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| straight cut gear sets, which is best https://ausmini.com/forums/viewtopic.php?f=5&t=71801 |
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| Author: | meeni [ Mon Jul 11, 2011 8:32 pm ] |
| Post subject: | straight cut gear sets, which is best |
this is a bit of a continuation from my other post but on the gearbox side of things, what are peoples experiences with straight cut gear sets? which have you found to be the best of the non race type ones ie, not the $2000 dog engagement things but the clubman kit that med sells vs say minisport uk etc. how long have they been going for in your gearbox, any things i should look out for etc. its a big investment for me and i dont want to make the wrong choice cheers sean |
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| Author: | bill.b [ Mon Jul 11, 2011 9:35 pm ] |
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just bought a set of S/C drop gears from mini sport, ill let you know how they go when i drop the engine back in next week. Bill |
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| Author: | 74snail [ Mon Jul 11, 2011 9:58 pm ] |
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Some people prefer the helical gear sets to the square cut, get a message to David Rosenthal he can explain . |
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| Author: | SuperCooper [ Mon Jul 11, 2011 11:08 pm ] |
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I just bought a SCCR gearset for a 4 synchro remote box (MKII S) from Min-its in the UK. same set as Guessworks sell - also UK . 330 gbp. Have not installed them yet. They are ST ratios so am going to install a 3.7 or 3.9 diff. Also arrived today was a 4 pin diff and gbox rebuild kit from Guessworks. 
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| Author: | simon k [ Mon Jul 11, 2011 11:15 pm ] |
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there have been a few good explanations of why straight cut gears don't handle lots of torque as well as helical gears... I believe race cars like straight cuts because they don't rob as much power |
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| Author: | SuperCooper [ Mon Jul 11, 2011 11:22 pm ] |
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The Ratio of 1 st gear is almost a normal 2nd gear , then 2nd, 3rd and 4th are closer together. Hence why you use a 3.7 or 3.9 or 4.1 diff to get it off the line. Ratios are: 2.544, 1.731, 1.258, 1.0 - ST ratios |
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| Author: | meeni [ Mon Jul 11, 2011 11:49 pm ] |
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im happy to bet theyre better then hellical gears that are 50 years old. what sort of freeway rpm are you expecting with a diff ratio like that? |
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| Author: | SuperCooper [ Tue Jul 12, 2011 12:10 am ] |
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Use this; http://www.guess-works.com/Tech/ratio.htm I am setting car up for hillclimbs and some track work. |
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| Author: | TK [ Tue Jul 12, 2011 3:24 pm ] |
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Sean PM Dave P at sitnlo62. His advice re; straight cuts could be usefull. 
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| Author: | meeni [ Fri Jul 15, 2011 7:14 pm ] |
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ok just bought a gear set, its called a clubman type which is a fancy word for poverty spec what it means is it retains the original first and reverse gears being already straight cut, does this mean il maintain an easy get away from the lights with the first gear not changing? heres the info from the website The 1st gear and reverse idler from the original gearbox are retained making this kit more affordable to some than the full 6 piece SCCR gearset. This kit produces the following 1st thru' 4th ratios 2.583 1.711 1.250 1.000 if it means il have a nicer takeoff that would be good cos im planning on running a fairly tall diff because everywhere from sunbury requires a freeway trip |
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| Author: | drmini in aust [ Fri Jul 15, 2011 7:27 pm ] |
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1st gear on a Mk2 S helical box is 3.3:1, so yeah it's taller, but IMO not too tall. I'd try it with a 3.44 diff....
[edit] typo |
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| Author: | justminis [ Fri Jul 15, 2011 7:47 pm ] |
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Sean I run the Clubman gearsets in my race motors, have done for nearly 10 years, no problems, they are a good set. 1st gear will be OK with 3.44 if the cam isn't too big. Thing to be aware of tho, that gearset uses A+ layshaft, the 3 step one. To fit to a non A+ gear case, need to modify either the case or the layshaft to fit. The thicker layshaft doesn't protrude thru the web far enough for the lock plate to engage. I machine the 3rd step back to allow it to fit, needs to be done on a crank grinder as very hard. Relieving the case is also OK. Need to use the A+ laygear thrust washer too. |
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| Author: | meeni [ Fri Jul 15, 2011 8:07 pm ] |
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oh ok, you havnt got a photo of what your talking about do you? |
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| Author: | justminis [ Fri Jul 15, 2011 8:23 pm ] |
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No, sorry I don't. Here is a link to an article written by Keith Calver where it explains it too, down the bottom. http://www.minispares.com/Articles.aspx?ty=ad&aid=114 I should have also mentioned that you need an A+ mainshaft too. Or have Kev mod an A mainshaft to suit A+ 1st motion shaft. If you fit an A+ layshaft to a pre A+ gearbox case you will see what needs to happen. The end of the layshaft won't protrude thru the web far enough for the lock plate to engage. |
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| Author: | drmini in aust [ Fri Jul 15, 2011 9:26 pm ] |
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Repaired A series mainshaft (14mm nose bearing inner roller bearing ring fitted) http://home.exetel.com.au/zoomini/zoomi ... GP2113.JPG A series mainshaft modified to suit A+ (18mm nose bearing ring, the 2nd diameter from RH end): http://home.exetel.com.au/zoomini/zoomi ... GP1472.JPG A+ shaft is shorter than A series, but I didn't cut the original end off the shaft in case the existing centre is needed. It clears the case anyway. |
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