Re: Never before has so little power been made from so much displacement!
Got enough room to run 4 Rzeppa joints? They laugh at that sort of angularity. The VW air cooled type are plentiful and cheap along with being rather thin.
The 24 Hours of Lemons Forums → The Airplane-Powered MR2 → Never before has so little power been made from so much displacement!
Got enough room to run 4 Rzeppa joints? They laugh at that sort of angularity. The VW air cooled type are plentiful and cheap along with being rather thin.
Got enough room to run 4 Rzeppa joints? They laugh at that sort of angularity.
the thought has been crossing my mind in the last few hours and yes, i sure do. i'd just need a couple of carrier bearings since i'd need more than 2 cv joints.
heck, technically, just 2 rzeppa joints would handle my situation just fine. and 1900RPMs is not even out of their operating range. it's only about 120-140mph equivalent if they were being used at a wheel.
that might be a much cheaper solution to bring as a backup than anything else.
that picture you posted is a cross-cut CV, not an Rzeppa. they only do 20-28 degrees or so. an Rzeppa will do 50 degrees.
you can tell the difference, an rzeppa has the races evenly spaced:
you guys are just sadistic
But we enjoy it sooooo much!
i know you guys are going to be shocked. but i went digging through my spare parts pile and came out with two twin turbo supra axle shafts.
the outboard joints are massive Rzeppa joints:
that just might work. they'll be at their max but otherwise happy.
scratch that, only one twin turbo. the other one is a regular supra and has cross-cut joints on both ends. the the C5 vette shafts i have use rzeppa joints on the outers. i also have a spare vette wheel bearing that would make a pretty bitchin' carrier bearing for the whole thing.
alright, nothing exciting. i took the rest of the day to finish everything i could on the to-do list instead of trying to make another crazy contraption.
added the petty bar:
removed the broken glass to make way for the lexan:
at this point, it's almost ready to race again. here's where the list stands:
-fix 3000 GT box (or make alternative)
-redo oil lines with something that is actually oil safe (lines ordered)
-make rear window out of 1/4" lexan (material to be picked up tomorrow 54"x14")
-paint cage if i have time (the rust looks terrible, but it comes right off with a green scotchbrite pad.
I'll drop by the machine shop with the shaft that broke and my friend's opinion on it. if he thinks it's workable then i'll get the parts to fix it. otherwise i think we'll be using 3 Rzeppa joints to make it all work.
Don't forget you need to allow some 'plunge' so the joints don't bottom out hard. The 'Vette inboard joint should be able to handle some plunge.
Don't forget you need to allow some 'plunge' so the joints don't bottom out hard. The 'Vette inboard joint should be able to handle some plunge.
if i go that route i'll have to put a traditional spline interface in the middle. the vette inboard joint only allows 20-30degrees or so. not enough either.
found a diagram that will help me pull the goldwing box apart
there's a bunch of space inside the ring gear that can be used but i thought it would take a bunch of machining to get there. I may be able to move the slip spline to the other end of the driveshaft and gain a bunch of strength by being able to use a bigger shaft.
it just came to me, a reason not to just use the shaft solution. the guibo would have to be removed which is doing a damn good job of removing killer vibrations from the system.
the 3000GT box stays. and i've got ideas on how to fix it to be much stronger.
Or you could put the guibo in the middle of one of the shafts to allow plunge and handle vibration. If it comes to that...
Or you could put the guibo in the middle of one of the shafts to allow plunge and handle vibration. If it comes to that...
there's just not enough length and the fact that the guibo isn't self aligning would add a degree of complexity i do not want at this point.
i did find a way to make the shaft coming out of the 3000GT have a weld diameter of 1.75" instead of the 1" I had previously. that almost doubles the weld and reduces the mechanical advantage on it by a fairly large factor.
given that the rest of the drivetrain survived the surging that broke that i feel quite good about everything otherwise holding together. the surging was caused by me forgetting to plug in the vacuum line on the ECU so megasquirt was hunting for idle between 500 and 1500RPM. the subaru flywheel loading from that probably caused the system to exert it's entire 600lb*ft of torque over and over in a high stress way.
machined everything for the new output on the 3000GT box:
i'm going to leave the welding to my friend that does this stuff for a living this time.
hopefully tomorrow I'll pick up the lexan and the oil hoses should be here tomorrow so i'll try to get both of those things done tomorrow night.
when the new goldwing box arrives i want to redo the driveshaft mount. i don't feel 100% comfortable with the current design now that i see how it comes apart.
Just in case the guibo issue comes back up:
https://www.pegasusautoracing.com/produ … RecID=5349
They should be easy to make.
Just in case the guibo issue comes back up:
https://www.pegasusautoracing.com/produ … RecID=5349They should be easy to make.
NEAT!
it's the wrong bolt pattern, but that's just a question of using the right rubber piece. i used the 93mm one, this is a 96mm one. thanks for the link, i'm sure it will come in handy in the future.
got the lexan today and i learnt that it's just a fancy name for polycarbonate, about to go out and have some fun. but i wanted to show you guys something first.
my friend got the new shaft welded up and i wanted to demonstrate the difference between a rookie welder (me) and some guy that's been doing it since he's been in diapers. both were done on the exact same machine, likely the same piece of tungsten, same bottle of gas and both welds were prepared in a similar way on the exact same machinery.
so here's what happens when i use the tools:
and here's what happens when a pro uses the same tools:
I probably have to clarify, both welds used the assistance from a rotary table, but both were done by hand.
Weld envy!
Mine would look worse than yours, but that is a pretty weld.
Weld envy!
Mine would look worse than yours, but that is a pretty weld.
Oh, yes! Those are both far better than I am capable of. Color me green (with envy).
another short evening in the shop, but there's a milestone today. everything that isn't drivetrain related is now done. i changed the oil lines and i added a lexan rear window. those nasty curves did take quite a bit of swearing to get in there, but they fit nicely. it could have been better had i spent more time, but it's deemed "good enough" for now.
you can't see the lexan easily, but you can see the 90 or so rivets holding it in.
so the todo list is down to the following:
-reassemble 3000GT box
-make driveshaft tweaks
-load trailer & GO!
well, the other goldwing box did now show up yet so i'll make the mods to the current one tonight instead. not that big of a deal, just a little extra clean-up first.
also, i found this to help size the new driveshaft: http://www2.dana.com/pdf/IJ900-02.pdf
input torque: 600lb*ft
torque after 3000GT box: 736lb*ft
power factor: 1.2 (gas engine)
angle factor: 1.3 (about 8 degrees or so)
life factor: 1.0 (we could probably go to 0.5 without issue)
minimum torque capacity needed 1150lb*ft (1560Nm)
this says i really should use a much bigger joint than the 1310, i'm outside of it's ultimate limits.
the 1350 joint is the smallest joint that i don't exceed the absolute limits on. since i'm short on space that's what i will use. i suspect that the u-joints will be wore out after the first day if it make it through the entire day so i'll bring 2 spare joints in case it makes it past the first day.
Is this coming to summit? God I would love to see it!
I'm glad you decided against the CV/Rzeppa joint. I've been there done that with disastrous results…twice. They are really not designed to operate at constant angles like that, or even half that. My experience was with a CV at about 20 degrees, and about 3 times the RPM, however the torque was nearly zero. It's the heat that destroys them. Didn’t last but a few minutes.
This is a marvelous piece of engineering! I hope you get it going in time.
Kris
Is this coming to summit? God I would love to see it!
I'm glad you decided against the CV/Rzeppa joint. I've been there done that with disastrous results…twice. They are really not designed to operate at constant angles like that, or even half that. My experience was with a CV at about 20 degrees, and about 3 times the RPM, however the torque was nearly zero. It's the heat that destroys them. Didn’t last but a few minutes.
This is a marvelous piece of engineering! I hope you get it going in time.
Kris
Thanks,
it's going to be some long nights, but i should be able to get it done.
Caitlin works this weekend so that kinda shoots most of the weekend away since i will be watching Sebastian. but i gotta do what i gotta do.
the heat will also be an issue in the goldwing and the 3000gt box. i suspect that's what's going to take out the drivetrain in the end.
*edit* no, this car will only ever go to Joliet in this configuration. no matter how it finishes the motor is getting traded for a turboshaft after the june 9th/10th race.
Awwwwe, well good luck!
Awwwwe, well good luck!
sorry, it's just not reliable enough. and besides, TURBOSHAFT!!!! (assuming i can get the blessing from the judges)
The 24 Hours of Lemons Forums → The Airplane-Powered MR2 → Never before has so little power been made from so much displacement!