Beware of the Double Hex

[dnschmidt]

I've found out another interesting thing about Toyotas. Two of my friends have multiple copies of Toyota trucks and one of them was removing the heads (or trying to) from one of them today to take it in for a valve job. No knock on Toyota the thing has 200,00 miles on it so no harm no file. However we almost made the fatal mistake of thinking that the head bolts were XZN or the notorious triple square that haunt most VW products. NOT THE CASE. Toyota uses a double hex internal design. These look almost exactly like a triple square but the angles of the points are not the same. The triple square naturally uses 90 degree points and the double hex sixty degree points. I knew this from my prior life as a TOPTUL seller so I got there just as he was about to strip out the head of one of his head bolts which would have truly sucked. Luckily NAPA had the special Toyota bit and the head removal went fine. First you need a special funnel now you need a one of a kind head bolt bit socket. These Toyota's are more complicated than I thought.

 

[Ricky Joe]

For the most part, very well engineered. I like them a lot for that reason. Honda is also pretty smart.

 

[KnurledNut]

The triple square naturally uses 90 degree points and the double hex sixty degree points.

DH is 120°.

 

[Walkers]

Isn’t this just 12 point?

 

[Fedwrench]

Isn’t this just 12 point?

I believe it is but, male 12 point.

 

[bubinga]

I believe it is but, male 12 point.

Oh hhhhh....
The socket is actually a male?

 

[Walkers]

I believe it is but, male 12 point.

Ahh, gotcha.

 

[dnschmidt]

Yep, like a Torx but with 12 points set at a 60 degree angle. Draw a hex and then draw another hex on top of it with the point of the second hex being in the middle of the flat of the first hex. KnurledNut is right the actual angle is 120 degrees.

 

[Fedwrench]

CTA 10mm x 12 Point Toyota/Lexus/Scion Headbolt Socket | 705509 | Pep Boys

www.pepboys.com

as an example

 

[bubinga]

CTA 10mm x 12 Point Toyota/Lexus/Scion Headbolt Socket | 705509 | Pep Boys

www.pepboys.com

as an example

Is that the same configuration VW used on the bolts the held the CV axles
Looks like it IIRC

 

[bubinga]

Like this.

 

[KnurledNut]

Euro=Triple Square
Asian=Double Hex

 

[toddmorr]

Other than Toyota head bolts are these double hex used elsewhere?

 

[bubinga]

Euro=Triple Square
Asian=Double Hex

Oh ok got ya. So VW is Triple Square

 

[dnschmidt]

Correct XZN. Except for the times when they're Ribe. VW does some weird *** ****.

Other than Toyota head bolts are these double hex used elsewhere?

I've never seen it anywhere else but I don't do this for a living.

 

[toddmorr]

wow this double hex must indeed be really rare. I thought surely Koken would make a bit socket for it, but not so.
https://kokenusa.com/ nice chart on page 40 of their catalog various socket configs.

you have to wonder, doesn't *anybody* at all review what some rogue engineer specifies on this stuff at the OEM.....

 

[SHIFT]

Koken makes double hex bit sockets in 1/2" drive.

Ko-ken Tools 1/2 Sq. Dr. Bit Socket 8mm Double-Hex Length 100mm For

Input Drive Size: 1/2" Drive Shape: Square Length: 100mm Type: Bit Socket for Cylinder Head Bolt Output Size: 8mm Output Shape: Double Hex Product - Palmac Tools

palmac.net

Ko-ken Tools 1/2 Sq. Dr. Bit Socket 10mm Double-Hex Length 100mm For

Input Drive Size: 1/2" Drive Shape: Square Length: 100mm Type: Bit Socket for Cylinder Head Bolt Output Size: 10mm Output Shape: Double Hex Product - Palmac Tools

palmac.net

 

[thool]

Ok, I'll ask: WHY? Is there some sort of advantage, or is it to prevent curious people with basic tool sets to remove the heads from their Toyota engines?

 

[bubinga]

Ok, I'll ask: WHY? Is there some sort of advantage, or is it to prevent curious people with basic tool sets to remove the heads from their Toyota engines?

I personally think they want to make it difficult for people so you have to use proprietary Toyota tools.

Do the new designs grip better? Quite possibly.

 

[bassJAM]

Wouldn't a regular hex/allen key work on a double hex?

 

[Fedwrench]

Ok, I'll ask: WHY? Is there some sort of advantage, or is it to prevent curious people with basic tool sets to remove the heads from their Toyota engines?

My guess would be ease of automated assembly at the factory. I don't think any manufacturer actually considers maintenance and repair into most designs.

 

[bubinga]

Wouldn't a regular hex/allen key work on a double hex?

Technically I would say it would probably fit but I would not chance it especially on something critical like a head bolt.

 

[bubinga]

My guess would be ease of automated assembly at the factory. I don't think any manufacturer actually considers maintenance and repair into most designs.

They sure do not!
Sometimes I have to think they make it difficult on purpose

 

[dnschmidt]

Size would be my guess. These and the XZN, Ribe, Torx, Torx Plus and whatever else these clowns come up with all attempt to maximize the contact between the bit and the smallest headed bolt that they can get away with. 12pt bolts, which Subaru and many other manufacturers use, along with ARP accomplish the same thing but use a normal socket to accomplish this but the head of the bolt has to be bigger in order to do that. One of these internal configurations should be made an industry standard by DIN or SAE but there clearly is no legitimate need for four or five of them. A normal hex socket is too easy to destroy as most of us have done that but the standards people should pick one of these contenders and scrap the rest.

 

[dnschmidt]

Wouldn't a regular hex/allen key work on a double hex?

Until the torque gets high. Then the probability of strip out goes through the roof as there is very little meat between the points.

 

[toddmorr]

may be thinking about this incorrectly, but I'd assume the double hex to take less torque than the XZN. Why? because the corners bend at 60 degrees versus 90 degrees on the xzn.....same logic why regular hex wrench more torque than 12 point box end. No?

 

[FMB4]

They sure do not!
Sometimes I have to think they make it difficult on purpose

Reminds me of the semi typical German vehicles of the '80s and '90s and their hardwired electrical/electronics.

 

[dnschmidt]

may be thinking about this incorrectly, but I'd assume the double hex to take less torque than the XZN. Why? because the corners bend at 60 degrees versus 90 degrees on the xzn.....same logic why regular hex wrench more torque than 12 point box end. No?

Draw it out. For the triple square draw three boxes on top of each other. For the double hex two hexagons on top of each other. No difference really. Both have twelve points just one (XZN) has sharper points (90) vs the double hex (120).

 

[Milton Shaw]

Torx is probably still patented and every bolt has to be licensed and paid royalty on. Triple square the royalty may be lower on. On the amount of bolts Toyota uses that amount to quite a bit of money. I worked in a GM factory in the mid 60's and if they could design out one screw or fastener in a car design it saved GM over $100,000 a year. So there is big money in screw, nuts and bolts to an auto maker.

 

[Al Borland]

Until the torque gets high. Then the probability of strip out goes through the roof as there is very little meat between the points.

So, same reason we like 6 point sockets on hex-head bolts.

 

[dscheidt]

My guess would be ease of automated assembly at the factory. I don't think any manufacturer actually considers maintenance and repair into most designs.

How many cylinder heads are removed, as a percentage of toyota engines made? It's not going to be a lot, and saving material on engines is worth a lot to them.

 

[dnschmidt]

I don't see where they are saving material. What I do see is that they're saving space which on modern engines is at a premium.