Ohlin ITC revalve and rebuild

[Jon McLean]

Thanks to all here for info and re-valving suggestions for Ohlin ITCs, especially in the 510 ITC rebuild thread. For these ITCs off an '84 500XC --used on an '83 500CR--I got the kit and Ohlin oil through Phillip, but no help with re-valve ideas to firm compression and slow rebound except as found on this site. Made the change per below for my 250lbs/Int-Exp MX riding and got fantastic results...best I've found on any twin shock bike.

Subtle changes with some discs and a valve plate stolen out of an old pair of remote reservoir parts shocks on Compression stack, change to Rebound was simple removal of a few discs.

Original valve stacks:
>> Compression -
.30 Valve Plate (triangle) 2-hole
21 x .20
.30 VP no holes
27 x .25
24 x .20
18 x .15
27 x .30
14 x .20

>>Rebound -
.25 VP no holes
27 x .20
24 x .30
21 x .20
21 x .25
18 x .30
18 x .30
14 x .30
14 x .30
14 x .30

Re-Valve stacks - 250 lb w/o gear, heavy 9mm spring, 4" rider sag, slow Exp/fast Int MX:
>> Compression -
.30 VP 2-hole
21 x .20
.30 VP no holes
27 x .25
24 x .20
18 x .25
.20 VP no holes
.27 x .30

>>Rebound -
.25 VP no holes
27 x .20
24 x .30
21 x .25
18 x .30
18 x .30
14 x .30

I was getting pogo'd on our local VMX track through deep braking and acceleration bumps and blowing through the stroke and then bounced hard from decent size jumps with flat landing jolts when over-jumped. After the revalve and fresh oil/rebuild, I got good hook-up through bumps and sailed jumps with the same confidence as on my modern bike with no hard bottoming, no bucking. Truly good.

Rebuild was with no special tools or know-how...bench vise, instructions from manuals (Phillip or elsewhere), cheap calipers to measure discs and brake cylinder hone from Harbor Freight to clean up body and reservoir. Retaining clips give a small fight but not tough.
Hope this helps.

 

[justintendo]

nice info jon..glad to hear you have them dialed in better

 

[Picklito]

On your new rebound stack... Did you remove the 21 x .2 or is that a typo? If you removed it, you made your low/mid speed rebound slightly lighter. Could be good for acceleration bumps coming out of those MX corners? But how was the rebound after full compression like big jump landings? It could be a little light for that.

 

[Jon McLean]

Yes, I did remove the 21 x .20 on Rebound stack...just followed some earlier "try this" stack in the 510 post. I thought maybe since the 24 x .30 above had to flex over a single 21 instead of a stack of 2, maybe it actually stiffened a bit--just a guess. Regardless, the overall rebound worked well everywhere--at last race's largest jump, there's a harsh flat landing if you hold on too long and over-jump the back side landing. It's thrown me on my head a few times and broke a footpeg off there in the past. I overshot it once last weekend- both Comp and Reb handled it well and soaked it up.

 

[Picklito]

That's great. If it works... it works!