Intuitive Fastening Torque

[Bookwus]

Hiya Colin (or anybody else out there in IACland who has an answer),

Recently in another thread you mentioned that the nuts holding the exhaust in place should be retorqued after initial run-in. I'm all for that as I can certainly understand how heat/expansion in that area can affect torque values.

What I don't understand is how one goes about getting a torque wrench on these nuts. The tops look they might be do-able but the bottoms are screened by the J pipes and assorted fittings. This would be mucho difficult with the engine out and seems impossible with the engine in. How does one get a torque on these nuts?

And that goes double for the forward nut on the intake manifold to head connection in a single port. I had to make a special tool just to get at that nut.

Is there a torque secret handshake thing I don't know about?

[hambone]

I've never officially torqued those nuts, just get them moderately tight with wrench. Maybe that's poor practice but I've never had issues.

[Bookwus]

Hiya Bob,

Yep...........on "matching pairs" like exhaust or intake nuts I'll wrench in both sides a little at a time so as to insure eveness. Then I'll torque the side I can get at and wrench the other down to an eyeball match.

That's about as close as I can get. And, like you, never had a problem.

But Colin does insist on "torque", so I'm curious as how to get that torque.

[spiffy]

Yeah, just tighten them up. And of course, use some anti-seize goop on them. Lest you like stubborn nuts and bolts.

[chitwnvw]

Book,

You would need to torque the nuts that hold the heat exchangers to the heads. There shouldn't be anything in the way except the bottom tin and that comes off easy enough.

You might want to check torque on the other exhaust nuts, but I don't think they are as temperamental as those studs sunk into the aluminum heads.

Chi'

[Bookwus]

Hiya chi,

Oh, I think not............those heat exchanger nuts on the bottom at each position are all but unreachable with any sort of wratchet/socket device (like a torque wrench). I can only manage to get a 13 mm box end on those guys.

So, how are you getting a torque wrench on those nuts?

.........And, I know of a 74 Bus that may well be up for grabs. It appears to be a 7 passenger. Interested? I can find out more if you'd like. It's here in southwest Portland.

[chitwnvw]

Hiya chi,

Oh, I think not............those heat exchanger nuts on the bottom at each position are all but unreachable with any sort of wratchet/socket device (like a torque wrench). I can only manage to get a 13 mm box end on those guys.

So, how are you getting a torque wrench on those nuts?

.........And, I know of a 74 Bus that may well be up for grabs. It appears to be a 7 passenger. Interested? I can find out more if you'd like. It's here in southwest Portland.

I just removed the heat exchanger nuts on my '79. It wasn't anything that tapping with a hammer, apply heat couldn't solve. The nuts certainly weren't buried. Maybe take some pictures, so we can visualize.

I am talking with Mark, deschutestrout, about his bus, it's up in the air, but sure, I am looking for a solid transporter, so whatever you have would be appreciated. Thanks.

Chi'

[Bookwus]

Hiya Chi,

......I just removed the heat exchanger nuts on my '79.....

Ah, well, this explains our seeming difference of opinion. On a Type 1 engine (I have a 70 Bus) the J-pipe coming off number 1 and 3 exhaust bends right over the bottom nut. That makes a reasonably easy removal with a open or box end wrench (less easy if the engine is still in the vehicle) but impossible (for me anyway) to get a torque wrench on the bottom nuts.

I'll check out that 74............just in case.

[Amskeptic]

On a Type 1 engine (I have a 70 Bus) the J-pipe coming off number 1 and 3 exhaust bends right over the bottom nut.

Use a torque wrench to 1 ft/lb less than final torque value on the nuts you can reach. Then carefully put your arm and wrist in the same position that you will need for the blind nuts. Tighten the upper nuts just to the point that the nut gives. This amount of force you need to memorize for the lower blind one. Works like a charm. After 25 years of this, you will find that you intuitively hit the correct value with your sense. Hambone, try this method. It does not hurt to "calibrate" your sense.
Colin

[chitwnvw]

Ah, well, this explains our seeming difference of opinion. On a Type 1 engine (I have a 70 Bus)

I should read your sig line! Dohh!

[Bookwus]

Hiya Colin,

.....Use a torque wrench to 1 ft/lb less than final torque value on the nuts you can reach. Then carefully put your arm and wrist in the same position that you will need for the blind nuts. Tighten the upper nuts just to the point that the nut gives. This amount of force you need to memorize for the lower blind one. Works like a charm. After 25 years of this, you will find that you intuitively hit the correct value with your sense. Hambone, try this method. It does not hurt to "calibrate" your sense.

Sort of the "muscle memory" approach. I get it. I'll give it a go on my exhaust nuts.

But consider the hold down plate for attaching a single port manifold to the head. That plate "rocks" on the manifold tube. I'm thinking that that torqueing one side of that plate will throw the other side off. I'm also thinking that one might need to tighten both in steps while measuring the torque on the one accessible.

All of which makes me wonder how they measured the torque on these "hidden" nuts at the factory.

[Amskeptic]

But consider the flange for attaching a single port manifold to the head. That flange "rocks" on the manifold tube. I'm thinking that that torqueing one side of that plate will throw the other side off.

Don't over-think, but I like your alertness. It does not matter the circumstance, any assembly gets cinched down evenly before you whip out the torque wrench, no? So, it is a GIVEN that you have brought things down evenly ahead of time. Yaah?
Colin

[regis101]

IIRC, the Germans call it, Zee-Gut-N-Tight. Sorry. Bad humor

[vdubyah73]

Bless you.