Dropped cam pin down head...help

[Cubieman]

One last question I have before I get the vanos on is in regards to the cam bolt torque spec.

I torqued my Lang Racing cam bolts to 109 in. lb, this is 9.08ft lb or 12.3nm, I wonder if that isn't a bit too much. One tutorial said to torque to 7.5 ft lb (90 in lb) and another said 100 in lb, but both of these were using the upgraded OE bolts.
I would sure love to move on and get this done but this is hanging me up.

Beisan lists 12nm or 9 ft lb and they are using the OE cam bolts (T30), again I used the Lang stuff.

[heinzboehmer]

Does Lang say to torque them higher? Lang sells grade 12.9 bolts, OE are 8.8.

Not a mechanical engineer (nor do I have any sort of training regarding the mechanics of fasteners beyond what I've learned in my free time), so I might be mistaken/missing something. However, as far as I understand, the clamping force of a bolt is dependent on the bolt geometry, its physical properties and the torque applied to it. Bolt geometry is the same between Lang and OE so no need to worry about that.

Generally, when bolts are torqued, they stretch slightly in an elastic manner. This means that when the load is removed, they return to their original shape (sidenote: some bolts are designed to go past the elastic zone and into the plastic zone so they don't go back to their original shape, like rod bolts or head bolts and are called torque to yield bolts, but don't worry about those).

The stretch that happens when torquing a bolt is (part of) what yields the desired clamping force. The grade of a bolt will influence how much torque is required to stretch it a certain amount, so a higher grade bolt might require more torque to get the same clamping force as a lower grade one.

All this rambling aside, if Lang says to torque them higher then it's probably because of the grade of their bolts. I would just listen to what they say and not worry about it.

[terra]

Lang’s bolts are class 12.9 while the oe bolts are 8.8. Should be safe to torque them higher. I have the modified ARP bolts in mine and torqued them to 12 lb-ft iirc

[elbert]

The grade of a bolt will influence how much torque is required to stretch it a certain amount, so a higher grade bolt might require more torque to get the same clamping force as a lower grade one.

This.

[Cubieman]

Well Lang doesn't give out a torque spec, maybe I'll contact them. They are currently at 109in lb w/ blue 243 loctite. I've already taken them out once to switch the loctite type, really don't want to do it again because my OCD would make me order another (3rd) set. I would definitely remove/replace/re-torque them if deemed worthwhile.

[eacmen]

Well Lang doesn't give out a torque spec, maybe I'll contact them. They are currently at 109in lb w/ blue 243 loctite. I've already taken them out once to switch the loctite type, really don't want to do it again because my OCD would make me order another (3rd) set. I would definitely remove/replace/re-torque them if deemed worthwhile.

Reputable shop I spoke with recently just orders 12.9 bolts from mcmaster and uses OE torque spec.

I think you’re fine.

[Cubieman]

Reputable shop I spoke with recently just orders 12.9 bolts from mcmaster and uses OE torque spec.

I think you’re fine.

Nice.

[sapote]

Well Lang doesn't give out a torque spec, maybe I'll contact them. They are currently at 109in lb w/ blue 243 loctite. I've already taken them out once to switch the loctite type, really don't want to do it again because my OCD would make me order another (3rd) set. I would definitely remove/replace/re-torque them if deemed worthwhile.

You’re fine with 109” lbs for Lang bolts. Same torque spec as the factory I think.
The original issue was tactory bolts backed out because no Loctite and not because not enough clamp force.

[Cubieman]

Out of curiosity why does BMW use two different style bridges for setting and checking timing? I just have the Metal bridge.

Setting timing:
Checking timing:

[Inizes]

Out of curiosity why does BMW use two different style bridges for setting and checking timing? I just have the Metal bridge.

Setting timing:
Checking timing:

I used the top cylindrical one.

[ATB88]

Out of curiosity why does BMW use two different style bridges for setting and checking timing? I just have the Metal bridge.

Setting timing:
Checking timing:

It would seem from some cutoff comments in your screenshots that the bottom one is the older original model tool they used until it was replaced with the top one (which we all use) in 2010. Maybe either for ease of use or manufacturing within proper tolerances. Maybe?

[Cubieman]

Just a quick follow up, I talked with Andrew at Lang Racing in regards to torque spec on the cam bolts. He said they tell people to stick with OE torque spec and the locite is the big deal. They included the red (263) loctite but I used the blue (243), I'm sure that's sufficient as you guys have already told me.

Can't wait to get this thing running again, with so little time to work on the car its moving very slowly. Was going to finish the vanos install last night but after work I was wrung out and had a stiff mixed drink.

I've learned before that I need to be in the right mindset and sober before doing critical precision type work. That being said for other things I love cracking a cheap beer or two while wrenching.

[heinzboehmer]

That being said for other things I love cracking a cheap beer or two while wrenching.

I still need to find a way to drink a beer while working on my back under the car. Most of the time I end up forgetting I opened one and when I do remember it's no longer cold lol.

[Cubieman]

I still need to find a way to drink a beer while working on my back under the car. Most of the time I end up forgetting I opened one and when I do remember it's no longer cold lol.

Man I've got some respect for you guys doing headers/RACP etc. on jacks. I've done a bunch of work on my Jeep on jack stands but since I've owned the M3 I've been spoiled and have access to a 4 post lift.
The 4 post even has a sliding jack so you can quickly raise the car to put it on jacks in the air on the 4 post. My dad let's me take over his garge, although once summer comes he won't be so happy to have all sorts of stuff spread all over his nice garge

[heinzboehmer]

Man I've got some respect for you guys doing headers/RACP etc. on jacks. I've done a bunch of work on my Jeep on jack stands but since I've owned the M3 I've been spoiled and have access to a 4 post lift.

I'll rent a lift if I'm gonna be doing something that I don't want to do on stands (recently rented one to do my clutch). Some jobs do suck doing on your back, but most of the time it's more of a hassle to rent the lift instead of taking a bit longer on stands.

The goal is to someday have a setup similar to your dad's. Definitely going to be a big factor once I buy a house lol.