RD Fork Overhaul

[2_DONE_THE_TON]

hey guys!

im currently restoring my RD 250 1 a 2.
when i bought it the forks were drenched in dried out oil so i´m gonna do the forks.

so heres the question: i asked the guy at the local suspension store..he told me that he usually would replace the oil seal and the circlip and the parts in between:

parts 3,4,5,6
in the diagram

plus new fork oil.

what you guys say?would yopu replace any other parts and if yes which ones?

 

[teazer]

Circlips and that top washer rarely need to be replaced. Just order a pair of fork seals from Economy Cycle in northern Illinois - all round RD freaks and good people.

Remove bolt #23 before you take the fork legs off the bike and before you remove the top screw #19. It's easier that way but be ready for some oil to come out all over the floor, so have a catch tray handy - I use cheap baking trays for that and get a couple more to put all the parts in as you remove them.

 

[2_DONE_THE_TON]

Circlips and that top washer rarely need to be replaced. Just order a pair of fork seals from Economy Cycle in northern Illinois - all round RD freaks and good people.

Remove bolt #23 before you take the fork legs off the bike and before you remove the top screw #19. It's easier that way but be ready for some oil to come out all over the floor, so have a catch tray handy - I use cheap baking trays for that and get a couple more to put all the parts in as you remove them.

thank you!
why do you remove the 23 before?
which number in the diagram is the "fork seal"?

cheers

 

[teazer]

#3 is the fork oil seal.

Screw 23 is hard to get out because it is loctited in place. If it comes undone when you are doing a wheelie, teh fork sliders and front wheel fall off. Seriously. So it's tight and loctited. That makes it hard to get out, so you need to clamp the fork legs in something - why not "clamp" them in the triple clamps?...

Spring pressure on the top of the damper rod #8 makes that harder to spin, so #23 which is bolted into #8 will come out easier as a rule. Sometimes it needs more pressure or a special tool to hold the damper rod and prevent it from turning. In some cases that special tool is a broom stick tapered at the tip so it can jam in the top of the damper rod.

If an RD damper rod spins, it needs a special socket on a super long extension.

While I think about it, get some 20Wt fork oil while you are at the bike store. Modern forks use 5-10 Wt oil but these are not modern forks. :-(

 

[jcjoey101]

Hey Teazer
I have just replaced the seals on my front forks, I'm just starting to reassemble them now.
In my shop manual is stays to put liquid sealant on to the hex bolt (bolt 23 in the above schematic), is this required and if so what should i use? or can i get away without it. I was thinking maybe plumbers tape around the thread might work as a substitute?
Sorry for the hijack Ryan, i figured it may help you as well haha
Thanks!

 

[teazer]

Clean the bolt/screw and make sure the threads are spotless. You can smear on a little of almost any silicon based sealant or Three Bond. It has to help seal the bolt and stop it from coming loose. And clean the threads in the bottom of the damper rod too.

 

[jcjoey101]

Awesome, thanks teazer.
I just re read your previous comment and realized i missed the bit about the bolt being loctited in, my bad!
Ill have to go buy some sealant after work today.
Cheers

 

[2_DONE_THE_TON]

#3 is the fork oil seal.

Screw 23 is hard to get out because it is loctited in place. If it comes undone when you are doing a wheelie, teh fork sliders and front wheel fall off. Seriously. So it's tight and loctited. That makes it hard to get out, so you need to clamp the fork legs in something - why not "clamp" them in the triple clamps?...

Spring pressure on the top of the damper rod #8 makes that harder to spin, so #23 which is bolted into #8 will come out easier as a rule. Sometimes it needs more pressure or a special tool to hold the damper rod and prevent it from turning. In some cases that special tool is a broom stick tapered at the tip so it can jam in the top of the damper rod.

If an RD damper rod spins, it needs a special socket on a super long extension.

While I think about it, get some 20Wt fork oil while you are at the bike store. Modern forks use 5-10 Wt oil but these are not modern forks. :-(

thanks teazer!

so im gonna loctite the screw afterwards into place....which loctite would you use?the red hard stuff?
why cant i use modern dampening oil?

and B:

will my RD 250 wheel?

 

[teazer]

You could get away with just yusing 3 bond as long as the screw is tight enough but best to have a drop of BLUE on the threads and some 3 bond or RTV on the sealing washer - just to be sure.


All RDs wheelie - it's in their nature

 

[2_DONE_THE_TON]

You could get away with just yusing 3 bond as long as the screw is tight enough but best to have a drop of BLUE on the threads and some 3 bond or RTV on the sealing washer - just to be sure.


All RDs wheelie - it's in their nature

all right thanks!
would you put blue loctite on the two screws on the below (23,...) too, to lock the axle from down under?
how can i make sure that 8 doesnt turn in place when i remove 19 screw?
sorry for the noob questions


i just had 1 chance to drive it yet,its currently in restoration,but oooohh boy when it hit the power band my pants got tighter.
the previous owner told me that the 250 even rev´s higher than the 400 or 350 cuz of its square piston layout.

 

[teazer]

19 is the top screw and nothing much turns when that is rotated, but it may pop off under pressure from the spring. Try it and you will see. Crack that 19 loose before you take the forks out of the triples.

I don't loctite anything else down there. You could I suppose but there should be lock washers #29 "under" nuts 28

 

[gijoe13844]

Using an air Impact on bolt 23 will often release it from its threads. If it just spins you can try reversing it back and forth until it releases. Might save you from having to make the "special" tool.

 

[2_DONE_THE_TON]

AW: RD Fork Overhaul

today i finally could remove the forks from the bike....
had to take them without wrenching the screws on top and below cuz i dont have such a huge inbus key for the top and not enough length of a tool for the bottom.
when i removed the caps i saw this...

do i have to open up the big inbus or the small rusted one...

the former owner seems to have been a total douche.
there is smthing fishy with the seal placement in the fork...
one fork has a metal ring the other has the seal totally exposed.

 

[gijoe13844]

Yeah than inner bolt needs to come out. You can use a big bolt and vice grip to get it out.

The lower seal looks wrong. Should be seal, washer, snap ring. That's an issue.

 

[teazer]

Get two suitably sized nuts and tack weld them together and use a wrench to loosen that top nut. What looks like a smaller nut inside there is just machining swarf from the broaching process.

Slide each fork leg back into the triples to clamp the steel staunchion and loosen the lower cap screw first. (after you drain the oil of course)

 

[2_DONE_THE_TON]

AW: RD Fork Overhaul

since i have no access to a welding tool ill buy a suitable tool for the upper hex screw?which diameter is this?

just tried to open up the lower 23 screw....doesnt move....the screw gets worn out easily...its prob the loctite...what shall i do?use heat on the screw to loosen the locite?

thx

 

[gijoe13844]

What do you mean it doesn't move? Doesn't turn or just spins and doesn't come out?

 

[teazer]

Smack the wrench with a mallet to shock it free if you don't have a rattle gun.

 

[jpmobius]

The bolt (#23) at the bottom of the fork leg(s) takes an 8mm (almost exactly 5/16") allen (hex key) wrench. I always use an impact with very light power. Never had an issue, but can see a nightmare if it goes wrong. Teaser has good advise in clamping the tube in the triples (also the smack it to shock it loose!) . I will add, be sure to totally free the top clamp before removing the cap. That part does not need to be that tight as an O ring seals it, but I have seen a couple of examples of caps ruined due to being clamped by the triple. So easy to remove once the "clamp" is loose (oh, the embarrassment!) The top cap you have is 17 mm. Must be common for something, a wrench that size is commonly at auto parts stores. The washer and wire clip are important. A big portion of the "spring" in your fork is the air that gets compressed when the fork compresses. The seal likely will pop out without this retainer.

 

[2_DONE_THE_TON]

AW: RD Fork Overhaul

the hex bolt 23 is just totally worn out and is impossible to turn with a tool.
shall i use heat?

whats really interesting is the forks seem to be perfectly fine there seem to be no leaks.i flipped them pushed it up and down several times,left them overnight upside down,no oil draining.

whats fishy is that when i bought the bike the forks where drenched in dried in oil....????