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Fork Baffle Kit

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Plumber

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Post Thu Oct 19, 2006 8:46 pm

Fork Baffle Kit

I have a set of 45775-49 of baffles coming from Kick-Start, part # 3236. My V-Twin '49-59 forks pound on re-bound. I have 7 oz. of oil in the tubes (no leaks from the sliders), but the forks didn't ship with the baffles. I can pull the tube plugs off and install the baffles without draining the sliders. If I have to drain the sliders, I'll have to turn them upside down. That's okay, just part of the new improved V-Twin Glide fork design. They also ship with the later 'Gary Bang" slider seals (for a reduced amount of slider seal parts). I'll post a photo of the baffles as soon as they get here, then install them. If they stop the pounding problem, then it's the fix.
Last edited by Plumber on Thu Dec 07, 2006 9:01 pm, edited 1 time in total.
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steph

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Post Fri Oct 20, 2006 1:01 am

Pound on rebound often comes from a missing 46045-49 spring spacer in repro forks.
Stéph
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Plumber

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Post Fri Oct 20, 2006 8:57 am

Yes, the 46045-49 spring spacer. Certainly would seem so. Once there was a spacer and now there isn't. I rebuilt an OE set of forks with a stock-style V-Twin kit. The kit didn't come with a new spacers. My forks had the spacer in there, but my springs were rusted so I ordered new ones. I was going to reuse the spacer, but I noticed that the spacer that is featured in the '49-57 Parts Book, is not in the '58-68 Parts Book. Then I noticed that the 46051-49 spring number changed to 46051-49A in the '58-68 book. I used the 49A springs from V-Twin (with baffles in the tube plug's), and no spacers, and the forks work without slamming. In fact, as I remember, I tried to use the spacer along with the new 49A springs and the spring rose so high in the tube that I couldn't compress the spring enough (to even get the plug threads down far enough to grab the first threads of the tube top) to screw on the tube plug. I removed the spacer. Kept them along with the old rusted springs.
We ran this topic for awhile over on http://hydra-glide.net
JohnHD has the same slamming problem. The way it ended up I believe, was that neither one of us could verify if we had baffles, but he has spacers and I don't. At any rate, when the baffles get here, I'll install them in my V-Twin forks and roll it down the street to test the system out.
Just know this for sure: I rebuilt my OEM forks years back with a V-Twin kit, (without spacers), new springs and baffles and have no pounding. I don't see how baffles could make a difference in the pounding problem either, since it's a metal to metal sound, but to know if the probelm is lack of spacers, we would have to know why the spacers were left out of the '58-up assemblies, and what was the difference between the -49 and -49A springs? Was it spring length? We know it was something, because they added that "A".
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If you can get your hands on a 2006 V-Twin catalog it's a keeper. They have less pages than last year, but more photos of everything antique AM (aftermarket). Somewhere in the catalog, at the bottom of a page, in tiny print, are the names of the people who put the catalog together. John White's name is listed. He laid the parts out (like we would do if we had the opportunity) and he took all of the photos. That's alot of work. You can tell an "antiquer" did the layout. All the dash bases are pictured, all the different tires, everything we'd be interested in. Nice work. Best catalog in their history.
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Last edited by Plumber on Thu Dec 07, 2006 9:06 pm, edited 1 time in total.
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john HD

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Post Fri Oct 20, 2006 5:56 pm

thanks for posting this plumber!

the pounding on rebound is the last little nagging problem i need to fix on my bike.

if it wern't for that i would say the bike was near perfect for me.

my plan is to tear into it this winter after deer hunting season, i have a couple of nice fork sliders i scored at davenport i want to try.

updates to follow...

john
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Plumber

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Post Fri Oct 20, 2006 8:42 pm

my plan is to tear into it this winter after deer hunting season.
....... Sounds good :!:
I think there's a reason why the forks slam and how the baffles prevent it. The spring on the baffle stem takes up the re-bound shock. Look at the cut-out made on each of the separate baffles. There was a reason why the factory didn't want you to stack the baffles in direct cut-out alignment.
Look at it this way: The fork re-bounds. Then what? The 7 oz's. of fluid won't compress, and it hits that single bottom-most baffle like a hammer, when the compressed fork spring tries to push the oil against the bottom baffle. The baffle is trying to be pushed upwards, towards the top of the fork tube, to make the damper assembly slam, but the spring behind the bottom baffle will dampen the shock from the slug of oil, because all the oil can do is labyrinth through the off-set reliefs in the stack of discs. Sound possible?
Kick-Start M/C. Part # 3236
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Oil gets pushed up through these reliefs in each off-set baffle disc.
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This end screws into the fork tube plug.
Image
Last edited by Plumber on Thu Dec 07, 2006 9:09 pm, edited 1 time in total.
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steph

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Post Sat Oct 21, 2006 12:41 am

The baffles on top are only to avoid oil coming out off the plug, instead off the fancy cover and rubber that didn't really work.Imo
Stéph
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Plumber

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Post Sat Oct 21, 2006 8:33 am

Oh yea, that 45729-49 .... Early 49-OHV......Fork upper bracket bolt kit. Haven't heard much about it.
Last edited by Plumber on Thu Dec 07, 2006 9:13 pm, edited 1 time in total.
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john HD

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Post Sat Oct 21, 2006 9:07 am

plumber etal,

my theory is that the reason the fork slams on rebound has more to do with the fit of the damper piston inside the fork tube.

i have successfully got it to quit slamming by varying the level and viscosity of oil in the fork.

usually when i get enough oil in the forks to get them to quit banging it drools out of the seals.

like i mentioned before, i will know more after it is apart! again!

john
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steph

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Post Sun Oct 22, 2006 12:29 am

The dampening inside the forks is regulated by 45826-49 shims, don't remember exactly iff it was adding or taking out to get more dampening, but maybe someone else still knows...
Stéph
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john HD

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Post Sun Oct 22, 2006 7:31 am

steph wrote:The dampening inside the forks is regulated by 45826-49 shims, don't remember exactly iff it was adding or taking out to get more dampening, but maybe someone else still knows...
Stéph


yes that would be helpful!

anyone?

john
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Plumber

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Post Sun Oct 22, 2006 7:47 am

A safe way to remove the fork tube plug is to remove the bracket (hex) bolt, and loosen the bottom-tree pinch bolt. Slide the fork tube down far enough to get a wrench on the plug flats, then tighten the pinch bolt, and loosen the fork tube plug.
Image
Then loosen the pinch bolt and raise the fork tube until the top of the plug is about a 1/2" away from the bottom edge of the top tree. Tighten the pinch bolt again. Then (wearing safety glasses) turn the fork tube plug out with a thin jawed wrench. The tube plug will snap upwards and into the top tree. :!: Careful. Keep your fingers away from the plug or you'll lose some skin. Let the wrench do the work. The plug will snap up suddenly and capture the wrench. (You can see between the spring coils - no baffle assembly.)
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45826-49 shims

The shims were another item that have been excluded from the "rebuild kits" and the repop forks all together. There would be some "slamming" though if the clearance between the lower damper bushing and the (damper) snap ring is greater than 0.004". Most definitely. I checked the clearance on my repop forks as part of the "Fork" chapter. I made a note that mine was tighter than 0.004", so in my case, the slamming from excessive free-play in the damper assembly is not the reason with my V-Twin forks.
When I rebuilt my OEM forks years back, with a V-Twin kit, I had to remove all the shims, but maybe one, in order to get the 0.004" or less free-play. I kept the thin shims for later, but each OE damper had about three of them in there. Paper-thin shims of different thicknesses. Obsolete now.
This is where the shim(s) would go - directly under the bottom spacer in the damper valve kit. There are no shims in the V-Twin damper.
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You measure between the bottom of the lower bushing and the top of the snap ring. 0.004" max. free play. I think I could get a 0.003 blade in between the ring and bushing, but not a 0.004.
Image
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When V-Twin or their jobber, re-popped the forks, they went through the fork assembly blueprints and removed as many parts as they could. There's no drain plug, no spring spacer, and I believe they re-made the damper bushings where no shims are needed, and they used a later, (fewer parts) "Gary Bang style" slider seal kit (no more felts). They knew what they were doing.
The "floor" of the repop slider is critical too. That floor that the 46125-48 damper gasket and 46121-48 lower bushing sit on has to be uniformily deep on each slider. The (+ or -) is as critical as 1/32" of an inch. Too deep and the damper stud will protrude past the [46128-48] "fixed" knurled washer that's a driven fit in the bottom of the slider.
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When that happens you have to use extra paper gaskets [46111-48 and 46125-48] to take up the space and force the stud to retreat back into the slider, so the 7725 nut and washer can pull the damper stud into the paper gaskets to seal correctly. They will and do, because I had that problem with mine. A leaky slider that leaks no more. Not a drop.
And another modification the V-Twin engineers made, was to compensate for 1/32" variances in the slider floor bottoms. Those engineer fiends added an "aluminum" washer between the 7725 nut and the (46161-49) "knurled" washer (the knurled washer's called a "plain" washer in the '49-57 Parts Catalog, but it's not plain, it's knurled), and the V-Twin aluminum washer is not in the original parts books. What this aluminum "crush" washer does, is to allow the protruding stud a maximum of 1/32" of crush-depth. So, if your damper stud protudes a tiny bit (but enough to where the slider will leak fluid like a sieve), then the dampers stud squared shoulders can sink into the crush washer and you still get a seal between the paper gaskets, because you haven't bottomed-out the threads on the damper stud, and the nut is still pulling on the damper against the paper gasket stack :!:
Here's where you have to muscle the tube plug against spring pressure. With the "spacer" left in the slider of my OEM forks, the fork spring would rise up so far, that I couldn't get the spring compressed enough to gain purchase on the first threads in the I.D. of the tube.
Image
Wear safety glasses.
Once the first thread starts, you can turn the fork tube (C.C.W) against the stationary plug (in your palm) as you're pushing down.
[Note there's paper covering the sliders. They scratch easily.]
Last edited by Plumber on Thu Dec 07, 2006 9:25 pm, edited 4 times in total.
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steph

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Post Mon Oct 23, 2006 10:17 pm

Taking out shims will give more dampening.
Stéph
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Plumber

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Post Wed Dec 06, 2006 7:33 pm

Fork Baffles and Lack Thereof

I rolled a rigid frame w/ rebuilt OEM forks down the street and compressed the forks pretty good coming up the driveway. They don't pound with the normal compression they'd normally get while riding or when you pull on the front brake lever to stop.

I think because my VT forks don't have the baffle stacks, that it could be why the VT forks pound more than the OEM set.

Look at the baffle assembly and you'll see how the bottom baffle disc has a 1/2 radius slot cut out for it. The other baffles have the same cutout, but they're staggered at 180 degrees to each othe
Image

The bottom baffle is backed up by a spring, to allow rebound when the (solid) bottom disc gets hit by the slug of fluid (the top of the damper rod is solid) on compression (and water and fluid do not compress... but they are fluid).
Image
So, the fluid is looking for a place to escape and the labyrinth of off-set baffle discs lets the fluid meander through the discs, with the spring on the rod moving backwards as the fluid pressure increases, which "dampens" the hit of the tube when it travel-stops. The shock is when the damper assembly shock-waves against the (0.004") free play at the slider tube snap ring (46172-48). [This is assuming that you don't have worn slider bushings, which would cause other problems.]
The information is found on page 2F-10 of the '59-69 Service Manual, to wit:
Check clearance between snap ring and lower bushing. If clearance exceeds .004 in.,remove snap ring, gasket and lower bushing and insert additional shims to bring to a maximum of .004 in. clearance.
So, the shims were used to adjust free play between the snap ring and lower bushing. The spacer first showed up in the 1949-57 Spare Parts Catalog as (46045-49) and was used from '50-53 and was then removed from future service. Then the spacer showed up again, albiet briefly, as (12A) for '65-66, in the 1959-69 Service Manual on pg. 2F-3, but with no part number given and it never made it into the 1958-68 Parts Catalog.
The engineers at Tedd Cycle, Inc. improved, and made affordable (by eliminating the drain plug which would have required more hand work to produce) the Glide forks. Those rascals didn't include the (tube plug) baffle assembly, so what's new?, but there it is and the forks will function as well as OEM, if in fact the slamming problem is eliminated by baffles.
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Plumber

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Post Thu Dec 07, 2006 6:43 pm

I installed baffles in the V-Twin forks. Without the baffles, there's an open 1/4 threaded hole through the tube plug, open directly to interior of the fork tube, so if you don't have the baffle stem installed, fork oil will geyser up unimpeded to the little breather valves that are within the top of the big hex bolts. So, you have to have the baffle assemblies installed in the tub plugs.
As far as slamming, once I installed the baffles, and rode tested it, I feel it slams less. If I hit a bump or apply the front brake lever hard, going downhill, I can't make the forks pound. But, it's a bare frame at present and it will handle differently fully dressed, and the forks won't rebound as much then as they can now.
I'm satisfied that the baffle kits helped.
A 4x4, a 2x4 and a 1x2, drywall screwed together, have a developed height of 5-3/4", which is a perfect height for working with fork change outs. Chock behind the rear wheel.
Image
The tang of the top baffle disc registers into a hole in the plug.
Image
Hold the fork tube at all times or it can slip down into the slider and you'll get 7 oz. of oil coming out of the top. Don't try to just support the bottom of the slider, you won't stop the tube from falling into it. :lol:
The pinch bolt controls everything. You're loosening and re-tightening it a lot during the process - Several times, in fact, when your removing the fork tube plug.
Image
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Plumber

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Post Wed Dec 13, 2006 10:17 am

From fourthgear @ http://hydra-glide.net/ :
"I rebuilt my whole glide front end including new leg bushings and tubes and adding the proper amount of fluid (7 oz. for dry ) and I still got that hammering only on full extention, like when the bottom drop out going over a pot hole or some thing like it . I have the OEM baffles in there , after adding another 1.5 oz.( makes it 8.5 oz. total so far ) fluid , it seems much better and I am going to add 1/2 oz. more and stop there. I'm using Bellray syn. fork oil."
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Reply:
I still got that hammering only on full extention

I have the OEM baffles in there , after adding another 1.5 oz.( makes it 8.5 oz. total so far ) fluid , it seems much better and I am going to add 1/2 oz. more and stop there.

Yep, those are statements worth pondering.

JohnHD thinks the problem may be related to the damper assembly itself...being a loose fit within the fork tube. The pounding only at full extension may be a clue. He said overfilling his tubes with fork oil did help, but some fluid was forced out of the various seals.
I asked JW at Tedd for some insight. No reply. No reply means he may not know either, so we're on our own with this problem.
Remember too, the fork springs had a -49 part number originally and then they changed to -49A. I think the -49A springs were made longer to eliminate the '49-50 spacer. That spacer was never used again until '65-66, maybe to compensate for the heavier weight of the Electra-Glide, and then it too was discontinued, but the -49A spring remained until '68 and probably beyond. So spacers being the source of the pounding problem seems doubtful.
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Plumber

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Post Tue Jan 02, 2007 12:26 am

There Is No Problem

I talked to Stett, he told me all the '49-59 forks will pound on rebound and that (and as presumed) they won't pound when the motor is installed and all the weight is keeping the forks from completely re-bounding. He said with later forks, they have bottoming cones in place of the -49 lower damper bushings, that hydraulically mate with the damper assembly and have retraction holes that slow the rebound down, etc., etc., - modern parts that we don't care about anyway.
V-Twin makes a GREAT set of replica Glide forks. They did some re-engineering in a couple of places. No drain plug, and a crucial aluminum crush washer for the bottom of the damper stud. If the slider leaks at the bottom, extra (46121-48) [paper] damper washers will make it oil tight. The only CAUTION, is that if your building '49-59 forks, then purchase the sliders, s/s slider covers, trees and dust cover, as separate items. Below: Buy your parts from the illustration on page 68 in the 1949-1957 Spare Parts Catalog [w/o needing the obsolete (46045-49) spacer, since you'll be using the -49A fork springs]. Make sure you buy a (48330-48) dust guard and not that later one that comes with the "complete" set of forks they sell, which has that (dust-guardless) "nut thing" and '60 up cups and (19) bearings. Buy the cups cad plated from (AMCA) Mark Blankenship and your done. V-Twin carries the '49-59 (16) bearing and race. The bearing number is #07100 and the race is #07196, available at any bearing shop - as Timken®, or Federated-Mogul®, to name a couple.
End of story. Thanks for your help. Let me know if you have any questions. There are no mysteries about 1949-59 forks. We stomped a mud-hole in the stinking problem over at the other spot. Forum II> Panhead>My Forks Go Clunk> http://www.hydra-glide.net/en_index.html
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Plumber

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Post Mon Mar 12, 2007 3:52 pm

Here's the obsolete (46045-49), '50-53, Fork spring spacer, and it's obsolete matching spring (46051-49) fork springs,(replaced by -49A, presumedly in 1954, when they dropped the spacer listing).
Image

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