John Coffey Posted January 11, 2016 Share #49 Posted January 11, 2016 Of course there's always this option - John Jeffries brought it to my attention.http://www.eliteracingtransmissions.com/products/datsun-240z-dog-gear-kit/ Link to comment https://www.classiczcars.com/topic/53047-black-fiber-synchros-on-all-5-gears/?page=5#findComment-484408 Share on other sites More sharing options...
Zed Head Posted January 12, 2016 Share #50 Posted January 12, 2016 (edited) Thanks for adding. Hope I'm not blowing up biodi's thread. It looks like the servo synchro problem has been confusing people for many years. Found another old thread that suggests improper fluid can cause problems. SWEPCO raises its head again, JMortensen's favorite from his Porsche days. Maybe the Redline MT90 isn't the best for this transmission? Who knows. http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=508611 p.s. I think that baulk essentially means "stop", which is what the rings do in a relative way. So both servo and borg warner style should both be baulk rings. People seem to be using "baulk" to differentiate. Anther confusion. Edited January 12, 2016 by Zed Head Link to comment https://www.classiczcars.com/topic/53047-black-fiber-synchros-on-all-5-gears/?page=5#findComment-484411 Share on other sites More sharing options...
John Coffey Posted January 12, 2016 Share #51 Posted January 12, 2016 (edited) Swepco 201 is the gold juice in the Porsche world for the 901 and 915 transmissions. In short order it ruined the synchros in my Nissan 4 speed after a day of racing at PIR. Edited January 12, 2016 by John Coffey Link to comment https://www.classiczcars.com/topic/53047-black-fiber-synchros-on-all-5-gears/?page=5#findComment-484412 Share on other sites More sharing options...
Chickenman Posted January 12, 2016 Share #52 Posted January 12, 2016 Just to clarify John , would that would have been Brass synchros in your 4 speed that the Swepco ruined? Not Porsche type steel synchros? Link to comment https://www.classiczcars.com/topic/53047-black-fiber-synchros-on-all-5-gears/?page=5#findComment-484432 Share on other sites More sharing options...
blodi Posted January 12, 2016 Author Share #53 Posted January 12, 2016 (edited) Any info on the fluid is good. I think the Redline MT-90 is what may have caused my steel 2nd gear synchro to fail so quickly. Mine are definitely the servo style synchro as shown here on the right vs the warner style on the left... Ok, so the trans guy counted the teeth on the gears....this is super confusing..... 1st- 33 Main 19 Counter=2.357 2nd- 28 Main 19 Counter=1.473 3rd- 26 Main 28 Counter=.928 4th- 22 Main 31 Counter=.710 5th- 19 Main 31 Counter=.613 This makes for really odd ratios that don't match up to anything I see listed. What am I missing? Cause this would mean 4th and 5th are both overdrive. I know that isn't right. The car wasn't that "long legged" when driving it. At 70 it was turning 3.5k in 5th on the highway. Edited January 12, 2016 by blodi Link to comment https://www.classiczcars.com/topic/53047-black-fiber-synchros-on-all-5-gears/?page=5#findComment-484452 Share on other sites More sharing options...
blodi Posted January 12, 2016 Author Share #54 Posted January 12, 2016 Ok, if I assume 4th is 1:1 and divide 1 by .710....then multiply the other ratios by that 1.4xxxx figure....the ratios fall into place and it's a wide ratio.... 32010-N3030 3.321 2.077 1.308 1.000 0.864 (wide ratio) Link to comment https://www.classiczcars.com/topic/53047-black-fiber-synchros-on-all-5-gears/?page=5#findComment-484457 Share on other sites More sharing options...
Zed Head Posted January 12, 2016 Share #55 Posted January 12, 2016 Weird. Plain old 77-78 ratios but with steel servo type synchros. What do you do with that? Link to comment https://www.classiczcars.com/topic/53047-black-fiber-synchros-on-all-5-gears/?page=5#findComment-484460 Share on other sites More sharing options...
blodi Posted January 12, 2016 Author Share #56 Posted January 12, 2016 (edited) Yeah...I mean, that looks like it was one of the options with the comp boxes.... http://www.zhome.com/ZCMnL/tech/GearRatios.html I think I'm just gonna keep this trans and save myself the headache of trying to sell it and find another, rebuild that one...etc... I doubt with the wide ratios it's too valuable to vintage racers. But, I still need to find a synchro ring that works. Edited January 12, 2016 by blodi Link to comment https://www.classiczcars.com/topic/53047-black-fiber-synchros-on-all-5-gears/?page=5#findComment-484461 Share on other sites More sharing options...
Chickenman Posted January 12, 2016 Share #57 Posted January 12, 2016 (edited) I don't think your Mechanic counted the constant mesh gearing ( Main drive gear) from the Input shaft to the Countershaft. Count those gears and you will probably find that the ratio works out to be 1.408xxx. Countershaft will always be rotating at 1.408 ( or whatever the ratio works out to be ) times the speed of the Input shaft. So that figure has to be multiplied across all the gear Teeth count for 1st through 5th. I'd double check all his teeth count and go from there. Edited January 12, 2016 by Chickenman Link to comment https://www.classiczcars.com/topic/53047-black-fiber-synchros-on-all-5-gears/?page=5#findComment-484463 Share on other sites More sharing options...
Chickenman Posted January 12, 2016 Share #58 Posted January 12, 2016 This picture of a FS5W71 should make it a bit clearer. Gear on Input shaft #15 drives Constant mesh gear #45 on counter-shaft. Countershaft can be at 1 to 1 ratio of mainshaft, under-driven or over driven, depending on design criteria. On most transmissions, the Countershaft is over driven so that mainshaft gears are smaller in diameter. That means less weight and less inertia to spin them up when Synchro's are engaged by sliding coupler. Link to comment https://www.classiczcars.com/topic/53047-black-fiber-synchros-on-all-5-gears/?page=5#findComment-484468 Share on other sites More sharing options...
blodi Posted January 12, 2016 Author Share #59 Posted January 12, 2016 Gotcha, yeah, that makes sense now. So for the Porsche synchro rings...sounds like there are two possible sizes...I'll have him measure mine today... http://forums.pelicanparts.com/4279865-post6.html The Porsche patent syncros are VERY sensitive to the installed size you are looking for. Additionally they must be used with the Porsche sliding sleeve and the Porsche engagement dog ring splined onto the free gear. These are sufficiently sensitive that in some cases, simply turning over a slightly worn syncro can prevent proper shifting. Needless to say you must use the Porsche stops and bands Even the side clearance from the circlip is important. There are two basic sizes: the 87.1 and 88.1 mm ones used on the 1st and 2nd gears of a 915 and the 78.0 mm ones used on the 3-4-5 gears of a 915 and all 901/911/914 gears. These are “free” dimensions with the syncro ring not installed on the gear. Acceptable diameters for installed syncros are in the range of 86.20- 86.25 mm for the large 915 1-2 syncros. This is with the syncro ring bottomed under the engagement dogs and the side clearance between the syncro ring and the circlip. Porsche specifies 86.20 mm to 86.54 mm. Normal diameters are about 76.25-76.35 mm for all the others with Porsche specification 76.12 mm to 76.48 mm. How is this Alfa retrofit accomplished? Does it use the Porsche hub for the sliding sleeve? How is it splined onto the shaft? How is the engagement dog ring attached to the free gear? Does the shift fork properly fit the sliding sleeve (side clearance spec is ? How much of the shift fork engages the circumference of the sliding sleeve? Porsche uses about 180º while some other manufacturers only use 30º or so. Best, Grady Link to comment https://www.classiczcars.com/topic/53047-black-fiber-synchros-on-all-5-gears/?page=5#findComment-484469 Share on other sites More sharing options...
Zed Head Posted January 12, 2016 Share #60 Posted January 12, 2016 Worst case, use the front case to make a more modern transmission. Sell the servo synchro parts to the racers out there that are also in your boat. http://zhome.com/ZCMnL/tech/240SX5spd/transmission.htm Link to comment https://www.classiczcars.com/topic/53047-black-fiber-synchros-on-all-5-gears/?page=5#findComment-484470 Share on other sites More sharing options...
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