DTSFab.com (Desert, Trail and Sand)
UTV's Off Road ( RZR, YXZ, Mini Buggy, Carts,etc.) => UTV Motor and Drivetrain => Topic started by: frankysfree on October 25, 2012, 02:22:23 PM
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So i have a stock bodied beetle and im in the process of having an adapter plate machined to mate a hayabusa engine to the T1 IRS transaxle. I am not certain about the gear ratio i need to run and i have looked at Masterfabr build and would like to do a similar thing(run the vw transaxle in a fixed gear and shift the busa engine) but want to make sure i get the gearing correct.
Keep in mind this will be a street ONLY driven beetle weighing in about 1800lbs so i dont need super low gearing. Once i figure out what i want to do i will be pulling the transaxle to put a super diff, Welded 3rd, etc to beef it up and also eliminate the uneeded gears inside.
I am getting my gear ratios off of this online calculator:
http://woodsware.aciwebs.com/gears/gears.asp (http://woodsware.aciwebs.com/gears/gears.asp)
It has a first generation hayabusa listed and gives all the ratios from crank, for each gear, primary, and final. It also lists what speed in what gear, rpm, etc. I can input my own figures to compare and it gives me a comparison of speeds/rpms as well.
From my research(might or might not be correct...) my transaxle has a 4.125 R+P in it, but i am unsure on what ratios are inside the transaxle as im still trying to find those. One source says they are as follows:
1st: 3.80
2nd: 2.06
3rd: 1.32
4th: 0.89
REV: 3.69
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Welcome to the site. First off we will need to know for sure the gear ratios (you're likely correct tho) and how tall your rear tires will be. What is your target top end and more importantly what MPH do you wish to cruise at down the highway?
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Thanks. Cool site here.
Being as i own a motorcycle shop and do some out of the box things this was really the next part of the evolutionary ladder for me.
Ill check when i get home and see if the Bentley manual lists the gear ratios.
I will also have to double check my tire sizes but they are stock rims so unless i decide to change rims they would still be the stock height and rim size. Ive just been plugging in the stock tire size on my calculations.
I would like a top speed in the(theoretical) 130mph range. Cruising speed on the hwy is not all that important. This wont be a daily driver but a pure weekend warrior/play toy so as long as the rpms are in a usable range im fine.
I do plan on turbocharging the engine once ive got a running, driving car. Dont want to do it beforehand as i am pooling resources to get the bug in driveable condition including fixing areas that need attention and to get the engine to bolt to the transaxle and move under its own power. I simply dont want a drawn out(expensive) project that build time is measured in years instead of days and months.
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How exactly would i calculate final drive ratio from the motorcycle, through the vw transaxle, to the wheels? Like if i have the busa in 1st gear which is a 1.596 ratio how do i calculate what the ratio is through, say 3rd gear in the vw assuming its 1.32 with a 4.12 R+P? Math was never my strong subject...
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I'll post up the math formula if you like but here is a good example of what you can expect with a gear ratio that works pretty well in the sand. For high speed highway/track (130 mph) use the r&p gear would need to be at least 1/3 higher.
OK ,this is what I've come up with using Albin R&P(5.43:1) and Albin 3rd(1.4:1) and 4th(1.0:1). Assuming the busa is capable of turning 10500 in each gear which makes countershaft =6862 RPM with busa in (1.043:1)6thgear. Use 31" tires.Assume no tire slip in sand.
1st-3.80:1=30.66 MPH
2nd-2.06:1=56.58 MPH
3rd-1.40:1=83.25 MPH
4th-1.0:1=116.54MPH
There is some good discussion about this for the first several pages of this topic-
http://www.dtsfab.com/index/index.php?topic=206.msg1331#msg1331 (http://www.dtsfab.com/index/index.php?topic=206.msg1331#msg1331)
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Thanks. I would actually like to use the busa transmission and keep the vw transaxle in one gear except to go in reverse. I was just using the gear choices in busa and vw as examples. I did read your thread and i will have to go back and take another look at it but i seem to remember you using the 3rd gear in the bus transaxle and shifting the busa as the primary transmission.
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I do use the busa trans as the primary trans with the vw being used as the "overdrive/underdrive" secondary trans. The mph numbers are nonetheless the same for top speeds based on my 091 custom ratios. It's getting too late for me to look up the actual formula tonite but if you wish I'll post it up tomorrow for you.
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3.8 first
2.06 second
1.26 third
0.89 fourth
4.125 R&P
Checked the transaxle code and according to that(and some very helpful vw guys at STF) these are the ratios.
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Yes, id be very interested in getting the formula for that. The last thing i want to do is get the car all together and find out the gearing is unusable. It would be better to know now when i go into the transaxle to upgrade the internals if i need to change anything.
Thanks for all the help btw.
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(rpm x tire diameter) divided by (differential ratio x transmission ratio x 336) = mph
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you can use one of the many online calculators such as these.
http://www.bgsoflex.com/rpmmph.html
http://www.wallaceracing.com/gear-speed.php (http://www.wallaceracing.com/gear-speed.php)
http://www.richmondgear.com (http://www.richmondgear.com)
There are many,many online calculators . You can either do all the math from the formula or ,as I do,use the easy way with the calculator programs..
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REMEMBER to adjust your engine rpm BEFORE doing any of the calculations. The busa has a primary ,internal before the trans ,reduction of 1.596:1 . What that means is that,for example, 10,500 busa rpm redline/1.596 = 6578 rpm at the vw trans input shaft. Using that example you would use 6578 as the engine rpm in the formula or with any of the calculators available for free online.
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I'd also consider at what engine rpm I wish to cruise comfortably at also.Say 70 mph at around 5000 engine rpm would only be 3132 input shaft rpm.
Using the richmond gear calculator above that has a neat alternative calculator to figure rear gear needed ,you will find that a cruising rpm of 3132 will give you 70 mph with a 31" tall tire needing a rear gear of 4.13:1 . Pretty close to what,IMO,you need.
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Here's another good calculator I found also.
http://www.tremec.com/performance/gear-calculators.html (http://www.tremec.com/performance/gear-calculators.html)
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Thanks. I havent had a chance to do any calculations yet as i spent all day yesterday at the drag races.
Ill see if i can do some figuring today.
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Math is really not my strong point.
So check it and let me know if this is right.
If i use the calculator that i linked to at first all i have to do is punch in the final drive numbers and tire size and it gives me the stock compared to the updated results. If my 3rd gear is 1.26 and R+P is 4.12 that would give me an axle ratio of 5.19 correct?? If i stick that number in the calculator along with new tire size(185/80-15) it comes out to a top speed at redline of 36.6 mph and a theoretical top speed in 6th of 91.8 mph. If the VW was in 4th that would give me 51.9 mph in first and top speed in 6th of 115.3 mph.
Does this sound right or am i doing it wrong. I figured the easiest way was to just use the final drive on the calculator (its assuming chain + sprockets) for the Vw final drive instead of doing all the calculations seperate. It also gives me a good idea of what the stock busa ran at certain rpm with stock gearing for a good comparison.
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Assuming the calculations from my last post are correct (i multiplied the vw gear by the R+P then put that # into the final drive on the calculator) then even with a 3.88 R+P and the Vw in 4th gear 0.89 that would give me a top speed of 122.2 mph when in 6th in the busa tranny at 10.5K rpm... I could live with that and it would give me a cruising speed in 6th @60 mph at 4568 rpm which isnt that good but isnt the worst... Wish they made a R+P in the low 3's or a 4th gear of less than .89 but i guess ill be stuck with what i can source...
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Weddle makes almost any gear ratio you may need . I have all 4 gears non stock ratios in my 091.
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Math is really not my strong point.
So check it and let me know if this is right.
If i use the calculator that i linked to at first all i have to do is punch in the final drive numbers and tire size and it gives me the stock compared to the updated results. If my 3rd gear is 1.26 and R+P is 4.12 that would give me an axle ratio of 5.19 correct?? If i stick that number in the calculator along with new tire size(185/80-15) it comes out to a top speed at redline of 36.6 mph and a theoretical top speed in 6th of 91.8 mph. If the VW was in 4th that would give me 51.9 mph in first and top speed in 6th of 115.3 mph.
Does this sound right or am i doing it wrong. I figured the easiest way was to just use the final drive on the calculator (its assuming chain + sprockets) for the Vw final drive instead of doing all the calculations seperate. It also gives me a good idea of what the stock busa ran at certain rpm with stock gearing for a good comparison.
Looks right to me. You understand it correctly. FWIW, I doubt that a non turbo busa will actually pull to redlne in 6th with an 1800# car but the math is correct.
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Weddle makes almost any gear ratio you may need . I have all 4 gears non stock ratios in my 091.
Dont know if i can afford weddle gears... Ill call them tomorrow and see what something like that would run.
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Looks right to me. You understand it correctly. FWIW, I doubt that a non turbo busa will actually pull to redlne in 6th with an 1800# car but the math is correct.
It will be turbocharged after its a running, driving car. I simply want to make it roadworthy first, then work on tuning it later. I have a bad habit of getting overwhelmed by taking a simple project and making change after change until its pretty much never ending(and very expensive)...
I would like to plan on getting a little more out of it than low 120's though. If i could get the gearing to where im running an 0.89 3rd and lower 4th then i could use the vw tranny as over/under drive as your doing.
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Just look up weddle and VIOLA! ,you have exactly what you need. If it were me though I'd invest my coin in an 091 if doing custom ratios and use the 3 rib as an anchor.
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I think ill just adjust the final drive ratio with the rims/tires. I didnt want to stick with the stockers anyway and im going to get the brake kits with blank rotors to have them drilled a more standard pattern like a 4x100mm or 4x114.3mm and found these rims i really like. If i get the 17" rims and go with anything over a 50 height it will gear it down over the stock 15" 80 height tires. If i go 215/55-17 for ex. it gives me a top speed of 126.6 vs 122 with stock tires and gets my cruising rpm @60 mph down to 4408 rpm all assuming i use the 3.88 R+P and vw gearbox in 4th.
(https://dtsfab.com/proxy.php?request=http%3A%2F%2Fi36.photobucket.com%2Falbums%2Fe13%2Ffrankysfree%2Fwheel.jpg&hash=cb7af171d2563797db794dab5016843e959c50ea)
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Just look up weddle and VIOLA! ,you have exactly what you need. If it were me though I'd invest my coin in an 091 if doing custom ratios and use the 3 rib as an anchor.
Looked them up but didnt find specifics or prices on their site. Im close enough in gearing that im not worried and with the rim/tire change i should be even closer to what i want.
Adapter plate is being manufactured to fit T1 box. I dont think it should be a problem unless i do some really hard launches, ie clutch drops.
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Sounds like a plan. Have you ran the numbers in busa first gear yet? You're going to find that take off from dead stop is going to suck. It'll be a bitch taking off from a stoplight on an incline. This is the reason for my using the vw trans as an under/overdrive.
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With the 215/55/17 tires and 3.88 R+P top speed in first gear with vw gearbox in 4th would be 50.5 mph. If the vw gearbox was in 3rd the top speed in first gear would be 35.7 so i should be fine. I would be going 35.7 mph with the engine revving to almost 10k rpm... I might keep second gear in the vw gearbox just as a really low gear but i dont really see me needing it. Of course you have driven your car with essentially the same setup so you probably know better than me. IIRC isnt it harder to take off in sand than asphalt though? Ive been planning on keeping 3rd and 4th in the vw gearbox as sort of a high/low anyway.
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I do a pretty fair amount of dirt road bonzai running.Even with my 4.56 r&p it's not an easy takeoff in vw 4th on a moderate incline like you will run into all the time on the street. . I also have a MUCH lower 4th gear ratio than you will be running. Therefore I have a much lower final ratio than you. If it were me I'd just keep all the gears in the box for now.
BTW,the weddle gears are NOT cheap.
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IMO,you will likely find yourself using 3rd a lot more than you think. Just remember that the torque input to the vw trans will be multiplied and that may be the deal (gear ;) ;D ;D) breaker ultimately.1800 pounds+high speeds+gear ratio multiplied torque input = I wish you had chosen an 091 for this project. ;D ;D
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Yeah, ill take your advice and keep all the gears for now. I can see firsthand how it drives and do any gear changes when i pull the engine to install the turbo. I will need to pull the gearbox to install the super diff, 3.88 R+P, weld 3rd + 4th gear, and freshen up everything else. I dont think ill have any trouble with the input shaft though. I did read about you breaking one, but i talked to the local VW shop and there opinion was i should leave it as-is. Their specialty is building transaxles from everyday drivers to full on drag cars and they told me they have full bodied drag bugs running the stock input shaft. Kinda weird but ill stick with it for now and upgrade as things break.
What is your tire size? I know they are 31" tall which is about 3" taller than mine but the calculator lets me input a tire size and it does all the hard work for me. I was going to punch in your ratios in the calculator and get a comparison of what your final numbers look like compared to mine. IIRC you said your car weighs in around 1800lbs which is almost spot on to what mine weighs so should give me a decent comparison.
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R&P(4.57:1) and Weddle gears 1st(3.44:1) 2nd (2.25:1) 3rd(1.78:1) and 4th(1.39:1). Assuming the busa is capable of turning 10500 in each gear which makes countershaft =6862 RPM with busa in (1.043:1)6thgear. Use 31" tires.Assume no tire slip in sand.
1st-3.44:1=40.25 MPH
2nd-2.25:1=61.55 MPH
3rd-1.78:1=77.80 MPH
4th-1.39:1=99.62MPH
These are my mph with custom ratios @10,500 rpm with busa in 6th.
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Im not getting the same mph readings from the calculator as you got. I input the VW gearbox in 4th (1.39) and the 4.57 R+P and for redline in 6th in the busa its showing me a top speed of 90.0 mph at 10,500 rpm with a 31" tire.
Am i doing something wrong here? Im sure its not going to be spot on as it only lets me input tire size and not circumference or radius so its up to the program to determine the actual size but i would think it would be closer.
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You are not doing anything wrong. Calculators work with theoretical tire sizes. MInor diameter differences will skew numbers. calculators using actual diameters are a bit more accurate. If you want spot on numbers you will need to work with effective diameter which is the distance from wheel center to the ground with the tire at proper pressure. The effective diameter will be less than the theoretical .
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Ok. That makes sense. So i guess i should doublecheck the numbers im getting with the actual diameter and see where that puts me.
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yup
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Havent been on in a while. Dont have much extra cash laying around because of the holidays but i did get the adapter plate, hardware, etc in and have the engine and transaxle mated together out of the car on my workbench. Just need to get the transaxle beefed up before i put it in the car, get the new wheels/tires, and get the radiator, etc positioned and mounted
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pics......................
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Laser cut out of 20mm aluminum so should be plenty strong enough. Need to make additional mounts from the right side of engine(opposite side from transaxle) so the plate isnt holding all the weight.
(https://dtsfab.com/proxy.php?request=http%3A%2F%2Fi36.photobucket.com%2Falbums%2Fe13%2Ffrankysfree%2Fmockup4.jpg&hash=8196011549a1fa62c676e3e4a08db40965562ba5)
(https://dtsfab.com/proxy.php?request=http%3A%2F%2Fi36.photobucket.com%2Falbums%2Fe13%2Ffrankysfree%2Fmockup3.jpg&hash=a5a7778431586bb9717a49c8c68fc6baa4242aaa)
(https://dtsfab.com/proxy.php?request=http%3A%2F%2Fi36.photobucket.com%2Falbums%2Fe13%2Ffrankysfree%2Fmockup2.jpg&hash=d190997e2f1433f4b34394375bbb23aa22d9df54)
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Looking good! You are running rear engine ,correct?
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Thanks. Yeah, rear engine and its stock bodied bug ill be running on the street. Should be able to shut the decklid and appear stock except for the rims/tires, body mods(filler panels for gas, door handles, etc) and of course the sound!!
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WOW, Nice work!
Keep the pics coming, that will be some serious eye-candy!
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Are you just hanging the busa out the back like a vw engine or is it supported otherwise?
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I will be making some mounts for the other side of the engine seeing as how the hayabusa was never meant to be held by only the motor mounts on only one side.
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That's what I was thinking also.
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Also hoping to drop a little weight off the car since it weighs roughly 1800 lbs or so and i want to put one of the Kafer bars to strengthen up the rear and maybe like a 6 point roll cage inside as well. Im thinking of going with a set of racing buckets and maybe fiberglass fenders, trunk, and decklid but these arent critical right now.
What do you guys think of cryogenic treating? I know a guy who owns a business around here and they can treat anything i want and was thinking of having the internals from the vw transaxle treated, ie shafts + gears, while i was in there upgrading the R+P, side plates, etc. I can get all the gears and shafts in the vw transaxle treated for like $60.
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Cryo done correctly has benefits. Just freezing parts is a waste of money/time.
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Cool. Ill give him a try then. Cant hurt
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for 60 bux why not?