Stripped Subframe mount

593 Views 24 Replies 9 Participants Last post by Saaberachi, 14 d ago

Saaberachi

Discussion Starter · 23 d ago

One of the nuts for the middle subframe bolt is stripped. Not completely, but its going. The last time was one of the rears. On that one i drilled & tapped it out one size bigger & its been holding great. Do you guys think a helicoil or time sert would be enough on this middle mount? Or should i drill & tap again? The middle bolt is the biggest with it being 14x1.5 already I believe. So that would mean tapping it out to 16 by 1.5 I guess. I'd really rather not go that big

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jvanabra

· #2 · 23 d ago

There's no reason why a thread repair is a bad idea here... Except that M14 is really expensive!

I would prefer a timesert here only because there is no possibility of it being pushed out the backside of the, what, weld nut? That said, either option is going to require drilling it out... It may not end up being much different tapping for M16 or timesert all said and done.

Reactions: 1

Saaberachi

Discussion Starter · #3 · 23 d ago

Ya time serts are nice but im seeing the kit coming in around $150 online! Nobody local has them. I need it done asap & would rather not spend that much on tightning one bolt! Lol i think i can get a new tap & bolt for around $40 or less. Helicoil is cheaper than timesert but for m14 it said 40 ft lb max torque so thats about 100 pounds less than spec

jvanabra

· #4 · 23 d ago

Wow, I am surprised the helicoil has such a low rating... what good is an M14 at 40 ft lb? :/

Saaberachi

Discussion Starter · #5 · 23 d ago

Ya me too. Seems too low huh, maybe i should dbl check those figures on a different site.

Carfixer2

· #6 · 23 d ago

If I remember correctly a heli-coil was the Saab approved method of repair. In EPC it shows as part number 90305069. But I am partial to time-sert as well. But if you don't have the kit it's expensive. Maybe a spark plug kit would be more affordable even with buying a 14x1.25 bolt.

Reactions: 1

BobSaabit

· #7 · 23 d ago

Carfixer2 said:
If I remember correctly a heli-coil was the Saab approved method of repair. In EPC it shows as part number 90305069. But I am partial to time-sert as well. But if you don't have the kit it's expensive. Maybe a spark plug kit would be more affordable even with buying a 14x1.25 bolt.

Is that what's in the EPC? I always thought that indicated some sort of a replacement factory insert. But a helicoil to repair it makes a lot more sense.

Saaberachi

Discussion Starter · #8 · 23 d ago

Is the spark plug thread kit 14x1.5? I didnt see a thread spec on the online package

Saaberachi

Discussion Starter · #9 · 23 d ago

Problem fixed. For anyone in this predicament this is what I used. I didn't have time to order an M16 by 1.5 thread bolt and tap online and it would have been more $$ anyway. So a trip to the local Napa store and hour later it's done. The Square end of the tap fits perfectly into a 11 mm 12-point socket. Local farm store had the 5/8x18 fine thread grade 8 bolt/washer Total cost 50 bucks

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jvanabra

· #10 · 23 d ago

Aye - the stepping between metric and SAE often works out really nice. I would be sure you somehow mark the bolt - paint it purple or something - so that whoever works on it next doesn't try and fit a metric socket and round it off or something.

Reactions: 2

Saaberachi

Discussion Starter · #11 · 22 d ago

jvanabra said:
Aye - the stepping between metric and SAE often works out really nice. I would be sure you somehow mark the bolt - paint it purple or something - so that whoever works on it next doesn't try and fit a metric socket and round it off or something.

Lol, i had to torque it down with a 24mm socket cause i couldnt find the 15/16 socket!! Nobody else touches this car. Although it would be nice to not have to do certain things on it sometimes. I got the 2 center bolts down to 120 ft lbs. Kinda scared to go to 140! 🥺

AUSSIE900

· #12 · 22 d ago

I bet that was a nerve racking process, nice fix

Reactions: 2

Saaberachi

Discussion Starter · #13 · 22 d ago

AUSSIE900 said:
I bet that was a nerve racking process, nice fix

Actually it went really smoothly. Not alot of material had to come off for the 5/8 threads. I soaked it all real good with penetrating oil & coated the tap with 3 in 1 oil. Using the socket & ratchet to drive the tap sped things up & the subframe didnt have to be removed

deyrag

· #14 · 22 d ago

Seems like eventually everyone has problems with these bolts. Has any one ever proactivley replaced them with a red loctite secured stud and put a nut on the bottom?

Reactions: 1

Saaberachi

Discussion Starter · #15 · 22 d ago

Not that i know of. That might work for the ftont & middle mounts but on the rears the stancion arms would be an issue

Reactions: 1

Germaniac

· #16 · 21 d ago

Bit late to chime in here but probably useful next time and/or for others:

Böllhoff | HELICOIL® thread inserts | B2B eShop

Thread reinforcement - HELICOIL® thread inserts. Böllhoff

eshop.boellhoff.de

AUSSIE900

· #17 · 21 d ago

Germaniac said:
Bit late to chime in here but probably useful next time and/or for others:

Böllhoff | HELICOIL® thread inserts | B2B eShop

Thread reinforcement - HELICOIL® thread inserts. Böllhoff

eshop.boellhoff.de

Helicoils were considered ( early in the thread ) But according to the OP's research they did not meet the torque spec required , albeit that is surprising .

Germaniac

· #18 · 21 d ago

I'm no engineer but as far as I had understood from the brochures, the inserts could carry a load up to 1400 Nm (depending on their size). 55 Nm for a M14 insert seems ridiculous low for me, too.

Another tip: ask the local garage for single inserts if you don't want to buy a expensivepack of which the 99 other inserts are likely to collect dust. Motorcycle garages do frequently use these inserts.

Reactions: 1

Saaberachi

Discussion Starter · #19 · 21 d ago

Just out of curiosity does anyone know the torque rating of a m12 or m14 size helicoil or timesert? When i google it it brings up 40nm. But then other sites say its stronger than the original material. Idk. I tapped it out & its working great. I do want to invest in some timeserts & those rivit style blind studs & nuts though

jvanabra

· #20 · 21 d ago

Neither rates their inserts, but both say "correctly installed" both will "match or exceed the original fastener." AFAIK.

Reactions: 1

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