Thread: Hilux inverted leaf springs

Hi my Hilux leaf springs are inverted & it's affecting the towing off big trailers to be fair it towing like shit now use to tow really well & are towing the same trailer with the same load.I have got a 3 year old Hilux it's done 90 thousand km the springs are factory the Ute is a double cab well side with a canopy on I'm thinking I need to upgrade the springs but don't know what to go to I don't want to give it a 2 inch lift I'm happy with factory height whatever I put in needs to be able to ride good when empty as I don't carry big weights in the canopy very often but do a lot off towing weight off trailer & load would be round 2-2.5 ton. So my question is what would you put in the back so it rides good empty but can handle the weight off a big trailer thanks

Factory rear springs but add another factory main leaf with the eyes cut off, taper the cut to avoid concentrating load stress at the cut

The D bolts are long enough, just make another centre bolt and trim to length

Adds a large amount of load capability and rear stability

Do a bit of math on it, work out what your standard weight on the rear spring pack is and then divide by about 75 (Kg, which is about what each leaf will carry). I went from the standard 3-leaf plus overload plate to a 7-leaf plus overload on the ranger. Fixed the junk springs it shipped with and the bs ride they gave, now much more acceptable although I would not like to be in it fully empty.

I have a wellside, liner tub, 75Kg of canopy and 65Kg of ute drawer in it permanently plus probably 45Kg of tools?

Plan to upgrade the shocks at the rear and you will need to adjust the front to correct the ride height and sort the alignment most likely. With more leaves in the rear spring pack you will gain lift which will also drop the nose and this is not good for alignment. I set the new foam cell front struts up with the factory coils but with a 10mm spacer to increase the preload which gave me 20mm lift at the front which pulled everything back into correct alignment. So far no issues with driveline angles, 136,000Km and the front lower ball joints need replacing it's the only wear item so far.

I'll add to that, for 2500Kg trailer that should be 250Kg of downforce on the towball which is all back end no load sharing to the front. With a canopy of say 65Kg for a plastic type your towing load increases over empty by 315Kg - I would think that a leaf pack designed for medium load carry or 50% of max rear axle load might work? Probably a 5 or 6 leaf pack depending on who supplies it. Or maybe the modified leaf mentioned above plus one standard mid pack leaf on each side, will need new u bolts and center bolt though you won't squeeze two more leafs in with the factory bolts.

Go to a decent spring / suspension shop.and ask for some advice. I did this with my navara and it tows way better. But these have coil spring rear end . I'm sure there will.be a heavy duty spring set that can be offered. It's no different than any industry .the best advice is professional advice. It's a good starting point you can always decide upon what to do on your budget. I wonder why they flip the leafs..we use to do this in our cars back in the day to lower them.lol

Originally Posted by Quackers

Go to a decent spring / suspension shop.and ask for some advice. I did this with my navara and it tows way better. But these have coil spring rear end . I'm sure there will.be a heavy duty spring set that can be offered. It's no different than any industry .the best advice is professional advice. It's a good starting point you can always decide upon what to do on your budget. I wonder why they flip the leafs..we use to do this in our cars back in the day to lower them.lol

I have been to 3 tyre shops & Toyota (witch I have tried twice & they haven't bothered to come back to me with anything) in town and the only 1 has come back to me & they are saying just to replace the rear springs and putting lot bigger shocks in and priced around $2000 we don't have any specialised suspension shops in the town that i live in

Ring auto lighn mt wellington In auckland and talk to Ian.

I will make some phone calls when I get a chance next week

Originally Posted by hunt08

I will make some phone calls when I get a chance next week

It’ll be all good, just explain what you are using the ute for, ute tray loads and trailer loads, types of roads. They’ll have a pretty standard product for you on the shelf, pretty sure of that. Remove the old, bolt on the new, not a big job, done it heaps of times myself at home with Hiluxs going back to the early 90s. Even did it once on a hill in Malawi. Carried spare spring packs on the front of the vehicle… very handy to stand on.



(yes, I know, posted probably a dozen times already)

Air bags. I adjust my load regularly

I've used airbags a couple of times on work vehicles, they can be a pain in the arse if for some reason one side ends up at a different pressure to the other. They do seem to improve the ride but to my thinking it's just another thing to have to do. If you are towing all the time but then for some reason not towing and deflate the bags for ride comfort and get a surprise tow job come up you have to pump up the bags. That means carting a damn compressor or pump with ya, just more crap!

My thoughts are just sort the suspension out right first time, get it set up for the loads you normally work with and the vehicle will go better for it. The chassis for one will be happier without smashing the bump stops all the time, and for some vehicles even things like airbags can stress the chassis where it's not reinforced for it.

Just keep in mind that adding cut down springs to spring packs, and airbags, all require cert.

A replacement spring pack perhaps? They're not expensive

https://motortech4x4.co.nz/product/o...hilux-2015-on/

Originally Posted by Tommy

Just keep in mind that adding cut down springs to spring packs, and airbags, all require cert.

A replacement spring pack perhaps? They're not expensive

https://motortech4x4.co.nz/product/o...hilux-2015-on/

Huh, didn't know that airbags require a cert. Also didn't know that a cut down leaf required a cert as well... I'm amazed if they are getting that strict that you can replace the leaf pack with an aftermarket and not need a cert!

But yeah, those leaf packs look about right from where my experience of these things go - they aren't that dear as indicated. But add to that price doing the rear shocks as the factory gas struts just won't handle those springs at all, the biggest single change you can make is replacing the shocks and even just doing the shocks will make a hell of a difference to how the factory springs behave.

I think that the main issue with the factory shocks is that they are designed and calibrated for the vehicle unloaded and they do that well, expect that we in NZ suddenly hang towbars on the back and expect the vehicle to suddenly do the work it's designed to do empty but at full axle loads. Something has to give, and in this case the gas-oil factory shocks suddenly find their operating cycles go up a huge amount and the result is heat. Heat is the enemy of shock oil, the viscosity lowers as the oil heats up and it passes through the shocks valving much more quickly and reduces the damping effect. This in turn means that the springs start getting smacked in to next week with no damping, and this is how the springs end up going past their elastic limit.

The next problem is the suspension at both ends must work together to keep everything pointing the same way - if you upgrade the back end the front will feel like absolute garbage. As a minimum get the matching set of front struts to the back, and retain the factory springs. You may require a spacer on the spring to increase the preload slightly - my understanding of the rules is that provided you don't increase the lift past 50mm and don't have anything adjustable without disassembly you are able to do this without cert. For reference, most of the ute double wishbone front ends run a 2-1 design ratio which roughly means a 10mm spacer increasing the preload on the factory spring gives about a 20mm lift at the wheel. You won't notice the effect of the spacer on travel or articulation in normal conditions.

I'm not putting airbags in I know off other Utes with them & they all hate them & wished they had saved there $1000 & are getting sick off taken them out for wof because they haven't cert them lol

Who makes the best springs is it is it best to go out off town to the likes off arb I have never change the springs or shocks in a vehicle before so that's why I'm asking on here as with only 1 shop coming back to me I'm not getting much advice sure i could chasse them up but I'm more like if they want my $ they will do what they say they will & if they don't I'll go elsewhere lol

Huh, didn't know that airbags require a cert. Also didn't know that a cut down leaf required a cert as well...
I'm amazed if they are getting that strict that you can replace the leaf pack with an aftermarket and not need a cert!
--https://vehicleinspection.nzta.govt.nz/virms/in-service-wof-and-cof/general/steering-and-suspension/steering-and-suspension-systems
the springs or shock absorbers are direct replacements, and
replacement springs are contained within unmodified OE seats throughout full suspension travel (Note 8), and
replacement springs are self-retaining in their seats at full extension, without the use of non-standard devices such as wire-ties, straps, or external spring locators, and
replacement springs have not been heated or cut, and
springs and spring seats are not height adjustable by any means (unless OE) (Note 9), and
replacement shock absorbers, including air-adjustable units, fit unmodified OE mountings (Note 8), and
suspension maintains sufficient travel for safe operation (Note 10), and
suspension components maintain sufficient clearance from unmodified bump stops when fully laden (Note 11), and
Suspension retains at least 40mm of rebound (droop) wheel travel (Note 12), and
a minimum of 100mm ground clearance (unladen and without driver) exists below any part of the vehicle structure, or any steering, braking or suspension component (Note 13) and
the normal relationship between front and rear suspension height is not unduly affected, and
clearance is maintained between all components, when tested from lock to lock at full droop

But yeah, those leaf packs look about right from where my experience of these things go - they aren't that dear as indicated. But add to that price doing the rear shocks as the factory gas struts just won't handle those springs at all, the biggest single change you can make is replacing the shocks and even just doing the shocks will make a hell of a difference to how the factory springs behave.
Yup, you'd chuck some decent shocks at it too
I think that the main issue with the factory shocks is that they are designed and calibrated for the vehicle unloaded and they do that well, expect that we in NZ suddenly hang towbars on the back and expect the vehicle to suddenly do the work it's designed to do empty but at full axle loads. Something has to give, and in this case the gas-oil factory shocks suddenly find their operating cycles go up a huge amount and the result is heat. Heat is the enemy of shock oil, the viscosity lowers as the oil heats up and it passes through the shocks valving much more quickly and reduces the damping effect. This in turn means that the springs start getting smacked in to next week with no damping, and this is how the springs end up going past their elastic limit.
Yep

The next problem is the suspension at both ends must work together to keep everything pointing the same way - if you upgrade the back end the front will feel like absolute garbage. As a minimum get the matching set of front struts to the back, and retain the factory springs. You may require a spacer on the spring to increase the preload slightly - my understanding of the rules is that provided you don't increase the lift past 50mm and don't have anything adjustable without disassembly you are able to do this without cert. For reference, most of the ute double wishbone front ends run a 2-1 design ratio which roughly means a 10mm spacer increasing the preload on the factory spring gives about a 20mm lift at the wheel. You won't notice the effect of the spacer on travel or articulation in normal conditions. Again, that's going to require cert - "Note 8- Strut or spring spacers always require certification."