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Supra Diff in Xratty - breakaway torque

Posted by jbass 
jbass
James Bass
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Supra Diff in Xratty - breakaway torque
January 30, 2014 08:17AM
So, I have a couple of the Supra 4.3 LSDs now, and I'm going to put one of those kits in to increase breakaway torque. I had a CV joint break, and it showed me how the stock LSD was - uh - not quite as "L" as it should be - i.e. car is completely immobile.

The question comes as to what one would be better? Since we do have to drive this thing on the street for transits (with gravel tires, of course), etc. I'd like it to not be like a spool, but I do want as much power delivery as I can get to gravel/loose surface. I'm not sure how to balance this. Wier sells the 100 ft-lb and 250 ft-lb kits. I'm not exactly sure how this translates into the 'real-world' though. Anyone have any insight as to which one I should get?
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john vanlandingham
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Re: Supra Diff in Xratty - breakaway torque
January 30, 2014 09:45AM
250 ain't bad on street. Done it. You do it



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jbass
James Bass
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Re: Supra Diff in Xratty - breakaway torque
January 30, 2014 09:49AM
Werd. I just found this old post from you as well http://www.rallyanarchy.com/phorum/read.php?5,39551 good shit fasho.
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MarkHille
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Re: Supra Diff in Xratty - breakaway torque
January 30, 2014 01:52PM
I emailed Weir about it a little bit ago and he recommended the 100ft-lb kit because I plan to continue running the tarmac event in NY. If you are just worried about the transits I'm sure the 250ft-lb one should be fine. Are you going to do it yourself or have someone else do the work?
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Re: Supra Diff in Xratty - breakaway torque
January 30, 2014 02:01PM
Dave Kern can talk more about the Weir stuff.
Shims are important. His went from full locker to no locker in short order with the Weir kit and I think it was wrong shims. I don't recall fully though.
Personally I'd go with the 250 lb kit even with running tarmac events.
I mean, you wanna lay stripes right?






Grant Hughes
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john vanlandingham
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Re: Supra Diff in Xratty - breakaway torque
January 30, 2014 03:37PM
Quote
MarkHille
I emailed Weir about it a little bit ago and he recommended the 100ft-lb kit because I plan to continue running the tarmac event in NY. If you are just worried about the transits I'm sure the 250ft-lb one should be fine. Are you going to do it yourself or have someone else do the work?

Wrong.
Look at the VC settings in the Ford stuff. Guys who i know who did both tarmac and gravel said 250 ft/lbs is "normal"..
Those guys were at 175 with FWD cars... YIKES!

I've driven plenty tarmac with a 510 with 4.88 and r180 diff set at around min 250.. Fine no problems.



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MarkHille
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Re: Supra Diff in Xratty - breakaway torque
January 31, 2014 10:39AM
Apparently Spence Weir never watched that video. Haha. I guess my biggest fear is losing the rear at 80+ miles per hour and I’m not sure if a 250lb diff would make that more likely than a 50 or 100lb one. I’ve never broken a cv joint so mine may not move under one wheel power either but it sure doesn’t have any problem spinning both tires. I have some snow tires on it right now and it is incredible how often the tires start howling just by driving around at a halfway decent pace….you don’t even have to try. One thing I am sure of is that I am NOT looking forward to digging into my diff to put in one of the Weir kits. I’m not sure exactly why but it seems like a total pain in the ass. I just put the .80 5th gear into my transmission….what a difference that makes. I highly recommend that if you have 2.95 gears a 4.3 diff and ever want to go faster than 80mph.
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john vanlandingham
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Re: Supra Diff in Xratty - breakaway torque
January 31, 2014 12:14PM
Quote
MarkHille
I just put the .80 5th gear into my transmission….what a difference that makes. I highly recommend that if you have 2.95 gears a 4.3 diff and ever want to go faster than 80mph.

Talked with your co-driver last night and suggested you clarify exactly what broke, now I see its CV. He said it was new. New? Or "reman" new? Can you tell if it was cage?
I wonder if Sean or the New and Improved Dave Clark have busted any?
All the cool kids in Merkuuuur Sprout with their pisser wicked powerful Xratties do "countless passes" drag racing and their don't seem to break them in their awesome auto-cross cars driving for a gruelling minute and 40 seconds...
And I never had a problem in the 330 Bee Haitch Peas 4x4 which uses US sized CV and axles.
Anomaly maybe?

As for gearing 4.3 and a 1:1 gear---like 4th is---+65cm tire will get you 18mph per 1000 rpm so 7000 gives 123mph......123mph seems pretty fast to me.
80mph should be 4444.4 rpm

Youse saying you set up----un-turboed turbo car that you're being compelled to use won't do more than 4444rpm?

Sumpin is zup.



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Re: Supra Diff in Xratty - breakaway torque
January 31, 2014 02:00PM
Quote
john vanlandingham
As for gearing 4.3 and a 1:1 gear---like 4th is---+65cm tire will get you 18mph per 1000 rpm so 7000 gives 123mph......123mph seems pretty fast to me.
Sumpin is zup.

My car wouldn't really rev past around 5500-6000 RPMs in 4th gear. With the .68 final shifting into 5th just dropped speed unless I was going downhill and with the wind.



Grant Hughes
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MarkHille
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Re: Supra Diff in Xratty - breakaway torque
January 31, 2014 02:13PM
Weird, when I put a 65cm tire, a 1.1 gear, and a 4.3 diff ratio into the mfactory speed calculator at 5000rpms it is going exactly 80mph. Which seems to translate into real life but maybe I’m wrong. Yes, because I’m using a ranger roller cam it really and I mean really doesn’t like to rev past 5000rpm in 4th gear even with the cam retarded so yes that might be my whole problem. But when I switch to a smaller profile tire for the tarmac stuff it makes it even worse. The average speed for the winner of the ESPR in 2013 was 78.8mph. His average speed was almost as fast as I could get my car to go. Haha. I am new and don’t know what I’m doing so rather than going down the straightaway at 80 thinking “I’m really not going any faster in 4th maybe I should shift to 5th…. Wait, now I think I’m actually slowing down, should I down shift.....wait was this a left or a right….should I brake yet….I’m gonna downshift….” I can think “I’m going to shift to 5th and focus when I should start braking…” haha. I did have a couple of moments like that at my only gravel event, less than the tarmac for sure, but maybe it is just me. Just trying to add positive information is all. It is my opinion that the .68 gear is totally useless.

At BRS I think it was Bombara who was like “I hit 127 (or something pretty high) mph on that last stage….” I went and looked at my gps...78mph. I laughed.

Oh, and I don't think 7000rpms on a stock block is a reality. 6500 is probably too much and thats just over 100mph.
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john vanlandingham
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Re: Supra Diff in Xratty - breakaway torque
January 31, 2014 02:18PM
My buddy down the street went to a DYNO-DAY and there got a printo that confirmed both our impressions that his POS would flatten out bad at 4600.
Dyno read out said "so solly lound eye, no more levs " at 4600..

Later when he popped a headgasket I got him NEW valvesprings...seems to rev past 6 then..


Boys sumpin is up if they won't do a simple 6500.

And the link just confirmed what I did with my ancient paper printing $4 Boeing Surplus adding machine. 123mph with 65cm, 4.3 and 1:1

Anybody want to buy a YB? Mine revs past 7500 easily---yeeee HAWWWW!



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jbass
James Bass
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Re: Supra Diff in Xratty - breakaway torque
January 31, 2014 02:36PM
Quote
john vanlandingham
Talked with your co-driver last night and suggested you clarify exactly what broke, now I see its CV. He said it was new. New? Or "reman" new? Can you tell if it was cage?
That musta been mine smiling smiley He's a Suba-rooin' type.

As for the halfshaft, I took it off (It is new, new - made with the larger inner CV), and found the out-board CV on the drivers side "popped" the hub through the cage part (hub still firmly attached to the shaft, circlip still on, etc.) - such that the shaft itself could be turned freely (the 'hub' was past the balls - balls were still in the 'cage').

Not quite sure how it happened, I mean - I know with absolute certainty I put the longer shaft (woah) on the passenger (right) side. Really not sure about how the eff that happened. The car was under zero power (it's N/A right now anyway, but I wasn't even 'getting on it') - and no "yumps" or anything - just a gear change, and "vroooOOOOM" - no power delivery.

I slapped the old ones back on we used in Perryville- and I'm going to tool around and see if those have issues (they didn't before). Not sure if there was a mis-assembly of the halfshaft, doofus installer issues, or-?

Mark- I'm probably going to do the breakaway kit/crush eliminator install myself - although, I'd rather have someone do it winking smiley
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john vanlandingham
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Re: Supra Diff in Xratty - breakaway torque
January 31, 2014 02:50PM
Oh shit, you sure you have the Left and Right right?
Remember, you aren't right if you aren't Left!

L and R are different.

The breakawy you CAN easily do. The specer I think you can--you're sharp and if you have a decnt mike you for sure can. Read here (till you go cross-eyed!)http://www.gearinstalls.com/



John Vanlandingham
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jbass
James Bass
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Re: Supra Diff in Xratty - breakaway torque
January 31, 2014 04:17PM
Quote
john vanlandingham
Oh shit, you sure you have the Left and Right right?
Remember, you aren't right if you aren't Left!

L and R are different.

Longer on right, right?
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john vanlandingham
John Vanlandingham
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Re: Supra Diff in Xratty - breakaway torque
January 31, 2014 08:00PM
Quote
jbass
Quote
john vanlandingham
Oh shit, you sure you have the Left and Right right?
Remember, you aren't right if you aren't Left!

L and R are different.

Longer on right, right?

Right and left is only dependant on where you're viewing from. Always confusion. Driver and Passenger is unmistakeable.. And I can't remember which is the slightly longer.... we better find out.. I'll send a note to Tony W in Chicago who has just been measuring cause he's making some custom stuff for his 500hp Duratech or Echo-Bewst thang.



John Vanlandingham
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CALL +1 206 431-9696
Remember! Pacific Standard Time
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