manual clutch for horizontal shaft engine
- Thread starter briggsscooter2
- Start date
- Tags clutch engine horizontal manual shaft
Danny Downs here...the reason that we use the lockwasher is because it effectively acts like a disc spring. When the clutch liner wears, the surface in contact with the fender washer will actually start to move axially down the shaft (we're talking thousandths of an inch), compressing the lock washer. If a bolt were installed and hand tightend, as the liner wears a large portion of the preload on the clutch liner would decrease until clutch slippage occurred.
This was actually one of the manufacturing issues we had with our supplier. The drive keys, by design, are supposed to be press fit into the keyway of the clutch. The Supplier missed that dimension, forcing us to go with a slip fit key.
In the future, we plan on incorporating a more elegant key retainer- but the loctite and lock washer method will work just fine.
This was actually one of the manufacturing issues we had with our supplier. The drive keys, by design, are supposed to be press fit into the keyway of the clutch. The Supplier missed that dimension, forcing us to go with a slip fit key.
In the future, we plan on incorporating a more elegant key retainer- but the loctite and lock washer method will work just fine.
Review #1: DBR 1 Manual Clutch - Installation
Out of the box, I was very impressed with the weight and construction of this devise. It really is a solid piece of work.
I wouldn't expect more if some huge multinational company were producing it. Installation was easy and the install video
instructions were clear and complete. This was fun. The installed clutch operates as described, although it's going to
take some getting used to. I am a very satisfied customer and it was well worth the wait. :thumbsup:
I can think of a couple of things to bring to your attention. They are small but this is why you wanted a test group, isn't it?
1) I had a little trouble with the cable-stop & the short set screw fitting together. The screw threads didn't quite fit through the stop.
With an allen wrench, I screwed it in and backed it out several times before installing it. (screw threads are always bigger than the hole)
2) My standard size allen wrench, used for the cable-stop, was to long to fit between the stop and the clutch. I had to cut it down with a dremel.
I was thinking, if a special size tool is necessary why didn't you include it? Adding this to the kit would help gain customer confidence in the product.
3) The same can be said for the cable-end as well. Isn't there something that the cable-end can be dipped into to prevent fraying? I almost got out
my soldering kit and coated it myself before the install, but the stop-hole looked so small. Does it have to be, can you drill it out a little?
4) I'd really like you to address this chain/clutch guard issue. I'd like to have one but the clutch uses one of the mount holes. Is it possible to slip
the guard mounting plate between the clutch and block (upper left hole), or do I resign myself to using the two remaining mounting holes
(upper-right & lower-left) for mounting a chain/clutch guard? This would suck because no nobody makes one.
Or, maybe you could make one and sell it as an addition, like your engine mounting plate?
Ok, I'll let you go now. Looks like a great piece of work guys and those are all my issues, so far. We'll be in touch... (My life should be so trouble-free.)
If you really want to see my whole installation in one video, click the link.
No full page iframe, I just didn't want to bore or irritate anyone with it...
DBR1 Manual Clutch install - YouTube
Out of the box, I was very impressed with the weight and construction of this devise. It really is a solid piece of work.
I wouldn't expect more if some huge multinational company were producing it. Installation was easy and the install video
instructions were clear and complete. This was fun. The installed clutch operates as described, although it's going to
take some getting used to. I am a very satisfied customer and it was well worth the wait. :thumbsup:
I can think of a couple of things to bring to your attention. They are small but this is why you wanted a test group, isn't it?
1) I had a little trouble with the cable-stop & the short set screw fitting together. The screw threads didn't quite fit through the stop.
With an allen wrench, I screwed it in and backed it out several times before installing it. (screw threads are always bigger than the hole)
2) My standard size allen wrench, used for the cable-stop, was to long to fit between the stop and the clutch. I had to cut it down with a dremel.
I was thinking, if a special size tool is necessary why didn't you include it? Adding this to the kit would help gain customer confidence in the product.
3) The same can be said for the cable-end as well. Isn't there something that the cable-end can be dipped into to prevent fraying? I almost got out
my soldering kit and coated it myself before the install, but the stop-hole looked so small. Does it have to be, can you drill it out a little?
4) I'd really like you to address this chain/clutch guard issue. I'd like to have one but the clutch uses one of the mount holes. Is it possible to slip
the guard mounting plate between the clutch and block (upper left hole), or do I resign myself to using the two remaining mounting holes
(upper-right & lower-left) for mounting a chain/clutch guard? This would suck because no nobody makes one.
Or, maybe you could make one and sell it as an addition, like your engine mounting plate?
Ok, I'll let you go now. Looks like a great piece of work guys and those are all my issues, so far. We'll be in touch... (My life should be so trouble-free.)
If you really want to see my whole installation in one video, click the link.
No full page iframe, I just didn't want to bore or irritate anyone with it...
DBR1 Manual Clutch install - YouTube
Last edited:
plunder... consider changing gearing, unless you are going to drag race or go really fast all the time. One thing we have helping us is the smaller tire diameters. If you have a 70t rear sprocket youll be coming from 5.38:1 with the max torque to 4.66 ratio,.... and lugging the engine alot or slipping the clutch at slow speeds. I have mine setup at appx. 5.9:1 and have some sprockets ordered to switch to 7:1 and 7.4:1. I know its easier with the jackshaft.... Im setting mine up to ride around the yard, lower speeds. I have a road gear too for the parade in windber next year. You bike should take the OldMiniBikes warehouse split sprocket adaptor, then you could go up to 85t, it it clears the ground:shrug:
Yes, tin the cable end, I did it with acid flux and 50/50 solder after having a issue with one strand popping out on me,
get some cheap allen keys and cut them down, I dremel tooled mine too...
I dont really care for the not being able to torque the mount bolt in the end of the crank, but it works...I plan on locktiting in a stud with a crimped locknut to hold it all together.
once finished I plan on putting the guard back on outside the clutch mount plate and space the other side with a washer, I guess it will look OK.:shrug:
good burnout about midway through....
http://s818.photobucket.com/user/5X8Rider/media/MB165sDB30_zps74d20acc.mp4.html
Yes, tin the cable end, I did it with acid flux and 50/50 solder after having a issue with one strand popping out on me,
get some cheap allen keys and cut them down, I dremel tooled mine too...
I dont really care for the not being able to torque the mount bolt in the end of the crank, but it works...I plan on locktiting in a stud with a crimped locknut to hold it all together.
once finished I plan on putting the guard back on outside the clutch mount plate and space the other side with a washer, I guess it will look OK.:shrug:
good burnout about midway through....
http://s818.photobucket.com/user/5X8Rider/media/MB165sDB30_zps74d20acc.mp4.html
Last edited:
I had a Max Torque 14t clutch sprocket so there is no change for me,
also a black spring (3100rpm engagement) because I needed the slip
for a smooth take off. That will take a little practice now.
I'm not sure which "mount bolt" you mean.. or how to use the upper-left
mount hole with the clutch cable there? if you get a chance,
when your finished send a pic. Thanks for your comments and
AWESOME VIDEO !!!
Plunder, we appreciate the in-depth and honest feedback. You've brought up a few issues that we have since been unaware of and will most definitely remedy the issues moving forward into production. I'll try to go through your points one by one.
1. I believe you may be referring to the axial hole through the aluminum cable housing mount. We'll make sure that we test fit each low head cap screw and if there's any burrs will knock them down prior to shipment.
2. This is an issue that we haven't seen before because we have been using the shorty style wrenches which have a short end. However, an easy fix would be to go with smaller set screws, maybe 10-32. This would allow the use of a smaller allen wrench giving more clearance during the install.
3. We kind of suspected that this would be an issue but wanted to get this out and see if it was a significant problem. I've been a little apprehensive about opening up the hole; doing so could lead to further issues with fraying and kinking when tightening the set screw. One thing that we can do is chamfer the entry and exit holes, i think this would help. Additionally, we're going to look into plasticating the cable end to minimize the chance of fraying.
I'm also going to look into possibly redesigning the cable stop entirely to allow the cable to enter from the side (if that makes sense!). The user would not to thread the cable through the hole then- solving the issue.
4. We're currently in the process of designing a chain guard to work with our clutch. More on this later.
my bike does burnouts like that but with me sitting on it 
I hope the clutch works how I need it to, sounds like it slips a lot. Anybody have a decently modded motor with this clutch on it yet?
I hope the clutch works how I need it to, sounds like it slips a lot. Anybody have a decently modded motor with this clutch on it yet?
you should be able to throw some big HP at it.
You guys should post up some reviews on KB2s thread too.
http://www.oldminibikes.com/forum/g...s-manual-clutch-review-thread.html#post745775
Last edited:
Yes, those little tires we have do help with the gearing deficit
its kinda like riding around my dirtbike in third gear....kinda funny, we throw a lockup clutch on our minibikes, and now we have to learn how to slip them...
crap, i forgot about that piece for the cable....
mount bolt... the crank bolt, my local hardware store sells hardened studs, gonna try to thread one in with red locktite and use a good locknut instead, I should be able to keep accurate to the installation video while keeping a tigher lock on the hardware....
its kinda like riding around my dirtbike in third gear....kinda funny, we throw a lockup clutch on our minibikes, and now we have to learn how to slip them...
crap, i forgot about that piece for the cable....
mount bolt... the crank bolt, my local hardware store sells hardened studs, gonna try to thread one in with red locktite and use a good locknut instead, I should be able to keep accurate to the installation video while keeping a tigher lock on the hardware....
Last edited:
I posted this on the 'review' thread but I also wanted to mention it here since it is important. When installing the clutch, the clutch lever should be adjusted for the clutch when it's warmed up. The clutch expands when it heats up, and this slightly changes the actuation points. The slack in the cable does not indicate wearing of the clutch. As the clutch wears, it will act to tighten up the cable, not loosen it.
Thanks again for the reviews everyone, keep them coming. We love the videos too!
Thanks again for the reviews everyone, keep them coming. We love the videos too!
I installed mine tonite after work. Took about 30-40 mins including the time it took to remove my left grip to swap my brake lever over to the other side. Now...my thoughts. The USPS box didn't fare so well but the contents were fine. The side of the box split open. The clutch looks good. Mine had a tooling mark on the outer diameter that was probably made by an end mill/program error. I noticed it when I was looking everything over but once on the bike, I doubt anyone else will. I have a GC190 engine on mine and had to use all the shims to shim the clutch per the instructional video. Would be nice to have another shim or two. Allen wrench clearance is tight. A box of 100 Allen wrenches from a supply company would be about $6 for that size. How about including a shortened one with the kit? Even though my tools have a lifetime warranty, I didn't want to go about that tonite. I like the cable that is included. Seems to be the perfect length and operates smoothly. I like that it has a bicycle sized barrel with an adapter that makes it dirt bike barrel sized. Dual purpose. I didn't install the included lever. It looked typical of a Chinese copy. I assemble Chinese Side x Sides on the side and sometimes Chinese quality is lacking. Depends on what expectation you set for them. I put on a used locking rear brake lever off of a Chinese four wheeler that needed a new brake light switch (they don't sell the switch separately so I had to order a new lever). Looks just like the Yamaha Bear Tracker lever that I posted a few days ago. Allows me to disengage the clutch for starting or idling.
I installed this on a DB30 with a Honda GC190 (supposedly 6.2 hp), 70t rear sprocket, 145/70-6 tires. I never rode a stock Doodle Bug. Since putting this bike together a few months ago, it has quickly became my favorite. 12/70 gearing with a stock Max-Torque clutch did fine around my yard. I turned the rpms up to 4000 rpm by adjusting the governor. Otherwise, its stock. With the Downs Bros clutch I need more gear. I actually anticipated this as when a centrifugal clutch slips, you are actually adding in another gear multiplication into the formula. Will probably get a PMR jackshaft. It just lugs too much when the centrifugal would have just slipped thru that rpm range. Its not a problem with the clutch, its my gearing.
My only complaint would be that while I was installing the clutch, if I grabbed the clutch lever, the clutch wouldn't spring back to the engaged position. I cycled the clutch about 20 times and it went away. It hasn't done it since. The clutch now has about an hour of run time on it.
I installed this on a DB30 with a Honda GC190 (supposedly 6.2 hp), 70t rear sprocket, 145/70-6 tires. I never rode a stock Doodle Bug. Since putting this bike together a few months ago, it has quickly became my favorite. 12/70 gearing with a stock Max-Torque clutch did fine around my yard. I turned the rpms up to 4000 rpm by adjusting the governor. Otherwise, its stock. With the Downs Bros clutch I need more gear. I actually anticipated this as when a centrifugal clutch slips, you are actually adding in another gear multiplication into the formula. Will probably get a PMR jackshaft. It just lugs too much when the centrifugal would have just slipped thru that rpm range. Its not a problem with the clutch, its my gearing.
My only complaint would be that while I was installing the clutch, if I grabbed the clutch lever, the clutch wouldn't spring back to the engaged position. I cycled the clutch about 20 times and it went away. It hasn't done it since. The clutch now has about an hour of run time on it.
Another thought I just had and will have to look into is...you only have the keyway machined in the clutch so deep. With me having to use all the shims, I wonder how much of the key is really engaged in the crank in my particular application. There's a possibility that I could screw up the keyway in my crank (again, in my instance). Maybe machine the key slot deeper into the crank.
Hi rmm727,
We appreciate the thorough and honest review of our product. It looks like you're running a 14" tire with a 70 tooth sprocket (5:1) which is just a little bit taller geared than our current setup (5.4:1). You could definitely benefit from running a jack shaft, which will give you a lot more freedom for gearing. Even going with a slightly larger rear sprocket will help you as well. The clutch is designed to stay fully engaged, and sometimes this is not ideal for 'putting around' at 5mph. Also, if you've never had experience with a standard clutch before, it does take some getting used to and to know when to slip it etc.
As far as the key engagement goes, please check out our data sheet here http://www.downsbrosracing.com/DBRT1DataSheet.pdf. We list the minimum shaft length at 2.125" with a continual diameter of 3/4". If you're within this constraint (>90% of the utility engines are), then you are fine with your current key engagement.
On the next iteration, we are going to wire EDM the bore of the male driver so that a key is not required, and shaft length is no longer a concern.
We understand that getting used to this manual clutch can take some time, but we'd love to hear a follow up from you later after you've had some more experience with the clutch. We've found that using a manual clutch just adds a whole new dimension to riding a mini bike once you get everything dialed in :thumbsup:
We appreciate the thorough and honest review of our product. It looks like you're running a 14" tire with a 70 tooth sprocket (5:1) which is just a little bit taller geared than our current setup (5.4:1). You could definitely benefit from running a jack shaft, which will give you a lot more freedom for gearing. Even going with a slightly larger rear sprocket will help you as well. The clutch is designed to stay fully engaged, and sometimes this is not ideal for 'putting around' at 5mph. Also, if you've never had experience with a standard clutch before, it does take some getting used to and to know when to slip it etc.
As far as the key engagement goes, please check out our data sheet here http://www.downsbrosracing.com/DBRT1DataSheet.pdf. We list the minimum shaft length at 2.125" with a continual diameter of 3/4". If you're within this constraint (>90% of the utility engines are), then you are fine with your current key engagement.
On the next iteration, we are going to wire EDM the bore of the male driver so that a key is not required, and shaft length is no longer a concern.
We understand that getting used to this manual clutch can take some time, but we'd love to hear a follow up from you later after you've had some more experience with the clutch. We've found that using a manual clutch just adds a whole new dimension to riding a mini bike once you get everything dialed in :thumbsup:
Last edited: