Is the 150 showing any signs of cracked inner guards

[krypto]

Finally had time to have a look at the new guard design, picture attached below. Also included a picture of an old style cracked guard.

I now understand why the cracking has been occurring and what Toyota have done to address the problem. My mechanical engineering design theory is pretty rusty but I'll try to give a brief explanation.

If you look under the guard you will see that the body, of which the guard is a part, is supported by a rubber mount at the front of the guard next to the radiator. The other mount is at the back of the guard just below the front door hinges. This in effect turns the guard into a 'bridge' and the battery creates a point load on the bridge (guard).

I have attached a diagram that shows what this looks like in terms of force and bending moment. The bottom diagram is the bending moment graph for the bridge, the one above it is the shear force graph.

The failure point on the guard is in tension and more than likely close to the point of greatest bending moment. The design of the bridge (guard) is not a problem in day to day driving but on corrugations or with sudden loads due to hitting bumps etc the force exceeds the capacity of the thin tensile section of guard causing it to fail. Microscopic examination would probably show some necking (thinning) around the crack, which precedes failure in this type of event.

The new guard solves this problem by changing the shape of the area under the greatest load, the bottom of the guard, and by providing double the strength in the high load area through the using of a spot/thermal welded backing strip.

The fact that Toyota have made this change clearly shows that they identified and rectified a design weakness. They will be hard pressed to deny a claim for cracked guards based on this evidence.

[rob_macca67]

Rob, had another look last night and it may help to run a support from the battery clamp. It is possible to run a support from one of the battery clamps back to a bolt next to the fuel filter mount. If done right that transfers some of the load to a completely different area. Any load put on the front near the radiator may still be transferred through the guard. Hard to really know without pulling apart or seeing detailed structural drawings.

Will have a look at it when I can....

[krypto]

That's what I've done for my Aux Battery - reduced the physical size/weight + I've added the extra support to the radiator support panel to prevent any fwd/rev movement..... so far so good.....

Rob, had another look last night and it may help to run a support from the battery clamp. It is possible to run a support from one of the battery clamps back to a bolt next to the fuel filter mount. If done right that transfers some of the load to a completely different area. Any load put on the front near the radiator may still be transferred through the guard. Hard to really know without pulling apart or seeing detailed structural drawings.

[rob_macca67]

That's what I've done for my Aux Battery - reduced the physical size/weight + I've added the extra support to the radiator support panel to prevent any fwd/rev movement..... so far so good.....

Unfortunately not so simple, need to either strengthen the guard or find a way to reduce the downward force exerted by the battery over bumps. Reducing the size and weight of the battery would be a great first step.

My mate has a much smaller auxiliary battery and that guard hasn't cracked.

Might not be so easy transferring the weight to the chassis as the body and chassis are sort of independent. Good luck with it.

[krypto]

Would replacing the top part of the battery tie-down that goes across the top of Battery - Just extend this across to the Radiator Support Panel & use this as another supporting mount point. This would prevent any forward/backward moment.

Unfortunately not so simple, need to either strengthen the guard or find a way to reduce the downward force exerted by the battery over bumps. Reducing the size and weight of the battery would be a great first step.

My mate has a much smaller auxiliary battery and that guard hasn't cracked.

[rob_macca67]

Yes both sides are a new design.

Incidentally got a chance to have a close look at a cracked guard and the crack opens and closes as you push down on the battery. So a simple solution is to cross brace the battery tray to another part of the chassis to transfer the load away from the guard. I'm going to have a look at doing that with my car and will post pictures if I do it.

Would replacing the top part of the battery tie-down that goes across the top of Battery - Just extend this across to the Radiator Support Panel & use this as another supporting mount point. This would prevent any forward/backward moment.

[krypto]

What about the Drivers side.... has that changed as well?

Yes both sides are a new design.

Incidentally got a chance to have a close look at a cracked guard and the crack opens and closes as you push down on the battery. So a simple solution is to cross brace the battery tray to another part of the chassis to transfer the load away from the guard. I'm going to have a look at doing that with my car and will post pictures if I do it.

[krypto]

Does the v6 have the same size main battery as the d4d?

[rob_macca67]

Yep, had a look today. Whole new design.

What about the Drivers side.... has that changed as well?

[krypto]

When you say the new one has a double skin, are you referring to the facelifted 2014 model?

Yep, had a look today. Whole new design.

[rob_macca67]

Just took the kids down to the park and saw a 150 in the carpark. Had a look and both guards cracked, took photos. Looked like it had done some dirt work.Common factor might be dirt roads, the two Prados with cracks have done regular trips on corrugated roads.

I reckon u hit the nail on the head here... A friend of mine use to work for a Hire company that hires vehicles to the mining companies..... he showed me a couple of prado pics where the whole LHS battery tray was ripped clean from the inner guard and swinging in the breeze.....Letting tyre pressures down if you're crossing corrugated roads for hours on end is the key i reckon too....

When you say the new one has a double skin, are you referring to the facelifted 2014 model?

[krypto]

Just took the kids down to the park and saw a 150 in the carpark. Had a look and both guards cracked, took photos. Looked like it had done some dirt work.

Common factor might be dirt roads, the two Prados with cracks have done regular trips on corrugated roads.

[krypto]

Geez, this is a worry..... Just checked mine and it's all OK. Just wondering if it would be wise to bend up & shape a thin piece of sheet metal to the inner guard shape and bolt it in place.....

The solution is that simple. The new one just has a double skin. Have a look at one.

It's not really structural, but also not sure how far it will crack.