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Fixing transfer case mounting threads or use longer bolt

yeti

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Joined
Oct 13, 2010
Messages
800
Location
san diego california
So I just swapped the clutch and when I took off the transfercase only two of the long bolts were mounting it.

So I grabbed a spare long bolt but the first few threads in the transmission are blown so it just rotates, I pulled the TC down and inserted the bolt into the tranny alone and it grabbed fine as there is extra length the that hole. ( top mounting bolt )

My question is , am I better if ordering a 12x1.25x150 bolt to insert inside in place of the 12x1.25x130 OEM bolt.

I could try a heli coil but I’ve never personally used or installed one.


Also linked is a picture of the bolt I’m going to order if local parts store has nothing for me

I know it should be grade 12.9 correct?
This one is titanium grade 5 will that work?

Sorry for the ridiculous questions, any help is appreciated
 

iceman69510

Turn Right Racing
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Mar 5, 2001
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10,918
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Longer bolt may work and be fine. That said, thread engagement may be an issue and possibly lead to pulling more threads. That's an expensive bolt.:)

I personally advocate fixing once and trying to keep hardware normal. I hate having to remember special fastener applications. I have one location on a car where it uses a 10x1.5 thread bolt because of a previous helicoil job instead of the normal 1.25 thread, and it drives me crazy.

Helicoil should work ok in those locations. Alternative are Timeserts, but they are more expensive. I use those in the cylinder head holes for the exhaust studs where expansion and contraction causes much higher tension forces on the studs.
 

yubh8tn

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Aug 21, 2019
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coeur d alene, idaho
Same thing happened to me. I had never done helicoil before but I did it just fine on those bolts. It was actually extremely easy, just used a corded drill and watched a couple youtube videos. Only problem is that the oil pan gets in the way of the highest one, so I ran without that bolt for a while. No problems, but now that my engine is out I went ahead and did that last thread.

Just helicoil it! That way you're not doing anything sketchy and you learn a new skill! /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif
 

VR6Eater

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Jan 22, 2013
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87
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Bristol, WI
Have a Helicoil in the front hole on mine also. Plus another one for the front lower trans to engine. I think you might have to trim the coil down a few threads for proper length but its a pretty straight forward deal. Like the others have said, couple youtube videos and once you've done it once you will end up with a drawer full of kits.
 

yeti

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Joined
Oct 13, 2010
Messages
800
Location
san diego california
Ok sweet thanks for the reply’s

That bolt was gonna take about a month or more to get here from China so I ordered a grade 10.9 zinc bolt ( pics included)

And figured fork it and ordered the two smaller bolts ( 12x1.25x70 in the transfer case from the same company same style bolts 10.9 zinc

Anyone know what grade bolts the transfercase mounting bolts are? Says #7 on the bolt idk what the means in Mitsubishi

I’m hoping these will do for the repair, if not I guess I’ll be re dropping the tranny to drill and helicoil
 

JNR

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Apr 23, 2004
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9,802
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ca
The '7' marking on the heads is a proprietary number, although many oem's seemingly use the same ID...IIRC the strength is ~ metric class 8.8 (or similar to grade 5 in SAE/std)

EDIT - given the choice, use a Timesert over a Helicoil. More expensive, but definitely better, overall...they sell install kits but what I did was make a drill bushing to keep the hole straight, sourced the drill bits and tap(s), plus the counterbore. Sounds like a lot of parts, although it's really not.

BTW - Class 12.9 is probably overkill as it's similar in strength to Grade 9 SAE/std [think like an F911 bolt]...Sounds like you may have ordered them already but I have some 12.9 'blue' bolts and could check the size/pitch and length if you're still looking...I do recall them being pretty long.
 
Last edited:

iceman69510

Turn Right Racing
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The number on the heads is a JIS strength rating. I don't remember the exact units and don't have access to JIS spec books anymore. As SAE fasteners yield strength is measured in psi, JIS are kilograms/cm2 or something like that. A 7 bolt is 70,000 or something like that, is what I remember. they are not the same as ISO. I have yet to find a good resource for this info online.
 

yeti

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Joined
Oct 13, 2010
Messages
800
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san diego california
So I got my new bolts and they are too large. Fork me,
The long bolt is too long as that hole only goes maybe another 10mm into the tranny and the bolt is 20mm longer than Oem.

Also the small bolts I ordered are nearly too big of bolts to be torqued down with a socket and torque wrench as it has a 19mm head opposed to a 17mm and comes in close clearance with the transfercase itself so the only option is to use a open ended wrench for the last 20 or so turns.

I also noticed that every hole that I’m missing the bolts for look to have worn threads and won’t catch the bolt so I went to the auto store and got some bolts with different thread pitch in hopes to grind a temporary thread in until the next time I drop my trans.

My only worry is damaging the tranny threads so much with these thick threaded bolts.

Someone else said they did this and haven’t had any problems for 9 years so far.

I was thinking for the long one I could just use a bunch of washers? Or is that not how fasteners work lol.

Once again sorry for the dumb questions.
 
Last edited:

CutlassJim

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Jul 17, 2006
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1,694
Location
Manchester, NH
</font><blockquote><font class="small">Quoting yeti:</font><hr />

I’m hoping these will do for the repair, if not I guess I’ll be re dropping the tranny to drill and helicoil


<hr /></blockquote><font class="post">


Bel-metric is the sh*t. And about 7 minutes away from my work. <img src="/ubbthreads/images/graemlins/cool.gif" alt="" />

I'd take the 20mm longer bolt and cut 11mm off it before I shoved a random larger bolt in there.
 

yeti

Well-known member
Joined
Oct 13, 2010
Messages
800
Location
san diego california
That’s awesome ya I called them directly, seemed like a cool company.

How should I go about cutting a bolt properly? A cut off wheel? Hacksaw?

Also would putting a bunch of washers to make up 10mm a decent idea? Or will I not get proper torque and it will loosen over time or something
 
Last edited:

JNR

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Apr 23, 2004
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9,802
Location
ca
Put a nut on the backside of the cut. Afterward, by loosen the nut off past the cut area it helps clean the threads. Otherwise, you may have a difficult time threading it in the hole properly.

Cut to, or use the proper size and don't apply the band-aid of washers, especially 3/8" worth of thickness.

Why did you order the fully threaded, or is that all they had?
 

988

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Feb 3, 2011
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151
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Malaysia
I Have All 5
 
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