Lots of threads about how and what it takes to break the damper pulley bolt loose on the XKR, but not much on what tool or how to accurately replace it to the 400-600 ft lbs of torque called for in the service manual. My largest torque wrench only goes to 250 ft lbs (I think). What measures that much torque (for DIYers)?

 

Isn't this the number?


That's 148 foot pounds + 180 degrees, no?

 

The highest torque value I've been able to find (difficult job, that) is 375 nm, 277 ft/lbs. That for both the 10- crank bolt (clockwise threads) and the 12- crank bolt (reverse threads). That was listed for the XF with the SC 5.0 engine, same engine we have. Finding values for the XKR is nigh unto impossible. Many people have discussed and decided that the torque specs in the WSM are invalid. Also, the wheel nut/stud torques are listed in the WSM at like 45 ft/lbs, or something close to that ridiculously low number.
Anyone else with better info on this? I've spent days in the past looking for valid info and this is the only thing I've found.

 

I'll read again, but I thought I read torque to 400 plus then 3/4 extra turn. With all the threads on how difficult removing the bolt is, I thought I checked to find crazy high numbers. I'll read again, this time without the rum.

 

You won't be ABLE to torque it to 400 + 270. The resultant actual torque would probably be in excess of 1000 ft/lb.
I did find what Sean W found, but it was for the 3.0 liter. I also found a torque for Land Rover that was 375nm + 270 degrees. That would be 276 ft/lb + 3/4 turn. That's huge by itself.

 

I copied from the 5.0 Manual, page 914 has the torques specs. That said, I think it wise to leave the question open until someone who's done it before jumps in.

 

Just checked page 914 for the 2010 XKR and it says 148 plus 270 degrees on the chart for "LH" bolt. First does "LH" mean clockwise or counterclockwise threaded? Second, wouldn't the additional 270 degrees still be in excess of 350- 400 lb ft or more? Thanks for the feedback all. Surely someone in the Forumverse has the answer.

 

Just searched youtube for "tensioners". Great video by Atlantic British sort of answers the question even though he's working on a Rover. I suspect the initial torque rating can be handled by a fairly common torque wrench then just muscle and huge breaker bar to finish. I guess the final torque number doesn't matter as long as you hit the 270 degree mark.

 

Just some extra information on the subject of rotation after reaching the specified torque.
Extra rotation is required to drive the bolt into an 'elastic' range, aka stretching the fastener. That is why many fasteners like this, head, and crank shaft bearing cap bolts should always be replaced rather than reused since they have already been stretched once.
Caution though, care needs to be taken not to over stretch the bolt by over rotating it after torque has been reached.

 

So, pretty much like a TTY, or Torque To Yield bolt, but not really. The stretch is built-in and required, I guess? TTY bolts are single-use-only. Are these crank bolts single use?

 

Search "torque wrench extension" as you can create an extension from the ratchet head.
The formula takes into account the length of the torque wrench + the added length of your extension. As the "arm" is longer, the torque setting is lower.
I liked this video for the DIYer.

 

I was just trying to generalize that it best to dispose of the old bolt rather than reuse it because it has gone elastic and nearer the plastic range. So attempting to rotate it again makes it more prone to breakage during installation. I don't remember crank bolts as classified TTY though they may be.
The balancer bolt exerts simple clamp load vs the dynamic loads presented to aluminum head bolts.