Guest 1SickZ Posted December 15, 2003 Share Posted December 15, 2003 whats the best ratio for the strip ? i was running a 3.7ratio w/ @ 120 mph in the 1/4 went to a 3.9 but added a 2-step whihc gave me a better 60ft actually 2 tenths better but my1/4 mile time was only 1 tenth quicker but @ 118 mph.... whats better stick with 3.9? go back to 3.7? or put this 3.5 that Gad gave me ? 2-step+3.9 gave me 12.1@118 3.7 gave me 120@ 12.2 should i go- 3.7+ 2-step? 3.5 plus 2-step ? Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted December 16, 2003 Share Posted December 16, 2003 I can only give you a seat of the pants opinion.. I tested a 4.11 a 3.9, and a 3.54 all in one afternoon on my turbo car.. Boost was set @ 11 psi, but only in 4th and 5th gears.. the lower gears, it would not hit much above 8-9.... The 4.11 was still in the car from my N/A days.. No matter what I had the boost cranked to.. with the 4.11's I could not reach my desired boost in the lower gears. The car actually got quicker each time we swapped in the next lower ratio. We had a supply of diffs and kept swapping.. My car was fastest with the 3.5.. I finally reached my desired 18psi in 1st gear! with that diff... Turbos like to be under load.... Quote Link to comment Share on other sites More sharing options...
Guest 1SickZ Posted December 16, 2003 Share Posted December 16, 2003 Thanks for your info- i have a 3.54 sitting here but its the old style with the 2 spider gears. the 3.9 in my car is the one with 4 spider gears.. making it a little bit stronger. can i just swap the ring gear out to make it a 3.5 with the 4 spider gears? or do i need to change the frt gear as well ? Quote Link to comment Share on other sites More sharing options...
JKDGabe Posted December 16, 2003 Share Posted December 16, 2003 A lower ratio will almost surely help as it gives more time for the boost to build. Obviously that depends on your individual setup... check out ScottieGNZ's site for what he did and why. Really interesting. Quote Link to comment Share on other sites More sharing options...
Guest 1SickZ Posted December 16, 2003 Share Posted December 16, 2003 Where is his site-? Quote Link to comment Share on other sites More sharing options...
spotfitz Posted December 17, 2003 Share Posted December 17, 2003 http://home.cfl.rr.com/scottiegnz/gnz.html There you go Quote Link to comment Share on other sites More sharing options...
Guest 1SickZ Posted December 17, 2003 Share Posted December 17, 2003 THNX! Any need to re shim it if i take it out and replace ring gear with a 3.54 ? or do i just slap it back together? Quote Link to comment Share on other sites More sharing options...
spotfitz Posted December 17, 2003 Share Posted December 17, 2003 If you switch out the planetary/spiders, you will need to relash it. Quote Link to comment Share on other sites More sharing options...
Guest 1SickZ Posted December 17, 2003 Share Posted December 17, 2003 i'd just be replacing the big ring gear.. thats not considered a spider or planetary is it ? and i can jsut swap the big ring gear to change the ratiop on a r200 right ? the frt pinion gear iss all the same ? Quote Link to comment Share on other sites More sharing options...
Savage42 Posted December 17, 2003 Share Posted December 17, 2003 and i can jsut swap the big ring gear to change the ratiop on a r200 right ? the frt pinion gear iss all the same ? Nope, the ring gear is matched to the pinion gear. You CAN NOT just change the ring gear and call it good. If you could do that, the ring gears would vary in size due to the number of teeth. If you change the ring gear ratio, the pinion gear has to be matched to that specific ratio. Hope that helps. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 17, 2003 Share Posted December 17, 2003 This 2 pinion vs 4 pinion thing came up fairly recently, and I had a question that never got answered. In a Ford 9" Traction Lok LSD, the difference between a 2 pinion and a 4 pinion is that the 4 pinion has a 2nd cross pin, and has the pinion gears and thrust washers in it. The cases are exactly the same. When I worked at a diff parts house, we used to sell the 2nd cross pin and spiders and thrust washers to people rebuilding a 2 pinion unit all the time. If you have a 2 pinion and a 4 pinion LSD, you may want to see if the case is machined for the 2nd cross pin. If it is, switching it to a 4 pinion would be as easy as taking the cross pin and pinion parts from the old unit and putting them into the new unit. Also, Savage is right, but even if the tooth count is the same on the ring gear they are cut differently for the pinion. 3.70 in a R200 is 37:10 and 3.36 is 37:11. The ring gears are not the same!!! The ring and pinion are matched and you need to have both ring and pinion from a matching set. Jon Quote Link to comment Share on other sites More sharing options...
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