Blown differential at 20K miles - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

tylerio · 12-22-2018, 07:22 AM

With about 35 track days on my Z, I noticed a whining sound coming from the differential. After another couple of track days, the whining grew louder, then a leak developed in the line from the diff cooler to the pumpkin.

Took it to the dealer since it was under warranty. Upon opening the pumpkin a huge amount of metal slivers dumped out. The bearings were galled something wicked. Dealer put in new diff under warranty.

I was in the habit of changing the gear oil every 3 track days. Guess I'll be changing it more frequently going forward.

I was using Amsoil Severe Duty 75-90W with 2 ounces of friction modifier. Car now has the OEM gear oil, which supposedly has the friction modifier in it.

MX621 · 12-22-2018, 07:28 AM

So I was under the impression the friction modifier was for clutch type limited slip differentials? Being our cars have Torsen diffs, it’s only gears no clutches, so why the need for the friction modifier? Hoping to learn something here.

If you did 4, 20 min sessions every track day, that’s roughly 46 hours of track time. If your only failure was the diff, id say that’s fantastic! How has the car performed so far? Any other issues ?

tylerio · 12-22-2018, 11:33 AM

You're right about no clutches in the diff. Maybe the AC Delco gear oil will help.

The car has been otherwise flawless. A very stout vehicle.

j o n · 12-22-2018, 02:19 PM

Track prep document says to change rear fluid after every track event

https://www.camaro5.com/forums/attac...6&d=1493920184

tylerio · 12-22-2018, 02:26 PM

Yup, shoulda, woulda, coulda...

wakespeak · 12-22-2018, 09:24 PM

I would change the fluid quickly after the diff change as some of the metal shavings could have gotten into the cooler lines and flushed into the new diff.

For my rebuilt TrueTrac diff, the builder strictly uses Lucas 85w-140.

hammdo · 12-22-2018, 09:30 PM

Torsion diffs don’t need the limited slip additive usually, you don’t want them to slip really — Interesting the service manual calls for that (track prep)...

I have a torsional diff (TrueTrac) and it specially says no limited slip additive...

Maybe GM’s is different...

-Don

tylerio · 12-23-2018, 11:29 AM

New cooler lines were put in. Nevertheless, l'll be changing out the new fluid at 500 miles if not sooner.

serviceguy · 12-23-2018, 07:19 PM

Not seen many rear diff failures on this forum ? maybe using non GM fluid and not changing after every track day resulted in the premature failure ?

olblue75 · 12-24-2018, 12:14 AM

Coolant lines are seperate from diff fluid, there's a small radiator attached to the rear cover and circulates trans fluid not gear oil.

Biergut · 12-24-2018, 09:08 AM

Quote:

Originally Posted by serviceguy

Not seen many rear diff failures on this forum ? maybe using non GM fluid and not changing after every track day resulted in the premature failure ?

Had a C6 track car that I thought I was being smart about and using fancy Amsoil -- the grinding/other noises only ceased when we went back to what GM recommended in those units.

Also, to those who do multiple events on their fluids... what does every race team do following a race weekend?

GM has outlined the proper procedure... I realize some folks smoke and others don't floss their teeth which is why YMMV.

Lord knows enough issues happen when we track WITH proper maintenance.

Doug Halsey · 12-26-2018, 06:51 AM

Just curious, but how much does it cost you each time to track your car? Understanding you may do all the maintenance work yourself.

Biergut · 12-26-2018, 12:22 PM

Quote:

Originally Posted by Doug Halsey

Just curious, but how much does it cost you each time to track your car? Understanding you may do all the maintenance work yourself.

I can only speak for myself regarding "fluid" changes, but between $200-$300. Variation is due to whether I need to flush brake fluid -- I have used Castrol SRF for years.

I consider my time part of the entire enjoyment of tracking as a hobby.

As for the cost for an entire track weekend... please don't ask.

Three days at Watkins in the Corvette including "absolutely everything" ran north of 2k with ease. I really don't want to sit and figure it out... and I certainly wouldn't want my wife to know. Also -- this is for HPDE and not a real "race" weekend. It just goes north from there...

kramard · 12-26-2018, 01:10 PM

Quote:

Originally Posted by Biergut

I can only speak for myself regarding "fluid" changes, but between $200-$300. Variation is due to whether I need to flush brake fluid -- I have used Castrol SRF for years.

I consider my time part of the entire enjoyment of tracking as a hobby.

As for the cost for an entire track weekend... please don't ask.

Three days at Watkins in the Corvette including "absolutely everything" ran north of 2k with ease. I really don't want to sit and figure it out... and I certainly wouldn't want my wife to know. Also -- this is for HPDE and not a real "race" weekend. It just goes north from there...

Awhile back I posted up some maths on the subject if you want to search for it which included reserves for CCBs - I recall 1500/day when you add pads, fluids, CCBs (front and rear), tires, insurance, HPDE fees and insurance. Instructing, buying used tires tires, selectively buying insurance based on the day's goals and steel brakes have driven down the full cost estimate pretty well.

12-22-2018, 07:22 AM	#1
tylerio EXTREMZ Drives: 2015 Z/28 #891, 2012 2SS 45th Anni Join Date: Jul 2012 Location: Southern Utah Posts: 131	Blown differential at 20K miles With about 35 track days on my Z, I noticed a whining sound coming from the differential. After another couple of track days, the whining grew louder, then a leak developed in the line from the diff cooler to the pumpkin. Took it to the dealer since it was under warranty. Upon opening the pumpkin a huge amount of metal slivers dumped out. The bearings were galled something wicked. Dealer put in new diff under warranty. I was in the habit of changing the gear oil every 3 track days. Guess I'll be changing it more frequently going forward. I was using Amsoil Severe Duty 75-90W with 2 ounces of friction modifier. Car now has the OEM gear oil, which supposedly has the friction modifier in it. __________________ ARH long tube headers, no cats Comp Cams stage 2 custom grind Ported throttle body JPSS Oil cooler JPSS SAI plates JPSS Rear sway bar Forza Continenti exhaust controller ZL1 Add-ons wickerbill Brey-Krause Harness bar Schroth 4 pt. ASM harnesses Auto-blip

12-22-2018, 07:28 AM	#2
MX621 Drives: 2014 z28 Join Date: Oct 2018 Location: DE Posts: 171	So I was under the impression the friction modifier was for clutch type limited slip differentials? Being our cars have Torsen diffs, it’s only gears no clutches, so why the need for the friction modifier? Hoping to learn something here. If you did 4, 20 min sessions every track day, that’s roughly 46 hours of track time. If your only failure was the diff, id say that’s fantastic! How has the car performed so far? Any other issues ? Last edited by MX621; 12-22-2018 at 07:41 AM.

12-22-2018, 11:33 AM	#3
tylerio EXTREMZ Drives: 2015 Z/28 #891, 2012 2SS 45th Anni Join Date: Jul 2012 Location: Southern Utah Posts: 131	You're right about no clutches in the diff. Maybe the AC Delco gear oil will help. The car has been otherwise flawless. A very stout vehicle. __________________ ARH long tube headers, no cats Comp Cams stage 2 custom grind Ported throttle body JPSS Oil cooler JPSS SAI plates JPSS Rear sway bar Forza Continenti exhaust controller ZL1 Add-ons wickerbill Brey-Krause Harness bar Schroth 4 pt. ASM harnesses Auto-blip

12-22-2018, 02:19 PM	#4
j o n Drives: 2015 Z/28 #0058 Join Date: Apr 2018 Location: Pittsburgh, PA Posts: 814	Track prep document says to change rear fluid after every track event https://www.camaro5.com/forums/attac...6&d=1493920184 __________________ Current: - '15 Z/28 #0058 \| White \| A/C \| Speakers \| Michelin PS4S 305/30/19's - '22 Ridgeline RTL \| White \| Ebony, '22 CR-V EX-L Hybrid \| White \| Ebony Sold: - '15 Z/28 #0048 \| White \| A/C \| Speakers \| Michelin PS4S 305/30/19's https://www.instagram.com/__jon__athan__/

12-22-2018, 02:26 PM	#5
tylerio EXTREMZ Drives: 2015 Z/28 #891, 2012 2SS 45th Anni Join Date: Jul 2012 Location: Southern Utah Posts: 131	Yup, shoulda, woulda, coulda... __________________ ARH long tube headers, no cats Comp Cams stage 2 custom grind Ported throttle body JPSS Oil cooler JPSS SAI plates JPSS Rear sway bar Forza Continenti exhaust controller ZL1 Add-ons wickerbill Brey-Krause Harness bar Schroth 4 pt. ASM harnesses Auto-blip

12-22-2018, 09:24 PM	#6
wakespeak Drives: 2020 ZL1 1LE Join Date: Sep 2012 Location: Austin, Texas Posts: 1,335	I would change the fluid quickly after the diff change as some of the metal shavings could have gotten into the cooler lines and flushed into the new diff. For my rebuilt TrueTrac diff, the builder strictly uses Lucas 85w-140. __________________ 2020 ZL1 1LE [Moroso SC Expansion Tank, otherwise stock]

12-22-2018, 09:30 PM	#7
hammdo 'It's an experiment' Drives: [COTW 2/09/15] '11 GPI LSA SC Z/LE Join Date: May 2014 Location: Dallas TX Posts: 8,694 View My Garage	Torsion diffs don’t need the limited slip additive usually, you don’t want them to slip really — Interesting the service manual calls for that (track prep)... I have a torsional diff (TrueTrac) and it specially says no limited slip additive... Maybe GM’s is different... -Don __________________ 747 RWHP 794 RWTQ "Horsepower sells cars, torque wins races." - Enzo Ferrari See My Build: http://www.camaro5.com/forums/showthread.php?t=385577

12-23-2018, 11:29 AM	#8
tylerio EXTREMZ Drives: 2015 Z/28 #891, 2012 2SS 45th Anni Join Date: Jul 2012 Location: Southern Utah Posts: 131	New cooler lines were put in. Nevertheless, l'll be changing out the new fluid at 500 miles if not sooner. __________________ ARH long tube headers, no cats Comp Cams stage 2 custom grind Ported throttle body JPSS Oil cooler JPSS SAI plates JPSS Rear sway bar Forza Continenti exhaust controller ZL1 Add-ons wickerbill Brey-Krause Harness bar Schroth 4 pt. ASM harnesses Auto-blip

12-23-2018, 07:19 PM	#9
serviceguy Drives: 2014 Z/28 # 89, 69 Camaro, 2013 ZL1 Join Date: Jul 2013 Location: Flint MI Posts: 669	Not seen many rear diff failures on this forum ? maybe using non GM fluid and not changing after every track day resulted in the premature failure ?

12-24-2018, 12:14 AM	#10
olblue75 Drives: 2010 2SS/RS Join Date: Dec 2009 Location: Clarksville Tennesse. Posts: 6,064	Coolant lines are seperate from diff fluid, there's a small radiator attached to the rear cover and circulates trans fluid not gear oil. __________________ Orange Krush II 1LE Front sway bar, Splitter, shocks and struts, Z28 dual mode mufflers, Intake, UCA Bushings, and Toresen 3.91 Diff. 1 piece DSS Drive Shaft, ZL1/C7 Calipers, and 32mm JPSS Rear Bar. ASC race spec splitter and wicker. 6th Gen M017 Wheels. Stainless Works 1 7/8 LTs. DSE and PAFDT Suspension components.

12-26-2018, 06:51 AM	#12
Doug Halsey Toy Collector Drives: 2015 Camaro Z/28 Join Date: Aug 2015 Location: Brunswick GA Posts: 133 View My Garage	Just curious, but how much does it cost you each time to track your car? Understanding you may do all the maintenance work yourself. __________________