Body Lift blocks

[dawg runner]

Gday,

Just a question on Body lift blocks.

Spoke to the engineer the other day and he advised me to get the metal type so i did not have to get crush tubes. He aslo advised to put a champher on the botton of it to stop them cutting into frame.

I would much rather put poly urethane ones in with crush tubes as they seem to be readily available. Would i need to put a champher on these or will they be fine?

Thanks

Dave

[90Mav]

i wouldn't champher them, will just reduce there contact diameter. And i can't see PU cutting into metal...

[Dak Dak]

Gday,

Just a question on Body lift blocks.

Spoke to the engineer the other day and he advised me to get the metal type so i did not have to get crush tubes.

Dave,

What are 'crush blocks' and why are they necessary?

Thanks.

[Wild West]

I thought you could only get alloy ones engineered now.

[Cruza62]

I've got steel blocks, got a mate to turn them up. They are starting to rust cos the paint's comin off. Going to replace them with aluminium blocks, for the extra cost - its well worth it.

[dawg runner]

Thanks guys.

Spoke to the engineer just before and he said he will only cert aluminium blocks.

Dak dak - Crush tubes are to stop the bush compressing or so i am told.

Cruza62 - How soon do you thing you will be replacing them? Do you know where to get Aluminium blocks? Are you going to buy meterial and get your mate to turn them up?

[Cruza62]

Yep, well in the middle of doin a 12ht conversion and full respray, and I'm takin the original blocks out to fit it in the garage for respray. The original blocks are definitely not going back in (rust), so yep it will be soon. Haven't priced aluminium bar yet though, it's pretty expensive stuff. If you're located close enough (I'm in Vic, SE suburbs), I might be able to get some whipped up for you aswell. What diameter do you need? I think the blocks under mine are bout 60 - 65 mm...

[dawg runner]

I am in NSW.

Is no biggy my bro lives down there.

Will take some measurements and get back to you.

Thanks

Dave

[chimpboy]

I would go metal for sure in case you want opinions. Aluminium ones are not really very expensive, especially if you just get them cut from rod and then drill the holes yourself.

[muckute]

I went steel for my blocks because of price, just went to local steel mart and got them to cut off 6 bits of bar for me and i just drilled them myself.

Ended up about 1/4 price of rubber or P/U ones that 4WD shop was selling

[Spimon_NH]

Crush tubes are to stop the bush compressing or so i am told.

I think you've been misinformed. If the bushes compressed enough that the weight of the body was supported by the inner tubes, they'd probably punch right through the floor.
Let's exaggerate and say the cab and occupants of a HiLux weigh 1000kg. That's putting bout 0.8MPa (116psi) of pressure on each block (6 of @ 2" wide).

HDPE has a compressive strength of 17 MPa (~2,465 psi).

Steel is MUCH stronger. AISI1020 MS or 'normal' mild steel has a compressive strength of bout 420MPa (~60,900 psi).

Aluminium (just normal alumunium, nothing fancy) has a compressive strength of bout 90 MPa (~13,000psi).

All these are plenty strong enough to use as lift blocks. The 'crush tubes' (silly name) are there to stop the bolts wearing on the plastic (possibly caused by vibrations from the road, engine etc..). Although there shouldn't be any movement anyway, once everything is tightened up properly.

I'm not sure why only metal ones are being passed by RTA,DOT etc. My guess is that with aluminium or steel it's easy for the inspector to be sure (every grade of steel or aluminium I know of is strong enough) but with plastics it's hard to pick what type it is.

Some plastics can look and feel almost identical, but have very different mechanical properties.
For example, there's often no physical difference between UV stabilised plastics and non UV stabilised plastics. Even the compressive strength of Nylon (type-6) can be almost doubled by injection moulding and extusion, rather than casting but after they've been turned into body blocks there's no physical difference.
It's much easier and safer to just outlaw all plastics, even though the right grades are perfectly safe (umm, except in a fire I guess).

[muckute]

Crush tubes are to stop the bush compressing or so i am told.

.
It's much easier and safer to just outlaw all plastics, even though the right grades are perfectly safe (umm, except in a fire I guess).

after the fire i don't think the lift blocks are going to be the biggest concern