TPC Motor Mount Upright Question

I just finished mating my rebuilt 2002 LS-1 motor to my Porsche front cross-member using 2014 vintage TPC motor mounts.

All went well as documented in my project thread, however one area that is still unresolved is the proper torque to be used on the upright mounting stud nut.  When I asked Kent at TPC, he suggested I pose this question to the forum.

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I worked the advanced search the best I know how and did not find any discussion on this topic.

With all the successful builds out there that use the TPC mounts or similar, I'm hoping that someone can get me and the rest of us correctly "torqued."

Thanks in advance!!

I remember looking for the same spec and could not find it either. Ended up just making an educated guess based on the stock LS and Porsche specs. Cannot recall what numbers i settled on.

Torque specs are largely based on material spec and fastener diameter.
I would guess the fastener is a typical grade, SAE 8 or Metric 10.9. I can't recall whether these were metric of SAE.
Measure the diameter and determine the unit system, then look up torque specs. Fastenal has torque specs.

948 wrote:Torque specs are largely based on material spec and fastener diameter.
I would guess the fastener is a typical grade, SAE 8 or Metric 10.9. I can't recall whether these were metric of SAE.
Measure the diameter and determine the unit system, then look up torque specs. Fastenal has torque specs.

Agreed! I'm in the process preparing a torque table and will publish my findings later this afternoon.

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Those are 1/2" grade 5 bolts.

As noted in my last post, I began preparing a recommended Metric Fastener Torque table based on data from Bolt Depot.  However, as I continued to snoop around the Internet, I found a better table already prepared on the Fastenal site, just as “948” eluded to.  Importantly, it included data based on different fastener conditions such as lubricant and zinc plating.   This is very useful as most of the hardware we use is plated for use in aluminum plus we often use anti-seize.  Below is the link:

Fastenal Torque-Tension Chart for Metric Fasteners
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Someday the link may be broken so I made a JPEG image of the table and it’s shown below. Hopefully I’ve credited Fastenal enough to preclude any copyright issues. (Plus, it’s not being sold!!)

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In the chart, I’ve highlighted two common bolt/nut sizes in our conversions, M10 and M12.

CORRECTION:
My TPC upright has a zinc plated 1/2"-13 SAE stud and Kent from TPC has confirmed it is an SAE Grade 5 material which is equivalent to Class 8.8.  From the SAE chart below, to maximize the clamping force of 9,046 pounds, the torque applied to the mounting nut should be 75 ft-lbs. For plated fasteners, K=0.20.
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I don’t know if the required “design” clamping force is anywhere near 9,046 pounds, but if the stud weld is good, there is no harm in it.  

TPC Motor Mount Torque Conclusion:  
Engine Block Bracket Bolts: 37 ft-lbs
Bracket Thru Bolt: 75 ft-lbs (head) / 59 ft-lbs (nut)
Upright stud: 75 ft-lbs.

…and there you go!!  

Below are some additional links from Bolt Depot for more information.  If you find something you like, I recommend that you copy it for future use.

Bolt Depot – Recommended Metric Bolt Torque
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Recommended Metric Bolt Torque (apparently plain and dry)
Diameter Class 8.8 Class 10.9
(mm)Nm / Ft-Lbs Nm/Ft-Lbs
5               7 3.7      9 6.6
6              12 8.8    16 11.8
8              30 22.1    40 29.5
10            55 40.6    75 55
12          100 73.8   135 99.6
14          160 118   215 158.6
16          245 180   335 247
20          480 354   650 479

The ft-lbs values listed above were converted by me.  Note they are slightly different than those published by Fastenal Engineering Design and Support.

Nm to Ft-Lbs Converter
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Bolt Grade Marking and Strength Chart
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Metric Bolt Head / Wrench Size
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Metric Nut / Wrench Size
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Hotrodz of Dallas wrote:[You must be registered and logged in to see this link.]

Those are 1/2" grade 5 bolts.

Bob,

You got me wondering so I checked the thread pitch on my upright studs and sure enough, they measure 13/inch as per my thread gauge.  Kent told me they were 8.8 material 1/2"-13 but my brain shut off after reading "8.8"

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This means that I incorrectly concluded that my 12 mm stud diameter measurement was for an M12 bolt vs. the 1/2" SAE bolt that it is.

Revisiting the Fastenal torque chart for an SAE Grade 5 -1/2 stud/bolt:
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Based on this revelation the nut torque required for a maximum clamping force of 9046 pounds is 75 ft-lbs.

I'm off now to correct my last TPC Motor Mount post.

Thanks Bob!!!