Design idea claim

[formulasuper]

Just in case Racer Russ builds his F1000 drive train using my design idea & it is a great success & everyone adopts the design, I am hereby claiming originator of the "F1000 Jack-Shaft Drive Train". (By the way, if it fails miserably it was all Russ's idea.)

[Stan Clayton]

Say whaaaattt??? Those have been used in roundy-round for years.

[formulasuper]

Say whaaaattt??? Those have been used in roundy-round for years.

Stan, Yes I know & F500 all use them. But it will be new for motorcycle powered formula cars as we know them. I'm sure this design has been used in European countries in their hill climb cars. Russ has a diff with the sprocket mounted nearly in the center & the jack shaft will make the chain alinement simple. Other benefits also.

[Stan Clayton]

Sweeet!!!

[Billy8910]

Although I'm not interested in claiming to be first, I have been working on a jackshaft design for my F1000 conversion for a couple of years. Progress has been very slow due to non racing responsibilities that keep croping up.

I have two designs on the workbench, one VW based, the other Mk 9 based. One is stronger, and one is cheaper!!!

My main concern is that both chains will be pretty short, and am wondering if that will lead to problems. Would appreciate comments from you guys that are working on similar projects.

Thanks, Bill Hiatt

[RussMcB]

A couple of weeks ago Scott and I were standing there, looking at my conversion project. At that time I was planning to have an angled engine (like Speads) so the rear sprocket could be closer to the center of the car, which would allow me to keep the original suspension pick up points and wishbones. But, the rear diff (with big 45 tooth sprocket) still took up a lot of room and was still a tight fit. Scott came up with the jack shaft idea and it was like an epiphany. The more we thought about it, the more problems it solved.

A few off the top of my head:
- Everything could be straight (not angled).
- With two more sprockets, rear sprocket could be smaller diameter (i.e., 40T).
- No suspension needed to be moved or modified.
- I didn't need to widen track or extend WB if I didn't want to.
- Less need for body work changes.

Of course, what we didn't know was if there would be brand new problems. Here is the list we've come up with since then:
- Shorter chains have less time to cool between sprockets.
- The strength and reliability of the jack shaft and its mounts.
- Rather than small front sprocket, now we want largest that can fit in the physical area.

As I've mentioned several times here recently, Mike Devins has been great to work with. He had, in fact, considered a jack shaft arrangement in the past, but decided against it primarily because it adds weight and that's a very big issue in DSR. For me and my F1000 project, I'm less concerned about weight and ultimate performance. I'm mostly interested in reliability. The jack shaft adds new challenges, but it makes other design and fabrication aspects much simpler.

Mike has been in contact with the DID Chain folks, Sprocket Specialists and others, and we think we've gotten enough feedback to decide a jack shaft will work without problems. For instance, the people at DID Chain didn't say, Sure, no problem.". It was more like, "It will probably be okay."

Mike is designing the jack shaft and bearings, mounts, etc. for me. The distance between the front sprocket and the centerline of the car is 5.25".

I think the only significant consideration will be that I will need to watch my chain closely so I can change it as soon as it shows signs of wear or O-rings starting to go bad. Needless to say, I will be running the best quality chains, and we've gone up to the 530 size.

I'm excited. I think it's going to work out well. At my current rate of progress, maybe my car will be finished by early Summer. There are so many little details to work out (fuel, oiling, clutch, shift, cooling, exhaust, etc., etc...). I haven't even started thinking about spring rates, shock revalving, etc.

[ianashdown]

Does such a thing as 530 duplex chain exist?

That sure would take the worry out of some concepts.

Ian

[formulasuper]

D.I.D. Sells a 630V professional O ring chain that's rated at 11,000 lbs tensil strength. Anyone tried one?
By the way, just for info, I ran my stock Suzuki Hayabusa RK 530 gold chain on my Busa powered Ralt FS for 8 races this past season and it still is basically showing no wear! And as for short chains having any problems, mine has a short center distance between sprocket centerlines of only 10.5", about as short as you can get with a 1 to 3 ratio, & never has any problem with heating up. I do try to remember to spray it with the wax type chain lub at least once a day at the track.

[RobLav]

Is there a picture of this jackshaft idea around somewhere?

[Matt Conrad]

I could be wrong...because I'm not sure how you'll still use a chain....but don't all the roundy-round dwarf cars use this set-up? From memory, they use a Toyota differential with unequal length axles and the driveshaft connects to the engine via U-joints and a "driveshaft adaptor" which is a splined billet aluminum piece that clocks onto the output shaft on the engine.

A few guys around here road-race their dwarf cars and I haven't seen them have any issues with the set-up, but it sure looks like there has to be some power loss.

Matt Conrad
Phoenix Race Works, LLC

[RussMcB]

Matt, it sounds like you might be confusing two different arrangements. Forgive me if I'm misunderstanding your post.

I think the dwarf cars have their engines "in line" and therefore their differential converts the torque 90 degrees. The jackshaft arrangement that will be on my car is simply an intermediate shaft with two sprockets, and it is parallel to both the engine crank shaft and the car's half shafts. All of those shafts are turning in the same direction.

I could be wrong...because I'm not sure how you'll still use a chain....but don't all the roundy-round dwarf cars use this set-up? From memory, they use a Toyota differential with unequal length axles and the driveshaft connects to the engine via U-joints and a "driveshaft adaptor" which is a splined billet aluminum piece that clocks onto the output shaft on the engine.

A few guys around here road-race their dwarf cars and I haven't seen them have any issues with the set-up, but it sure looks like there has to be some power loss.

Matt Conrad
Phoenix Race Works, LLC

[Matt Conrad]

My post was actually supposed to go with another discussion....

Matt Conrad
Phoenix Race Works, LLC

[S Lathrop]

Richard and I drew up a design with a jack shaft.

We look at it as a way to have a reverse. The design used a silent chain inside a case. Every thing was run wet. With the reverse, the thing was like a 2 speed gear box. We also used an FT200 gear for connection the jack shaft to the final drive. The jack shaft was as close to the final deive unit as we could get it.

It was a fun design exercise but we rejected the project as too complex and expensive.

[LJennings]

My father did the same thing around 1969/1970 in a 3/4 midget powered by a motorcycle engine as a birthday present. The car was too powerful (for a 7 year old) and a maintenance nightmare.

Maybe he was the first, but I doubt it.