 904 mainshafts, Anyone interested in repros? |
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| ME733 |
 Dec 12 2009, 11:12 AM
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#21
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Senior Member  Group: Members Posts: 842 Joined: 25-June 08 From: Atlanta Ga. Member No.: 9,209 Region Association: South East States  |
... (IMG:style_emoticons/default/popcorn[1].gif) ...Racer chris, Dr. Evil., Jp stein,R towel,Brant,and others....This is a very intresting Post I hope it continues into some detail ..such as what gears/ ratios would be suitable ...for...street use...autocrossing...and road racing/ D.E. track days......there are plenty of gear charts available (thanks Dr,evil) and others...but as J.P.Stein pointed out, FINDING some of the gears can be difficult/impossable. From experience I am not a fan of aftermarket gears. they are usually not properly HEAT TREATED to about 58/59 on the rockwell "c" scale. I had numerious "reproductions" break.(not 901 transmissions). I WOULD LIKE TO PURCHASE A LARGE SIZE (poster size) 901 914 transmission blueprint/ diagram, or something of quality/ detail that could be blown up. From what LITTLE I know about the existing possibilities for regearing , removing and welding on a different 2nd gear seems to be the most cost effective. It also seems to be a reliable way to go. However if a mainshaft were made / remachined which would allow interchangable 2nd / 3rd gears in 2nd gear position that may be a better option for some people. I think that both of you should be concerned about quality. welding on the mainshaft may aneal the shaft and gear. It may require rehardning to get back to O.E.M. specs. Making a new shaft will require a hardning process. both process will require quality control on strightness. I think what you guys want to do is great and needed. (IMG:style_emoticons/default/popcorn[1].gif)
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| ChrisFoley |
Dec 12 2009, 01:21 PM
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#22
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I am Tangerine Racing Group: Members Posts: 7,937 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None 
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QUOTE(ME733 @ Dec 12 2009, 12:12 PM)  I think that both of you should be concerned about quality. welding on the mainshaft may aneal the shaft and gear. It may require rehardning to get back to O.E.M. specs. I'm way ahead-a ya... (IMG:style_emoticons/default/smile.gif) I make sure that I am not heating the gear teeth or the shaft core enough to soften them. As I mentioned before, the material is prone to hot cracking when the gear is welded on - so going slowly, keeping heat input to a minimum, and making sure the weld endpoints are properly filled is of utmost importance. I did repair and assembly welding for machine shops for years so I have plenty of experience with hard-to-weld alloys, highly restrained weld joints and precision build-up for re-machining. This stuff isn't that difficult, it just takes time. (IMG:style_emoticons/default/welder.gif) |
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| brant |
Dec 12 2009, 07:25 PM
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#23
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914 Wizard Group: Members Posts: 11,641 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains 
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QUOTE(Racer Chris @ Dec 12 2009, 08:23 AM) Rich, I don't think a gear specialty machine shop is necessary. All I need is a good precision machinist to do the preliminary cut to establish the minor diameter, and a final cut for the shoulder. The shop I've used locally for the previous shafts I've modded is perfect for this. In fact I will be seeing them soon for a little ski shooting. (IMG:style_emoticons/default/smile.gif) Maybe I should plan on bringing them several mainshafts to get the ball rolling. Dave P, I read Grady's article before I started my first shaft mod and decided to go one better by building up half of the splines before welding the gear in place. I think this method should handle more than the 200hp limit Brant mentioned. the 200hp rule is because of the active first gear with the "F" installed on it and hanging on the back end of the intermediate plate... Were using 1st gear in slow corners at full throttle. So the 200hp rule is about 1st gear. The 2nd gear portion of the re-splined main shaft is not the weak point. |
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| J P Stein |
Dec 13 2009, 12:03 PM
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#24
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Irrelevant old fart Group: Members Posts: 8,797 Joined: 30-December 02 From: Vancouver, WA Member No.: 45 Region Association: None |
Mine was/is a specialty box. ....tain't worth spit for other than AX and has modified to be prolly the only one in existance. I no longer own the car so it ain't my prerogative to tell you what is in there. IF IT WORKS we'll call it the Donahue box. (IMG:style_emoticons/default/biggrin.gif)
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| ME733 |
Dec 13 2009, 05:32 PM
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#25
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Senior Member Group: Members Posts: 842 Joined: 25-June 08 From: Atlanta Ga. Member No.: 9,209 Region Association: South East States |
(IMG:style_emoticons/default/popcorn[1].gif) ...J.P.STEIN...I think you are ...(not)...suggesting....that ...HEWLAND stright cut , dog tooth, gears, ...available in numerious ratios,..and a lot cheaper than some of the porsche special gears...will fit the 901 mainshaft.....Oh probably not, or maybe, or lets keep wondering. (IMG:style_emoticons/default/popcorn[1].gif)
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| J P Stein |
Dec 14 2009, 07:46 AM
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#26
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Irrelevant old fart Group: Members Posts: 8,797 Joined: 30-December 02 From: Vancouver, WA Member No.: 45 Region Association: None |
QUOTE(ME733 @ Dec 13 2009, 03:32 PM) (IMG:style_emoticons/default/popcorn[1].gif) ...J.P.STEIN...I think you are ...(not)...suggesting....that ...HEWLAND stright cut , dog tooth, gears, ...available in numerious ratios,..and a lot cheaper than some of the porsche special gears...will fit the 901 mainshaft.....Oh probably not, or maybe, or lets keep wondering. (IMG:style_emoticons/default/popcorn[1].gif) No, it's a 914 box.....a CSOB special. |
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| ChrisFoley |
Dec 30 2009, 02:20 AM
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#27
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I am Tangerine Racing Group: Members Posts: 7,937 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None
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Last week I dropped off 4 mainshafts at my machinist (at their Christmas party) after grinding off the F gear teeth.
Today we discussed options for securing the removable gear and came up with a workable solution. In order to retain the removable 2nd gear we plan to use a thin hardened washer between the gear and the intermediate plate bearing inner race. This will require moving the gear forward on the shaft slightly to create clearance for the washer. A small misalignment of the two gears in the 2nd gear pair shouldn't cause any problem. The rear side of the retaining washer will be at the same position as the existing shoulder that the bearing race presses against so the overall position of the shaft will remain the same. |
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| J P Stein |
Dec 30 2009, 10:20 AM
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#28
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Irrelevant old fart Group: Members Posts: 8,797 Joined: 30-December 02 From: Vancouver, WA Member No.: 45 Region Association: None |
Now I can show a pic of the CSOB special trans. It's rather specialized. (IMG:style_emoticons/default/blink.gif)
10-12lbs of rotating mass has been eliminated. Attached image(s) 
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| McMark |
Dec 30 2009, 11:18 AM
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#29
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
That's RAD, JP. (IMG:style_emoticons/default/smiley_notworthy.gif)
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| Dr Evil |
Dec 30 2009, 11:28 AM
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#30
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Send me your transmission! Group: Members Posts: 23,002 Joined: 21-November 03 From: Loveland, OH 45140 Member No.: 1,372 Region Association: MidAtlantic Region
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Pretty cool (IMG:style_emoticons/default/thumb3d.gif)
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| J P Stein |
Dec 31 2009, 10:33 AM
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#31
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Irrelevant old fart Group: Members Posts: 8,797 Joined: 30-December 02 From: Vancouver, WA Member No.: 45 Region Association: None |
We ran it for a season with all the gears intact but locked out as a "proof of concept". As it now sits there were some more mods that we were quite a bit more work than we were willing to do if "things" didn't work out...like, is there enough motor to pull that F gear off the line in an expeditious manner? Will we find a course that we run out of 3rd gear? No problem....onward. It is still easy to return to a 5 speed.
Autocross is still a place that you can let your imagination run wild.....unlike too many other forms of motor sports. In this case we've stripped the car to the bare essentials needed to get it to the other end of the course. |
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| ChrisFoley |
Mar 2 2010, 05:02 PM
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#32
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I am Tangerine Racing Group: Members Posts: 7,937 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None
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QUOTE(Racer Chris @ Dec 30 2009, 03:20 AM) Last week I dropped off 4 mainshafts at my machinist (at their Christmas party) after grinding off the F gear teeth. Last week I got the 4 mainshafts back from my machinist. Next step is to build up the splines.   Thats a stock 3rd gear in the picture. The sleeve is a spacer from a 914 trans. It still needed to be machined to length when I took that picture a couple weeks ago. Not shown is the thin washer that goes between the bearing and the gear. |
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