40 replies to this topic

[JohnnyW]

Hi Guys,

Looking for some help and advice. I finally got round to pulling the forks off of Matlock's "Old Yeller" that I bought last year. I wanted to change the fork oil back to 10wt as he had put ATF fluid in them and I'm finding the front end a bit stiff and hard. That's maybe down to my wimpy physique and inability to compress the suspension to the same extent as Chris.😜

After only a couple of swearing episodes trying to loosen bolts that haven't been moved for some time, I got the forks off. The first thing I noticed was that the oil that came out of each leg was a different colour. I also noticed that as I was pumping the forks to expel the fluid one fork leg was moving smoother and easier than the other. The oil that came out of the one that was moving easier was dark grey and cloudy in appearance. The oil in the leg that was a bit stiffer and notchier, was cleaner and was still reddish in colour.

So, got a couple of questions. Does the difference in movement between the two fork legs indicate that the fork seals might need replacing. As far as I know, the fork seals on the bike are the original. The bike is now 20 years old with 106,000 miles on the clock but I hadn't noticed any oil leaking from the seals. Would the stickiness of movement indicate the seals are on their way out? If they are the originals then they've lasted well, a testament to Chris's maintenance regime.

My other question is about the different condition of the oil in the forks. Anyone any suggestion as to why or how that might have occurred?

Cheers,
JohnnyW

[Snowbird]

I seem to recall Matlock running atf in one side and regular fork oil in the other explaining the difference or was that someone else?

If it's not leaking and you're not planning on stripping the forks right down I'd leave the fork seals for now and just change the oil.

[trevini]

I seem to recall Matlock running atf in one side and regular fork oil in the other explaining the difference or was that someone else?

If it's not leaking and you're not planning on stripping the forks right down I'd leave the fork seals for now and just change the oil.

I think that was Fixitsan that was experimenting with different oils in each leg.

[Snowbird]

I think that was Fixitsan that was experimenting with different oils in each leg.

That's a good possibility, I know it was someone here but been asleep and in the pub since, who am I again?

[trevini]

Brian, your name is Brian   

[Snowbird]

Brian damage?

[trevini]

Quite possibly. Who am I to judge 

[dablik]

Hi Guys,

Looking for some help and advice. I finally got round to pulling the forks off of Matlock's "Old Yeller" that I bought last year. I wanted to change the fork oil back to 10wt as he had put ATF fluid in them and I'm finding the front end a bit stiff and hard. That's maybe down to my wimpy physique and inability to compress the suspension to the same extent as Chris.

 

 

So basically Johnny, your saying Chris is a fat fooker 

[AliG]

 

So basically Johnny, your saying Chris is a fat fooker 

He isn't that fat!!

[leehenty]

Also you don't know if Chris added extra stiffness in the springs

[JohnnyW]

 
So basically Johnny, your saying Chris is a fat fooker 

I would never say that, I would merely say tha I present a different profile.😀
I'd rather not change the fork seals if I can avoid it, it was just the fact that one stantion was moving smoother and easier than the other that was concerning me.

[fixitsan]

I think that was Fixitsan that was experimenting with different oils in each leg.

 

Yup, it's me

 

Incidentally, Dexron 2, very common ATF, has an equivalent weight rating of about 10wt, depends which manufacturer's fork oil you're comparing it to.

 

ATF WS is lighter and has an equivalent Wt range of 5Wt - 7.5Wt fork oil  (WS = world standard, used by Toyota).

 

Dexron 2 ATF is a reliable standard. and different manufacturer's D2 ATF all have a tight range of viscositieis (usually 30 - 32 Cst). 10Wt Fork oils on the other hand have no real standard in terms of viscosity, and one manufacturer's 7.5Wt can have the same viscosity as another maker's 10Wt (26Cst - 35Cst). ATF seems to have better temperature degradation resistance than fork oils too, not that your forks should ever get to 100C !

 

My experiment is Dexron2 in one fork leg (10Wt equivalent)  and 30Wt fork oil in the other. It's working well and a lot of the bounciness of the front end has gone thanks to the increase in rebound damping of the 30Wt leg I suspect..

Edited by fixitsan, 25 May 2022 - 08:21 am.

[Matlock]

 

So basically Johnny, your saying Chris is a fat fooker 

I am still here you know! I have feelings too!  . I had a chat with John last night, quick precis - 

• Fork seals are original as far as I know, I've never changed them.
• I was running ATF in both legs, I found that suited me best. I can't remember the brand and spec.
• I replaced the fork oil about every 12k miles and flushed with diesel each time, before leaving to drain overnight.

I wondered if some diesel was left in one leg, which contaminated the ATF? I also wondered if perhaps the bushes had worn and there was metal particles contaminating the ATF? That might explain the stickiness in that leg too.

[JohnnyW]

As it looks like I'm going to be taking the forks apart, I was thinking I should take the opportunity to change the springs as well. After 106,000 miles I'm sure they're not functioning at their best. Any recommendations?

[Snowbird]

If you're going for it I would suggest oem seals rather than the pattern ones, it's not much more.

[Favs]

As it looks like I'm going to be taking the forks apart, I was thinking I should take the opportunity to change the springs as well. After 106,000 miles I'm sure they're not functioning at their best. Any recommendations?

yeah - meaxure the spring free length and check with spec. b4 u spend.

[JohnnyW]

yeah - meaxure the spring free length and check with spec. b4 u spend.

👍

[wicklamulla]

Cud be a swolen seal as the steel spring within the seals are prone to rusting and expanding thus binding on the slider?

[JohnnyW]

Cud be a swolen seal as the steel spring within the seals are prone to rusting and expanding thus binding on the slider?

It could be, Wicky, I'll find out when I strip them down. I'm going to replace the seals,dust covers and bushes and probably stick in a new set of springs while I'm at it.

[dablik]

There real easy to take apart Johnny, bit of gentle heat around the seal and they should pull apart, i've actually got a set of oem 900 springs in the loft, approx 16000 miles on them when i swapped for progressive, yours for the postage if it helps..