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FJ2400 - Bonneville Land Speed Racer

Started by freakhousecustoms, January 01, 2021, 06:58:52 PM

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freakhousecustoms

Quote from: freakhousecustoms on January 02, 2021, 11:31:23 AM
...  I was at 45º rake with The GloWorm and this time around, I think I will be keeping the rake at 35-38º.  I think stock is 35º?

I just went out and measured... I believe stock is 28º, there's 35º on my dragbike, so I'm pretty sure I'm going to limit this build to a maximum of 35º rake.
40º would be too much and even 38º, I think, is more than I need.


The Juggernaut: Dual-Engine FJ2400
Watch the build on The Freakhouse Customs Channel

fj1289

Spot on - the FSM says 27.5 degrees. 

I wonder when some of us jack up the rear ride height how much it is decreased?!

I'll have to go out to my trailer and dig out the plate - but yes, similar to that.   If nothing else it can be an easy template. 

fj1289

Here is the plate and the sprocket:






Don't know how much of a template this can serve as in reality — looks to be more chassis specific than engine specific. 

This was buried in some boxes that came with a couple billet transmissions i purchased recently.   They were in a last bunch of parts that were part of Rod Mumford's estate.  Also found a very interesting clutch setup while digging through the boxes.   Looks like an FJ back plate, but it is a VERY bizarre clutch setup.   I'll post more of it on my dragbike project. 

fj1289

Holy cow!  The pictures worked on the first try!  2021 is looking better already!!!

freakhousecustoms

 :shok:
WHOA!  Yes, that looks massive (and awesome)!
Says the guy who's outboard bearing support is going to be 2-feet long!

Looking at that sprocket reminds me to ask the question:

Are you still using the stock chain size & sprockets?  I bought before I thought and I will be using the stock sprockets to build my "driveshafts".


The Juggernaut: Dual-Engine FJ2400
Watch the build on The Freakhouse Customs Channel

fj1289

Those "parallel" sprockets are one of the methods I was thinking of.   Haven't thought a lot about coupling two engines - fun problem set!

I've got countershaft sprockets from 15 to 20 teeth.  16, 17, and maybe 18 offset sprockets (only 3/8" offset!).  I  can confirm 19 teeth clear the cases and clutch push rod - haven't tried the 20 tooth yet.  I use a 530 chain - non o-ring drag race style chains.  I'd think an o-ring chain would be smarter on the salt.  

freakhousecustoms

Quote from: fj1289 on January 02, 2021, 09:18:52 PM
I've got countershaft sprockets from 15 to 20 teeth.  16, 17, and maybe 18 offset sprockets (only 3/8" offset!).  I  can confirm 19 teeth clear the cases and clutch push rod

Excellent to know.  My 18T sprockets showed up last week, I ordered 6 of them, so I have 2 chances to make the driveshafts correctly.  :bomb:
I just have to get some "lathe time" set up with my buddy so I can get that step crossed off the list.  Since everything is welded, I'm kinda "stuck" picking one size up front and going with that.  When I ran the GloWorm in 2019, I had a few different rear sprockets on hand, but after running, I don't think any of them were actually small enough.

How small did you go on the rear sprocket for the CO Mile?  I'm thinking I'd need to get down to a 30-32T back there... with 2 engines, I won't be lacking any torque. :-D
The Juggernaut: Dual-Engine FJ2400
Watch the build on The Freakhouse Customs Channel

fj1289

I had a 27 tooth on the back - with an 18 or 19 on the countershaft.   I think the smallest you will get on the stock rear is 38.  I run an old school PM Chicane rim with a solid rear hub - so you can run a ridiculously small sprocket. 

Maybe you can fab a spacer for the cush drive to allow you to run a smaller sprocket?  Especially since you are going to be modifying the drive line already.

freakhousecustoms

A 27!  Perfect - that reinforces my thinking that I need a S M A L L sprocket. 
I'll cross that bridge when I come to it, but if push comes to shove, it shouldn't be too (relatively) difficult to fabricate/machine/cobble together some small stuff.

Thank you!



The Juggernaut: Dual-Engine FJ2400
Watch the build on The Freakhouse Customs Channel

freakhousecustoms

The VERY FIRST episode of The Juggernaut Build has finally arrived:
The actual name is the "F'n Juggernaut" (see what I did there... F... J...  :wacko1:)


Click the pic to view it!  :greeting:




Please Like & Subscribe on YouTube!

The Juggernaut: Dual-Engine FJ2400
Watch the build on The Freakhouse Customs Channel

fj1289

I've got some good gearing spreadsheets from the purple sage trading post site (purplesagetradingpost.com - good land speed site if you haven't wandered across it yet).  

I'd gear for your calculated top speed and add maybe 20% for tire slippage.  

I'm guessing with two stock engines in a naked style frame, you should end up right around 200 mph.  An 18/31 or 22/38 combo would gear you for 205+/- assume zero slip.  

If you can build a flange into your outrigger output, you could change the "front" sprocket (using a bolt-on rear wheel style sprocket) and achieve pretty much any gearing you desire - even if you leave the stock sprocket carrier stock and be limited to a 38 tooth rear sprocket.  

edit - just realized those calcs were based on a 17" tire - the stock 16" size is actually a bit taller so would give more speed...

freakhousecustoms

Purple Sage is an invaluable resource, not only to land speed racers, but anyone who's curious about "how gearing works".
Tire slippage seems to be that X-Factor that increases exponentially as I add engines! LOL!


The Juggernaut: Dual-Engine FJ2400
Watch the build on The Freakhouse Customs Channel

freakhousecustoms


This is where I start having fun!  She's a quick/short episode so I hope you enjoy it as much as I had fun making it.

Click Pic for Video:


The Juggernaut: Dual-Engine FJ2400
Watch the build on The Freakhouse Customs Channel

fj1289

Anyone seen "The Greasy Hands Preachers" on Amazon Prime?

An Indie film I'm sure not for everyone - bit touches for me some of the "why's" for loving this hobby and doing some of the things we do.

Looking forward to "doubling up" the frames!

fj1289

Does 15-20% slippage jive with what you've experienced?  If I remember correctly that was kind of the range I was expecting to see. 

Scott Guthrie has a series of articles where he talks about twin engined bikes and cars.   The simplified logic was for salt beds more weight = more traction and more power = more speed, so adding an engine gives you both!