Always use the right tool (torque heads)

[mpetry]

OK, so I've searched this forum and the rebuilding forum, looked in the bentlley, etc, and cannot (quite) get the answer to this.

Next valve adjust I'm going to torque the heads, since my rebuild has 5000 miles or so on it. Running fine, no oil leaks or strange sounds.

I cut a 10mm allen key to do this job - my question is - how long should I cut it, so that I can get the torque wrench in on those pesky ones in the back ? I'd rather get it cut in advance since it's a PITA. Can somebody measure their Porsche 10mm allen tool and let me know ? Right now I've got mine at 6" / 155 mm, see pic.



thanks muchly

Mark Petry
Bainbridge Isand, WA

[dtw]

Huh? Just go to Sears and get a set of metric 3/8" Allen sockets. That and a 3/8" extension and you're all set.

[James Brown]

yes the allen head should be 10 MM and you add a 3/8 extention to the torque wrench. the reason is the long allen sockets are "softer" then extentions so the torque value is more accurate.

NAAAAAA just kidding, your overthinking this! 6" inch allen socket is fine or do what DTW did, a lot easer.

[dtw]

Ohhh now I see the pic...that thing should probably be fine...

[mpetry]

on the 356 cars the socket would not get in there, you needed the "long allen".

much appreciated.

Mark Petry
Bainbridge Island, WA

[RWebb]

by softer, he means less stiff - the Allen bit can twist, making the torque inaccurate

I've never measured this but a mech. told me that & it makes sense.

[Wavey]

like a torsion bar

[Jim Sims]

"by softer, he means less stiff - the Allen bit can twist, making the torque inaccurate

I've never measured this but a mech. told me that & it makes sense."

Wrong, the torque will be the same at both ends of the bit no matter how long it is. The mechanic is confusing torsional deflection ("windup") with torque - they are not the same.

[RWebb]

thx Jim. Now that you explain it, that makes sense. There would not be a difference until velocity or accel. changed.

[mpetry]

at 25 foot pounds, I doubt it would wind up very much.

any idea if I'm in the ballpark on length ? Pretty cramped in that engine compartment.

Mark Petry
Bainbridge Island, WA

[j_mancini]

Originally Posted by mpetry

at 25 foot pounds, I doubt it would wind up very much.

Agreed. 25 ft-lb is not a lot of torque, hard to imagine it making any difference. If you were twisting 180 ft-lbs-- that's different.

[RWebb]

seems no one knows the length - I sure don't remember

try: PET (tools section); Wayne's book; Bruce Anderson's book - IIRC, there is a table with all the tools you need on one page

[prschmn]

Twist in the driver isnt going to make any difference-the torque is still the same. Now if you were torquing by angle-that would be messy

[MBEngineering]

HI Mark Petry
Bainbridge Isand, WA

the Porsche tool for you 8in total length and 1/2 in drive,






regards Mike Bainbridge

[mpetry]

that is BEAUTIFUL!

On ebay now ? I'll check.

thanks man

Mark Petry
Bainbridge Island, WA

[James Brown]

HOW TO COMPUTE TORQUE WHEN USlNG ADAPTORS

If an adaptor or extension is attached to the square drive of a click-type torque wrench and this adds to its length, then the applied torque will be greater than the pre-set torque. A formula can be used to find what the preset-set torque should be in order to obtain the correct applied torque.

Here is the formula:

preset torque = torque wrench pullpoint X torque desired
.....................torque wrench pullpoint X extention lengh

this becomes RS= A X T
.........................A + B........WHEN

RS= A X T OR 12 X 30 OR 360 OR 20 FT/LB
....................12 X 6.......18

RS = Torque setting of the torque wrench.



A = Distance from the center of the square drive of the torque wrench to the center of the handle grip pull point.
B = Length of the adaptor from the center of the square drive to the center of the nut or bolt. Use only the length which is parallel to the handle. See figure 1
T = Torque desired. This is the actual torque applied to the fastener. Here is a typical problem: What should the setting be when ‘‘A’’ is 12’’, ‘‘B’’ is 6’’ and ‘‘T’’ is 30 Ib. ft.

Therefore 30 pound foot of Torque will be applied at the fastener when ‘‘RS’’ is 20 pound foot.

Note: If the torque wrench reads in pound foot, then ‘‘T’’ should also be in pound foot. ‘‘T’’ and ‘‘RS’’ should be in the same unit of measurement. ‘‘A’’ and ‘‘B’’ should also be the same unit of measurement.

Hope this helps or just muddles the waters. if the torque is 25 ft/lbs, I don't think this matters much.

[James Brown]

just some more torque fun, doesen't really apply in this case, just for extentions FWIW

[prschmn]

It should be understood that this does NOT really apply to "extentions" but things along the line of a crowsfoot such as you'd use for old style cam nuts. Only an attachment that increases the overall length of the torque wrench has this effect.

[James Brown]

like a "extention"

[James Brown]

like this one, B in the diagram