Thread: drop arms for lifted P38A

If you cut down your bump stops, will the longer dampers compress enough or will they 'top' out?
That's usually why longer bump stops are fitted.

Originally Posted by Scouse

If you cut down your bump stops, will the longer dampers compress enough or will they 'top' out?
That's usually why longer bump stops are fitted.

Good question Scouse. All I know is that at the moment it doesn't take much of a bump on the road until I feel/hear a thud. Here's a pic of the 3 bump stops I have...


The original yellow ones are fitted at the rear and were on the car when I got it from Hardy.
The red ones were on the front, but one of them was split so I ordered a replacement set from HRA - the blue ones.

As Hoges rightly pointed out, the yellow stops are quite soft.
The red ones are quite firm, and the blue ones seem to be firmer again.

Interesting that the red ones are exactly 50mm taller than the oiginals... exactly equal to the lift kit on the car. The lift at the rear is via 50mm blocks mounted under the airsprings, so a 110mm bump stop makes sense.

At the front no blocks are visible, so the lift is either spacers at the top of the airsprings... or possibly the extended shocks? Hmm, just doing some maths on the shock lengths. I'll ponder this and come back with my findings.

cheers, Paul.

Here's the maths I could figure based on...
- What I call "Standard" are Bilstein B46-2214 shocks at front and B46-2215 at rear.
- What I call "My front" are modified Bilstein B46-1477 for LandCruiser 80 series.
- What I call "My Rear" are Bilstein B46-2214 (normally used for P38A front).


So the front shocks have 32mm more travel than standard, and 33mm more at the rear.

Observations from these numbers:

• The closed length at the front is 53mm taller than standard, so the bump stops should be at least 53mm longer, assuming shock is near vertical.
• the open length at the front is 85mm longer than standard, so what gives first - the airspring or the shock?
• closed length at the rear is 26mm longer so the bump stops should be <X>mm longer than standard, where <X> = 50mm (height of lift blocks) + extra shock height corrected for angle, approx 18mm if angle is 45deg... <X> = 68mm taller than standard.
• open length at rear is 59mm more than standard.

Does this make sense or are there additional factors I've missed?

Thanks for your consideration and suggestions on this... I promise to write something up and publish it if/when we get this sorted for the reference of other P38A owners who want a bigger "air gap"

Cheers, Paul.

Originally Posted by PaulP38a

The closed length at the front is 53mm taller than standard, so the bump stops should be at least 53mm longer, assuming shock is near vertical.

The original bump stops are designed to squash quite easily, so I don't think the standard damper would be close to full compression when on the stops normally. Therefore your harder bump stops give a bit more clearance than is measureable when compared side by side.

You'll find the damper is the limiting factor in the downward travel of the suspension. It is on other models & there's no stop built into the bag at all. The bag can pop off the alloy/plastic mounts if longer dampers are used with standard bags.

the way to setting the right bumpstop height is:
1, remove all your bumpstops.
2, drop the suspension down with no air (normally bumpstop level) - dont drive anywhere
3, measure the height between the diff and where the bumpstop should be.
4, add an inch to this measurement, and that is how long your bumpstops should be.

Andy

Thanks guys, I was planning to try something along the lines Andy described over the weekend. 1" seems about right for those harder stops.

Cheers, Paul.

have you talked to bruce davis landys in sydney?

Are p38s able to have slotted swivels for castor correction or is it a different setup?

Originally Posted by blackrangie

have you talked to bruce davis landys in sydney?

Are p38s able to have slotted swivels for castor correction or is it a different setup?

No swivels. They have upper and lower balljoints with an exposed rubber booted cv joint. The only way to change the castor at the axle ends would be to cut and weld.