Erik Christiansen Erik Christiansen Godlike Moderator Location: Culver City, CA Join Date: 05/16/2008 Age: Possibly Wise Posts: 73 Rally Car: VW GTI |
Hi! So, here's some background. While I had my gearbox apart after 2nd gear stripped out, a post from Josh sparked the idea of getting 3-4-5 from MTS instead of a super short final drive. Then Wildert really sold it with the posts that Hoche quoted. Here's what my gearbox looks like in a format that will make JVL happy: Gear Ratio Final Drive Overall Ratio Speed at Redline (7200rpm) 1st......3.455......3.94............13.62...............37mph 2nd.....2.118......3.94.............8.35................60mph 3rd......1.68........3.94.............6.62................76mph 4th......1.35........3.94.............5.32................95mph 5th......1.17........3.94.............4.61................109mph Speed is calculated using Pirelli 175/70R15 which have a rolling circumference of 1876mm. In practice, my gps reads a percent or two lower, so actual top speed might be 106 or 107mph. Also, keep in mind these tires are about as large as you can realistically run in a mk2 (perhaps a tad too big). Anyway, I'm not sure why you would call this a compromise. I think the gears and final drive are perfectly matched for the events I run. I did not get into 5th in Idaho, but I can guarantee I will spend plenty of time in 5th at Prescott and HDT. Maybe the events by you are slower? Let me admit upfront I'm not a fast driver. I'm generally mid pack and have been working on improving my driving skills, so I try to compare year over year. As I was quoted, I took about three minutes off my total stage times on Saturday compared to the same stages 2014. Some may be just keeping my foot on the gas over crests, but I do think the gearbox helped with some of that improvement. Here's the deal - a modded gearbox can make you faster in two ways: mechanical advantage (shorter ratios) and the ability to keep the engine in the power band (closer ratios). Changing the final drive helps with the first (shorter ratios), but not with the second. Case in point, my 2.0l 16v with mild cams and a header makes decent power from 5,000rpm all the way up to redline (7,200rpm). Prior to getting the MTS gears I had a 4.81 final drive in an otherwise stock AGB. A redline shift from second to third would drop the engine speed down to 4,900rpm. Now, with a stock 2nd and the 1.68 3rd from MTS the revs only drop to 5,700rpm! This means I'm always in the powerband, and somewhat counter-intuitively means I have to shift less. There's more overlap between the gears. For example, 5,000rpm to 7,200rpm in 2nd translates to 41 to 60mph, and in 3rd it's 51 to 76mph. That's a 9mph range where I can be in either 2nd or 3rd and still be happy, while stock 2nd and 3rd have no overlap. Shifting less also means you can concentrate more on things like braking and cornering. As for only using 1st gear for starts, you were absolutely correct when I had the 4.81. With that final drive, first gear was just about useless and I could power out of hairpins in 2nd gear. Which means I essentially had a four speed... But with my current gearbox, first is tall enough to be useful. There were a number of uphill 2's at Idaho where I went down to first gear because I would be way below the powerband in second. the 1-2 shift did make me wish MTS would hurry up and offer 1st and 2nd gear input shafts soon... But it's definitely not a priority. I hope this helps clarify things. My advice in general would be to figure out what top speed you want and work backwards from there. That will dictate mechanical advantage. Then work out the gear ratios from there. In an 020, 1st and 2nd are limited, so at the end of the day there's not much you can improve on over what MTS already offers. Edited 2 time(s). Last edit at 06/17/2015 12:52AM by Erik Christiansen. |
john vanlandingham John Vanlandingham Infallible Moderator Location: Ford Asylum, Sleezattle, WA Join Date: 12/20/2005 Age: Fossilized Posts: 14,152 Rally Car: Saab 96 V4 |
Edit:
This is Josh's supposed ideal gearset for something....presented in a simple clear format... This is supposed to be "better" and evidently cheaper than the one that follows. Gear Ratio Final Drive Overall Ratio Speed at Redline (7200rpm) 1st......3.455......3.94............13.62...............37mph 2nd.....2.118......3.94.............8.35................60mph 3rd......1.68........3.94.............6.62................76mph 4th......1.35........3.94.............5.32................95mph 5th......1.17........3.94.............4.61................109mph Gear.......................final drive**..................overall ratio ------speed at 7000 on gravel tires I)....3.45.*................4.2...........................14.5..........35...........aka 56 km/hr II)...1.9*...................4.2...........................7.98.........64...........aka 102 km/hr III)...1.44*................4.2...........................6.04.........84...........aka 132 km/hr IV)...1.17................4.2.............................4.9.........103..........aka 165 km/hr V)....1.03..................4.2............................4.32.......117..........aka 188 km/hr *stock out of some box **cheap Again I'm "just in time senile" according to one wise ass (he said "Oh no not premature at all, just in time" but I don't see VITAL differences in the 2 gearsets except one you buy 3 fancy gears and use some final drive on hand, vs 2 fancy gears at 440 Euros and a final drive at under 200 euros. I am confuse. John Vanlandingham Sleezattle, WA, USA Vive le Prole-le-ralliat www.rallyrace.net/jvab CALL +1 206 431-9696 Remember! Pacific Standard Time is 3 hours behind Eastern Standard Time. Edited 1 time(s). Last edit at 06/17/2015 11:17AM by john vanlandingham. |
Josh Wimpey Josh Wimpey Ultra Moderator Location: VA Join Date: 12/27/2006 Age: Midlife Crisis Posts: 649 Rally Car: Sneak the Golf |
Yes it does. Take for example, the shift from 2nd to 3rd gear. The two configurations suggested above have a 20% and 25% difference between 2 & 3 respectively. So, a 6500-rpm redline vs a 8500-rpm redline yields a 400 to 500 rpm larger drop. I have no idea why you think that having 5th gear ratios of approximately 1 matters at all as you have to multiply that by the final drive. Anyway, the point is that the two motors would likely require quite different gear ratios in order to have a rally-optimized box unless they have the same torque profile with one stretched over 6500 rpm and the other across 8500 rpm (highly unlikely) in which case, only the final drive would need changing.
The spreadsheet linked above is far more useful ____________________________________________________________- One. Class -- 2WD www.quantumrallysport.com http://www.facebook.com/home.php?#/pages/Quantum-Rally-Sport/281129179600?ref=nf |
ElectroTech Steve Wheeler Ultra Moderator Location: Fork Lake, Alberta Join Date: 06/09/2015 Age: Midlife Crisis Posts: 336 Rally Car: 1992 Golf |
This is more or less what I have been trying to get at not trying to argue about philosophies drawn from different experiences. An affordable solution, the Power means nothing if you cannot control it! Edited 1 time(s). Last edit at 06/17/2015 12:13PM by ElectroTech. |
Josh Wimpey Josh Wimpey Ultra Moderator Location: VA Join Date: 12/27/2006 Age: Midlife Crisis Posts: 649 Rally Car: Sneak the Golf |
No worries John, I edited the tables to make them apples to apples comparisons instead of relying on tire size differences and different redlines to exaggerate your points. Congratulations, you have a 3-speed box to 107mph and will see 5th gear once a season.....
So, you chaps keep playing like saving $250 by buying an ebay R&P of unknown origin is going to be the smart way to go.
____________________________________________________________- One. Class -- 2WD www.quantumrallysport.com http://www.facebook.com/home.php?#/pages/Quantum-Rally-Sport/281129179600?ref=nf |
hoche Michel Hoche-Mong Mod Moderator Location: Campbell, CA Join Date: 02/28/2006 Age: Possibly Wise Posts: 1,156 Rally Car: Golf, Golf, RX-3 |
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ElectroTech Steve Wheeler Ultra Moderator Location: Fork Lake, Alberta Join Date: 06/09/2015 Age: Midlife Crisis Posts: 336 Rally Car: 1992 Golf |
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Josh Wimpey Josh Wimpey Ultra Moderator Location: VA Join Date: 12/27/2006 Age: Midlife Crisis Posts: 649 Rally Car: Sneak the Golf |
Glad to see that no one is learning.
Anyway, for what it is worth, a moderate build 2.0L 16v VW motor will make about 80hp at 4000rpm (the approximate rpm you end up at from the 1-2 shift in John's box) and just over 100hp at 4500rpm ( the approximate rpm you end up at from the 1-2 shift in the MTS box). That is a 25% difference in output. Not only that, the overall ratio in John's box for 2nd gear is considerably longer which compounds the 25% motor output difference at that shift & rpm. The differences continue to be striking in the 2-3 gearchange at 5460rpm vs 5700rpm --- about 10-15hp difference in output between those two rpm levels in a moderate 2.0L 16v build (about 10% output difference in percentage terms). Again, compounded by the taller overall gearing for John's 3rd gear by 10% again. But you know, John can't operate a spreadsheet and says RPM drops aren't the metric. Plus, he highlighted important numbers in purple so, go ahead and save $250 and enjoy the 3-speed box. ____________________________________________________________- One. Class -- 2WD www.quantumrallysport.com http://www.facebook.com/home.php?#/pages/Quantum-Rally-Sport/281129179600?ref=nf |
ElectroTech Steve Wheeler Ultra Moderator Location: Fork Lake, Alberta Join Date: 06/09/2015 Age: Midlife Crisis Posts: 336 Rally Car: 1992 Golf |
Not sure why anyone is getting worked up, FFS RPM drops, where's the factor for the car slowing down way more in the first couple of gear changes, didn't know the 020 had the ability to shift instantly or does the spreadsheet show that. What about the fact that 80hp in 2nd is like 400 in 5th, this reeks of paper racing without real world chucked in. One set of gears will cover 90% of anyone who rally's a NA VW gas 8 or 16V, yes in search of perfection we would all have the absolute finest of everything. Do you gap and clock spark plugs, measure the SG of all your fuel, calibrated your tachometer, revalved your shocks because one rally has a lot of square edged stuff and the next is smoother.
When I say you shouldn't have to compromise I mean inject some common sense with it. To expect perfection from one thing and to not follow it in others is just an exercise in futility. I posted the damn thing in the first place just as a possibility to use for some rather than searching scrapyards for harder and harder to find stuff. Nobody has said not to use whatever gear you figure you need. Some people feel better when they spend more money I guess. Well look at me I paid 6 times what something should be sold for. That link I posted does illustrate the many ways to skin a cat regarding this stuff, it matters not though, build what you want how you want and the BS stops at the finish line. I might be new here but I'm not brand new to the world. Been around racing my whole life. Anyway here is one set of gears I'm looking at, VWMS stuff, maybe get a small batch run made. Some case clearancing will be required. 16V based. 1st-2.72 2nd-2.06 3rd-1.68 4th-1.43 5th-1.26 Power means nothing if you cannot control it! |
john vanlandingham John Vanlandingham Infallible Moderator Location: Ford Asylum, Sleezattle, WA Join Date: 12/20/2005 Age: Fossilized Posts: 14,152 Rally Car: Saab 96 V4 |
i wonder if any person here knows what gears are made of---with Goggling---knows how gears are made and understands how subcontracting works...
Hint: you have no idea where ANYTHING in a all stock car actually comes from, only a belief.. John Vanlandingham Sleezattle, WA, USA Vive le Prole-le-ralliat www.rallyrace.net/jvab CALL +1 206 431-9696 Remember! Pacific Standard Time is 3 hours behind Eastern Standard Time. |
john vanlandingham John Vanlandingham Infallible Moderator Location: Ford Asylum, Sleezattle, WA Join Date: 12/20/2005 Age: Fossilized Posts: 14,152 Rally Car: Saab 96 V4 |
And speaking of learning---and not..
HA HA! I ain't the ones trying to re-invent the wheel by buying a mish-mash of parts to avoid spending $3000-5000 for a car which bends beams if you look at them angrily, has spat up CV/Driveshaft/spindle constantly since the last 30 years and has no particlar advantage to compensate for the inherent, built in problems... I drove something better... And only met a couple of Golves I couldn't beat. John Vanlandingham Sleezattle, WA, USA Vive le Prole-le-ralliat www.rallyrace.net/jvab CALL +1 206 431-9696 Remember! Pacific Standard Time is 3 hours behind Eastern Standard Time. |
ElectroTech Steve Wheeler Ultra Moderator Location: Fork Lake, Alberta Join Date: 06/09/2015 Age: Midlife Crisis Posts: 336 Rally Car: 1992 Golf |
LOL,
There's not 100s of gear manufacturers, one that built a foundry just to make the best for MTS? And another to supply eBay? Wonder how the companies that make $200 R&Ps even stays in business, oh yeah, costs next to nothing once you've made the initial investment. Hey Mr.Gear Maker, here is a sample, what's your MOQ? Power means nothing if you cannot control it! |
If you wanted to get crafty, you can just buy gear blanks that are inductively hardened on the gear teeth area and machine them to fit on the stock VW shafts. You just need to keep the center distances the same (duh), and find the proper ratios. It's not exactly rocket surgery. You just need some basic machine tools and a WHOLE LOT OF TIME. Drill and pin them with a little weld material for good measure.
I think Tom B had a gear kit like that at one point. |
ElectroTech Steve Wheeler Ultra Moderator Location: Fork Lake, Alberta Join Date: 06/09/2015 Age: Midlife Crisis Posts: 336 Rally Car: 1992 Golf |
True grassroots motorsports right there! Power means nothing if you cannot control it! |
ElectroTech Steve Wheeler Ultra Moderator Location: Fork Lake, Alberta Join Date: 06/09/2015 Age: Midlife Crisis Posts: 336 Rally Car: 1992 Golf |
LOL, that's the fun in it, taking a inferior piece and making it slightly less inferior! Everyone thinks they are fast, but put the average meth head in a high speed chase would pass us sideways one handed in a 96 Cadillac with 2 flat tires and still spend the same amount of time between the ditches! Power means nothing if you cannot control it! |