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Discussion Starter #1
Hi,

I am about to renew the fork seals on my 1979 T140D due to the left leg leaking. I have read the forum posts I could find on this, but still need some clarification before I order new seals.

My bike had the "old" seals with the interference fit, which I believe is 97-4001. There are no grooves for circlips in the fork legs.

The parts catalogue (99-7102) I have for 1979 T140D/E shows the fork seals as "97-7079 Oil seal c/w retainer". This is not what I found on my bike.

I have read on the net that the seals complete with retainers are 97-7010, or 97-7079 for the seals only and 97-7016 for the retainer washers.

My question is:
Are the retainer washers the same regardless if the fork legs have grooves for circlips or not? It puzzles me that the retainer washers should be the same both with or without circlips. I would be grateful for advice helping me to order the correct items.

Thanks,
Helge.
 

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Hi Helge,
Take care not to damage your fork leg sliders when changing the seals, the T140D has sliders unique to that model, it might be hard to find replacements.

I think your catalogue might be wrong, 79 was the first year that the floating seal was introduced 97-7010, this is what you should have and this is what you appear to have by your description.

This will be the floating seal with THICK ALLOY knock in retainer, no circlip groove.

Later in 1980 they changed the design to the circlip and THIN STEEL retainer that drops in and is held in by a circlip- I do not think you have this type.

If you are lucky you can change the seal, without having to remove the thick alloy spacer, with the spacer removed you should be able to squeeze the seal and pull it out of the middle hole in the retainer.
There seems to be two types of replacement seal on the aftermarket, harder and softer types, if you have the softer type it can be squeezed back through the middle hole in the retainer, making it a very easy change and you do not need to buy the retainers.


if you take the retainers off refitting new ones is quite hard as they are a very tight fit in the slider. You will definitely need to replace them, taking them out without destroying them is nearly impossible.

I have used LP Williams in the UK to supply me with seals in the past, always with good results.

I Fork Oil Seals

Regards
Peg.

PS
If you do not already have this, you might find it useful:
 

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Discussion Starter #3
Thanks Peg,

Not being native English, sorry I may not have explained properly. The seals I removed from the fork legs were the "old" interference fit type, without any steel or alloy retainer on top.
However, I think I get it now. As I understand it, there are two types of retaining washers for the newer type seals. Thick alloy for legs without grooves/circlips, and thin steel for legs with circlips.

So, since I have no grooves for circlips, I would need the thick alloy retaining washers.

I hope I have got it right now.

Helge.
 

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Thanks Peg,

Not being native English, sorry I may not have explained properly. The seals I removed from the fork legs were the "old" interference fit type, without any steel or alloy retainer on top.
However, I think I get it now. As I understand it, there are two types of retaining washers for the newer type seals. Thick alloy for legs without grooves/circlips, and thin steel for legs with circlips.

So, since I have no grooves for circlips, I would need the thick alloy retaining washers.

I hope I have got it right now.

Helge.
(y) Yes you have it.

I will warn you, the thick retaining washers are tight and can be difficult to press in. Only press them until they are level with the top of the fork no deeper. It seems strange but the new seal will be a floating loose fit between the retaining washer and the fork slider. The seals are supposed to move up and down a little in the fork leg.
because the seal is now working on two surfaces, they both have to be in good condition, the stanchion must be good and importantly also the inside of the slider where the seal sits must not be scratched. Polish this area to a bright finish before fitting the seal.
This is one of the best upgrades you can do to these forks, if you get it right, you will not have to change a fork seal ever again.
If the left seal has been leaking it might be prudent to check the brake pads, just in case the leaking fork oil has contaminated them.

Good Luck
Peg.
 

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What is the situation with seals for ‘77 forks ? The stock seals came out easily. The replacement seals were an extremely snug fit and I gave up after getting them flush with the top of the fork lower, fearing I’d damage something. I did not install the washers. The seals aren’t going anywhere without dynamite.
 

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Discussion Starter #6
Thanks Peg,

This has been most helpful! Now I feel confident to get this job done properly.

From what I have learned about the fork seals, the ones I removed were a very snug fit, and to get them off without applying too much force I held the legs under the hot water tap for a minute or so before levering them out. These were the seals with part number 97-4001. While not having tried the newer 97-7079 seals yet, as Peg says they should not be a tight fit in the legs. Not sure, but I believe the '77 forks shouldn't be any different from mine.

Helge.
 

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Hi,

What is the situation with seals for ‘77 forks ?
"stock seals" in the '76/'77 parts book (99-2257) were/are 97-4001:-



... they are (should be) an interference-fit in the top of the sliders but they should not be any more "interference-fit" than a 'tap fit' in a warmed (so slightly expanded) slider top; certainly you should not have to "give up ... fearing I’d damage something" nor do they require any sort of "washer" to secure them.

First shown in the '78 parts book (99-7003) are what became known as the "Leakproof" seal and the "Super seal":-



... if these "were an extremely snug fit", something is badly wrong; as Peg posted, the seal itself must be able to move up-and-down between the 'step' in the slider where the original 97-4001 used to sit and the retaining circlip or washer.

This seal's part number is slightly confusing:-

. it's identified from the late-'79-on parts book 99-7102A as 97-7079, which is just the seal itself, because it was secured in the slider with a circlip (60-7269) and a loose (not interference-fit) washer (97-7093);

. in the '78 parts book 97-7003 and early-'79 parts book 99-7102 no-suffix, the seal and thick interference-fit (in the slider) retaining washer are identified as 97-7010; nevertheless, if you're replacing one of these, as Peg posted, only the seal itself (97-7079) should be required.

As Helge posted, there isn't any difference in the seal area of any conical or disc slider whether it's a '71 conical or an '83 disc; any seal will fit any slider, only the retention method differs.

Hth.

Regards,
 

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Hi, If you pull up gaiter or dust scraper you can see top of slider. If you see a solid rubber seal or a solid ring it is early version. If you see snap ring it is later version.

Snap ring version is "leak proof" type seal. Super easy to change. Remove snap ring & washer. Lift out seal. It is NOT a press fit. It is an easy sliding fit. You slide in seal open part down. Drop in washer, install snap ring. NO SEALANT. Lube with provided lube or just lube with fork oil that you are going to use. Lube liberally inside & out. There will be large gap between the steel washer you put in & snap ring. That is normal & MUST be there. The seal must be free to float up/down in slider.

Other ways to do it, but I take slider off to replace seals. A must on early fork. After installing seal I lube all well, then cut a piece of thin plastic page protector & wrap around upper to protect seal. Overlap plastic only a little. A bit of a fight but it will go. Plastic is thinner than clearance in slider so work it in. Even the most tiny scratch in rubber of seal will leak. Make sure all the plastic comes out. Usually easy to pull out.

Here is USA all the 97-4001 seals have very poor service life. I've tried lots of brands. I've only had good success with leak proof type. Very good success even with very worn sliders. Again the free movement of seal must be maintained. Study LeakProof web site.

I've always used the original LeakProof seal. They have very low stiction. Way less than 97-4001.

I've not seen alloy press in retainer rings in USA. The LeakProof we get has steel press in ring. Basically a very thick flat washer.

As was stated a tight fit. I have home made seal installer driver & always use it. You can also use a large socket or tube of pipe etc. I've never warmed leg. Maybe retainer would go in better if you warmed to very warm to touch with heat gun? Not so hot to ruin seal of course. I'll try that next time. Deburr slider & retainer ring as needed for smoother installation of retainer ring.

LeakProof doesn't want you to wad up seal to replace rubber. Personally I'd try it. I've never replace rubber yet as none have leaked even after 18K miles. I'd warm a dish of oil & warm seal first. I'd afraid to remove ring & press new one in. They fit very tight, I don't know what would happen.

The weight of fork oil has a huge influence on fork operation. A change of just 2w up or down is very noticeable while riding. I find many folks in my area end up liking Belray 5w the best. Fork oil is very much personal preference.

At the same time with slider off, I like to replace the rubber damper piston o-ring with LP Willams fiber ring. Together with LeakProof seals the stiction will be less than half it was before. I think a big (gigantic) improvement in smoothness of ride & wheel following road when healed over on bumpy curves. I found I could corner safely way faster. In every condition felt smoother & safer. Reduces fatigue greatly on long rides.

Here's a few photos of my '73 Tiger LeakProof conversion.
Don
 

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Hi,

replace the rubber damper piston o-ring with LP Willams fiber ring.
+1. Damper valve seal conversion 1971 on (pair)

+1. If your bike doesn't have them already, and you want them, I advise using only Commando ones specifically made by Andover Norton - they seem to be the only ones that don't perish into a stack of large O-rings ... :love:

Here is USA all the 97-4001 seals have very poor service life.
I've never had good service from them, even on the T160 I bought brand-new,

With a standard single front disc, always the disc-side one that used to start leaking a little after 3,000 miles. I noticed the forks used to twist if I braked hard; this was even with the fender slider mounting that Meriden later fitted '76-on, so I'm not surprised if Don experiences the same(?) problem with the earlier fender mounting. Before I fitted Leakproof/Super seals (and second front discs :sneaky:), I ended up replacing 4001's at a 3,000-mile service to avoid the leaks.

Btw, L.P. Williams also sells 97-4001A, a version of the 4001 by Ariete; I haven't tried 'em (because Leakproof/Super seals work for me without problems) but several posts around from happy campers that have. (y)

Hth.

Regards,
 

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What is the situation with seals for ‘77 forks ? The stock seals came out easily. The replacement seals were an extremely snug fit and I gave up after getting them flush with the top of the fork lower, fearing I’d damage something. I did not install the washers. The seals aren’t going anywhere without dynamite.
 

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Hi duc96cr, I don't know what seals you had. Would be interesting so see photo of them. Do you have record of the purchase, where you got them from etc? I've not heard of lip seal installing that hard or lip seal with retaining ring. The 97-4001 basically fills the space so I don't know a lip seal would fit.

I've found original type 97-4001 to fit tight, but not that tight. They press in like most lip type seals do. there is no retaining ring for these type seals. 97-4001 seals generally lift out fine, as expected.

The LeakProof seals are a snug sliding fit on outside diameter. They have oil retention lips on both inside & outside, but no spring or other metal or plastic in them. In practice the seals end up riding up to the retaining ring most of the time.

I feel the key to LeakProof seal is the hollow space allows the inner & outer of seal, but mostly inner to conform to irregularities & movement between leg & slider better than normal lip seal. Whatever the reason, they really do work well.
Stuart, I have observed left seal tended to leak more also. I didn't know why.
Don
 

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I had 97-4001 seals from two different sources, I’d forgotten I had some on hand. They looked identical. The LeakProof Brand seals are criticized widely as not living up to their name, so I don’t buy them for any of my bikes.
It’s not just Triumphs, the caliper side fork seal usually starts leaking first on most bikes.
 

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Hi Don,
I think you hit the nail on the head (as usual) Don, I also thought the inner chamber caused the seal to expand with pressure, so the harder the fork compresses the harder it seals.

As to why the left seal fails, there is the ever watchful Meriden extension to Murphy’s law; If anything can go wrong it will go wrong, the Meriden extension dictates, that it will go wrong in a way that does the most collateral damage and at the most inconvenient time.
Not only do you have to replace your fork seal, you have to replace your brake pads as well.
(Of course It might just be that this is the fork flexing the most).

If fitted correctly I have never heard of a set leaking; I wold propose that the leaking sets were fitted to sliders that someone had butchered trying to lever the old 97-4001 rubbish seals out.
There was a previous post on this subject where someone posted a photo of the inside of the slider where the seal sits, beautifully mirror polished.

I am very impressed with your large tool Don, the lower half looks like a cut down taper top stanchion, but how did you make the top part.

regards
Peg.
 

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Hi Peg, I have a lathe. I turned the tool from solid aluminum 6061 bar stock. I counter bored the hollow ring to allow the upward portion of 97-4001 seal to enter. The OD is such it allows pressing seal (or retainer ring) below the tiny chamfer at top of slider. I wanted a long lead in for the guide so it would assure a straight push. I've used it many times & has worked well. Prior I used pipe tube I ground down from plumbing pipe. That works too, but I wanted more fool proof for straight push.
Don
 

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Hi duc96cr, Like Peg says the LeakProof that leak something is wrong. Most often the retainer ring is too deep not allowing the required end float. That's #1 cause. After that, cutting seal lips installing slider onto leg. Of course if leg is rust pitted, or damaged by grooving, no seal will work.

I've fitted LeakProof in T140 sliders that are very worn & loose. Still no leaks.

Finally when Triumph started fitting LeakProof at factory, they didn't have fork leaks. They first used pressed in retainer, later snap ring. I've only use genuine LeakProof brand here in USA.
Don
 

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Hi,

LeakProof Brand seals are criticized widely as not living up to their name,
I've used 'em since the early 1980's, always the 'soft' version; same as Peg and Don posted, none have ever leaked.

not just Triumphs, the caliper side fork seal usually starts leaking first on most bikes.
Never on any of my other single-disc bikes, even ones without gaiters.

Hth.

Regards,
 
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