Excellent points, Steve. I don’t like the 55# number as it sounds like a SWAG to me. As the temp on the diff changes, so does the lockup…which is dependent on oil, clutch disks, springs, etc. Another rule with good intentions, but generally unenforceable. I would hate to have my diff blueprinted and get to the track and have to spend the money again if the lockup was too great. That does not come under the heading of low buck racing. My .02 Chuck
My not-so-great Ebay Diff...
jlevie
#42
According to Metric Mechanic, break away torque on a stock E30 diff is 55ft-lb. And my understanding is that number is from a cold diff.
leggwork
#43
why can’t you drive a simulated race, or test it after practice or qualifying?
bruce
Steve D wrote:
[quote]OriginalSterm wrote:
Long (fruitless) discussion here:
http://spece30.com/component/option,com_kunena/Itemid,94/func,view/id,37406/catid,16/limit,10/limitstart,10/
Nowhere in the rules does it permit modifying the LSD. If the shop manual prescribes “lockup modification” then it’s fair game.
If the breakaway rule is addressed in the future, it would be nice to add a “cold breakaway” number since the only way to test compliance now is within 30 minutes of a track session. I have a pet peeve about rules for which compliance can’t be tested before hitting the track.
Steve D.[/quote]
leggwork
#44
how much would it cost to get your diff “blueprinted” - is that low buck racing?
As always, the rules committee is very open to suggestions on how to improve the rules.
bruce
cwbaader wrote:
cwbaader
#45
We are racing old diffs…25 to 16 years old. Any of them should probably be inspected and adjusted as a minimum. I respect MM as a builder, but the question is where did they get a new/unused e30 diff to check the break away torque? I hope the number is right, though. Chuck
laz
#46
Moderately off topic: a coupla cars thwarted the diff lock up test here in Norcal by having the nut locking rings in place on their rear wheel hub nuts. The socket on the torque wrench didn’t have enough metal to grab onto, so they were waved through.
rsafreno
#48
Actually it was only one car that the breakaway could not be tested. I got information from an independent party that it was a new diff so we let the car go for now. Since then I have purchased a different socket. I will try it on my car that I am building to see if it will work.
I don’t believe anybody thwarted the check. I believe that most people are trying to comply with the rules (1 exception that we know about).
The breakaway is 65 not 55. Not sure about additives. Most limited slip differentials require a friction modifier or special oil.
Hope to be racing with you guys in August if I can complete my build. Some of it has been a PITA.
L8Apex
#49
Hey Ranger - glad to hear you had better luck with “jose” than I did…
I guess I taught him a lesson about selling diffs with the wrong ratio. I guess I need to check my 19 yr old diff now and see how tight it is. Actually I’m going to start designing my super-secret F1 style variable diff - computer controlled depending on input from the ABS sensors… Muhahahahaha !!!
I really think everyone needs to calm down and enjoy your racing - last time I checked there wasn’t any prize money involved…
jlevie
#50
cwbaader wrote:
Getting a new and unused diff to test isn’t a problem, just expensive. Any dealer can get you one.