Motor mount thread issue

[ziwang55]

Installed my jbr rmm 70 duro. Great product. Couple days later got loose to I tried to retorque everything.

As I was retorquing the bolt that goes up into the frame and through the rubber bushing. It kept turning. So I took it out and realize its stripped.

The hole us stripped. Now I'm clueless. Idk what to do.

Sent from my HTC Amaze 4G using Tapatalk

[TexasSpeed3]

i forgot what the guy did but i know this has happened b4

[bigriver]

See my "How to" thread. easy to fix so dont sweat it. My repaired nut is holding just fine.

Here the link:

http://www.mazdaspeedforum.org/forum/foru...ir-kit-105601/

[crazyp]

you can probably get away with installing a helicoil on it. I know sears sells helicoil sets not sure where else

[bigriver]

Originally Posted by crazyp you can probably get away with installing a helicoil on it. I know sears sells helicoil sets not sure where else

I bought my kit from Grainger since they had it in stock (m12 x 1.25) and there was a store nearby.

[Meder]

I did this 3 years ago and my heli coil is still going strong with several re installs of the rmm.

[bigriver]

OP -- also, FYI, the bolt in the second pic of your post is the bolt that connects the rmm and the tranny bracket. The bolt for the rmm in the subframe is the same size and thread pitch but the thread starts immediately from the end of the bolt. I don't think it matters but you may want to switch the bolts.

[IshiKage]

Helicoil. I have had one in for a year

[ziwang55]

Originally Posted by bigriver OP -- also, FYI, the bolt in the second pic of your post is the bolt that connects the rmm and the tranny bracket. The bolt for the rmm in the subframe is the same size and thread pitch but the thread starts immediately from the end of the bolt. I don't think it matters but you may want to switch the bolts.

lol i had a feeling it was the wrong one. so i put the correct one in. thanks for the heads up.

and thanks for everyones quick reply.

how long can i go before something goes wrong? i cant fix it right away. since i dont have all the nessesary stuff. and i need to use my car.

[TexasSpeed3]

i wouldnt drive it without the mount installed

[bigriver]

Originally Posted by TexasSpeed3 i wouldnt drive it without the mount installed

THIS

There are only three mounts (RMM, PMM TMM). The other two will not be able to hold the engine. The TMM will fail and your tranny will be dragging on the ground while your dp bangs the firewall.

[ziwang55]

oh what i meant was not fixing the thread. i have the mount and the car still pulls strong since the bolt doesnt just come out.

i saw your how to. im gonna get to it right away. its awsome. thanks alot.

[bigriver]

Oh. Too risky imo. Cheaper to just rent a car or take a cab. The issue is with all that vibration, the bolt may back itself out. Its probably being held by a small piece of thread in the nut that didnt come out.

[ziwang55]

ur right it actually is. the bolt just spins tight then loose. tight and loose again. so im gonna go to grainger tomorrow and get it done.

[bigriver]

Where are you? If you are near me you can borrow my kit. I have extra coils.

[ziwang55]

im in mn no where near. i wish i was close. cuz grainger is closed now. so ill have to wait.

unless theres other stores that sells?

[bigriver]

Problem is the bolt size. M12 is hard to find. Autozone sells helicoil kits but not in m12. Maybe check other auto parts stores. Mcmaster and Fastenal also have them but they would be closed tonight.

[gearhead750]

subbed and a little scared. Just installed JBR RMM a few days ago. Just re-checked torque on bolts today everything seems to be fine. Is the recommended 90 ft lbs on this bolt too much?? Good luck OP.

[bigriver]

Originally Posted by gearhead750 subbed and a little scared. Just installed JBR RMM a few days ago. Just re-checked torque on bolts today everything seems to be fine. Is the recommended 90 ft lbs on this bolt too much?? Good luck OP.

I believe torque is 70. At least for jbr dogbone and corksport inserts.

Edit - oh jamie says 90 for the billet mounts. Idk maybe check with him.

[Crarrs]

Probably. The factory service manual says 54-66 ft-lbs. Most of the other aftermarket mounts say 70-75 ft-lbs. That's probably why people keep stripping them at 90. Page 01-10B-44 in the Gen2 manual for those who want to check.

[gearhead750]

90 is what the JBR installation guide says for the billet RMM

[Crarrs]

The part that's stripping is a Mazda part. It's been established that some of these welded nuts are weaker than others due to heat effects during manufacturing.

[gearhead750]

Originally Posted by Crarrs Probably. The factory service manual says 54-66 ft-lbs. Most of the other aftermarket mounts say 70-75 ft-lbs. That's probably why people keep stripping them at 90. Page 01-10B-44 in the Gen2 manual for those who want to check.

@jbarone

Any input?

[Crarrs]

Originally Posted by gearhead750 @jbarone Any input?

Perhaps somebody based their torque spec off the N-m one in the manual....

[ziwang55]

I think 90 torque is too much. I would've been fine if I did 70 I'm guessing

Sent from my HTC Amaze 4G using Tapatalk

[gearhead750]

But what doesn't make sense is that if it was torqued down to 90 and it held there, how does it just strip on it's own? Somehow it had to have gotten cross threaded... IDK

[Crarrs]

That's not a normal strip. That is the threads actually being pulled out of the nut in one piece. The manufacturing process weakens the nut allowing that. I've seen them at work before, and I've only seen it happen on welded nuts.

[ziwang55]

Probably just weak oem welded nut.

Sent from my HTC Amaze 4G using Tapatalk

[bigriver]

Originally Posted by Crarrs That's not a normal strip. That is the threads actually being pulled out of the nut in one piece. The manufacturing process weakens the nut allowing that. I've seen them at work before, and I've only seen it happen on welded nuts.

Mine stripped exactly the same and I pulled out the thread in one piece. I never overtorqued mine and suspect the vibration and forces on that one nut could be enough to shear it clean. Just speculation but I have no other explanation.

[gearhead750]

Should i leave mine at 90??? Or maybe back it out to 65-70. Maybe leave it alone and just mark the bolt and check it periodically to see if it's moving? Fuck I'm thinking of just taking the damn JBR RMM out, but I really don't want to back that bolt out and see threads come out with it...

I also noticed that the JBR billet RMM instructions are the ONLY ones that say to use 90 ft lbs on this bolt and also on the 3 transmission bolts. All the other mounts require only 70 ft lbs. Why would it be so much different?

@bigriver I notice you went with the CS RMM inserts instead. Why?

[JBR]

90 ft/lbs is fine for that bolt and the others. As mentioned, it's the nut not the torque.

Jamie

[bigriver]

@gearhead750 I switched to cs rmm inserts because of the stripped nut. I previously had 88 duro rmm, 88 duro tmm and 80 duro pmm. When you consider that the pmm and tmm have multiple mounting bolts while rmm has just one, there is a lot of stress being placed on the rmm subframe nut and it may be the weak link. I guess the tmm and pmm have a single bushing bolts but those sre much larger than the rmm bushing bolt. However the rmm bushing bolt is the only bolt that directly mounts in the frame.

Again just speculation, but when the entire thread from the nut comes out in one piece, i couldnt find any other cause. Maybe someone else can figure this out for sure, I really dont know.

So recently Lex also said he would either use cs rmm inserts or cpe stage 2 rmm. I place a lot of value on anything he says. This convinced me to switch to cs inserts because both of these mounts place less stress on the rmm subframe nut. While I'm 100% sure the repaired nut is fine, I just wanted more peace of mind. So far I've been impressed with the inserts and they work just fine. The inserts are not as good as the dogbone for torque steer and wheel hop, but I'm okay with that. I also reinstalled stock pmm and tmm as some other folks I've talked to have no issues with stock pmm and tmm. But just as I finish typing this, a thread pops up on a failed oem tmm.

Please do not interpret my reply as bashing of stiff mounts. That is not my intent. I had a problem, fiixed it and made the switch purely for my own peace of mind since my car is my DD and I commute over 80 miles each day. Repairing the nut is easy but when it strips, that is just an awful feeling.

[Crarrs]

Originally Posted by gearhead750 I also noticed that the JBR billet RMM instructions are the ONLY ones that say to use 90 ft lbs on this bolt and also on the 3 transmission bolts. All the other mounts require only 70 ft lbs. Why would it be so much different?

Good point. What's the reason for this @jbarone?

Originally Posted by jbarone As mentioned, it's the nut not the torque.

How is the torque not the root cause for the nut stripping?

[gearhead750]

Originally Posted by jbarone 90 ft/lbs is fine for that bolt and the others. As mentioned, it's the nut not the torque. Jamie

I think a more in depth answer might help as all of your other mounts except for the billet say to use 70 ft lbs. And why use 90 ft lbs on the 3 transmission bolts as well? 90 seems like an awful lot when the stock specs say up to 66 (Bushing). This would make pulling all of those threads out of the nut make more sense than blaming it on a faulty nut.

Sorry OP didn't mean to jack your thread just trying to get some information for those of us with these mounts that have followed these torque specs.

[JBR]

The torque spec I used is based on the size and grade of bolt 86-93ft-lbs dry. Do I think the 90 vice 70 is the cause, no. Why do the molly instructions say to torque to 70 and the billets 90; don't recall it's been a while since either where written. I'll change them shortly.

In the 3 years I've been doing this I have only heard of stripped nuts 2-3 times so that makes the higher torque spec, IMHO less likely. With that said I'll change it.

Thanks,
Jamie

[bigriver]

@jbarone - I agree with Jamie that the 90 lbs torque is not the issue. Cpe also recommends 90 lbs and guys are using breaker bars to tighten the nuts too so if 90 lbs was the issue we should be seeing a lot more stripped nuts. My issue popped up when I started doing wot logs for my etune and going close to redline. Eveything was fine when I was on ots maps and not really getting close to redline.

[Vinnie]

subbed

[ziwang55]

got it fixed. a shop did it for 40 bucks. heli coil. watched him do it just like in your how to.

[ziwang55]

they do sell heli coils in small packs. without the drill bit. which i think it much cheaper.

[bigriver]

Yup. If you have the matching bit and tap then its no problem to just buy the coils.