Making fork stiffer

[77brapp]

My stock 77 fork is quite soft .
I know i can buy pregressive springs and other brands of newer springs.
Just wondering if there is some way i can put a spacer in fork to compress springs a bit making it stiffer.

I Also only have 15 weight in the fork .
would putting a heavier oil in give me more stiffness to make it worth doing?
thanks

 

[GreasyC]

Raising the oil level will firm it up some. Air compresses easily so the air filled portion acts like a spring. More oil = less air = less squish. Thicker oil would feel stiffer too but it will also change the speed the fork moves at.

 

[jchrisk1]

Heavier oil or spacers or both will help. There are lots of threads here about it. Use the search function and you will find lots of info. I use 30wt in mine. It's a little stiff on the bumps for me but doesn't nose dive so much when braking. I also put a little more oil in the tubes.

 

[77brapp]

ok thanks guys

 

[Grinder]

If you stroke the tube with some lubrication that usually stiffens it right up!!

 

[TampaSVT]

If you stroke the tube with some lubrication that usually stiffens it right up!!

And, that typically causes fluid to go all over the nearest chick's face...

 

[jamesgs4]

a spacer to increase preload will help. If the springs are too worn, nothing you do will be enough.

 

[dwyatt]

Add air caps to the forks, then run 10 - 15 psi, adjust to taste.

 

[retiredgentleman]

My stock 77 fork is quite soft .
I know i can buy pregressive springs and other brands of newer springs.
Just wondering if there is some way i can put a spacer in fork to compress springs a bit making it stiffer.

I Also only have 15 weight in the fork .
would putting a heavier oil in give me more stiffness to make it worth doing?
thanks

5 years ago, I installed new fork seals and new fork oil. I first used 10W oil and found it to be way to soft, with lots of fork dive. Replaced that with 203 cc (7 oz) of 15W40 oil per leg. That's the weight of oil I still have in the forks because it has worked so well for me. I still use the stock springs.

Try changing to heavier oil first, and you may well find no need to change the springs or add spacers.

 

[77brapp]

You just used engine oil ?

 

[oldbiker]

you could cut some white plastic tube thats the same o.d as your springs .. say ,,eg,,, 50mm long and that will pre load them ..making them stiffer also add a little more oil that will help as well regards oldbiker

 

[77brapp]

do the tubes go on top or bottom of spring

 

[jamesgs4]

top, so they are easier to remove and replace.

 

[retiredgentleman]

You just used engine oil ?

Yes, I used diesel 15W40, because I was using that in the engine at the time.

My 78 SE has a 3 position fork spring adjustment at the top of the spring. I have it adjusted in the most firm position. I'm not sure about your 77, but I think the 3 position adjuster only started in 78.

 

[grizld1]

As usual on this topic, we have advice that confuses two suspension parameters--spring rate and damping. You can't really correct sacked springs by using stiffer oil; that will only slow down compression damping--the speed at which the forks react to a bump or forward weight transfer. Springs should be adjusted/tuned by measuring laden sag: Google "Paul Thede plush ride" for procedures and recommendations.

You can add preload to stiffen the springs, but only to a point; if you go too far, the forks will bottom due to coil bind. To find out where that point is, measure the wire diameter of the spring, count the number of coils, and multiply diameter by coil count. Subtract that number from the free length of the spring. The result is the spring's free travel. Next, refer to your manual for the rated travel of your forks. The maximum preload for your spring is free travel minus rated travel.

 

[77brapp]

My 77 has no adjusting what so ever . so i will probably try the spacer and thicker oil . Im not too consercned on race track performance i just want it stiffer so it doesnt bottom out when i stop

 

[ReycleBill]

If your springs are bottoming out, spacers and oil won't fix it. Spacers will simply make it bottom out at a higher point in its travel and make handling worse.

Thicker oil might help slow down the suspension but it will still bottom.

More oil will do the same as a spacer but maybe not be quite so hard.

The only solution for bottoming out is replacing worn out springs.

PS. That said, if your oil is too thin or too low then checking and adjusting the oil level might make the ride acceptable.

 

[ReycleBill]

Add air caps to the forks, then run 10 - 15 psi, adjust to taste.

Did you do anything more than just adding the air valves? Different seals perhaps?

 

[77brapp]

can you just add air valves to any fork?

 

[oldbiker]

hi the tubes go on top of the spring....... ..put the bike on centre stand... lightly jack up the front only an i" or so above ground ,, remove top nut from tube and just checkhow much slop or gap is in the top of spring to the nut ..easy to do you may find it need ...eg,,,2" it does work but requires a little bit od playing around with as you are pre-loading the spring and taking out the slop ..and you only need to use white electrical plastic tube ,,, grap a metre .. its dirt cheap and works regards oldbiker