Angle of rotation torque ? - PeachParts Mercedes-Benz Forum

konstan · #1 03-30-2010, 11:51 AM

I searched and I found references to "oh no, not another angle vs torque thread", but I could not find any actual threads that explain this.

So, could someone please explain the "angle of rotation torque" to me in popular terms? What exactly does that funny looking tool do, other than measure the angle and stop me from tightening once the angle is achieved?

vstech · #2 03-30-2010, 12:05 PM

bolts have a yield point of stretch and the angle meter shows you supposedly where that yield point is. if you use specific TTY bolts, and the recommended lubricant, and you are facing the correct direction with your tongue in JUST the right position. you will have a perfect maximum hold on the device you are torquing down.

jt20 · #3 03-30-2010, 12:12 PM

it just measures the angle.

some people fudge it by marking dots on the bolt and head, then guesstimating the rotation of the bolt.

nothing beats the accuracy of that simple tool.

leathermang · #4 03-30-2010, 12:21 PM

Mercedes specifies BOTH Torgue measurements ( in newton / meters which most convert to ft/lbs) THEN the addition of a 90 degree turn added to that situation.
Always check to see if your head bolts are the type which can be reused... or can be measured at the ' waist' ..... or need to be new.

konstan · #5 03-30-2010, 12:25 PM

So I need to order that silly tool? Where can I find it? Is it going to be another hundred bucks??

jt20 · #6 03-30-2010, 12:29 PM

its nice to have.

others use protractors and other measuring devices.

On the flywheel, I think its more important than the head. If you can't find one for cheap, you can rent mine in a few weeks

hope you're not in a rush

leathermang · #7 03-30-2010, 12:31 PM

a two dollar protractor can work just fine..
the main thing is to know how to use the torque wrench properly...
how to hold and read it is important...as the starting point for the 90 degree extra turn...
Note that when you do the extra turn you use a breaker bar or something...not the torque wrench you had on it for the first step..
..Also, you must have some preconditions extant .... Cleaned and lightly oiled threads...and clean threads in the hole... which means you must use a tap and clean out the hole properly if you hope to get the hold down force specified by the engineers.

vstech · #8 03-30-2010, 12:36 PM

autozone has it on the shelf for 9.00...

vstech · #9 03-30-2010, 12:38 PM

Quote:

Originally Posted by konstan

So I need to order that silly tool? Where can I find it? Is it going to be another hundred bucks??

having the silly tool is only 1/2 the battle. you need to make sure your bolts can be reused, and if they can you need to know if they HAVE been reused... new bolts are not a huge investment...

jt20 · #10 03-30-2010, 12:39 PM

Quote:

Originally Posted by vstech

autozone has it on the shelf for 9.00...

really?

I was not so lucky, good info.

konstan · #11 03-30-2010, 12:53 PM

Going to autozone for lunch break. This meeting is taking too long.

DeliveryValve · #12 03-30-2010, 01:14 PM

.

As stated above TTY (torque to yield) bolts stretch at a given point compared to conventional bolts. TTY bolts are used on the 617 are on the cylinder head, flywheel and con rods.

TTY Bolts for the most part should always be replaced. As posted previously, they can be measured for stretch length or width at the neck and reused if within spec.

Examples from the FSM.

Cylinder head bolts.

Flywheel bolts.

As posted previously, there is a procedure required for TTY bolts. The initial torque settings and then final turn of the bolts measured in degrees.

FSM example procedure. This one is for the cylinder head.

Simple Angle of Rotation Gauge/tool needed for the procedure.

Can also be found at sears for $13.99. Cheap and smart enough to have.
http://www.sears.com/shc/s/p_10153_12605_00971020000P

.

konstan · #13 03-30-2010, 03:36 PM

I am a proud owner of a new angle of rotation tool from a-zone... Do u guys want to see pix?

leathermang · #14 03-30-2010, 03:38 PM

Sure, love to see pictures....

leathermang · #15 03-30-2010, 03:42 PM

As to replacing the head bolts with new ones " on principle" as Mercedes uses for ' recommended procedure'...
The incredible amount of work it takes to replace a head gasket makes the cost of a new set of bolts a really really cheap insurance investment... Same with a tap of the right size to clean out the block holes.... a little care and patience at the proper time is important.
There are a couple of other sized bolts holding the head on... don't miss them...