****** Bell Housing thread stripped need assitance

[chicane]

Hi guys. I am putting the my auto ****** on a late model BMW back in the car after doing some work. The engine is still in the car and the car is on jack stands which has not made for the easiest extraction and install. Just to explain how I am getting to these bolts, with the engine still in the car you jack the ****** put in all of the easy bolts then let the weight of the ****** tip the engine and ****** so you can finish off the bolts on top.

All the bolts on the bell housing are installed and my friend who is helping me thinks he can get to the last bolt which is the absolute tightest space you have ever seen sandwhiched between the BH and the ****** tunnel with a bunch of heat shielding mixed in. Well you guessed it he stripped the bolt.

I am about done with this entire project and I need to back away and think about how to deal with this last bolt. I really could use some advice.

The way I see it I can:

1. Go without this one BH bolt

2. Find some way to tap a thread back there

3. Remove the engine and ****** and tap a bolt in there

Guys help me out.

 

[JKady]

I would probably go without, or ram a slightly larger bolt in with my impact, but I'm just a hack ****** R&R guy.

 

[KinzeMech]

You said he stripped the bolt? Get a new one.

Did you mean he stripped the bolt hole?

If all the further assembled you are is the BH bolts, I'd drop the transmission back out and get a better look at the problem.

 

[Deafautotech]

if you have all bolts go on the transmission to engine except one as stripped? if it has all other bolts to hold the transmission to engine then i would not worry about the one...

 

[Dick in Wisconsin]

Bolt goes into aluminum?

Go to a good auto supply store or a good hardware store and buy a Heli-Coil kit that matches the bolt threads. Take the bolt along. Hopefully the bolt is a standard (probably metric) size (length, head thickness, etc.)

But a new bolt to match (grade 8).

The Heli-coil kit will include a handful of little Heli-coils and the insertion tool. On the package it will tell you what size drill to buy. You might not need the drill if its stripped bad enough.

I would find a thick piece of steel or aluminum and "practice" putting the Heli-Coil in. I'm sure if you Google "install heli-coil" you'll find lots of instructions and videos.

You will probably need to pull the trans to get the Heli-Coil in.

If the bolt goes into aluminum, the steel heli-coil will work better than aluminum IMHO.

Good luck and keep us posted.

 

[coolreed]

Have you tried loosening the motor mount to allow the engine to tilt more? That may help with access to the bolts.

 

[buildmyown]

Depending on how many bolts there are i wouldnt even worry about it. Option 2 load it up with red loc-tite and slam it back in at least then you have a chance of taking it out again. Option 3 a little JB Weld on the bolt and put it in but thats a little perminent.

 

[pipsters]

Did you strip it or cross thread it?

If you stripped it, it would mean you tightened it down too far...from the sounds of it that didn't happen

I vote not worry about it, keep the bolt and if you ever have to go at it again, fix it then.

 

[Skin]

Bolt goes into aluminum?

Go to a good auto supply store or a good hardware store and buy a Heli-Coil kit that matches the bolt threads. Take the bolt along. Hopefully the bolt is a standard (probably metric) size (length, head thickness, etc.)

But a new bolt to match (grade 8).

The Heli-coil kit will include a handful of little Heli-coils and the insertion tool. On the package it will tell you what size drill to buy. You might not need the drill if its stripped bad enough.

I would find a thick piece of steel or aluminum and "practice" putting the Heli-Coil in. I'm sure if you Google "install heli-coil" you'll find lots of instructions and videos.

You will probably need to pull the trans to get the Heli-Coil in.

If the bolt goes into aluminum, the steel heli-coil will work better than aluminum IMHO.

Good luck and keep us posted.

In his situation you're talking about a lot of work. He'd have to completely remove the transmission again, and even before that he'd have to confirm he has at least a foot of clearance to allow for the tool to do its job or else he's wasting his time. Helicoil is great, when you have the hole in front of you with ample work space. ***** in situations like this. Plus it may be an ear on the block and oversizing the hole risks cracking it.

 

[Autorotica]

Skip the 1 bolt and finish up... Im sure you have dowel pins and X number of other fasteners...

Chris

 

[Lotek]

Mfg's aren't noted for putting "extra" bolts in, was it mine I would fix it now, rather than later. Is it crossthreaded or stripped? Sometmes you can restart the bolt straight and it will reform the damaged threads. Stripped...if you are getting paid for the job,the trans comes back out, that's what being a professional means, your own...only you can decide.

 

[chicane]

Hi guys and thanks for the responses. You know how you need to just back away from a project to collect your thoughts? There are a total of eight bolts plus two dowels.

http://www.realoem.com/bmw/showparts.do?model=AM33&mospid=47718&btnr=24_0827&hg=24&fg=10

I say I stripped it, but I guess it would be crossthreaded (There were a couple of metal threads in the bolt when I removed it). Buildmyown's idea is interesting: Option 2 load it up with red loc-tite and slam it back in at least then you have a chance of taking it out again.. I might try that.
The question is HOW do I slam it in there.

Taking the ****** out and trying to tap the thread isn't even an option. There isn't even room to get a drill in there (even with the ****** out).

 

[buildmyown]

By slam it back in I just ment get it started and let it catch whatever threads are left in the hole but dont go all crazy and try to crank it down once the lock tite sets up it will bond and almost form new threads. With 8 bolts total and 2 dowels i wouldnt be to worried about one missing.

 

[Outlawmws]

In his situation you're talking about a lot of work. He'd have to completely remove the transmission again, and even before that he'd have to confirm he has at least a foot of clearance to allow for the tool to do its job or else he's wasting his time. Helicoil is great, when you have the hole in front of you with ample work space. ***** in situations like this. Plus it may be an ear on the block and oversizing the hole risks cracking it.

Not really.

If it is truly striped two options:

1. Use a tap wrench an a jobbers drill (grind the drill shank if needed), you only need to to "ream" the remainder of the threads out of aluminum. (I've tapped directly into the stripped threads of a hole in aluminum in a pinch). Then run the tap in; you only need maybe 4" to get it done...

2. How deep is the hole? Can a longer bolt be used to get to good threads? If you can catch at least three you are good to go. Not ideal, but better than leaving it out.

 

[wornoutoldman]

If the rest of the bolts are in and tight.......

You will be the ONLY person worrying about it!

I would very hesitant to make a (not really that) bad situation, potentially MUCH worse.

 

[TwoInch]

i agree, if you can get the bolt in with some loctite, you will be fine. dont crank it in, just get it in there.

if it wont catch anything, which i doubt. leave it out, there will be no issues, just try to forget about it.

that said, if its a customers car, i would pull the motor more than likely... and the guy who buggered the hole up would be my gopher for ANYTHING i needed for a good week... just sayin

 

[jethro29]

I would probably go without, or ram a slightly larger bolt in with my impact, but I'm just a hack ****** R&R guy.

that sounds like a good way to bust a bell housing.

 

[5mall5nail5]

Hi guys and thanks for the responses. You know how you need to just back away from a project to collect your thoughts? There are a total of eight bolts plus two dowels.

http://www.realoem.com/bmw/showparts.do?model=AM33&mospid=47718&btnr=24_0827&hg=24&fg=10

I say I stripped it, but I guess it would be crossthreaded (There were a couple of metal threads in the bolt when I removed it). Buildmyown's idea is interesting: Option 2 load it up with red loc-tite and slam it back in at least then you have a chance of taking it out again.. I might try that.
The question is HOW do I slam it in there.

Taking the ****** out and trying to tap the thread isn't even an option. There isn't even room to get a drill in there (even with the ****** out).

Hey man - just did a clutch on my 525 this past weekend. Which bolt is it:


IMG_2588.jpg by Jon Kensy, on Flickr

Almost everyone can have a nut behind it other than the top two and side two which on an E46 is into the aluminum block (iron on my car). You could also buy a stud and loctite it in and use a nut on the trans side. BTW even the M12 bolts only get ~53 ft lb on an iron block - you don't need much.

 

[CWP1616L]

Taking the ****** out and trying to tap the thread isn't even an option. There isn't even room to get a drill in there (even with the ****** out).

Does that mean the bolt hole is threaded on the engine side? Or is the hole in the bell housing threaded?

 

[helterskelter]

Either pull the motor and heli-coil or don't worry about it. Realistically, missing 1 bolt is negligible.

It would bother me though. If it was a toy/2nd car I would fix, if I had to drive it to work on Monday I would go without. Regardless I would fix it next time I was in there. I wouldn't ram a bolt in there that I'd have to remove later.

 

[5mall5nail5]

Does that mean the bolt hole is threaded on the engine side? Or is the hole in the bell housing threaded?

The engine block and oil pan are what the bolts thread into.

Either pull the motor and heli-coil or don't worry about it. Realistically, missing 1 bolt is negligible.

It would bother me though. If it was a toy/2nd car I would fix, if I had to drive it to work on Monday I would go without. Regardless I would fix it next time I was in there. I wouldn't ram a bolt in there that I'd have to remove later.

Don't pull the motor. If you need to, lower the subframe. It's so much easier. Remove the suspension from the towers (3 nuts on each side). Remove radiator hoses. Unplug harness. Lower the entire subframe away from the body. You can do it by lowering the car onto some pallets, unbolting the subframe from the body, and then raising the car away. This will give you access to the block without the crazy process of trying to pull it from the top.

**** my apologies, you're on jack stands. ew.

 

[smothers33]

i wouldnt worry about it i did the same thing on a wet bell housing once and never leaked. the dowels and other bolts will be enough to hold it together.

 

[TwoInch]

Does that mean the bolt hole is threaded on the engine side? Or is the hole in the bell housing threaded?

arent they nearly always threaded into the block?

 

[5mall5nail5]

The only problem here guys is that although there are 8 bolts, only 4 are M12. The rest are M8 or so. We install early model transmission on late model blocks where only the 4 bolts line up, but its 4 M12 bolts. I dunno how I feel about missing an M12.

 

[chicane]

Hey man - just did a clutch on my 525 this past weekend. Which bolt is it:


IMG_2588.jpg by Jon Kensy, on Flickr

Almost everyone can have a nut behind it other than the top two and side two which on an E46 is into the aluminum block (iron on my car). You could also buy a stud and loctite it in and use a nut on the trans side. BTW even the M12 bolts only get ~53 ft lb on an iron block - you don't need much.

Not really analogous, this is a 3 series (much smaller ****** tunnel, and different engine) and an it is an automatic so it's bigger than a manual. But it would be the one in the far right hand corner.

http://www.realoem.com/bmw/showparts.do?model=AM33&mospid=47718&btnr=24_0827&hg=24&fg=10

The one right above the #4 bolt in the above link.

 

[5mall5nail5]

Not really analogous, this is a 3 series (much smaller ****** tunnel, and different engine) and an it is an automatic so it's bigger than a manual. But it would be the one in the far right hand corner.

http://www.realoem.com/bmw/showparts.do?model=AM33&mospid=47718&btnr=24_0827&hg=24&fg=10

The one right above the #4 bolt in the above link.

It's very much similar - its the same block dimension (M52 or M54) and the automatic bells are all the same on the M5x generation which means it fits in my car or your car. 5 series is no bigger in the tunnel believe it or not.

 

[chicane]

The engine block and oil pan are what the bolts thread into.




Don't pull the motor. If you need to, lower the subframe. It's so much easier. Remove the suspension from the towers (3 nuts on each side). Remove radiator hoses. Unplug harness. Lower the entire subframe away from the body. You can do it by lowering the car onto some pallets, unbolting the subframe from the body, and then raising the car away. This will give you access to the block without the crazy process of trying to pull it from the top.

**** my apologies, you're on jack stands. ew.

Umm, yeah. Was this a joke?

 

[5mall5nail5]

Umm, yeah. Was this a joke?

A joke? No, I didn't realize it was on stands.

 

[TwoInch]

The only problem here guys is that although there are 8 bolts, only 4 are M12. The rest are M8 or so. We install early model transmission on late model blocks where only the 4 bolts line up, but its 4 M12 bolts. I dunno how I feel about missing an M12.

so 4 m12s are fine

but 3 m12s plus 4 other bolts is not enough.

i disagree.

 

[5mall5nail5]

so 4 m12s are fine

but 3 m12s plus 4 other bolts is not enough.

i disagree.

Disagree all you'd like. I've had transmission bolts back out on these cars. I have a few (5).

The main bolts are M12. They thread into the block. The smaller (M6 and M8) thread into the oil pan. The oil pan is cast aluminum. If you think the cast aluminum pan can support it... I dunno what to say.


Auto Trans Bolts by Jon Kensy, on Flickr

Actually, there you can see he is missing on M12, and has 3 M12 holding it on. The M10 bolts (#6) actually hold the starter to the bell, not supporting the trans at all, and that means the rest of his bolts are M8 into a cast aluminum pan.

Again, we run 4 M12's into a cast iron block. The OP here is on an aluminum motor. Totally different.

 

[TwoInch]

you have had bell housing bolts "back out"?

were they in swaps? where the dowels used, and correct in size in both bell housing and block?

ive never had a bell housing bolt back out, ever. and yes, i have a fair share engine and transmission jobs, and swaps.

 

[JASTECH]

If you can get to it with a tap holding socket, a couple locking extensions and a universal taped to the correct angle (or angle locking universal). My next step would be a self tapping bolt. My next would be a regular G8 bolt, washers and locknut. Last would be nothing. Can you tell I've did this before, lol..not...I had not stripped it.

 

[ra42mario]

just skip the bolt and be done with it. You are over thinking it. We pull transmissions all day long, it won't be the first time a bolt has been left out.

 

[CWP1616L]

arent they nearly always threaded into the block?

Probably, but the thread title makes it sound like the bell housing is threaded.

 

[5mall5nail5]

you have had bell housing bolts "back out"?

were they in swaps? where the dowels used, and correct in size in both bell housing and block?

ive never had a bell housing bolt back out, ever. and yes, i have a fair share engine and transmission jobs, and swaps.

Nope, not in swaps. Standard M50 engines with factory ZF 310Z transmission bolted up - M12 bolt in the lower passenger hole loose as a cannon. I specialize in BMWs, I've built a ton (have an 800 HP 5 series) and own 5 total. I've been involved in building a lot of the turbo ones in the mid atlantic region. I've seen loose trans bolts and I wouldn't want to run one down. If it was an M8 bolt into the pan I wouldn't car, but a main M12 into the block is asking for trouble. I am sure you can hold a trans to a block with a ratchet strap but I rather not find out if its ideal or not. Its not that big of a job to fix what the OP broke.

 

[AZ_Catskinner]

I've used this stuff on heavy/industrial equipment as well as a boogered bellhousing bolt on my CJ7 without any concerns. Seeing as a 12.9 graded M12 bolt is barely over 100 ft/lbs, it'll be more than strong enough.

 

[mds5951]

I'd probably just leave it go. But if I were to do something I'd run a stud with some jb weld on it into the damaged hole and use a nut on the other side.

 

[Nak]

I would either re-tap or time-sert or heli-coil or even heli arc, drill and tap. In other words, I would do whatever it takes to be able to reliably torque the bolt to spec. Just leaving it out because it might be difficult or time consuming is a disservice. If you take it as a learning experience you'll be better for it. Probably very few cross threaded fasteners in the future!

 

[TwoInch]

Nope, not in swaps. Standard M50 engines with factory ZF 310Z transmission bolted up - M12 bolt in the lower passenger hole loose as a cannon.

did you put the bolt in originally, and you noticed that it had backed out next time you took it apart?

the reason i ask, bolts backing themselves out is a result of a specific set of circumstances, which trans to block surfaces are usually engineered to avoid... hence the dowels, which keep the two mating surfaces(block/BH) from sliding against one another and causing the bolts to loosen on their own. dowels take up nearly all the slack left from the manufacturing tolerances of the fasteners and their threaded holes. you shouldnt have bell housing bolts backing out on you. i would suspect either they were left untorqued/undertorqued, or a dowel or both were left out. seen it before.

not trying to hijack the thread. OP, as long as the only thing left out is the one bolt, and you are not racing/abusing the car, you should have no issues. but it is your vehicle(hopefully), so its ultimately your choice.

 

[03protege]

How deep are the threads and how deep is the damage? If it is just the beginning threads that are missed up could you just drill past that and use the clean threads behind it?

Would probably need to clean it up with a tap and locktite certainly wouldn't hurt.

Also is this an engine block/car you plan on keep or is this the last service of this type? Could you drive a different thread pattern bolt in the hole with an impact? It would mess the threads up worse but if this is the last time this service will be performed for ever or some time it might be the best/easiest fix.