donut exhaust clamps

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dingo
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donut exhaust clamps

Post by dingo » Sun Sep 20, 2015 7:39 pm

Did Nordhoff really sign off on these miserable type 1 donut exhaust clamps...?.ill- fitting, and insufficient clamping power, almost always unaccessible around the moustache bar. Decades of great engineering and ingenuity and then these clumsy things ? quite mystifying
Definately my most despised part of type 1 engine
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

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asiab3
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Re: donut exhaust clamps

Post by asiab3 » Sun Sep 20, 2015 9:36 pm

dingo wrote:Definately my most despised part of type 1 engine
Absolutely mine too.

I honestly do not know how they would have arrived from the factory. Every bus I've seen has cutouts in the mustache bar for them. I have had better luck with NOS asbestos gaskets, though the new engine has not been so fortunate with parts availability. Colin has posted detailed bits on how to install them in various itinerary threads; I'll look around and post them for you. The biggest deals are A) making sure the donut is at least a push fit onto the heat exchanger. It should not slide freely, and B) making sure you check the torque regularly, as a single minuscule leak can not be stopped, and the Grand Canyon of exhaust leaks will form from that hole shortly after.

For now…
Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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Re: donut exhaust clamps

Post by asiab3 » Sun Sep 20, 2015 9:47 pm

1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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Amskeptic
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Re: donut exhaust clamps

Post by Amskeptic » Mon Sep 21, 2015 4:53 am

Those miserable donut gaskets worked fine back in the day. You used the muffler as a press. Now they are shoddy skinny little things with awful cheesy clamps that bend like aluminum foil.

The factory was a little tight at the mustache bar, but hey, go change the rear spark plugs on a transverse V6 General Motors car and get back to me. Or replace the distributor on a LT Corvette, and you will be singing the praises of easy accessibility AND plenty of daylight to see what you are doing. I blame the replacement parts.

By the way, it IS easier to remove the exchanger to replace those gaskets if they leak.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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dingo
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Re: donut exhaust clamps

Post by dingo » Mon Sep 21, 2015 8:21 pm

yeah youre right its a lot of old worn out stuff mixed with cheap aftermarket mimicry....still, exhaust stuff needs to be robust and trustworthy to withstand heat cycles and rust and vibration....those donuts belong on bicycles or lawnmowers. Gimme a triangle flange , a gasket and three torqueable bolts....
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

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Re: donut exhaust clamps

Post by sgkent » Mon Oct 19, 2015 9:59 am

there are a couple secrets to making them work.
T1 motor:
1) use only the bus style clamp.

Image

2) lightly clean the pipe and exhaust a little with a wire brush or piece of sand paper.

3) use some RED high temp RTV when installing them and they will last 50,000 miles without leaking.


T4 motor:
1) Use red RTV with clamp. Try to find the original VW ones that have lots of crushed steel fiber in them.
TBone208 wrote: "You ppl are such windbags. Go use your crystal ball to get rich & predict something meaningful. Nobody knows what's going to happen. How are we supposed to take ppl who don't know the definition of a recession & "woman" seriously?"

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wcfvw69
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Re: donut exhaust clamps

Post by wcfvw69 » Mon Oct 19, 2015 3:51 pm

sgkent wrote:there are a couple secrets to making them work.
T1 motor:
1) use only the bus style clamp.

Image

2) lightly clean the pipe and exhaust a little with a wire brush or piece of sand paper.

3) use some RED high temp RTV when installing them and they will last 50,000 miles without leaking.


T4 motor:
1) Use red RTV with clamp. Try to find the original VW ones that have lots of crushed steel fiber in them.
Steve, what is that clamp from? I've never seen that style clamp before.
1970 Westfalia bus. Stock 1776 dual port type 1 engine. Restored German Solex 34-3. Restored 205Q distributor, restored to factory appearance engine.

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Re: donut exhaust clamps

Post by asiab3 » Mon Oct 19, 2015 4:38 pm

It's sold by many clueless parts shops as the "68-71 bus" muffler to heat exchanger clamp. It is not, in fact, suitable for any automobile. The principle behind the clamp is wrong. There needs to be zero radial force on the clamps for a good seal; all of the clamping force needs to be axial to squish the metal ring, wire donut, and muffler together. There is no one-piece clamp on the market that does this.

Your exhaust leaks will be immense, and your CO levels in the cabin will be headache-inducing.

Airhead parts used to sell them for "68-71 bus," and I wrote them a scathing email last year, followed by a phone call or two. Now they list the two-piece clamps for the early bay.

Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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Re: donut exhaust clamps

Post by wcfvw69 » Mon Oct 19, 2015 9:52 pm

asiab3 wrote:It's sold by many clueless parts shops as the "68-71 bus" muffler to heat exchanger clamp. It is not, in fact, suitable for any automobile. The principle behind the clamp is wrong. There needs to be zero radial force on the clamps for a good seal; all of the clamping force needs to be axial to squish the metal ring, wire donut, and muffler together. There is no one-piece clamp on the market that does this.

Your exhaust leaks will be immense, and your CO levels in the cabin will be headache-inducing.

Airhead parts used to sell them for "68-71 bus," and I wrote them a scathing email last year, followed by a phone call or two. Now they list the two-piece clamps for the early bay.

Robbie
No wonder I've never seen them before. I guess I've been lucky in that I've always had a stash of new and used asbestos seals with the dual clamps that have been leak free. I think Colin is on point in saying that in order for them to work, the muffler really has to push/press them on against the heater boxes. The last new muffler I bought from Bus Depot did connect with that attachment pushing all the way in on the heater boxes.

The only time in my past that I had issues with that connection was with aftermarket headers. They NEVER seemed to seal up with no matter what kind of seal/clamp you used.
1970 Westfalia bus. Stock 1776 dual port type 1 engine. Restored German Solex 34-3. Restored 205Q distributor, restored to factory appearance engine.

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Re: donut exhaust clamps

Post by asiab3 » Mon Oct 19, 2015 11:04 pm

Both the good asbestos and crap wire mesh gaskets require a positive interference fit with the heat exchanger pipes too. Without it, all the proper clamps in the world won't work. We have to have a two-pronged approach; the fit of the mesh (with copper RTV) seals the donut to the heat exchanger, then the axial clamp secures the donut to the muffler.

I have a Coke Can shim wrap on mine, because the good German heat exchangers were not up to snuff after 45 years of wear, rust, and a brutal sandblasting. The good asbestos donuts pushed on nice enough, but the one-piece clamps cracked them. The wire mesh donuts slide down like throwing a sausage down a hallway.

RobbieFlangingSoon

Image
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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Amskeptic
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Re: donut exhaust clamps

Post by Amskeptic » Sat Oct 24, 2015 11:56 am

sgkent wrote:there are a couple secrets to making them work.
use some RED high temp RTV when installing them and they will last 50,000 miles without leaking.
After severe monoxide asphyxiation brain damage, I am hear, you here, to . . . what am I hereing hear that I am to tell you?
Oh yeah, don't use red RTV, use only the top of the temp chart Ultra-Copper and work it into the mesh style gaskets and let it cure. Then apply a thin assembly coat just before, you guessed it, assembly.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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Re: donut exhaust clamps

Post by asiab3 » Wed Nov 04, 2015 11:40 pm

I quit. :pirate:

I quit the game of donut clamps. Last night I both learned a little about welding and had my heat exchangers custom-flanged to match the new custom flange on each side of my Leistritz* muffler. I wish I would have done this before I broke in the engine. My donut clamp leaks have been the ONLY thing worrying me about the up coming winter. When the leak developed again last month, for the sixth time on this engine, I said screw it. Saved the bread, thought it through as far as fitment, and made an appointment with Adrian @ HFM. Regardless of some folks' experiences, he is still a valuable resource to the local community here, and he will bend over backwards to accommodate customers. When I asked if I could watch, he gave me a discount since I helped!

Image


So at first I was the 13mm wrench-monkey, dutifully mounting and remounting the exhaust system to my spare single port heads while he dug though boxes of exhaust flanges before we settled on new 1 1/2" flanges. They are BugPack (bye bye!) 3/8" thick solid behemoths. The larger flange ID allowed them to slip over the existing exhaust metal, and keep the OD of the heat exchangers inserted into the ID of the muffler. We even clearanced the welds on the muffler sides of the flanges to sit flush with the eventual hold down nut so I don't need to back-wrench the nuts during installation.

Installation was almost a breeze. There was a few millimeters of mustache bar to Dremel down, but the PO hack on the mustache bar needed some stress riser elimination anyway! :drunken: It's all smooth and match painted now, so there's that… Tonight I battened down the hatches and let the Ultra-Copper cure for about 45 minutes before torquing down a little bit on each nut (now 12 instead of 8) and seeing every gasket close down all perfect like. 12 foot-pounds-isn on each nut, and an hour more cure before I started it up.

Holy cow. This is what my engine should have sounded like all along.

Pictures, and two retorques, tomorrow,
Robbie


* "I" before "E" except after "C" or when sounding like "A" as in "neighbor" and "Leistritz."
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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Re: donut exhaust clamps

Post by Amskeptic » Thu Nov 05, 2015 5:49 am

asiab3 wrote: I quit the game of donut clamps.
[/img]

So at first I was the 13mm wrench-monkey, dutifully mounting and remounting the exhaust system to my spare single port heads while he dug though boxes of exhaust flanges before we settled on new 1 1/2" flanges.
Installation was almost a breeze.
Pictures, and two retorques, tomorrow,
Robbie
Looking forward to pictures for a "how-to" that I can execute on Chloe. Too late to save me from brain damage, but hey.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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Re: donut exhaust clamps

Post by sped372 » Thu Nov 05, 2015 7:02 am

I read a lot of lamenting about the one-piece style clamps, but I reluctantly went BACK to trying one after multiple unsuccessful attempts at fixing a leak with the two-piece style. So far it's holding well. To me, I see no reason why it shouldn't work... whether the "diameter" is shrinking as a result of two halves coming closer together or a circumference shrinking the net effect is the same. It's collapsing! That collapse gets transferred to a squish/pinch by the angle of the flange and conical washer underneath. Sure was easier getting it positioned vs. the two-piece style right next to the mustache bar, too.
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX

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asiab3
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Re: donut exhaust clamps

Post by asiab3 » Thu Nov 05, 2015 8:29 am

sped372 wrote:I read a lot of lamenting about the one-piece style clamps, but I reluctantly went BACK to trying one after multiple unsuccessful attempts at fixing a leak with the two-piece style. So far it's holding well. To me, I see no reason why it shouldn't work... whether the "diameter" is shrinking as a result of two halves coming closer together or a circumference shrinking the net effect is the same. It's collapsing! That collapse gets transferred to a squish/pinch by the angle of the flange and conical washer underneath. Sure was easier getting it positioned vs. the two-piece style right next to the mustache bar, too.

The problem with the"squish" you mentioned is the complete sealing of the system requires two pipes to seal together. The squish only seals the donut gasket to the heat exchanger, it does not seal anything to the muffler flange. When these cars were new, the donuts were tough to slide onto the pipes, and the clamp actually compressed the metal ring to the muffler flange, and through this compressed the donut enough to seal the heat exchanger too. Nowadays the donuts slide all loosey-goosey onto the heat exchanger, and the two-piece clamps don't stand a chance against that leak.


Colin, pictures will be later. I'm busy taking this dang apron off every single time the engine cools to retorque everything. I was skeptic at first, but I'm a true believer of getting every nut tight every heat cycle now. Why, after ONE heat cycle on the new system, a few were as loose as 5 ft-pounds.

I recommend doing this on the heat exchanger/muffler you want to keep forever. The $200 NOS Leistritz on eBay might still be for sale. It bolts up "like a Bentley manual procedure." Now though, my muffler and heat exhcangers are married, and I can't just pop into Bob's Buggy Supply and get a new muffler/exchanger, so I really recommend getting the parts professionally sand blasted then ceramic coating them yourself, following the VH instructions to the T.

Another key component is the "CB Performance Graphite Compression Gasket," which allowed us to weld the flanges with the exhaust bolted to heads without gaskets. The compression gasket is thicker than stock, and fills in the gap created in the new flange joint perfectly. It also allows for some expansion and contraction, as well as coming in sizes that fit any flange you might buy. The stock gaskets won't work if you don't cut off the heat exchanger pipes; the ID of the gasket will be to small. This way I have room for a expansion AND I retain the stock insertion depth of manifolds into the muffler.

Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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