Installing exhaust pipes/muffler...

[rustynuts]

i have been struggling with these clamps all weekend.

still not resolved. could someone please throw me a line here. i would like to move on with my project. i think 3 full days devoted to two little clamps is long enough- don't you.

[bobdo]

Rustynuts,
I'm also struggling with the same problem. I think, (but could be wrong), that the clamps you have & what most people use because of availability & the type that are repopped, are actually 45 flathead. Someone with definite knowledge hopefully will join in. I remember seeing in Palmer's book Big Twin front header pipe clamps having the tabs bent perpendicular to the center of the round openings. The 45 clamps have the tabs tangent to the circle. Does that make sense? I made clamps for my EL, but I'm unable to position them at the top of the sidecar loop casting as they should be. Mine fit much further up the down tube. My header pipe is repop, I plan on replacing my pipes with more accurate repops hoping that it might correct this clamp issue. Hope this helps.

[Steve Little]

Hi Rusty.
I recently fitted a aftermarket exhaust to my 1937 Knuckle. And some of the issues that I had to cure along the way as follows:
Front exhaust header nedded a 1/2" wide X 1/8" deep depression knocked in it "about 1" long, running along the side of the header" to clear the case stud and nut. If you dont put this in, it will be impossible to move the header around while try to mate it with the squish pipe. If you dont put the depression in the header it will put stress on the exhaust spigot and could start a crack. Your exhaust header should fit into the exhaust spigot with no stress load.
I spent 5 hours fitting/modifying the front header and clamps alone. The header clamps that were supplied with my kit were 1941-47.
I had to put the clamps in the vise and put a shifter on the clamp ends and put a little twist on the ends.
When I was tightening the header clamps to the header I had a little nylon hammer that I would lightly tap the clamps then tighten the nuts and tap it again etc etc. This method stops the clamps from pinching on the header and pulling it in a direction, other than stress free.
I gave up on the squish pipe that was supplied and used an original.
The rear pipe was one of the Olsens make and it need no alteration.
The last alteration probably wont affect you as I had one of the aftermarket fish tail mufflers.
When my muffler/Y pipe was fitted to the squish pipe it hit one of the trans kicker cover studs and forced the muffler sit with the fish tail rolled out at an angle to the bike. I think the Y fitting for the muffler was fitted at the wrong place. I had to make a 1/4" deep depression along the side of the Y pipe so that the muffler could roll back to the correct look and also so the transmission case could go through its full adjustment for the primary chain.
Also had to port out the hole in the Y pipe with a die grinder for the gas from the rear cylinder to enter the muffler. It was rough oxy cut to only 3/4" diam.
I have read the complaints and struggles of people trying to fit reproduction exhaust systems on this site and others, and now have a real appreciation for thier efforts.
I got mine to fit but it required a great deal of thought and effort.
Your picture of the brackets is clear. I do not know the manufacturer of your clamps but my system came with 41-47 clamps. The only way I could get them to fit was to have the flat backs of the brackets, facing to the front of the motorcycle....and then twist the ends to meet each other. I had the bolt facing inward and put a small spacer between the nut so that I could get onto it for tightening.
I have since purchased a set of early style clamps to make it look right, and I relish the thought of fitting them with the ease and hassle free style that I am foolishly hoping for.
Regards Steve.

[duffeycycles]

The last one I did was a '46 knuck with Teds exhaust parts .I'm used to modifying this stuff.It took about 3 hours to do the complete install. I was very happy with the end fit,it came back off and on easily cosidering that the pipes were flat on the ends from manufacturing and shipping.

[sirhrmechanic]

Mine took the better part of a day, but the AAOK system pretty much dropped into place.

That said, a lot of the exhausts we put on cars need some bending or tweaking. You may have to do some bending... do you have access to a press? Doing some radiusing may be needed. Sometimes it's as simple as putting a fat dowel in each end of a pipe and spreading them a bit. Sometimes a 20 ton press can be used to 'spread' a bend just a fraction. It usually doesn't take much.

Don't assume that a new system is bent perfectly!

Also, where is your engine positioned in the frame? Does it need shimming? Are the mounts the right height, etc? If the engine is off, the exhaust won't fit.

We have a saying in the old car world: Parts that 'almost' fit.

Cheers,

Sirhr

[rustynuts]

thank you for responding, especially for your input Steve. i believe the clamps in my photo are actually servicar types. but i guess they could still fit. when all else fails- check Palmer's. hope he's right on this one. also the 36 parts book.

anyway, i have another set, correct style (i think). and once the tabs are twisted like you so clearly described, and then tightened and loosened a few times, they fit. when these pieces have never been together before, they act like they don't want to be. But it's a beautiful exhaust when it's fitted together correctly. so many of these fishtails end up twisted in all sorts of directions because of ill fitting pipes. you can see it a mile away. Hey, if it was easy, everyone would be doing it.

the lesson here is to fit up these parts on the bike before finishing them, duh. I am now re-spraying 2 front header pipes and 2 S pipes and a rear header pipe. 2 OEM and 2 repop and one unkown, so after 4 days, not counting an extra day for paint drying, I should be able to move on. the difference in the OEM front pipe and the repop front pipe (that I have): the repop bumps the case bolt, but the OEM curves upward a little more so that it doesn't. the repop is also a longer at both ends. probably left long by the maker on purpose. no kinks or deflections in the OEM, repop not so much.

my rear header pipe (repop) was nearly an inch too long. but once it was shortened, the muffler fell into place nicely and i got clearance for the brake shaft lever. muffler clamp was a piece of cake after dealing with the fronts. still not really satisfied with the stress the rear pipe seems to make on the cylinder.

these pipes have to be shoved in pretty hard b/c of their diameter (repop seems larger than OEM). they are a tight fit in the exh spigot. there was enamel paint in the opening from the cylinder respray, but i got that out. and the ceramic paint on the pipes has to be nearly sanded off before the pipes will really even fit in to the spigot.

So I worry these are too stressed, but there is nothing I can do about that now. if the OEM front pipe wasn't dented up I think I would be home free. As is, I'm moving on- but I have a feeling this system will need some improvement before I have an up and over the pass bike.

thanks again all for the replies.

[PSANTORA]

It seems that the big problem with the fitting of the Knucklehead exhaust systems is the rear header pipe. I have had that pipe faithfully reproduced and have sold quite a few without a single complaint. They are long at the exhaust port end and do need to be trimmed. The pipes that I had reproduced are being sold by another vendor, however I had another batch made and they are available for $67.00 + shipping each. Quanity discounts available. Feel free to call, if you don't like the part return it for the cost of shipping only. AMCA handle PSANTORA Thanks, Phil 216-312-4098

[Robert Luland]

So once again the twelve pack and a bible thing holds firm. Told ya so! Bob L

[Steve Little]

The rear header pipe that I purchased from the Olsons may have been one of yours as I bought it from them about 12 months ago.

It seems that the big problem with the fitting of the Knucklehead exhaust systems is the rear header pipe. I have had that pipe faithfully reproduced and have sold quite a few without a single complaint. They are long at the exhaust port end and do need to be trimmed. The pipes that I had reproduced are being sold by another vendor, however I had another batch made and they are available for $67.00 + shipping each. Quanity discounts available. Feel free to call, if you don't like the part return it for the cost of shipping only. AMCA handle PSANTORA Thanks, Phil 216-312-4098

[bobdo]

Rustynuts,
This might be an old thread & this info may be too late, but...
I might have misled you unintentionaly in my earlier post. I found info on a front header pipe clamp on the AAOK website that states that the clamp you have in your pic is correct for a '47, actually 1937 - '47. The clamp I had mentioned is also shown on that website, it states that it is for a 1936 model. That's assuming the website is correct.