Manifold rubber bands discussion study

Late Shovel type

All Shovelhead topics
Post Reply
Excalibur
Senior Member
Posts: 882
Joined: Mon Jul 27, 2015 1:01 pm
Bikes: '61 Pan
'83 FXWG
'74 T150
'41 Indian, '29Norton
'25 HD
'13 JAP
'12 BSA,
'11&'12 NH
'08 Triumph
Location: NZ
Has thanked: 505 times
Been thanked: 361 times

Manifold rubber bands discussion study

#1

Post by Excalibur »

Noticed a clamp has moved on the rubber so I wondered if the rubber was relaxing and loosening the clamp.

A lot must have been learnt since these was introduced 40+ odd years ago. There must be lots of different rubber materials/manufacturers over these years. Some must have been better than others.

Any comment or tip regarding the rubbers, clamps and fitting methods is welcome.

When the motor was assembled, I aligned the heads so the manifold was a nice fit. I have a carb support strut to upper crankcase stud.
SU, upswept manifold, SS clamps.

Would prefer the o-ring style, but heads are band type so am stuck with it.

Some questions to start with,,
Are the rubbers Viton? NBR?
What clamps are best, tightness and rechecking tightness?
What works, what don't?
Could I cut my own hose from hose stock?

Thanks for any thoughts.
Mongrel505558
Senior Member
Posts: 1418
Joined: Thu Mar 26, 2020 5:46 pm
Bikes: Rigid Panhead bobber, 68 Shovelhead, 2000 Road King Police bike, 2000 Dyna Wide Glide
Location: Rhode Island
Has thanked: 991 times
Been thanked: 701 times

Re: Manifold rubber bands discussion study

#2

Post by Mongrel505558 »

I use the stainless steel aircraft-style clamps. They're relatively easy to install and my manifolds don't leak.
You do not have the required permissions to view the files attached to this post.
nifty
Senior Member
Posts: 591
Joined: Wed Apr 29, 2020 8:24 am
Bikes: 68 FL
Location: Nambour Qld Australia
Has thanked: 256 times
Been thanked: 476 times

Re: Manifold rubber bands discussion study

#3

Post by nifty »

Excalibur wrote: Mon Oct 24, 2022 10:13 am Are the rubbers Viton? NBR?
What clamps are best, tightness and rechecking tightness?
What works, what don't?
Could I cut my own hose from hose stock?
Thanks for any thoughts.
Viton is good*, easy to get Viton o-rings, on Shovels I use metric Viton o-rings, slightly larger section. Not so easy to get Viton bands. *unless you burn with torch and release hydroflouric acid.
Many no-name orings sold for H-D manifolds are at best Nitrile/NBR, many are crap pretending to be fit for purpose. Not all Viton o-rings are brown, many are black, you have to trust your supplier, I wouldn't trust alibaba or similar.

For later Shovels, the rubber bands can be good & bad, some last years, some only months. I would tend to trust name brands like S&S, James etc
Material must be able to handle heat and fuel and remain supple, without cracking.
You can cut your own bands, but I've never found an industrial hose which ticked all the heat fuel and stock OD boxes, you might get lucky.

Silicone coolant/turbo hose from auto shops works, but OD is bigger, but with 4 narrow worm drive clamps gets the job done. Do not over-tighten, resist temptation to re-tighten.

Trial fit without clamps or bands/orings, carb supports must hold carb & manifold in alignment with heads. The seals and clamps should play no part in alignment. Don't overtighten clamps

T-bolt stainless clamps such as in Mongrel pic are good if alignment good and not over-tightened. In US these clamps available from industrial suppliers, not so in OZ, you may get lucky in NZ, or buy from S&S etc (you say you already have S&S clamps).
Mikalor and clone T-bolt clamps have a floating shoe which is wider than the desired 3/4" and shoe fouls heads & manifolds.

Seeing as you have band type heads, manifold & clamps, just buy decent bands.
If you buy cheap bands, buy spares coz you will likely need them soon.

Nifty
RooDog
Senior Member
Posts: 5327
Joined: Tue Oct 31, 2017 1:00 pm
Bikes: 1950 Panhead, Resto-Mod
1968 90", 5 Speed Shovelhead,
1984 Home Built Custom Evo 100" Bagger
Location: Knoxville, Tennessee
Has thanked: 2801 times
Been thanked: 2158 times

Re: Manifold rubber bands discussion study

#4

Post by RooDog »

While wrenching at the local stealership in the late 1970s I fell in hate with the flat bands. I only had to deal with a few of them , that I remember, so I never learned ant easy way to deal with installing them. All of my subsequent projects with Pans and Shovels have been with O rings. Sorry fellas, never paid much attention to the material most likely since I never had any problems with them. Now then, I have had issues with some of the two piece clamps pinching the O-rings at their parting lines, So I always choose to use the aircraft T-bolt clamps, and all is rainbows & unicorns in my world....
....RooDog....
DSC02555.JPG
You do not have the required permissions to view the files attached to this post.
Hogey
Member
Posts: 203
Joined: Thu May 26, 2022 5:10 am
Bikes: 2001 fxst 68 shovel
Location: Victoria
Has thanked: 301 times
Been thanked: 83 times

Re: Manifold rubber bands discussion study

#5

Post by Hogey »

I cut some heat and fuel resestante hose and 4 hose clamps i think their still on the bike today 30 plus years back
Excalibur
Senior Member
Posts: 882
Joined: Mon Jul 27, 2015 1:01 pm
Bikes: '61 Pan
'83 FXWG
'74 T150
'41 Indian, '29Norton
'25 HD
'13 JAP
'12 BSA,
'11&'12 NH
'08 Triumph
Location: NZ
Has thanked: 505 times
Been thanked: 361 times

Re: Manifold rubber bands discussion study

#6

Post by Excalibur »

Thanks for the ideas guys, really great food for thought as I ponder the next step.

Been studying. Have uncovered a number of interesting points.

Following on from Nifty's mention of silicone hose I found this kit
sil1.jpg
This kit uses narrow clamps with a liner. Looks like this liner covers the perforations and the lumpiness of the worm housing thingy.
Cost is $56 plus shipping $61 equals $117 USD total. Nope, that isn't happening. Not for 2 short bits of hose and 4 hoseclamps.

Hose clamps in pic above are marked Ideal or Tridon. A scan of Idealtridon website does not show those exact ones. Interesting website. Lots of innovation going on.

S&S intake bands 10pack are on Ebay. For me that's $98USD landed cost for 5 sets. Continue using my existing so called aircraft clamps if I went this way.

Checked Aliexpress for silicone hose and yep, 3" length of 51mm could be landed for about $10USD but spoiler alert... I bought the exact same one locally for about $11USD. This hose is a very light push fit onto manifold so when inverted manifold doesn't fall out. Yet to find any reasonable clamps but this hose is one option atm.

Over at JP's they have Red Silicon bands that get mostly good review. Couple guys said they were tough to fit. Another claimed stock clamps were too small. Cheap at $4ea USD.
They also have S&S seals at about double the price. I trawled through the reviews to see what I could learn. Most were happy with just one particularly scornful response.

Looking closely at my manifold/seals/clamps...
Clamps are stainless aircraft type, I hear them called T-bolt clamps. 3/4" wide.
One seal had split internally. They feel soft and an embossed impression of the gap manifold-to-head was pronounced.
When bare manifold is offered to heads, gap for band to occupy is maybe an 1/8" (3mm) wider than existing bands. The thought here is to cut the bands wider up to 7/8" (22mm). Fitting would be more awkward but would give more purchase area for clamps to bite onto stubs.
You do not have the required permissions to view the files attached to this post.
nifty
Senior Member
Posts: 591
Joined: Wed Apr 29, 2020 8:24 am
Bikes: 68 FL
Location: Nambour Qld Australia
Has thanked: 256 times
Been thanked: 476 times

Re: Manifold rubber bands discussion study

#7

Post by nifty »

Excal,
Are your approx 2-1/4" "aircraft" clamps not same as S&S 16-0231 band clamps?

I wonder how supple your pictured "green linered" hose/bands are? Is green liner a bonded part of hose? If not one would have to also look out for snagging and folding of green liner during installation/wrestling.
Bigger OD of bands makes getting clamps on more difficult. If bands stiff they are a bitch to install, which Roodog mentioned re OE bands, and why I suggested silicone hose. Hose bigger OD than OE bands more difficult again.

Nice narrow worm clamps in your pic, I've never seen narrow clamps before with plain wrap under cut slots, no doubt adds to price.
Norma narrow clamps (German) don't have cut slots, instead indentations which don't cut into rubber, good auto parts places have them, or BMW R models 70's etc use them at top of fork boots, anyone who parts out BMs should have some used ones.

Re manifold gaps
Is this due to your manifold being AM early Evo and then modified to adapt to your Shovel?
Ally or PTFE spacers to fill void and resist band deformation theoretically a good idea, but you have to assemble, doable with OE style bands, but with industrial hose, good luck.
If you have room for 7/8" wide bands, I can't see extra band width being much help due to "aircraft" clamp only being 3/4".
You could maybe use 7/8" wide bands with Mikalor clamps.
Given your gaps and apparent love of cheapest option, possibly 7/8" wide bands with narrow clamps best compromise.

Apart from reducing cost of production, the band type heads & manifold presented 3/8" of parallel sealing surface at each side of manifold & each head. The 3/4" wide band and 3/4" clamp ensured maximum chance of a good seal.
A couple of years ago S&S 16-0238 bands were $3.99usd each from J&P.

Nifty
RooDog
Senior Member
Posts: 5327
Joined: Tue Oct 31, 2017 1:00 pm
Bikes: 1950 Panhead, Resto-Mod
1968 90", 5 Speed Shovelhead,
1984 Home Built Custom Evo 100" Bagger
Location: Knoxville, Tennessee
Has thanked: 2801 times
Been thanked: 2158 times

Re: Manifold rubber bands discussion study

#8

Post by RooDog »

Nifty....
Are you saying that th early Evo manifolds, designed for "compliance fittings" can be used on a Shovelhead?

I can't seem to get anything right today. The part number is plainly visible, and not a compliance manifold.
....RoDog....
You do not have the required permissions to view the files attached to this post.
Last edited by RooDog on Thu Oct 27, 2022 4:09 am, edited 3 times in total.
nifty
Senior Member
Posts: 591
Joined: Wed Apr 29, 2020 8:24 am
Bikes: 68 FL
Location: Nambour Qld Australia
Has thanked: 256 times
Been thanked: 476 times

Re: Manifold rubber bands discussion study

#9

Post by nifty »

Roodog
No, I'm not saying an Evo manifold can be used to Shovel.

In one of his earlier posts, Excal has an AM SU early Evo manifold modified by sleeving up to 2" OD at head ends to "work" on his Shovel, but with it he also now has approx 1/8" gaps to heads and apparently one band has already failed in the short time he has had bike running.
Rebuild engine from boxes

BTW Roodog, is your pic not a late Evo, post compliance fittings manifold, ie. wide manifold that pokes into heads, sealed by rubber rings compressed by flanges?

Nifty
Excalibur
Senior Member
Posts: 882
Joined: Mon Jul 27, 2015 1:01 pm
Bikes: '61 Pan
'83 FXWG
'74 T150
'41 Indian, '29Norton
'25 HD
'13 JAP
'12 BSA,
'11&'12 NH
'08 Triumph
Location: NZ
Has thanked: 505 times
Been thanked: 361 times

Re: Manifold rubber bands discussion study

#10

Post by Excalibur »

Nifty, will add some pics to this post to clarify...

Don't know the maker or the marketer of my stainless band clamps. Upthread I referred to them as SS an abbreviation for stainless steel.
Pics below.

I see the Norma hose clamps in local market. I have a number of good leads for narrow band clamps now. 9mm wide should do fine as manifold stubs are 11mm and head stubs 10.5mm. I know what you mean about hose clamp slots cutting into rubber, makes a mess.

The "gaps" I was meaning is the difference between the rubber width (18.5mm) and the space they have to occupy approx 22mm. To correctly align manifold there is a slight gap of maybe 1mm between stub abutments. The witness marking on the old rubbers suggest manifold has migrated outward. This could be because old rubbers are too soft and squidgy? Possibly excessive tightening? There is a single steel strut 20mm x 5mm from top crankcase bolt. A better way to anchor manifold would be ideal.

Makers of the kit upthread use a hook tool to help engage the hose. Basically they get one side in place then use the hook tool to pull the 2nd rubber into place. In the pics it looks suspiciously like their hoses are longer than stock bands. In addition if those are 9mm clamp bands, then the hose is 22mm++-ish.

Roo, manifold is early Evo adapted to Shovel by sleeving. It has the correct angle plus I have a late Shovel S&S manifold to model it from.

Existing aircraft clamps. Silicone hose 3" long length.
mm1.jpg
mm2.jpg
Manifold in situ with old bands
mm3.jpg
Better pic of how short hose is compared to area it has to occupy
mm4.jpg
Yet to figure a neat way of cutting hose so I get it perfectly square. Bet it's trickier than it looks.

As a side thought, what would be ideal clamp tightness or torque?

As a last thought, the "juice" for me is solving this kind of problem in a manner that is reliable, affordable and repeatable. With the time I spend studying the issue and solution, I could easily earn the money at my job to pay the outrageous price and the ludicrous shipping... but what fun would that be? :lol: My even bigger wish is that it helps others. But I totally get where the kit makers are coming from. A mans time, energy, effort, investment, they need a return on that. And if people are paying it, then who's to argue it's not the right price?

Thanks for any thoughts, help, ideas etc
You do not have the required permissions to view the files attached to this post.
nifty
Senior Member
Posts: 591
Joined: Wed Apr 29, 2020 8:24 am
Bikes: 68 FL
Location: Nambour Qld Australia
Has thanked: 256 times
Been thanked: 476 times

Re: Manifold rubber bands discussion study

#11

Post by nifty »

Excal,
Thanks for clarifications, apologies for thinking you were a total cheapskate.

IMO the aircraft clamps you have are a tad small for your new hose.

Don't know about current production, but old narrow Norma clamps which I have, are stainless and all beautifully radiused on all their edges, no cutting into hose rubber, or your fingers when you are wrestling.

Cutting hose: Lathe, push hose onto a wood or plastic mandrel, not too fast, use a knife blade in parting-off tool-holder (grind blade from old power hacksaw blade or similar, needs to be fairly rigid or it will flex & make cut crooked), quick spray of WD40 or similar before you plunge stops side friction on blade. Yields factory-look rubbers to perfect length and dead square, quicker than it took to type this.

Installing bands: Snap-0n have a nice set of 4 different o-ring & seal picks, or knock-offs, or make your own, they need good handles so you can grip, pull & twist. Useful for many other jobs. A very light smear of high temp grease inside bands helps ease their passage and sealing. Install bands, & manifold, then open clamps right up and slip over, think about positioning for future access to clamp fasteners, one day you may need to nip up slightly, or take off under roadside conditions.

Ideal clamp tightness or torque?: Just tight enough to make the band seal 100% and no more. I go by watching the band, stop when I see slight deformation, its not much torque, way less than you would use on a typical screw. This gives you a good seal and several re-uses of bands. Only works well with really good alignment and support. Over-torque and more likely to have air leaks and short life of bands.

Support: Hard to have too much support for manifold, carb & air cleaner. Late OE Shovels had a bracket from each rocker box (for late large air cleaner) Earlier front-only rocker boxes have one bracket for oval air cleaner, can drill & tap early rear rocker box. Some folk regard as ugly and ditch, same folk cry about air leaks and resultant carnage. Strap from case bolt better than nothing. Plenty of scope for creativity.

Nifty
Hogey
Member
Posts: 203
Joined: Thu May 26, 2022 5:10 am
Bikes: 2001 fxst 68 shovel
Location: Victoria
Has thanked: 301 times
Been thanked: 83 times

Re: Manifold rubber bands discussion study

#12

Post by Hogey »

When i cut my hose i fitted it to exhast pipe and used a lathe
guppymech
Member
Posts: 74
Joined: Fri Sep 22, 2017 2:33 pm
Bikes: 1984 FXE, 2002 883R
Location: Chicagoland
Has thanked: 17 times
Been thanked: 26 times

Re: Manifold rubber bands discussion study

#13

Post by guppymech »

I've tried just about all the solutions offered and have settled on aircraft clamps with James flat bands. I used paired narrow worm screw clamps on stock type bands and the band split along the sharp edge of the clamp causing a vacuum leak. I liked the idea of the 4 individual worm screw clamps so I bought some reinforced hose and cut my own bands. The O.D. of the reinforced hose was almost twice the thickness of the stock bands. I found the hose would cold flow over time forcing the manifold out of alignment with the head spigots. I tried the Norma clamps with the homemade bands and they worked good without cutting into the bands but they have wider straps and the way the worm screw is captured in the clamp is quite a bit wider than the rest of the clamp. The homemade bands still cold flowed with the Norma clamps and the clamps being wider made getting everything installed in the space available difficult.
Excalibur
Senior Member
Posts: 882
Joined: Mon Jul 27, 2015 1:01 pm
Bikes: '61 Pan
'83 FXWG
'74 T150
'41 Indian, '29Norton
'25 HD
'13 JAP
'12 BSA,
'11&'12 NH
'08 Triumph
Location: NZ
Has thanked: 505 times
Been thanked: 361 times

Re: Manifold rubber bands discussion study

#14

Post by Excalibur »

Great thoughts, thanks for taking the time. Awesome.

Cut hose on the lathe using a sharpened power-hacksaw blade. Perfect result even though I forgot about adding WD40. Cut 3 hoses to 22.8mm from the 3" length..
m11.jpg
Came up with additional brace for the upswept manifold. A little bracket was added to existing support to bolt to a 2nd lower flange bolt, then a 1/4" rod was used to anchor that to my custom coils bracket. The object was to stop manifold pulling away from head stubs.
Pictured here atop my vintage Boothmac tractor seat.
m12.jpg
Coils on bracket. The 1/4" rod attaches behind and between these coils.
m15.jpg
Clamps have 9mm wide bands, non perforated, unknown brand. The worm housings were about 3mm (1/8") wider but the way I staggered these meant they don't clash with anything. Tested perfect with 8psi.
m13.jpg
Time will tell how it works ongoing. Bike started up perfect, now if only rain would stop...

Hope this is interesting
You do not have the required permissions to view the files attached to this post.
RooDog
Senior Member
Posts: 5327
Joined: Tue Oct 31, 2017 1:00 pm
Bikes: 1950 Panhead, Resto-Mod
1968 90", 5 Speed Shovelhead,
1984 Home Built Custom Evo 100" Bagger
Location: Knoxville, Tennessee
Has thanked: 2801 times
Been thanked: 2158 times

Re: Manifold rubber bands discussion study

#15

Post by RooDog »

I give you an A+ rating on the coil(s) bracket....
....Good Show....
....RooDog....
Post Reply

Return to “Shovelhead”