change there is not total length. And here's another school thing, I think it's related to the cos of the angle to the bag, so at 45 degrees is extending 0.7 times the bag ..

If the shock is almost sideways in mount then it would barely change as the bag went down, if the shock is vertical then it changes the same. I thought the same as you before so I could still be wrong :-)

Peter

[Pete38]

pbrown,

Ronron, a p38 lover from Sweden went through exactly what you are trying to achieve see link Range Rover P38 On-Off-road project he finished up with Bilstein 7100 long travel. But watch out for your height sensors!

Gary

Thanks. Will look into it. I thought I looked at the 7100 series but couldn't find any with the standard closed length of less.... But will look at your link in hope ;-)