BP-51 Setup

[superclarkey]

Hey,

I have tried to search but I might be using wrong terminology to retrieve information...

I have fitted BP-51 kit to my 2022 hilux, originally they supplied me the incorrect rear leaf springs and swapped them to the EL105R which is the lowest spring rate they offer.

I've not driven the car yet, so it's just been moved around my yard and back onto the ramp, I've made sure to bounce the back and make sue the leaf springs are moving correctly. So it's defo settled as much as it's going to go. (I put some weight in the back also with the forklift to really compress it).

As I don't have any accessories on the front, I followed the instructions and used the +10mm preload setting on the front, I feel the front is still way too low. (or rear way too high)

Here is a picture of front to rear. (click on it to open it as front is cut off in my view).



Now I can add the +20mm preload to the front to lift it (So 10mm more then its currently), but measuring the stroke of the shock, its moving 15 mm down its stroke when the vehicle goes from full lifted to the weight fully on it, now this seems to me like that is already too close to topping out, and if I raise the preload by +10 from where it is now, its going to be 5mm down the shock travel (which is 100mm total). This seems like a really bad idea.

Not sure of the motion ratio on the front, but guessing it's about 0.5x, so 15mm at the shock is about 30mm at the wheel. (measured it to be closer to 27mm at a quick test).

I don't want the suspension to be constantly topping out as this will cause a horrible ride. (bearing in mind if your cornering at the vehicle is leaning a bit, you're going to be super close to topping out).

So the question is, if I trade say 10-20mm of preload for a spacer would this cause an issue for the CV's ? I.e I'm changing the droop of the suspension and the limiting factor.

Normally I want at least 1/3 to 2/3 of compression static on a shock, I appreciate that we are raising the truck so some compromise needs to be made, so if aiming for 1/3 of available travel, that would be around 33mm of travel, so in an ideal world, I would actually lower the preload around 18mm (giving 15mm I currently have plus 18mm gives me 33m of shock travel static), and add a 18mm spacer to get me back to where I currently am, then to give it some lift say add another 10mm, so 28mm spacer.

Now as its not possible to remove 18mm of proload as I only have 10mm added, If I set that back to the 0 position, this would give me travel of 15mm + 10mm extra, so would be 25mm of static compression. so to get back to the same height I would need to add a 10mm spacer minimum to top of the shock, again if I then what to raise it I would then need to add to that 10mm spacer. so again 25-30mm spacer.. but now at that height I'm no where near topping out... but cv's might suffer.

Hope that make sense, I know that will defo work, but your allowing a 30mm extended drop on the shock length.

had anyone run shock spacers with the BP-51's.

If not I will have to get some other leaf springs for the rear as it would be easier to just drop the back, for the lightest rear spring that ARB sell, and I have a large 33 Tyre (40Kg?) and rear summit bar, so another 50kg, so just about 90kg static on the rear.

Not that I think it will make any difference but I have ome uca.

If spacers are a no-go on the front, then rear leaf is going to have to be changed imho.

EDIT: To just clarify, I get full articulation on the front (well all the way to the bump stop anyways), I have modified the front to allow the wheel not to catch on anything so I don't need to raise the car to stop any rubbing, this is just to get the most out of the shocks and get a nice tune.

[superclarkey]

I’ve just ordered one of these diff drops…

https://www.kaon.com.au/diff-drop-kit-t ... -arm-style

So if I do need to raise the truck to match the rear with spacers I’m not doing it at the cost of the CV joints. I would guess the next limiting factor will be the upper control angularity of the ball joint on binding.

Presume this is a good idea?

[Chopps]

Diff drop - good idea
Strut spacers - nasty
Whats the wheel offset and tyre size?

[superclarkey]

33x12.50R17 8.5J ET0

[Chopps]

Surprising - the photo appears a lot more negative.
There may be some wheel scrubbing with 0 rims, particularly under compression and turning


Leaf springs are designed for carrying heavy loads - there is no way of getting around that... well, you could bolt on a fortuna 5-link coil spring config

The rear will come down over a few months. Just needs to be loaded up like a ute was intended to be used.

[superclarkey]

There would have been rubbing for sure, but I’ve modified the front for 33’s (chassis mount is modified and inner panel flange is removed). I think the tyres give the look as the are so squared shouldered (kinda the reason I went for them)

Yeah I guess putting weight in will fix the issue, but I don’t want to load it up all the time when I don’t need too. However it is extremely nose heavy.

[superclarkey]

I know I’m going to do a diff drop, but is it worth addressing the propshaft on the rear? Should I space down the centre support bearing?

[Chopps]

Ok cool. That front mount mod will help.

You wont have to drive around all day with weight.
Could try to load the tub up with 800kg to flex the springs - just dont drive it with all that weight

[superclarkey]

I have squashed the rear down a few times with the forklift and observed inner-spring slippage so fairly confident it is sitting at the hight it should be sitting at. Only way for it to settle any further would to be get the springs to go beyond their elastic limit and get plastic deformation to cause permanently deformed springs lol... can't see what else there is to give. (OME springs have plastic spacers between the leafs, these have been lubricated).

I was looking at the driveline angles today and I was a little concerned, I did a quick drawing to better see where I'm at. This is at full droop hanging on a ramp though, so some pinion angle change will happen however I can't see it being more than a few degrees tops.



The far left is the diff, the far right is the gearbox..

Angle coming out of the gearbox is 4° to the first working shaft, but bear in mind that the gearbox isn't level with the ground so I've just used it as a starting point so the diff isn't normally pointing at the ground, so ignore that, its just the relationships I'm interested about.

I was shocked to see a 4degree angle out of the back of the gearbox tbh, but nothing with Hilux is shocking me anymore tbh.. lol

In short, the rear diff needs to be rotated upwards (nose of diff up from the ground) 10° to match the first working shaft (Fixed).

I thought dropping the centre would help, but any spacers would make this terrible as its already at 4° which is a bit shocking.

Can you even get 10° wedges for these axles and is that going to work with the shocks...

How do people not notice the vibrations when lifting their trucks haha..

What do people do to solve this? (This is my first 4x4 truck and I'm learning that most people just shrug their shoulders and be like, whatever)

(EDIT: Please note this was just a quick measurement, I'm going to do more pinion angle measurements at different angles once I have time, for now this is just a quick static view on how it sits.. fully understand it needs to be at ride height and not fully dropped on a ramp).

[Rob_Wood]

I have squashed the rear down a few times with the forklift and observed inner-spring slippage so fairly confident it is sitting at the hight it should be sitting at. Only way for it to settle any further would to be get the springs to go beyond their elastic limit and get plastic deformation to cause permanently deformed springs lol... can't see what else there is to give. (OME springs have plastic spacers between the leafs, these have been lubricated).

I was looking at the driveline angles today and I was a little concerned, I did a quick drawing to better see where I'm at. This is at full droop hanging on a ramp though, so some pinion angle change will happen however I can't see it being more than a few degrees tops.



The far left is the diff, the far right is the gearbox..

Angle coming out of the gearbox is 4° to the first working shaft, but bear in mind that the gearbox isn't level with the ground so I've just used it as a starting point so the diff isn't normally pointing at the ground, so ignore that, its just the relationships I'm interested about.

I was shocked to see a 4degree angle out of the back of the gearbox tbh, but nothing with Hilux is shocking me anymore tbh.. lol

In short, the rear diff needs to be rotated upwards (nose of diff up from the ground) 10° to match the first working shaft (Fixed).

I thought dropping the centre would help, but any spacers would make this terrible as its already at 4° which is a bit shocking.

Can you even get 10° wedges for these axles and is that going to work with the shocks...

How do people not notice the vibrations when lifting their trucks haha..

What do people do to solve this? (This is my first 4x4 truck and I'm learning that most people just shrug their shoulders and be like, whatever)

(EDIT: Please note this was just a quick measurement, I'm going to do more pinion angle measurements at different angles once I have time, for now this is just a quick static view on how it sits.. fully understand it needs to be at ride height and not fully dropped on a ramp).

When lubricating the spacers between leaves it is advisable to use lanox (or some other lanolin lube) as lanolin tends to attract & hold onto less dirt, grit & other abrasive materials than many other lubricants.

[superclarkey]

Good to know! I used Loctite 8023 which is very expensive but its marine grade so for our salted roads in the UK would work good. (Also has high washout resistance).

[Bushwalker8]

Greasing ARB Interleaf Liners was discussed here: viewtopic.php?f=126&p=439861

[Rob_Wood]

Good to know! I used Loctite 8023 which is very expensive but its marine grade so for our salted roads in the UK would work good. (Also has high washout resistance).

Salted roads add a whole new dimension to rust issues, however dirt, grit & other abrasives (including salt) getting between the leaves of your springs will at the very least take the paint & protective layers off to expose potential oxidation starters. I only mention this because you strike me as one who tends to polish everything until the cloth turns to dust. Just something to keep in mind.

[superclarkey]

Haha, I don't know if to take that as a compliment or a dig lol.

I see the inserts as a disposable item that will be replaced when they wear out or start to look like they need replacing. Regular maintenance will be key I'm sure

As my hilux came with ever painted weld on the chassis cracked and already rusting.. my leaf springs are the least of my worries from corrosion. I feel the leaf springs will outlast the chassis at this point haha.

[Rob_Wood]

Haha, I don't know if to take that as a compliment or a dig lol.

I see the inserts as a disposable item that will be replaced when they wear out or start to look like they need replacing. Regular maintenance will be key I'm sure

As my hilux came with ever painted weld on the chassis cracked and already rusting.. my leaf springs are the least of my worries from corrosion. I feel the leaf springs will outlast the chassis at this point haha.

Compliment, I'm a lazy prick when it comes to looking pretty. My utes' beat-up 0ld look is testament to this. As for the chassis, my uncle went to the expense of hot dipping the chassis in his old 40 series.

[Rob_Wood]

Haha, I don't know if to take that as a compliment or a dig lol.

I see the inserts as a disposable item that will be replaced when they wear out or start to look like they need replacing. Regular maintenance will be key I'm sure

As my hilux came with ever painted weld on the chassis cracked and already rusting.. my leaf springs are the least of my worries from corrosion. I feel the leaf springs will outlast the chassis at this point haha.

Compliment, I'm a lazy prick when it comes to looking pretty. My utes' beat-up 0ld look is testament to this. As for the chassis, my uncle went to the expense of hot dipping the chassis in his old 40 series. It outlasted him by decades.

[Chopps]

.. fully understand it needs to be at ride height and not fully dropped on a ramp).

Answered the issue there. Unless the hilux is jumping it never gets full droop. One wheel should always be on the ground

[superclarkey]

.. fully understand it needs to be at ride height and not fully dropped on a ramp).

Answered the issue there. Unless the hilux is jumping it never gets full droop. One wheel should always be on the ground

Yeah agreed, I remeasured it while on the ground and I worked out I need a 2.4° wedge to correct the angle, so not too far out at all. However the 4° at the tail shaft from the box isn't ideal, be nicer if that was about 1°, but I'll wait to see if there is an issue before remaking the chassis haha.