Rupp Torque Converter Advice

joebiodiesel

joebiodiesel

Member
#41
#41
I wanted to add a few pics and a little more info in case anyone else was looking to substitute a 20 Series clutch on a Rupp.

I ended up taking a bit more than 1/8" off the clutch. Now that I have a close fit on the belt, the clutch engagement is much nicer. I wish it was at a lower RPM, but unless I substituted some lighter springs on the drive clutch, it wasn't going to happen any better than what I have it at now.
Here's a pic of machining the fixed portion of the clutch. You have to remove material from the hub. If you take more than 1/8" out, you'll have to trim the bushing a little as well. If not, it'll be fine.


Then you have to machine the button. Whatever you take off the hub, you have to remove from the button.


I ended up with a nice fit. No dragging. Engages as soon as I rev it.


The only down side so far is that it likes higher RPMs than I prefer to push my 45 year old HS40. I'm at 4500 RPMs top governed speed, and if I want to top out the clutch I need to go even faster. I'm not a top speed guy, so I don't care about it, but others are. If that's you, you're going to need some more RPMs to get top gear out of this drive clutch. I'm hoping as the springs wear that it will shift to a higher ratio easier.

While I'm on the topic, what is a safe top RPM for a 1970 HS40 with an aluminum flywheel? I'd prefer to stick with the stock 3600, but that's not going to happen with this clutch.

Joe
 
Ruppelstiltskin

Ruppelstiltskin

Member
#42
#42
I've been away from the forum for awhile so missed out on your discussions. Glad to see your progresses. I have the driven sitting in a box but not messed with it. I took my Rupp apart a few months ago to put new Coker Trials tires on that I got from OldMiniBikes. It was a bear to get the old Pirellis off and once I did get the first one apart found the inside to be heavily rusted/pitted. Ended up having them blasted and powder coated. I've been too lazy/busy with car projects to get it back together. Also need to figure out how to fix the brakes because they are warped pretty good and drag a lot.

Also, just made a deal with a friend of mine. Hes got a new 212 Predator Hemi that he bought for some unknown reason and did the basic mods to but has nothing that needs a motor. I've been hunting for a good deal on a used GX200 or at least a GX160 Honda but haven't found anything reasonable enough. So that will be on the to do list in near future.
 
GustoGuy

GustoGuy

Well-Known Member
#43
#43
The Predator is a decent engine and it will turn your Rupp into a little speed demon. I bought a Rupp Roadster 2 roller with the 12 inch wheels and it came with a newer Tecumseh H40 from 1995. I replaced a H50 5hp snow blower engine on my MTD snowblower with Predator 212cc and it works great and tosses snow 40+ feet now so I may be disappointed with only putting a Tecumseh flat head on it. If your going to use it as a working bike the better reliability of the Predator is so worth it.
 
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Ruppelstiltskin

Ruppelstiltskin

Member
#45
#45
Got my self in gear with my 72 Hustler. Mounted up my Pred with both the drive and driven comets. Wouldn't say its exactly the same for others but I ordered the 8-1/4 to 8-1/2 comet belt as it was the only thing close to my measure of 8-1/8
 
danford1

danford1

#46
#46
What are you using for an exhaust? I tried a Predator on my 72 Hustler but the exhaust looked like it was going to be a problem so I abandoned the idea. I then tried a Briggs Animal OHV engine and that was much worse as the exhaust port is on top of the head and a Pred is more on the side of the head. I put the stock HS40 back on it...
Any up close pics of how you guys run the exhaust on Predator/Rupp combos?
I have the 20 series clutch and want to put in my power than the HS40, just need to know what to do for the exhaust...

Danford1
 
R

Rezolution

New Member
#47
#47
markus said:
Either you currently have the wrong belt, your driven is not fully retracting, or you have some seriously wore out halves or ramp buttons, etc.. This is the only photo I have that shows the belt on one of my old bikes (its a 1970 so it may look slightly different than yours, but your belt at rest/idle should sit pretty high up in the driven, sometimes higher than whats shown on mine):




When you have it apart to service you can in fact fine tune them. The have 3 holes to position the spring-the center is usually factory setting, the setting that makes the spring tighter will delay the shift a little keeping it in low longer and not as much on the high end (heavy offroad) the setting that makes the spring the looser will let it get into high gear faster for onroad, flat applications. I honestly never messed around with them because I am too lazy to take it apart a few times to see how much of a difference it makes between the points though.....I just always put them in the center and go.
Click to expand...
I have the same torque converter that you have pictured, with the 4 weights that fly out when you give it gas. Can someone please send me a link to the right toque converter guard/cover? Ive ordered a few off Amazon but none of them fit right.
 
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