Like stories like this? You’ll see every article as soon as it's published by reading the print edition of Grassroots Motorsports. Subscribe now.
story by per schroder
We’ve all heard the legends: wonderful, almost magical stories of speed secrets that unleash performance for a pittance. They’re usually told long after the race cars have left the protest shed and …
On old British cars with lever action shocks they're refillable with a plug on the side. Tried this several years back, seat of the pants no difference.
On old British cars with lever action shocks they're refillable with a plug on the side. Tried this several years back, seat of the pants no difference.
In reply to The Staff of Motorsport Marketing :
Where are you getting these legends? Who are these People?!?!? Lol.
Yes I can... on my motorcycle.
purplepeopleeater said:On old British cars with lever action shocks they're refillable with a plug on the side. Tried this several years back, seat of the pants no difference.
I think the shocks have to work before changing the oil in them will do much of anything. 
But does increasing the damping actually increase performance of the car? I'd guess on a lowered/stiffer sprung car yes, but that is not always the case.
In reply to dcamp2 :
Most street cars are significantly under damped for performance use, in favor of better apparent ride quality. So while that may not always be the case, it probably will be most of the time for people looking into such things. Already well damped or over damped cars don't generally make people want to stiffen them up as much.
for a sealed damper it seems like the ticket would be to drill a hole in the side and tap the hole for a plug to fit.
cheap dampers plus good shock oil = good dampers?
Awesome I'm a so gonna try this!...
Wait where is it safe to drill the hole exactly?(as in is there stuff inside that won't work after I hit it with the drill bit? ) Could I drill two holes and make it adjustable with a bleeder screw and an external set of lines?
I have drilled a hole in the side of a strut, welded a nut to it, reassembled the strut, filled it with motorcycle shock oil, and plugged it with a bolt and crush washer. It worked for the most part. Ended up blowing the seals out of them.
I refilled the wet struts on my '85 RX-7 with ATF.
Worked great, until the winter. Then the front suspension would compress with bumps and not rebound.
Common mod on the Swift/Metros
If there is a viable way to do this to sealed struts count me in. Id love to experiment. I can easy TIG any fitting to the body to make this work
I'd also be careful if wanting to do this on pressurized shocks.
In reply to purplepeopleeater :
I used motorcycle fork oil on my MG level arm shocks. Went to 50 weight and found a serious increase in reaction.
I changed the oil in my TR3 lever arm shocks to 30wt and changed the valve to an AH 3000 valve and found a significant increase in damping.
The limitation is that it will increase both compression and rebound by the same amount. Most (good) single adjustable shocks only increase rebound for roll control. Increasing compression tends to make a bumpy ride. When increasing spring rates for performance use, the compression should be reduced and rebound increased. That's because the spring and shock work together during the compression stroke, but work against each other on rebound. Many of the "YO JDM" super coilovers adjust both compression and rebound with one knob. That may be OK in Japan where the roads are glass-smooth, but it doesn't work in the old US of All those speed bumps and potholes.
Now, if you have some worn out shocks that won't go "ka-blam!" when you open them up, you can add thicker oil and get back some of the damping lost to wear.
djsilver said:When increasing spring rates for performance use, the compression should be reduced...
You seem to have misunderstood the explanation used to describe the general belief that there should typically be some amount more rebound than compression damping...But that is still, and always has been, based on needing to increase both proportionally to the spring rate in order to maintain the same relative damping ratios for each.
I also have done this with TR6 rear lever shocks. Going from the stock rear springs (~350 lb/in) to 470 lb/in springs required more damping. The valving was adjusted per JK Jackson's recommendations, but going to 30 wt. oil really dialed them in. No more bouncy bouncy.
If you're drilling/tapping the pressurization in the shocks could be seen a good thing. It keeps the metal shavings from entering the shock body by putting them into your face.
Just go back to friction shocks. Could be adjustable.
iceracer said:Just go back to friction shocks. Could be adjustable.
At least friction shocks have the desirable digressive "valving" built in by nature of physics. Getting separate damping curves in compression vs rebound might be a little more difficult though.
I' going to play around with some of this on my challenge car to help with my budget
In reply to freetors :
I dunno if I'd call digressive valving desirable in a lot of applications. It works on very smooth surfaces, but on pretty much anything else, it's bad IMO due to blowing through the travel way too easily on big bumps.
You'll need to log in to post.
