how do you make a spacer to keep a torque converter out of overdrive?.

joshua. c.

Active Member
#1
before I begin this is what I currently am working with. I have a bike and a trike with torque converters and un governed modified engines and I'm trying to get the most speed out of my current setup. I already upped the engagement to 3100 using the white garter springs for the driver and installed the stiffer yellow spring in the driven on the stiffest setting. on both and I have a set of the lighter cast aluminum weights to try that I just need to order the correct springs for. I currently am useing the 6 inch drivens and may swich to the 7 inch at some point because I hear they allow the engine to rev better.

on the main topic: I have read you can get more speed out of the setup by making a spacer that keeps the clutches out of overdrive and I've read a few posts where people claim they've done it. but I haven found a good description or any pictures of what these should look like and where they should go. I could try to figure it out but I don't want to get it wrong and brake something. also the engagement chart mentions mod aluminum driver weights that are even lighter at 90 grams but I cant find a source for those.

If anyone has a set of these pleas post a picture of them and a description of how they work. I'm sure I'm not the only one this will help.
 
#3
The Monster Moto / Mega Moto MM-B212 Pro Series had a "speed limit spacer" that was simply a ring that fit over the bronze bushing of the driver, it limited how far the driver sheaves could close, thus limiting ratio change. The width of the ring would determine how close the sheaves would get to each other. What about a gearing change (larger rear sprocket) that would allow your engine to rev higher while retaining the full ratio range of your TAV?
 
#6
Those aluminum weights totally changed my bike for the better. Worth every penny.
I ended up going with the black springs with those

sorry i don’t know about the spacer
 
#7
josh , i'm assuming your trying this on your three wheeler your racing with? if you really what your torque converter to work at it's best. I would dump that 30 series 6 inch driven and go with a 7inch 20series setup, so both sides of the belt are working. now if you want to win I would go with a good clutch setup and have it geared so the engine is pulling correct amount of rpm's the cam made for. for example if your cam a 4000-7000+ power band. then make sure it's pulling just about it's max rpm right before you let up on it going back into the corner. ideally you want the engine only going down to 3300-3500+(right above your stall springs) so when you get back on the bike it pulls hard right back up to 7000+. with a clutch setup you are now creating a direct drive and will not have any slippage when accelerating. not like a torque converter will. also with a direct drive you are now using the engine to help brake the bike when going back into the corner. not like a torque converter. when you let up on a torque converter/engine you are now kind of putting the torque converter in neutral and the split second your engine is waiting for it to engage again the guy next to you with clutch setup is now passing you. clutch still doesn't mean your going to win. it takes a lot of different things to make it all come together right.
 
#9
On one of the Facebook groups, there is a person who makes the spacer that doesn’t allow the driver to go into overdrive. He had them for sale, I don’t remember what group.
 
#10
thanks for the advice but i would like to see this setups full potential realized before deciding to switch to a clutch. and from what you guys said the mmb 212 has a spacer over the bushing to prevent the clutch from fully engaging. so if i bought one of those I could cut it down to only prevent overdrive engagement. that might just be the ticket. now dose anyone know where to find a source for the mod aluminum 90 gram weights?. the less rotational mass the bike has the better. I might even cut holes in the rear sprocket to reduce weight further. and I had thought about making a different cam for the driven to further slow the up shift. but I'd have to have somone else make that, I dont have the training or equipment to do it myself.
 
#12
On one of the Facebook groups, there is a person who makes the spacer that doesn’t allow the driver to go into overdrive. He had them for sale, I don’t remember what group.
sorry, i didn't notice this post earlier. I don't have a Facebook account and never will, that type of personal info sharing just isn't for me. not to mention the insane data collecting Facebook dose on there members.(pages upon pages) so even if I found the group I couldn't make contact unless a phone number or email address was listed but thank you for the info.
 

cfh

Well-Known Member
#15
That comet 218006A is a speed reducer. that's different than what the OP wants to do.

I've used the aluminum weights and black springs like Mass mentions. Personally i do not like that set up. For me it made little to no difference on my particular bike (which is completely different than the bike Mass is using.)

Bottom line... you have to have all the weights and springs and play around (a lot!) to figure out what works for YOU.

The one simple solution i have found is the Juggernaut. I have a couple of them, and when put on any given bike, it really does allow for the "high rpm thing".

Also personally i think the series20 system is a better thing for a high rpm bike. it does not have overdrive. it just seems to work better than a series30. But you can't switch back and forth (at least easily). Because the driven series20 pulls inward, where driven series30 pulls outward.

My plan for this weekend was to try the overdrive limiter. I will report back with the results...
I have the Broncco with 7" wheels and a series30. It's running a Tecumseh HS50 with a big cam and 22mm carb. It has that problem of not going above 3500rpm because the gear changes are wrong. i have played with gearing which has helped.

here's what i have tried to change this...
1. juggernaut which replaces the drive. kept everything else stock. PROBLEM SOLVED. but expensive and big...
2. back to series30 driver.... yellow spring on driven. helped, but not enough. All following tests used yellow driven spring...
3. aluminum weights stock springs. engagement so high it was not workable.
4. aluminum weight black springs. engagement 100rpm lower than stock (2200 vs 2100). did not find this to do much of anything.
5. stock weights black springs. engagement too low (1400rpm). that was just silly...
6. next plan is aluminum weights and pink or orange springs. changes engagement to 2300 or 2800. waiting for those to show up to try....
7. overdrive limiter on stock set up (well with yellow driven spring.) should be able to test that this weekend....
 

cfh

Well-Known Member
#16
One other thing I forgot to mention ....
Changing springs and weights on a comet style system really only changes the engagement speed. That’s the speed that the clutch initially starts to pull in from a dead stop

What I really want to do is change the speed at which it changes gears. This is why I think the juggernaut just works better

The question is, does changing the garter springs on the drive change the speed at which the drive switches gears? From what I can tell it does not. And this is the problem that cannot be solved in the comet system on the drive. You can change the spring on the driven, but you only have one choice there. This is why people are liking the juggernaut, which seems to be tuned for more high rpm motors.

The comet drive is more of a general application torque converter. It works well for the masses, but probably not the best system for people racing or trying to squeeze more out of their engine. A Salsbury/juggernaut style drive is a better race design.

Of course this information applies to the drive side. The driven side is essentially the same for every tour converter ever made for Minibikes. There’s less choices there...
 

cfh

Well-Known Member
#17
I believe it works like this... remove idler brass bushing from stationary sheave. Install overdrive bushing onto stationary sheave. Then install idler brass bushing onto stationary sheave. The moving TC sheave still moves over the brass idler bushing, but is stopped from going all the way towards the stationary sheave by this oversized overdrive lockout bushing. This prevents the belt from riding up too high on the drive unit, essentially locking out overdrive. This means the TC can't change the drive ratio "too tall", thus preventing the engine from "nosing" down in rpm, as the TC drive unit changes the gearing too tall (into overdrive).

I talked to Eric at OldMiniBikes about selling these. He didn't want to get involved because he felt it was too easy to install the two rings backwards. This would essentially render the drive TC unit useless, and probably damage something. He likes "idiot proof" items, and just felt this would generate too many service calls.

 
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#18
before I begin this is what I currently am working with. I have a bike and a trike with torque converters and un governed modified engines and I'm trying to get the most speed out of my current setup. I already upped the engagement to 3100 using the white garter springs for the driver and installed the stiffer yellow spring in the driven on the stiffest setting. on both and I have a set of the lighter cast aluminum weights to try that I just need to order the correct springs for. I currently am useing the 6 inch drivens and may swich to the 7 inch at some point because I hear they allow the engine to rev better.

on the main topic: I have read you can get more speed out of the setup by making a spacer that keeps the clutches out of overdrive and I've read a few posts where people claim they've done it. but I haven found a good description or any pictures of what these should look like and where they should go. I could try to figure it out but I don't want to get it wrong and brake something. also the engagement chart mentions mod aluminum driver weights that are even lighter at 90 grams but I cant find a source for those.

If anyone has a set of these pleas post a picture of them and a description of how they work. I'm sure I'm not the only one this will help.
Have you looked into the new juggernaut driver pulleys? they are supposedly designed specifically for High RPM/high power engines
 

cfh

Well-Known Member
#19
I made a test piece so could try this out. i would say the results are mixed. Me thinks the problem, on my bike, is more related to gearing.

spacer (.175" wide) installed:


comparision of belt height on drive:
 

Li'l Popeye

Well-Known Member
#20
Some good info you have.
The comet 218006A is a speed reducer, yes. As far as I can tell it limits the travel of the weights and therefor it limits the travel of the moveable sheave. Just like an overdrive lockout bushing would do. Or am I missing something?
Btw: the lockout bushing is an easy-to-make piece. I will make one and test it.
In 1 minibike I have a Juggernaut (runs good) and in the other I have installed aluminium weights with orange springs. It needs some adjustments on the driven, because it goes high in rpm's from standing start, but rpm's drop down to much and to fast. I thought a yellow spring in driven would make it better.
 

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