Velvet Drive Problems Please Help!

good to hear, very common mistake along with leaving the fat snap ring out because the person rebuilding thinks because it doesnt fit in the groove, it doesnt belong

everything else looks correct, it will not work the way you currently have it stacked

Hi Eric

Here are the pics you can see where the gear has been scuffing the spring, looking at it now is the whole thing in backwards? ie the end plate with the raised bump is nearest the spring and not the other way round as it is in the pics? I am 99% sure this is how it came out as I laid each component out in order and the slight marking on the end plate I put nearest the spring that matched the snapring. This may account why forward was never too great when I got the boat? Only if I am right of course! If not I am still lost!

Regards
Mark

Ive only seen 1 transmission with the combination of 3 and 2 plates and were talking many, the belleville spring makes contact with the endplate, it fits between the fat snap ring and when the piston comes out it puts pressure on the spring also acting as a return spring....take some pics, i need to see the clutch hub and make sure it accomadates the 3 and 2 combo

btw, you can air check the pack once assembled on the bench thru the 2 holes on the shaft end, it will give you a nice sound of engagement with a little air leak thru the bleedhole

these will run on water, it sounds as if you have the forward pack assembled incorrectly. it goes: with drum facing up
endplate, 5 clutches, 4 steels, endplate, thick snap ring (which does not fit in groove) spring, spring wear ring, piston and cylinder, then thin snap ring which will fit in outside groove.
can you take a pic when you get it disassembled?

Apologies for the long post but I wanted to explain fully what I have done and what the problem is straight away.

I can’t work out why my clutch pack has failed? I have a Velvet Drive AS1-70C gearbox with a 2.1:1 reduction ratio it is coupled to a small diesel engine (54hp) and we run the engine at about 1000 - 1200 rpm to give us cruising speed (canal boat doing 3-4mph). We did a three hour run with no problems and moored the boat for the night, the next day I started the engine and there was a horrible grinding coming from the flywheel area, when I engaged forward we had little to no power same with reverse. I checked the oil and it was nice and pink but a little low, I topped it up but that did nothing. I removed the gearbox and saw the drive plate was broken but it looked like it had been for some time? When I opened the gearbox I instantly saw the reverse clutch had snapped in two and the internal teeth looked mashed! So I ordered a rebuild kit, a new oil pump (thought it was best to replace) and a new drive plate. The info in the 70C service manual is a little sketchy but I am no novice mechanically, so armed with my digital camera I stripped the drive and replaced all the seals, clutch plates and gaskets all went well. The only problem I came across was I could not figure out exactly how the forward clutch system worked? Looking at it in my opinion no matter how much the forward piston pushes the clutch spring it can’t put pressure on the plates because the snap ring bottoms out on the gear teeth of the ring gear? I called a place in the US and queried the snap ring that the clutch spring sits on, he said it looks weird but that’s how it works all he said was to ensure I put the thicker of the two springs in first which I did do. When I assembled the clutch spring compressed the top of the unit (forward piston) into the ring gear and inserted the last snap ring there was obviously pressure pushing down on the snap ring in the ring gear but you could easily move the clutch plates I would say there was about 1mm or more of play. In the 70C there is no rear snap ring and no mention of having to set any clearance with gauges. Totally baffled on how the clutch would bite I rebuilt the box, all looked well on the bench. I re fitted the gearbox back in the boat and got drive, I took the boat out for an hour to test the box and that’s when things got weird. Firstly moving forward 2mph all was well however put more power on and we slowed down, put the box in reverse (700rpm) and there was this loud constant clunking noise increase the revs (1200rpm) and clunking went, boat worked well in reverse apart from clunking. I checked the engine rpm with the gearbox output rpm and in forward at 700rpm I only got 280rpm out, then at 1000rpm I got 280, then at 2000rpm I got 280 out. Obviously for some reason the clutches were slipping? In reverse at 700rpm I got 330 out and at 1000rpm I got 480 out so apart from clunking all looked well there. I need to find out if I was given the correct ATF as it was supplied by the place I got the parts from but they re bottled it so I have no knowledge that it was totally correct but they do state it is for use in 70C, 71C, 72C borg gearboxes. I was careful checking the oil level and I know it was spot on so I was stumped. Today I decided to change the oil with some that I knew was Dexron II to see if the oil was the problem, I sucked the oil out and instantly saw bronze dust and discolouration as I got near the bottom of the fluid so I know the clutches have been slipping bad! With little to loose I started the engine to get the pump to shove as much oil back into the sump as I could so I could get more of the oil out, putting the box in fwd and reverse I noticed a strange thing, we obviously had no forward output but I did have reverse and it still looked good but the clunk had totally gone? Obviously I only ran the engine in total for about 10 seconds and moved through forward / reverse to get oil out. It worked and I took out another 0.5 litre. I re filled with new oil Dexron II and fired it up exactly the same problems as before? I am at the point where I will get a pressure gauge and read the pressures on the box to see what valuable info that gives me, then I will remove the box and replace the clutch plates again. Hopefully someone with greater knowledge can clear some of my problems up and clarify how the forward clutches work? What I don’t want to do is rebuild again and have exactly the same problem!
Thanks in advance.