1980 GS850G Front Forks

[climber_dhl]

Hey I posted earlier asking for some brake help but now I have a question about forks. By the way thanks for the awesome welcome and all the great information. I would have been so screwed if I didn't have this forum. Thanks you so much.

Now my question is the best way to tell if my front forks are bad and what to do about them. My friend and the prior owner of the bike said that they were bad and they feel really loose but I am not how to tell how bad they are. I have read prior posting and help sites, and I have heard that you can replace the seals and put new/more fork oil in them. The seals on my bike look fairly new so I am not sure if this will help. Also someone mentioned buying progressive springs or new springs. I couldn't find any progressive springs for the front shock on line but I did find some replacement springs, but there are some many other parts for the front shocks I was not sure how much of a difference that would make. Is it possible to get a rebuild kit for the front fork, and if so is it worth it. I was told just to take it apart, see what seals were bad, and order new parts and put it all back together. That sounds good, but I am scared the whole fork will fall apart and I will have to buy all new parts since the bike is in pretty bad shape (cost only $300, just going to be a commuter bike my Dad and I are working on for me at college; It runs well just cosmetic damage, and bad brakes.). Thanks again for reading this and I appreciate any and all help you could give me.

Daniel

 

[Dogma]

I agree with the theory of taking it apart to see what's wrong. If the front end feels loose, check the front wheel bearings and steering head bearings too. Once you have it apart, you may find that the Teflon wear sleeves inside the fork lowers are worn and making things loose. The service manual BassCliff hosts has procedures for all of this.

If it was me, I wouldn't worry about Progressive brand springs unless your springs are out of spec. The stock springs are acceptable if everything is working. The Progressives are a performance upgrade. Of course, better performance = safer on the front end, but you have a budget to think about.

 

[climber_dhl]

Thanks

Thanks

Ok I was wondering how to best tell if the front end is acceptable. Should I take it to a mechanic? Would simply reoiling the fork help at all?

 

[tkent02]

Ok I was wondering how to best tell if the front end is acceptable. Should I take it to a mechanic? Would simply reoiling the fork help at all?

Mechanic won't touch it, nor do you want him to.

See how far the forks sag, standing on it's wheels, and then with you sitting on the bike.

If they compress more than an inch and a half to two inches, the springs are weak.

Pull the wheel off, spin it on it's axle. It should turn smoothly, silently, with no drag, no looseness or movement of the axle inside the wheel. Also next time you ride a little distance, see if the bearing area is getting hot.

Take each fork leg, push and pull on it, checking for any play, it should be able to telescope or twist, but have no other movement.

take both fork legs together and see if you can make the steering head bearings wobble, again they should move smoothly, with no notches, no play up and down or side to side.
Check for a notch right in the straight ahead position.

Push the fork legs up, compress them all the way, and let them go. Have someone hold the handlebars so you don't push the bike off the centerstand. How fast do they return?
Instantly or does it slide back out slowly under control? If you remove the spring cap you can feel the damping by itself, with no interference from spring tension. Are both legs the same?

Either way, the oil needs to be replaced periodically, as it gets contaminated with water, dirt, parts of bugs, etc.