dat2kman Posted October 4, 2011 Posted October 4, 2011 Ratio change on 2nd to 3rd sift will still give you a lot of rpm drop, thus "falling" off your cams torque peak. Sorry Greg, only way to fix it is a close ratio gear set, which will eliminate the rpm drops, unless you don't mind revving the tits off it at 9000 rpm! I'm doing two boxes at moment with these cr sets, and will have one for sale soonish, and no don't want swaps for a 80 series Landcruiser!!!! The original early 260 box with 2.9 first gear will be better, it has same ratios as 240z and Datsun Sports 3 piece boxes Quote
Luni260z Posted October 4, 2011 Posted October 4, 2011 If you go to another diff .. .please for the love of luni, donate that diff. My auto diff is a turd. Quote
PZG302 Posted October 4, 2011 Posted October 4, 2011 Greg, I will know in the next week or so if I will have one of the early 260 boxes for sale. Just waiting to hear if the car goes as a whole or not. Plus for a little extra, my fresh race motor will also be available for you...... Quote
bluerat Posted October 5, 2011 Posted October 5, 2011 Hey Pal, Dial it all into Gearcalc (google it..) I did it for mine, early 260z box as above with 16x225 tyres and a 4.4 diff. If your a softy and change at 6500 it will drop back to 4480 rpm, or a bit more game and shift at 7500, it will drop back to 5170rpm. Your typical 3 gear Hollinger or Albins modded box is approx 500rpm better.. I just did my Option 1 and at 6500 it drops back to 4843 rpm and 5588rpm if you shift at 7500. Mind you it's the same as a 4 speed with an extra gear, if that makes sense? Best value Datsun close ratio box is the mighty 240k 4 speed, if you can find one and your road miles are on a trailer. Hodgo Quote
bluerat Posted October 7, 2011 Posted October 7, 2011 Did I say something wrong? What I should of asked, was It falling off the cam? or just dropping lower in the rpm range than the other shifts? and was the engine pulling cleanly back into the upper rpm range. Sometimes that taller 3rd gear can be handy, being able to hold 3rd longer between corners rather than having to grab 4th. Gearing can be tricky for hillclimbing as you want max acelleration, but minimal time wasting gear changes I navigated for a good mate of mine in his Zed back in 2001, with the same gearbox and 4.4 diff as above and clearly remember thinking how well the torque of the 6cyl handled the 2nd the 3rd jump, no real gap. I also recently watched some video footage of the same car at our local hillclimb thinking the same thing, hence trying the same set up straight up in mine. If you were trying to competitive in class A with an L16 I would give you different advice but with a grunty, flexable L28 I would of thought a 4.4 would work very well enough with a 260 or 280Z box? If your still having problems, or feel that it is effecing your times, the cheapest way is to try a 4.8 R180. I noticed that's what PZG said he ran at hillclimbs and they are easy to find, If you were in Tassie I'd would be happy to lend you one. Your 100% right when you say...Horsepower fixes everything... Quote
PZG302 Posted October 8, 2011 Posted October 8, 2011 Greg, it's only a couple of hours to change the diff. I may have a locked 4.8:1 diff to match the gearbox soon up for sale. Quote
dat2kman Posted October 8, 2011 Posted October 8, 2011 Few hours? Ppfffttt it can be done in 15 minutes, gearboxes swapped in 30, mind though, this is done in the dirt on the side of a road on a rally somewhere! Quote
PZG302 Posted October 9, 2011 Posted October 9, 2011 Few hours? Ppfffttt it can be done in 15 minutes, gearboxes swapped in 30, mind though, this is done in the dirt on the side of a road on a rally somewhere! Jason, I was including time required to keep the throat from getting parched with the sacred amber beverage of my choice. Quote
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