New PB but problems with rear end

[12OKGT]

I've been lurking a while and don't post much, but I got my car out to the track Friday night. Car is a M6 with 3.73's, offroad X-pipe, AED tune, and DSS driveshaft. I was running on 28x10.5 Hoosier drag slicks mounted on 15x8 Weld RTS wheels, stock 19" brembo front wheels. I ran a 11.84 @ 117.79mph with a 1.67 60'.

The problem I have encountered, is after the track, my rear end is howling like crazy, on acceleration and deceleration. Before I had the normal slight whine on decel, but now it is about 10 times worse... This happened to me the last time I had the car out at the track, but I was stock and was able to get it warrantied, and they replaced my gear set and bearings. So the only two times I've had it at the track, this has happened. I know launching at 5000-5500 isn't easy on the rear end, but am a little surprised this keeps happening. Any ideas?

Here is my attempt at posting my video. Burnout was weak because I was hooking so good if I did a long one I would bog down really bad...
[youtube_browser]dr09w9ud5qI[/youtube_browser]

 

[stangn]

There are many post on the 8.8 being a problem. Hit the search bar.

 

[12OKGT]

There are many post on the 8.8 being a problem. Hit the search bar.

I've seen the posts with people breaking their spider gears in their limited slips and stuff like that, I'm just kind of stumped because I'm not actually breaking anything necessarily, it's just like something is coming out of spec causing it to whine. I'm mainly just trying to figure out how to strengthen it. It doesn't seem like it is my limited slip, so switching to different style differential like a truetrac wouldn't help me would it?

 

[toomnymods]

Did you find out anything more on this? This same issue happened to me and I've had to get my rear end warrantied as well. took them 3 weeks to fix. Kinda reluctant to go back to the track again till I know what I can do..

 

[toomnymods]

forgot to subscribe..

 

[Elwood617]

Repeated hard launches with drag tires causes a lot of flex in the rear end. Have you braced your rear end at all?
Cool video, that was at 5000 rpm?

 

[grnenvy]

True trac and some new gears should fix it. Just make sure u use someone that knows what there doing or it will make noise again.

 

[12OKGT]

Did you find out anything more on this? This same issue happened to me and I've had to get my rear end warrantied as well. took them 3 weeks to fix. Kinda reluctant to go back to the track again till I know what I can do..

No, haven't had time to work on the car lately. Took them a while to fix mine as well the first time when I had it warrantied, they weren't in much hurry.

 

[stang8psi]

Sure its not the trans? I know on hard launches the trans gets imprints on the gears a d this is where the whining comes from per adam at revolution automotive.

 

[12OKGT]

Repeated hard launches with drag tires causes a lot of flex in the rear end. Have you braced your rear end at all?
Cool video, that was at 5000 rpm?

I have the Ford Racing girdle on it, with the studs to brace the main bearing caps, but no bracing on the housing or anything. Is their anything you would recommend? Yep, that launch was 5000-5500 rpm. Car was bogging really bad at any launch lower than that.

 

[UnleashedBeast]

This happened to my GT500 at the track. After new gears were install, with minimal noise, I went to the track. Driving home from the track, gear noise was much worse to the point of being unbearable.

Culprit, crush sleeve collapsed more throwing off backlash clearance of the gears, pinion depth, etc. The 8.8" has issues in these cars. Your gears will have to be reinstalled with a new crush sleeve and hope that none of the gear teeth were damaged like mine that day.

 

[12OKGT]

True trac and some new gears should fix it. Just make sure u use someone that knows what there doing or it will make noise again.

Thats been the hard part, I'm trying to find a place around here with a good reputation, but haven't had much luck with my search yet.

 

[12OKGT]

Sure its not the trans? I know on hard launches the trans gets imprints on the gears a d this is where the whining comes from per adam at revolution automotive.

I'm pretty sure it's the rear, because it's exactly what happened the last time, and when they changed out everything in the rear end, it went away, until I decided to go to the track again...

 

[12OKGT]

This happened to my GT500 at the track. After new gears were install, with minimal noise, I went to the track. Driving home from the track, gear noise was much worse to the point of being unbearable.

Culprit, crush sleeve collapsed more throwing off backlash clearance of the gears, pinion depth, etc. The 8.8" has issues in these cars. Your gears will have to be reinstalled with a new crush sleeve and hope that none of the gear teeth were damaged like mine that day.

Thanks Beast, That definitely sounds like it could be what happened. Probably a stupid question, but do they make a better crush sleeve or an alternative to the crush sleeve, so I can keep this from happening again? Also, any way to diagnose this by myself, without having to pull everything out and check it?

 

[JUIC3D]

This happened to my GT500 at the track. After new gears were install, with minimal noise, I went to the track. Driving home from the track, gear noise was much worse to the point of being unbearable.

Culprit, crush sleeve collapsed more throwing off backlash clearance of the gears, pinion depth, etc. The 8.8" has issues in these cars. Your gears will have to be reinstalled with a new crush sleeve and hope that none of the gear teeth were damaged like mine that day.

Interesting. I've noticed the exact same thing in mine. My gears were whisper quiet the day I picked the car up, but after the first track day, they have been much louder, especially on acceleration.

 

[UnleashedBeast]

Thanks Beast, That definitely sounds like it could be what happened. Probably a stupid question, but do they make a better crush sleeve or an alternative to the crush sleeve, so I can keep this from happening again? Also, any way to diagnose this by myself, without having to pull everything out and check it?

They do have stronger material crush sleeves for this, and I had to install one to prevent it from happening again under heavy load.

You'd have to remove the driveshaft to see if you can feel extra play (movement in and out) in the pinion yoke.

 

[mantis118]

Put a solud shim setup in. Problem solved.

 

[Elwood617]

Upr makes axle tube braces that help to prevent flexing under load. The Fox body guys have been using them for years. On our cars you have to work around the exhaust, the over the axle tubes are in the way for ideal placement. I removed the exhaust but, I've seen people weld the braces under the axle tubes.

 

[Stevem17500]

True trac and some new gears should fix it. Just make sure u use someone that knows what there doing or it will make noise again.

How would a true track help....?

 

[04compgt]

Interesting. I've noticed the exact same thing in mine. My gears were whisper quiet the day I picked the car up, but after the first track day, they have been much louder, especially on acceleration.

Mine have been like this forever now, I just brace myself every time I spray it out of the hole and expect the worse. I am going to be taking it apart and putting a solid crush sleeve in it soon.