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Alot of p38 pilots (including me) are toying with bigger tires, GenIII springs, longer shocks to take advantage of the genIII springs and some other offroad tweaks. I started with the GenIII springs and moved the front Bilstein shocks to the rear to get more travel BUT the rear sensor arms are too short to handle full extension. After noodling for a while on it, it was brought to my attention (by an Australian no less..) that the rear sensors mount to the arms at about 1/2 way, so 1/2" extension = 1" lift without re-calibrating the heights. I made up several sets of extensions and quickly found that the original design (just a balljoint) was too small, so I had spacers made up to go between the off the shelf balljoint and the cut/threaded sensor arm.

the sensor arm is cut just below the elbow and threaded 1/4"



BUT now the height sensor is TOO long, when trying to re-calibrate for 1" lift gives out of range errors, and the ECU defaults back to pre-programmed starting points. I pondered brackets, new mounts, all kind of stuff, until the rally last month, I bent the snot out of my sensor arms (before the spacers were put in) and it hit me, bend the arms!

After straightening the upper arms and cutting replacement lowers, I played with the angles:



So drawing a line towards the 1/2" mark, I GENTLY bent the arms, holding the sensor pivot end with a channel-lock plier, and pushing on the other end by hand (to prevent over-bending)



Line up the sensor portion with the line pointing towards 1/2", and put the pivot on the full extended mark



 

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Discussion Starter #2
To calibrate, I put in my high blocks, with 1" bumpstop pad extensions (more on that later :) ) and read the current heights ( I recommend Storey's free software). Since the ECU had reverted to default settings, I tweaked the bends to get the "as read" heights close as possible to the default settings (I got lucky and hit spot on after a couple tweaks :thumb: )

The front sensors attach much closer to the frame so they don't need to be extended, but a 1" lift is close to the limit for defaulting and reverting settings, bending the sensor arms DOWN (up for the rear since they're longer, and a bit too long) does the same thing. tweak to get close to the default values and calibrate from there.

the rear brake lines come down to the axle in the middle, longer mounting bolts and some plastic spacers from Ace lift the bracket off of the axle enough to prevent any issues with pulling brake lines. The bracket along the axle on the right can be swapped end-end to raise it as well (I'll take a photo of that tomorrow).

Questions, comments, concerns?

Highway height is a bit lower than original standard height, so driveline vibrations should not be an issue, since you can run highway speeds locked in standard height if so desired. More than 1" overall lift may (will?) need some other changes.



The extensions will be up in the store soon, after I do a bit more playing to ensure they're long enough.
 

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Dennis,
I'm satisfied that you did re-engineer those with a detailed thread. Great work!
I'm still waited to get my front shocks.

May you tell me something :

Is it possible using height sensor extensions and longer shocks, to keep OEM access height or at least Highway height with stock tires?


Cheers

Flo
 

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Discussion Starter #4
996TURBO said:
Is it possible using height sensor extensions and longer shocks, to keep OEM access height or at least Highway height with stock tires?


Cheers

Flo
depends on the shocks. The bilstein set designed for the p38 are longer than stock, and you don't have to mess with settings. The way I have it, the shocks will bottom out before the bumpstops do, so a bumpstop extension is required to protect the shocks from damage. I don't remember the dimensions, but to determine a safe length:

-remove all 4 shocks
-lower the RR to the bumpstops (completely deflate)
-measure mount to mount.

Look for a shock that is 1/4" less than that length for safety.

You could also fabricate new mounts but that's a different can of worms.....
 

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Discussion Starter #5
on the drive to work this morning I had no vibration issues, offroad height I cruised ad 34mph for a while, on the highway at 70 locked in standard height, and then at highway height. no problems.
 

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I modified mine in a bit of a 'Heath Robinson' manner but they seem to work.
The main difference is that I lengthened both arms an equal distance.
This keeps the original geometry but allows greater extension.
 

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Discussion Starter #8
q-rover said:
I modified mine in a bit of a 'Heath Robinson' manner but they seem to work.
The main difference is that I lengthened both arms an equal distance.
This keeps the original geometry but allows greater extension.
I've thought about that, but every time I start workign on them, it ends up Rube Goldberg. I like to keep things simple, for simplicities sake (but it is a Rover...)
 

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Discussion Starter #10
feedback from the test sets? Mine are still doing good, love the extra height. I sent out 5 sets for testing, need some feedback.
 

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Mine work brilliantly still. I still need some extended bumpshocks though, because if you let all the air out, it bends the arms a bit.
 

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q-rover said:
I modified mine in a bit of a 'Heath Robinson' manner but they seem to work.
The main difference is that I lengthened both arms an equal distance.
This keeps the original geometry but allows greater extension.
Quentin,

I'm in the same boat. Any photos of your work?

Thanks

Florent
 

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Ok,

After few tries with only one arm lengthen, it's a real nightmare. Truck isn't level. I get lot of out of range errors. I do not want to bend the upper arms. It only cancels the mod on the lower arms, that's it.

i arrived to the conclusion that you MUST lengthen both arms equal like Quentin or Storey did.

I'm gonna work on my sensors again and solve that EAS upgrade 8)

Florent, running on MARS kit since 2 weeks /:(
 

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shupack said:
depends on the shocks. The bilstein set designed for the p38 are longer than stock, and you don't have to mess with settings. The way I have it, the shocks will bottom out before the bumpstops do, so a bumpstop extension is required to protect the shocks from damage. I don't remember the dimensions, but to determine a safe length:

-remove all 4 shocks
-lower the RR to the bumpstops (completely deflate)
-measure mount to mount.

Look for a shock that is 1/4" less than that length for safety.

You could also fabricate new mounts but that's a different can of worms.....
Dennis, I'm a little worried about your last comment. What model are the "bilstein set designed for the p38"?

I currently ride on coils (HD set from Atlantic British) and Bilsteins (Front: F4-B46-2214-H0 & Rear: F4-B46-2215-H0). According to AB I got a 2 inch lift from the HD coils. Do you think that on my setup I need to upgrade to extended bumpstops ? This thread got me thinking because I recently found out there's a crack on one end of my front crossmember (the one supporting the transmission). I was wondering if these 2 things where somehow connected. What do you think ?

N.
 

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Discussion Starter #15
The 2214/15 set are the Bilsteins designed for stock p38's. With the 2" lift you'll top out the shocks before you bottom them.
 

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Discussion Starter #16
996TURBO said:
Ok,

After few tries with only one arm lengthen, it's a real nightmare. Truck isn't level. I get lot of out of range errors. I do not want to bend the upper arms. It only cancels the mod on the lower arms, that's it.

Not true at all (the last sentence). I had the same troubles, which is why I bent the arms you do it so it takes up about 1/2 of the added length because you've gone too far.

Lengthening the lower arms makes the assembly long enough that you won't rip it in half. Making it long enough gives you about a 3" lift without recalibrating. Bending the upper arm puts the sensor back in a reasonable range for a 1-2" lift so the ECU will accept the values.

You can achieve the same result by lengthening both arms, but I find it simpler to do just
one. Less cutting/threading, fewer parts (cheaper) and less to go wrong(potentially).

Either way you need to add about 2" to the total length AND keep the sensor in it's normal sweep. Both methods do just that.
 

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shupack said:
The 2214/15 set are the Bilsteins designed for stock p38's. With the 2" lift you'll top out the shocks before you bottom them.
Ok, it won't bottom out riding the 2"coils + bilsteins. But what about topping out ? Do you think that those bilsteins can't cope with the 2" lift ? I'm asking because Atlantic British sells the coils + bilsteins as a kit. Therefore I assumed it was a safe combination. Sorry for the offtopic, but you got my mind wandering....

N.
 
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