Front shocks are shot?

R

Rutabaga

Member
Pulled the front shocks off today and not too surprised. Left one may have had a boot replaced recently and did not show signs of any leakage. The right was pretty ragged on the boot and did have a leak and it’d been that way for a while. Arizona dust can be pretty brutal in its ability to migrate into damn near anything because it can be very fine in size. Both pistons show galling of the chrome but I don’t have the knowledge yet to make a call on their state. I’m very inclined to replace both and start from a known point. I like tinkering but not having to do things twice because of stupidity or being my natural cheap self. IMG_4591.jpeg
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Completed disassembly of both shocks, cleaned and polished pitting of piston rods. Not as bad as I thought and the pitting does not appear to be from friction but possibly a chemical reaction. I polished the rough spots and although they are visible with the piston fully extended I can not visualize the suspension ever being in that situation except during disassembly so that the seal would not be compromised by it. Wiser minds please correct me if that is not the case. Left photo is before disassembly, apart with top collar installed to check for seal interference.

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Does the done shaped protrusion at the base of the shock tube act as a variable valve during in compression by limiting intake diameter to the interior of the piston to control fluid flow and provide rate dampening during compression and the two holes in the piston provide a path for fluid escape? Any reason to remove it for inspection if that Phillips head screw on the interior base of the shock above the axle is what holds it in place. The screw looks a little buggered up so I think it may have been out before. Based on what I see and what I surmise to be likely, I am going to put it back together with the rebuild kit and give it a go. If the seals fail I’ll put new shocks on and be wiser for the experience. Well, maybe not wiser, just a few days older.
 
Finished with the shock rebuild today and test rode it for about 8 miles down a less than perfect road, went over about five speed bumps and did some aggressive front braking. Nothing fell off and no leaks. Neither shock came off the triple fork without a fight and even with some widening of the mounting clamps both were a struggle to get back to the needed height for proper installation. Finally got two ratchet straps connected to the axel bolt as persuaders for the final half inch. My guess is that in the last 48 years the only part ever replaced on both sides was one boot, all else was long overdue. Next project is a revisit to the timing to assure myself it is set to the F mark and not the T.
 
Sorry you haven’t seen a response.
The issue with these bikes is that they’re so incredibly reliable, over time it’s just easy to take them for granted, and the deep dive on repairs and rebuilds fall on like-minded members of this forum. I too, hate doing things twice, but I believe you took the right path. We did ours about 3 years ago and they’re still working great.
 

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I'm not too familiar with the 90cc bikes...but the forks look similar to my CT70's. When I see that same kind of damage on the inner tubes...I figure they are bad...unusable in that condition. You may have proved me wrong. I check to be sure they are straight...and that the damage wasn't caused by a bend in the tube. If they're straight...they could be re...paired and re-chromed with "centerless grinding"..? Expensive I think.
Not sure if replacements are available for your bike or not.
The cone piece in the bottom of the outer is only a bumper I think. It might have some function for dampening...but I don't know about that. No reason to remove it except maybe for easier cleaning and such.
 
Dr atv has a replacement set that are 50% stiffer and a a little under a couple hundred bucks. Spendy for sure but if you really want to get deep into it theyre worth the money. Replaced a set on my neighbor's bike and took it for a test ride and they felt very nice. Normal shocks for me are pretty squishy with a 220lb rider but these felt about perfect.
 
joel1234567 said:
Dr atv has a replacement set that are 50% stiffer and a a little under a couple hundred bucks. Spendy for sure but if you really want to get deep into it theyre worth the money. Replaced a set on my neighbor's bike and took it for a test ride and they felt very nice. Normal shocks for me are pretty squishy with a 220lb rider but these felt about perfect.
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I had thought about going that route but thought I’d try the twenty dollar rebuild first so I had something else to tinker with instead of just a straight replacement. Probably go for replacements if the seals don’t work out.
 
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