Anti-Dive Adjustment? Mis-assembled Forks? Or What?

[Captain Murph]

I just bought a very clean, low-mileage '84 and am working my way through a few issues. Probably the most troubling is the bottoming and nearly complete lack of dampening on the front forks.

 

They are so bad that I can bounce them up and down (with or without brake applied) and hear them hit what appears to be the end of their travel.

 

The PO had someone do a variety of work to this bike including "replacing fork seals" although I don't see any parts on the work order for over 6 hours of labor!

 

Since I could see that there was a leak at the lower mating surface of the left anti-dive, I drained all the oil from that side. After removing the EAND, I cleaned and inspected the o-rings and grooves. They were not hard not flattened and had no nicks. So, I put them back in, put a light coating of Yamabond on the surface and tightened the bolts.

 

After I put in 13.5 oz of 15W oil, I let it sit for 24 hours, aired it up to about 13 with the CLASS and found virtually no difference.

 

While I have a spare set of forks from another '84, I really hate to do the swap and brake bleeding if I don't need to.

 

There is an apparent adjustment at the bottom of each of these and some mention in the Tech area about the Service Manual "being wrong". All it says is to "turn the bolt to the maximum (??) position. Compress the front forks while applying the front brake. If the forks compress easily, the anti-dive system may be damaged.

 

Is it worth fooling with this adjustment?

 

Is it worth swapping out this unit from a different fork?

 

Is it possible that the fork springs are so weak that this might be the only cause (It is 24 years old, but only has 31K).

 

Could the mechanic that the PO used have misassembled something that would allow such clunky bottoming? (There are no apparent fork leaks).

 

If he simply put the springs in upside down; would that allow this condition?

 

Any ideas will be appreciated.

 

Murph'

[Gearhead]

I think your 84 has different anti-dive than my 87, so I can't speak of the adjustment. However, I can say that:

1. If there are no oil leaks, the seals are OK. Bad seals won't cause the fork to stop working (until the oil is gone).
   
2. I suppose it's possible something is installed wrong in the forks. You never know.
   
3. Springs don't really care which way they're installed.
   
4. Could this be old, floppy springs? YES! They all have old, floppy springs. I think the springs were old and floppy the day they were first installed :-) Seriously, mine maybe wasn't as easy to bottom as yours, but I've found it to be true on both my 87 Virago and the Venture that the old, stock springs were horribly inadequate. I remember on the Virago finding that it was riding about 1" from bottoming out, just with me sitting on it (called static sag). Progressive Suspension springs did the trick in both bikes. The Virago is a little stiffer now than I'd prefer, but it's much better w/o the bottoming. The Venture rides pretty nice. There are people on this site who prefer Sonic Springs.
   

Jeremy