Setting Up an IRS Super Diff

[Bruce]

[MichaelBrenner]

maybe I didn't measure it very well, my dad bunged it up a bit getting it out, I think it was actually a 0.60mm or maybe a 0.50mm. Anyway, I will do that, I need a 0.40mm or so to get me into the right range. Then the pinion drama next.
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Brenner Racing
SNORE 1179

[MichaelBrenner]

Does anyone know what I need to do to adapt the 091 first gear idler for use in my transmission? What do I need to have machined? is it as simple as cutting it down to the same width as the stock 1st gear idler?
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Brenner Racing
SNORE 1179

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[MichaelBrenner]

Steve at Weddle didn't know what I was talking about.

So do i need just the slider outside or the inside too?
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Brenner Racing
SNORE 1179

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You'll need the later splined inner hub portion, and the early outer slider portion. The issue is that the center of the keyed hub that fits the keyed gears is quite a bit smaller in diameter than the center of the splined hub. You could simply turn down the inside of the splined hub to the size of the keyed one, but this doesn't leave too much material on the hub. I'v talked with some that will turn down the hub some, then either narrow the early gear without the syncro hub to clear the modified mainshaft hub before welding them together, or turn down only a portion of the gear after it has been welded. The only time I have come in contact with this situation was when the 3.78 mainshaft was ground down to use the unmodified keyed hub, and gears. I received some good info about this over on the Ultimate Aircooled Forum.

http://ultimateaircooled.com/simplemachinesforum/index.php?topic=6256.0

Maybe you can contact some of the users that replied to the thread to get actual dimensions for the modification.

[MichaelBrenner]

Hey John,

Thanks for all that! I just got a call back from weddle and they said to have the 091 cut to the same width as the stock gear from the engagement teeth side only.

Then have the stock type 1 slider machined 0.020" off the first gear side.

You just have to talk to the right people, communication is so important.

If I come out to Vegas I have to visit you and talk some class 11...... I think my second transmission will be better, and simpler than this first one.
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Brenner Racing
SNORE 1179

[MichaelBrenner]

Great news everyone that was helping me figure this out. I finally installed the diff, measured the bearing preload and it was HIGH, about 15 in lbs. I had about 0.120mm total shims. I reduced it to 0.100mm and it came in right at 7 in lbs turning torque on used bearings. PERFECT. Then I split the shims equally 50/50 and had Zero backlash, not good, changed to 0.70mm on the case side and 0.30 cover side, TA DA, I got 0.006" backlash measured with a tool I made that measures at the radius of the ring gear! For everyone that has helped me understand what to do THANK YOU! Now I'm just working on getting the gearstacks fixed up and that's taking a while since I need some surface grinding on my 091 idler and the 1-2 slider. Everyone wants a ton of money for a 10 minute job.....
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Brenner Racing
SNORE 1179

[Bruce]

[MichaelBrenner]

The gear mesh pattern looked great, centered height and depth wise. I think I may have had a little luck doing this. I took it apart and put it together at least a half a dozen times. I used a heat gun to heat the pinion bearing area and it is nice and snug. Remember I'm not too worried about the noise that so many are, this is a race car....
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Brenner Racing
SNORE 1179

[Bruce]

This is what's called "Beginner's Luck". Next time you'll pay the price.
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[MichaelBrenner]

FYI. You need to surface 091 first gear idler 0.010"-0.015" depending on which end of the spec for side clearance you want to end up on..... The 1/2 slider needs to be surfaced 0.020" to fit the idler gear engagement teeth all the way......

Those details are HARD to find, I consider this transmission Karma that should come back to me some day in the form of more good tips or good luck.

A wise man once told me, 'You'd rather be lucky than good, believe me'...
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Brenner Racing
SNORE 1179

[MichaelBrenner]

For the transmission gurus like Bruce on here that really get it when it comes to advanced mechanics I wanted to say thanks for helping me. My dad and I have now built 3 good transmissions. The first you remember was an OK build but unfortunately had a gleeson R/P in 4.12 along with the 1.26 3rd gear and a keyed super beetle (9 tooth) mainshaft.....

Not ideal. Since then I have built another offset rib cased, 4.12 O r/p, with a modified 113 1.32 third gear (cut to fit the stock late mainshaft), it also has a weddle side cover (thick) and a weddle diff cover (nice) and a 300m input shaft. 4th gear is stock 0.93 fine tooth because it's just in there for the ride anyways. That transmission too I got 'lucky' and hit the backlash at 0.0055" on my first try after setting the diff preload to 8 in lbs using used bearings.......

For anyone interested in the 091 first gear idler conversion you simply take the gear (Weddle $14) and get a belt sander (80 grit) and grind it about 0.008-0.010". It will setup perfectly if you do that. On the clutch gear just grind the 1st gear side 0.020" so it engages fully. Don't forget you'll need the 091 1st gear syncro for this conversion as well.

My first transmission went approximately 600 race miles and I changed the gear oil every time to monitor how much of the r/p was coming off. Overall it looked very good each time.

Then we built this newest trans and it's got about 200 miles on it. The first transmission is sitting as a good spare incase we have a problem and we will upgrade some stuff in it soon using a 1.32 3rd, a 4.12K I have sitting around and probably a stock 4th gear all on a stock late mainshaft.

Overall I got a lot of good racing out of that first trans and I want to say big thanks to you guys. Racers kind of trip out when they see me passing them and know that I build our motor and trans.... My dad can't believe we do it all and I just tell him it's the power of the internet....
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Brenner Racing
SNORE 1179

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There is a lot of info on the internet, some good, and some bad. It's the people like Bruce that actually know what they are talking about, and are willing to help others, that makes it great. I've had one too many life situations in different forms of competition where I've eventually learned everything I needed to know by myself, but certian people around me could have made life so much easier by simply "throwing me a bone", but chose to be assholes keeping everything to themselves. I try and help any way I can. It's cool you've been able to find out how to rebuild a transaxle, but you're one of the few that have seen it through to the end. There are a lot of people that aren't as adventurous as yourself, and give up very easily when things don't work out. Now you can save a little bit on rebuild labor for the future, and have the satisfaction knowing you're the one that built the tranny.

[mcmscott]

How many times have you passed Robert Johnsen? Or Erick Solorazano? I know who does there trans, keep it up, you will be an ace before you know it. GOOD LUCK

[MichaelBrenner]

If you want evidence of me beating up on Robert and Eric just check out Laughlin and Primm from last year and this year..... I have GoPro video of Eric pulling over for me on the last lap at Laughlin day 1, never saw him on day 2. The first time I ever beat Eric/Robert they were actually having transmission issues, but I'm sure there's a story behind that too.

But I don't want to talk smack, those guys are cool guys. Eric shook my hand when I passed him at Laughlin and Robert is always nice to me too.

I don't know the metalcraft guys but I know some racers swear by them. I would love to touch base with those guys sometime, do you know them well? I'm sensing some tone there???

snoreracing.net
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Brenner Racing
SNORE 1179

[mcmscott]

No tone just playful sarcasm, I enjoy building vw trannies and experimenting with different setups and such, if you ever have any questions on how I set them up feel free to ask, I'm always willing to help fellow racers. Btw the mcm in my avitar is for Metelcraft motorsports, I'm also the only central Cal. Mendeola dealer. Keep working on it, only experience will prove what works and what don't.

[RockCrusher]

[mcmscott]

I just relized my spelling really sucks! Its MetalcraftMotorsports, not Metel , time for another beer!

[MichaelBrenner]

I have built two SSC transaxles with the 091 1st gear idler and adjust the gear by surface grinding the gear approximately 0.012" to get the proper side gear clearance. On the slider gear I have ground the 1st gear side 0.020". On the most recent transaxle, it won't go into first gear, it just grinds the engagement teeth. I was reading on shoptalk forums that the 091 slider is 0.940" wide and most sliders from a type 1 are 0.980" and that I could just use a 091 slider. Should I grind my slider another 0.020"? On the first transaxle it worked great with just 0.020" ground only.
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Brenner Racing
SNORE 1179