Transmission to bell housing bolt torque

[bkahler]

I searched through the forums and I've looked in the service manual and can't find the number.  I believe the bolts are 9/16-12 and searching online I find specs for grade 5 and grade 8.  Grade 5 is in the 70s to 80s and grade 8 is over 100 up to 115 or so.

 

I'm guessing the mounting bolts are grade 8 or better but I'd hate to torque a grade 5 to a grade 8 spec!

 

Anyone know the torque number?!

 

Thanks!

 

Brad

Edited December 26, 2019 by bkahler

[kencombs]

I think those bolts have a 9/16" head, but are 3/8" bolts.  Probably  no more than grade 5.  Grade 8 is normally reserved for certain engine or suspension fasteners or critical areas.  These fit neither of those criteria.  I'd shoot for 20something ftlbs.  Or find a chart and get the real value for grade 5 3/8x16.

[bkahler]

5 minutes ago, kencombs said:

I think those bolts have a 9/16" head, but are 3/8" bolts.  Probably  no more than grade 5.  Grade 8 is normally reserved for certain engine or suspension fasteners or critical areas.  These fit neither of those criteria.  I'd shoot for 20something ftlbs.  Or find a chart and get the real value for grade 5 3/8x16.

 

Morning Ken,

 

The heads on the bolts are 15/16" (or was it 7/8"?!).  Regardless, they are definitely not 3/8".  I was thinking the bolts were 5/8" diameter but I found a post that mentioned them being 9/16" which led to my torque search for 9/16" bolts.  I will verify size tonight.

 

The bell housing to engine block bolts are 3/8" as I removed a couple of those last night.  

 

Brad

 

[JBNeal]

I've had older mechanics tell me that if it isn't spelled out in the shop manual, then torque bolts hand tight +1/4 turn, which should be about 30-35 ft.lb...screws smaller than 1/4" should be finger tight + 1/4 turn max or they'll strip faster than a girl named Destiny

[bkahler]

7 minutes ago, JBNeal said:

I've had older mechanics tell me that if it isn't spelled out in the shop manual, then torque bolts hand tight +1/4 turn, which should be about 30-35 ft.lb...screws smaller than 1/4" should be finger tight + 1/4 turn max or they'll strip faster than a girl named Destiny

 

Hmm.....any idea where I can meet Destiny? ?

 

Those older mechanics must have had crescent wrenches for hands!  For me a 1/4 turn on a 9/16" bolt with a lock washer won't even compress the lock washer!   

[kencombs]

3 hours ago, bkahler said:

 

Morning Ken,

 

The heads on the bolts are 15/16" (or was it 7/8"?!).  Regardless, they are definitely not 3/8".  I was thinking the bolts were 5/8" diameter but I found a post that mentioned them being 9/16" which led to my torque search for 9/16" bolts.  I will verify size tonight.

 

The bell housing to engine block bolts are 3/8" as I removed a couple of those last night.  

 

Brad

 

You're correct of course.  I read  bellhousing and missed transmission then substituted engine for it.    Anyway, I just checked a bellhousing laying in the shop.  The holes are for a 1/2x13 bolt.  Probably a grade 5 as mentioned earlier. That would require a 65ftlb torque setting according to an online torque chart.   Not a high stress location. 

[JBNeal]

I have to agree with DC about torquing by feel, it's how I was taught...with practice you can tell when helical lock washers have flattened and that's when the +1/4 turn is added.

 

Now if you're looking for Destiny, there seems to be one in every town...but one man's Destiny could be another man's disaster, especially if ya get caught watching the paint dry ?

[bkahler]

47 minutes ago, kencombs said:

You're correct of course.  I read  bellhousing and missed transmission then substituted engine for it.    Anyway, I just checked a bellhousing laying in the shop.  The holes are for a 1/2x13 bolt.  Probably a grade 5 as mentioned earlier. That would require a 65ftlb torque setting according to an online torque chart.   Not a high stress location. 

 

Not 1/2" either.  I just measured the bolt and it's 9/16.  

 

The attached picture show a 3/8, 1/2 and my transmission mounting bolt.  Assuming grade 5 that would place the torque range at 82 to 91 ft/lbs.  

 

[bkahler]

8 minutes ago, JBNeal said:

I have to agree with DC about torquing by feel, it's how I was taught...with practice you can tell when helical lock washers have flattened and that's when the +1/4 turn is added.

 

For the most part I used to torque by feel and never had issues.  I had heart surgery a little over a year ago and I still don't have the strength in my right arm that I used to.  It's getting better but when it comes to the large bolts I feel more comfortable using a torque wrench.  I'm pretty sure when I installed them the first time 20 years ago I didn't use a torque wrench and they were more than tight enough when I tried to remove them the other day!

 

8 minutes ago, JBNeal said:

Now if you're looking for Destiny, there seems to be one in every town...but one man's Destiny could be another man's disaster, especially if ya get caught watching the paint dry ?

 

I've had my share of disasters and I certainly don't like watching paint dry!  Oh well....... ?