Fork rebuild questions.

Kevin Werner

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I have '77 forks that need seals/rebuild badly. I did the Minton mods on my '81 and am very pleased with them. I planned to do the same on the '77 forks but got sidetracked and ordered new progressive rate springs. Do I still do the Minton mod on the damper tube and add 1 inch of preload?
 
OE springs are progressive. Treat Progressive the same way. The Progressive spring will be shorter than OE. You’ll need to add that much more spacer.

In May, I’m going to talk you out of the whole thing, so you’re going to have to do it over.
 
I've never added a preload spacer to the aftermarket progressive springs, didn't need to. I think they're a little stiffer than the originals.
 
I've never added a preload spacer to the aftermarket progressive springs, didn't need to. I think they're a little stiffer than the originals.
Ah. I thought they were six to eight inches shorter than the OEM springs. I could be remembering what I read on the XS11 forum rather than the XS650 forums.

As an alternative there’s RaceTech Gold Valves. Straight rate springs are required for their use. YSS and MikesXS also have P&D valves for less and way less respectively.
 
You're going to find the '77 damper rods differ slightly from the '78 and newer ones, mainly at the top. The holes are the same so you do the same Minton Mod drilling. However, you're going to need a different way of holding the damper rod from spinning while you remove and install the retaining bolt from it's bottom .....

'77 &'78 Damper Rods.jpg


Damper Rod Tops.jpg


A simple holding tool can be made by flattening the end of some 1/4" steel rod with a hammer and then jamming it down into the top of the rod between the roll pin and the side of the hole .....

'77 Fork Tool.jpg


'77 Tool Inserted.jpg


You're also going to find that there are no little top out springs installed, but you can add them if you like .....

Damper Rod Tops2.jpg
 
You're going to find the '77 damper rods differ slightly from the '78 and newer ones, mainly at the top. The holes are the same so you do the same Minton Mod drilling. However, you're going to need a different way of holding the damper rod from spinning while you remove and install the retaining bolt from it's bottom .....


A simple holding tool can be made by flattening the end of some 1/4" steel rod with a hammer and then jamming it down into the top of the rod between the roll pin and the side of the hole .....

View attachment 294672

View attachment 294673

You're also going to find that there are no little top out springs installed, but you can add them if you like .....
I did the cold forge trick on 1/4 round. The internal pin bent some on disassembly on one fork.
How critical are the top out springs?
 
Ah. I thought they were six to eight inches shorter than the OEM springs. I could be remembering what I read on the XS11 forum rather than the XS650 forums.

As an alternative there’s RaceTech Gold Valves. Straight rate springs are required for their use. YSS and MikesXS also have P&D valves for less and way less respectively.
I am happy with the Minton mods on my Red Bike So I will pretty much go that way. I hope the progressive rate spring does not messthat up.
 
Not real critical I guess. The forks may top out occasionally on the road and every time you put the bike on the centerstand. You'll get a little "clunk" if and when it happens.
 
It seems Yamaha put a little more time and effort into making the first year 35mm fork damper rods a bit nicer. They polished them up more than the later ones and beveled the oil holes. An engineer buddy of mine told me beveled holes flow more and better. So now, I incorporate these things into the later rods I Minton Mod as well .....

MyBeveledHoles.jpg


MyBeveledHoles2.jpg


Polished Rod.jpg
 
I've never added a preload spacer to the aftermarket progressive springs, didn't need to. I think they're a little stiffer than the originals.
I will not add a spacer. My old springs measure in 12mm short at 470mm. New springs measure in at 520mm so are roughly 1 1/2" longer than the spec 482mm already. That should be plenty of preload. I suppose it is easy enough to change preload one fork leg at time anyway when the bike is reassembled but on a lift.
 
I might experiment with MikesXS knockoff emulators. I have RaceTech on my XS11. It’s not in the same league as progressive springs. For me, I would not spend money on a Progressive upgrade. Stock is fine. If not, I take the leap.
 
I might experiment with MikesXS knockoff emulators. I have RaceTech on my XS11. It’s not in the same league as progressive springs. For me, I would not spend money on a Progressive upgrade.
 
I might experiment with MikesXS knockoff emulators. I have RaceTech on my XS11. It’s not in the same league as progressive springs. For me, I would not spend money on a Progressive upgrade.
I had to replace my springs. They were sagged more than12 mm. Once reassembled and rideable I can easily play with preload and/or oil weight and level.
 
Well actually, no, your original '77 springs aren't sacked, they differed in length from the '78 and newer springs .....

35mmForkSpecs.jpg


They also should have a factory preload spacer. If they didn't, that would explain why they seem so soft .....

Fork Springs.jpg


Fork Top Caps.jpg
 
Well actually, no, your original '77 springs aren't sacked, they differed in length from the '78 and newer springs .....

View attachment 298219

They also should have a factory preload spacer. If they didn't, that would explain why they seem so soft .....

View attachment 298220

View attachment 298221
Thank you. That makes more sense. The spacer on my '77 fork assembly is ~37mm. I will play around with a "no spacer", "1/2 s[acer" and "spacer" set-up on reassembly, pick one and then reassess after putting sme mile on. I already have thenew progressive springs so I may as well use them.
 
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