Lowered Manitou Minute topping out

[sich nich]

I bought my 08 MRD TPC Minutes a while ago when they were mega cheap from Dirtworks with the intention of lowering them from 130mm down to 80mm for my 4X/DJ bike. Stripped them down straight of the box, worked out where the spacer needed to go on the air spring rod, machined up a nice nylon spacer, and put it all back together.

Now, I've been putting up with this problem ever since, but it's time I cracked down on it. No matter how slow the rebound speed is, it seems to top out worse than I think it should. It's like a constant speed extending, then, *bonk* top out! Even when the fork takes like a whole second or two to extend, still tops out. Not a metallic top out sound, just a sudden one, not nice with a usual rebound setting.

The nylon spacer is a neat fit on the air spring rod, loads of clearance on the outside diameter, and the length determines how far it lowers the fork. It's positioned on the rod so it DOES engage/squish the rubber top out bumper, and I'm damn sure it doesn't block any ports or anything on the rod.

Is there a point of extension when the fork is 130mm travel where air from the spring chamber shares pressure with a negative chamber to smooth the topping out, and the lowered fork just can't reach that point? There is only one schrader valve on the fork, so I assume the pressure must automatically share into a negative chamber somewhere.

Using this fork for dirt jump has been OK with this problem, because I can mask it by having super slow rebound, super high pressure and the TPC round all the way on, almost making a rigid fork with a blow off. But I want it plusher now for different/non polished trails, and I'm just not getting it.

Any solutions anyone? Or do need to run 130mm for it to be schweet?

 

[Tech-DW]

Is there a point of extension when the fork is 130mm travel where air from the spring chamber shares pressure with a negative chamber to smooth the topping out, and the lowered fork just can't reach that point? There is only one schrader valve on the fork, so I assume the pressure must automatically share into a negative chamber somewhere.

Using this fork for dirt jump has been OK with this problem, because I can mask it by having super slow rebound, super high pressure and the TPC round all the way on, almost making a rigid fork with a blow off. But I want it plusher now for different/non polished trails, and I'm just not getting it.

You have hit the nail on the head i think. From my online diagnosis/speculation, there might be two things going on, both related to the air side, i dont think the damping side has anything to do with this problem.
Maybe drop me an email at tech"at"dirtworks.com.au with your phone number or give me a call on the Dirt Works hotline 1800 996757 and ask for Phill in the tech department.

 

[U.D.O]

I bought a set of the same forks too whilst they were on sale. Mine had similar sounding issues with topping out and had little to no effect of adjustment with the rebound and compression knobs. I sent them back for warranty and it turned out there was simply no oil in the fork from factory, which the guys at Dirt Works fixed, and the problems were solved.
Not saying this is the solution, but your forks could possibly have been in the same batch and have the same problem?