| Trans installation question [message #351101] |
Tue, 31 December 2019 05:01  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
|
Senior Member |
|
|
Well I re-installed my trans a couple of days ago. Then I ran around with a torque wrench tightening everything up. There are three 7/16" bolts on the rear of the trans that mount it to the vertical bracket with the rear trans on it.
The version of the manual I have says they are 3/8"x 16 bolts and are torqued to 55 ft-lbs. They are really 7/16" bolts so the book is in error on the size. They go through the bracket and thread in to the aluminum rear of the trans. 55 Ft-lbs seems awfully high to be threading into aluminum.
Then I got thinking that maybe GM put Heli-coil type inserts in to those aluminum holes so it could be tightened to 55. I can not see in there now because I have the trans installed.
Does anyone know if there are heli-coil type inserts in there?
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
[Updated on: Tue, 31 December 2019 18:22] Report message to a moderator |
|
|
|
|
|
| Re: Trans installation question [message #351103 is a reply to message #351101] |
Tue, 31 December 2019 07:33  |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
|
Senior Member |
|
|
None of the ones I've messed with (more than I wanted) had anything but a threaded case.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
|
|
|
|
|
|
| Re: Trans installation question [message #351124 is a reply to message #351102] |
Tue, 31 December 2019 18:20 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
|
Senior Member |
|
|
Thanks guys. What you do think about 55 ft-lbs torque into aluminum 7/16 - 14 UNC (course) threads?
I just found a bolt chart on line that says grade 2 - 24 ft-lbs, grade 5 - 37 ft lbs and grade 8 - 52 ft-lbs. No where in the chart do the address being threaded into aluminum.
Maybe I am being overly pessimistic, but unless I find something to the contrary I think I'll go with 25 ft-lbs. I am not worried about the bolts. I am worried about the aluminum case threads.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
|
|
|
|
| Re: [GMCnet] Trans installation question [message #351140 is a reply to message #351124] |
Wed, 01 January 2020 05:09 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
|
Senior Member |
|
|
Just "turn 'em ' till they're tight", Ken. I want to watch you get a
torque wrench up in there anyway. :-)
Have you followed my suggestion to drill an access hole in the step riser
behind the top left bolt? Sure makes that go in a lot easier. Before
that, I'd sometimes spend as much time on it as the rest of the
installation.
HAPPY NEW YEAR!
Ken H.
On Tue, Dec 31, 2019, 7:21 PM Ken Burton via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Thanks guys. What you do think about 55 ft-lbs torque into aluminum 7/16
> - 14 UNC (course) threads?
>
> I just found a bolt chart on line that says grade 2 - 24 ft-lbs, grade 5 -
> 37 ft lbs and grade 8 - 52 ft-lbs. No where in the chart do the address
> being threaded into aluminum.
>
> Maybe I am being overly pessimistic, but unless I find something to the
> contrary I think I'll go with 25 ft-lbs. I am not worried about the
> bolts. I
> am worried about the aluminum case threads.
>
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
|
|
|
|
| Re: Trans installation question [message #351143 is a reply to message #351101] |
Wed, 01 January 2020 08:39 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
|
Senior Member |
|
|
I bored the hole in my step. Saves half an hour per install. And I simply apply blue LocTite<tm> to the bolts and snugged them up nicely. I'd be interested in someone else's luck with 55 ft lbs into that case, preferably tested on a broken case. Then if it takes the threads out, no loss and we have the answer. When I got the coach, it had some transmission shop's label on the bumper, and had only two bolts tight on the bellhousing. One missing, the rest finger tight. Ran it two thousand miles home that way without it falling out. Currently the mount bolt for my compressor which goes into the intake has stripped the threads. Since it's winter I haven't addressed it, and probably won't unless or until I need the dash air. Given the length of the bracket to that bolt, there's a pretty good level to put stress on it. I suspect a helicoil <again tm> is in my future.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
