rear end questions

[gjp]

Now I am back home and so is my sy its time to fix it again. last summer I was street racing. (made 2k in a weekend) and the last race the sy started to slip bad off the line. I know it cant be the trans foward. It would slip before the build but I thought it was the trans. After the build it felt fine. One night I decited to do some street racing. Sorry guys no camera but I tore appart a 2007 351 saleen, a few hondas, 2003 z06 and I lost to a 600hp sti. I raced a 67 camaro with a big block and blower. that race something let go. only things left stock is the transfer case and rear diff. The rear diff needs a fluid change anyways. What fluid do I use. I thought it was the same as the front diff with an additive? I have 3 quarts left over from the rebuild. under normal driving truck is fine. under wot it will tac out first for a seccond then grab and launch. I am lost again. Oh, and hi to everyone. I missed it on here. I had a horable year but I feel great now.

 

[Tooky]

Re: rear end questions

Post your DM file or a pic, the RPM graph will show, if you can compare to how it "used to shift".. When my trans started slipping it would not drop nearly as much RPM on the 90* drops in RPM after an upshift.

 

[turbodig]

Re: rear end questions

Post your DM file or a pic, the RPM graph will show, if you can compare to how it "used to shift".. When my trans started slipping it would not drop nearly as much RPM on the 90* drops in RPM after an upshift.

x2. Also, the shift peaks themselves will be more rounded, with less of a point.

 

[EcSy#2671]

Re: rear end questions

Great to see you back!!:tup:

 

[George Blake]

Re: rear end questions

If anyone that lives around Gary can take a look at it with him, that would be a huge help. Just to help, back when he had his 700r, it behaved this way. Did the 4L80e---same issue remained. So it's not in the trans. It got a new front prop, rear driveshaft redone, new converter and trans. Transfer case, rear end, front end, all of that is the same. I'm wondering if the viscous in the transfer case could be an issue on this? The input shaft for the t-case goes into the planetary. Planetary sets in a ring gear that is meshed to the viscous. So the viscous splits the power. I've got them if you want to try to put in a new viscous, but they are expensive about $380.00. Is it possible at all that you could be spinning the tires? I hate to sound stupid but if the tires broke loose, you'd get an rpm surge.
I don't know as much on the engine side, but is there a possibilty that a bad IAC could make rpm surges? It's just weird that it was there before, swapped the entire transmission to a completely different style and the problem remained. It's as if whatever it was finally let go.

 

[George Blake]

Re: rear end questions

Now, one other thing you may try. Is to lower your WOT 1-2 shift rpm by a couple hundred rpm. What may be happening is that your beyond your power range and it's revving but not making more power so it quits pulling then you finally get the rpm it needs for shift and then "grabs hard" onto 2nd. This wouldn't require you getting dirty, just need a laptop.