Nice link to Supra diff and LSD set up
Posted by john vanlandingham
john vanlandingham John Vanlandingham Godlike Moderator Location: Ford Asylum, Sleezattle, WA Join Date: 12/20/2005 Age: Fossilized Posts: 14,152 Rally Car: Saab 96 V4 |
One of the boys doing a Supra diff into his Xratty sent me this nice link
http://www.supraforums.com/forum/showthread.php?t=430339 covering this I probably have mentioned to all youse guys getting the Supra diff but it's on the Intra-webz so it means its true-er-er than me babbling on the phone. Have a look and bear in mind one thing: the break away torque typically used on gravel cars where folks go fast--ie Sweden and Finland, is typically at least 175 ft/lbs It talks about "crush sleeve eliminator kits" which really is an excellent idea. Now most of us just want to sling the thing in and be done but we gonna pound things and we're on and off the gas constantly and that on-off-on off thing leads to the crush sleeve eventually collapsing microscopically and when it does, the absolutely critical bearing pre-load is lost and pinion position---which is 'spossed to be right down to 1/100th of a mm is also lost. Now they're big strong diffs but if we can kill two birds with one stone----make them MORE reliable and stronger, might be a worthwhile thing to think about... John Vanlandingham Sleezattle, WA, USA Vive le Prole-le-ralliat www.rallyrace.net/jvab CALL +1 206 431-9696 Remember! Pacific Standard Time is 3 hours behind Eastern Standard Time. |
NoCoast Grant Hughes Mega Moderator Location: Whitefish, MT Join Date: 01/11/2006 Age: Midlife Crisis Posts: 6,818 Rally Car: BMW |
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john vanlandingham John Vanlandingham Godlike Moderator Location: Ford Asylum, Sleezattle, WA Join Date: 12/20/2005 Age: Fossilized Posts: 14,152 Rally Car: Saab 96 V4 |
NoCoast Wrote:
------------------------------------------------------- > Nice find for sure!!! > > Some great information there! I have three of > these diffs, at least one of which needs a > complete rebuild. > So am I wrong in thinking that I should shim to > get to 150-175 pounds of breakaway torque then? > > Grant Hughes > www.nocoastmotorsports.net > Denver, CO Not wrong at all. It just take time assembling and dis-assembling a bunch of times cause the values rise very rapidly. John Vanlandingham Sleezattle, WA, USA Vive le Prole-le-ralliat www.rallyrace.net/jvab CALL +1 206 431-9696 Remember! Pacific Standard Time is 3 hours behind Eastern Standard Time. |
Ted Andkilde Ted Andkilde Junior Moderator Location: Windsor, ON, Canada Join Date: 04/30/2006 Age: Possibly Wise Posts: 329 Rally Car: 1968 Mini |
Hmmn, reading all the way through the Supra thread, breakaway torque seems to be limited to 75lbs or so by the spring, regardless of shimming. How do you change that? Swap the spring for a stack of Belleville washers? Custom spring?
Am I right in thinking that lighter car equals less desirability for high breakaway torque? Too much breakaway torque on pavement equals massive, death inducing, understeer? High breakaway torque on gravel makes a diff act primarily like it's locked all the time? Low breakaway torque equals lots of slipping equals mucho heat and quickly worn out friction plates? I see lots of discussion of one-way, one-and-a-half-way, two-way, three-way (wrong site) -- I assume this is referring to LSD action on and off power? ie more locking action with the power on, more "open" with the power off. I imagine this is fairly fundamental but most of the interweb info is "drift" focused and I have a hard time understanding the sideways baseball cap brigades' explanations of how the world works. Cheers, Ted Pure mathematics is the enemy of every truly creative man -- Sir Alec |
john vanlandingham John Vanlandingham Godlike Moderator Location: Ford Asylum, Sleezattle, WA Join Date: 12/20/2005 Age: Fossilized Posts: 14,152 Rally Car: Saab 96 V4 |
Ted Andkilde Wrote:
------------------------------------------------------- > Hmmn, reading all the way through the Supra > thread, breakaway torque seems to be limited to > 75lbs or so by the spring, regardless of shimming. They're wrong. We've shimmed the fuck outta one and breakaway rises VERY rapidly. > How do you change that? Shims, preferably hardened. Swap the spring for a > stack of Belleville washers? Custom spring? Preload the spring. > > Am I right in thinking that lighter car equals > less desirability for high breakaway torque? No. > > Too much breakaway torque on pavement equals > massive, death inducing, understeer? No. If you had studied the Ford Motorsport set up charts you'd see that they increase the stiffness of the diffs hugely on asphalt---front, center and rear. > > High breakaway torque on gravel makes a diff act > primarily like it's locked all the time? Yep, we only need a little bit of differentiation on really tighter than 90, slow corners. Damn near locked--or even welded works fine. > > Low breakaway torque equals lots of slipping > equals mucho heat and quickly worn out friction > plates? The tendency is increased and corn-cidering that most ol' wives tales in 'Merikuh originate from 'Merikun car fans, and corn-cidering most US and jap diffs come set up around 35-45 ft/lbs they differentiate a lot, and that may be where this old story of clutches wearing out originates from. I have the same clutch plates in my Saab diff since 1985 and its seen a couple or three million miles, no problemo-- Breakaway set about 90-100 ft/lbs. > > I see lots of discussion of one-way, > one-and-a-half-way, two-way, three-way (wrong > site) -- I assume this is referring to LSD action > on and off power? ie more locking action with the > power on, more "open" with the power off. I > imagine this is fairly fundamental but most of the > interweb info is "drift" focused and I have a hard > time understanding the sideways baseball cap > brigades' explanations of how the world works. Few understand hopw things work, not surprising their explanations are screwy.. More later. > > Cheers, Ted > > Pure mathematics is the enemy of every truly > creative man -- Sir Alec John Vanlandingham Sleezattle, WA, USA Vive le Prole-le-ralliat www.rallyrace.net/jvab CALL +1 206 431-9696 Remember! Pacific Standard Time is 3 hours behind Eastern Standard Time. |
SgtRauksauff Jorden Junior Moderator Location: Baraboo, Wisconsin, USA, Terra, Sol, Milky Way Join Date: 01/24/2006 Posts: 372 Rally Car: whichever one i happen to be driving at the time |
Interesting.
I'm actually using a crush sleeve eliminator in my Toiletta Commode-a. I didn't have the tools or experience at the time to set my diff up myself, (2-way kaaz, w 4.778:1 gears, for what it's worth), so I had my supplier do it for me, since it's his main business. I've had nothing but good times with it, although none of those have been on non-paved surfaces. I'm not even sure what the breakaway torque on it is, but I'm sure I could find out. --sarge ---** To be in compliance with the Anarchy **--- Jorden R. Kleier Baraboo, Wisconsin, USA 1990 Mazdog Protege 4WD 1973 |
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