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Racing differential oil #4413469
05/24/17 06:01 PM
05/24/17 06:01 PM
Joined: May 2017
Posts: 105
Pittsburgh, Pa
Fastcompany Offline OP
Fastcompany  Offline OP
Joined: May 2017
Posts: 105
Pittsburgh, Pa
Hi all. I'm actually sure this is a waste in time but I'm asking anyways. I prep 3 triumph gt6 race cars and they eat rear ends constantly. I've seen one grenade in every way possible now. Right now my set up is timken bearings complete,arp hardware complete and a quaife limited slip carrier. The last one I put together I put redline heavyweight​ shock proof in....made 2 laps before knocking a tooth off the ring gear. Got it apart,checked my backlash and my tooth pattern and it's right on. So all I'm certain of is my diff case is no longer flexing my bearings are no longer exploding and my posi carrier isn't snapping in half. I'm down to a ring gear that I have no choice but to run. Is there a gear oil out there that "might" help this out. I was thinking of amsoil sever gear 190 or 250. Was also wondering if making that jump should I increase backlash? Other oils with failure have been Mobil 1 and rp 75-90 and shell spirax 80-90.

Re: Racing differential oil [Re: Fastcompany] #4413483
05/24/17 06:17 PM
05/24/17 06:17 PM
Joined: Apr 2016
Posts: 1,185
Campbellsville, KY
Alex_V Offline
Alex_V  Offline
Joined: Apr 2016
Posts: 1,185
Campbellsville, KY
If you've tried all those with little change, I doubt any gear oil will solve the problem but I've used it in several applications and am impressed with Amsoil so it's worth a shot.


I like Chevy and Valvoline.

'13 Cruze, 1.4T, 113K
'85 GMC C3500, 454, 130K
'82 Mercedes 300CD, OM617 turbo, 169K
'67 Suburban, 350, 331K
Re: Racing differential oil [Re: Fastcompany] #4413492
05/24/17 06:34 PM
05/24/17 06:34 PM
Joined: Apr 2003
Posts: 120
TX
fields Offline
fields  Offline
Joined: Apr 2003
Posts: 120
TX
I would like to hear what solves you problem, if you can remember to let us know.

Re: Racing differential oil [Re: Fastcompany] #4413496
05/24/17 06:37 PM
05/24/17 06:37 PM
Joined: May 2017
Posts: 105
Pittsburgh, Pa
Fastcompany Offline OP
Fastcompany  Offline OP
Joined: May 2017
Posts: 105
Pittsburgh, Pa
Last time I used amsoil gearlube was when I drag raced a 2 stroke quad. The big tires I had made the wet clutch slip bad. Amsoil fixed that real good. Just never picked a fluid to solve actually detroying a component. So fingers crossed someone on here Rock crawls with a diff that is way to small and they figured something out to make it last

Re: Racing differential oil [Re: fields] #4413500
05/24/17 06:40 PM
05/24/17 06:40 PM
Joined: May 2017
Posts: 105
Pittsburgh, Pa
Fastcompany Offline OP
Fastcompany  Offline OP
Joined: May 2017
Posts: 105
Pittsburgh, Pa
Originally Posted By: fields
I would like to hear what solves you problem, if you can remember to let us know.


Got a race in 3 weeks. So I'll know if they can last an entire weekend or not then. I got 2 and a half weeks to build another diff and pick my fluid.

Re: Racing differential oil [Re: Fastcompany] #4413509
05/24/17 06:48 PM
05/24/17 06:48 PM
Joined: Mar 2013
Posts: 4,755
The Midwest
skyactiv Offline
skyactiv  Offline
Joined: Mar 2013
Posts: 4,755
The Midwest
I doubt any oil will solve your problem. Sounds like you are running waaaay more power than it's designed for. Now you know why people like the Ford 9" rear end, which you probably cant fit. Is there a conversion possible to something that will hold up?


Wife: 15' Audi A4 quattro 6 speed manual
Me: 13' VW GTI 3 door 6 speed manual
Re: Racing differential oil [Re: Fastcompany] #4413526
05/24/17 07:10 PM
05/24/17 07:10 PM
Joined: May 2017
Posts: 105
Pittsburgh, Pa
Fastcompany Offline OP
Fastcompany  Offline OP
Joined: May 2017
Posts: 105
Pittsburgh, Pa
Yes but with alot of mods to the chassis. It's an IRS car. A Subaru diff can fit but custom axles need made and the frame has to be cut up. The cars have historic value. As far as triumphs go these were the 2 hot cars on the circuit back in the day. Sadly I am not permitted to permanently alter anything. I recently made my own big brake kit up front buy using Toyota 4 piston callipers and 200zx rotors. It's a vented rotor vs the old solid ones. Brakes got hot enough that it ruined timken wheel bearings packed in timken racing grease and melted the piston seals out of my fresly rebiult calipers. But no brake fade though lol. The change to wilwood 600 fixed that. That was the lowest friction race pad we could get that generated that much heat.

Re: Racing differential oil [Re: Fastcompany] #4413529
05/24/17 07:13 PM
05/24/17 07:13 PM
Joined: Jul 2005
Posts: 304
ohio
oliver88 Offline
oliver88  Offline
Joined: Jul 2005
Posts: 304
ohio
Way back in the late 1970's Porsche was having trouble with the diff transaxle grenading on the 935's...these cars could produce north of 800 HP and tons of torque...Tried a lot of different gear lubes and finally settled on Swepco 201...problems solved. Bruce Andersen of Porsche fame used to tell that story quite often...Swepco 201 is a staple in many of the older 915 Porsche style transaxles to this day. Might be worth a try....I run it in my Austin Healey 3000 and my older Porsche 911...quiets them down too. FWIW i run Miller's 75w110 or Amsoil 75w110 in our Porsche 996 cup and 964 cup race cars. They do well and look great when we do the annual inspections...I have rebuilt the 964 box once and replaced a few bearings in the 996 cup...Those cars are raced pretty hard.

Last edited by oliver88; 05/24/17 07:16 PM.
Re: Racing differential oil [Re: Fastcompany] #4413540
05/24/17 07:21 PM
05/24/17 07:21 PM
Joined: May 2017
Posts: 105
Pittsburgh, Pa
Fastcompany Offline OP
Fastcompany  Offline OP
Joined: May 2017
Posts: 105
Pittsburgh, Pa
All of our Porsches get 201. We started running it in our t44 transaxle in the GT40 as well. Actually never thought of dumping it in a rear end. Might be worth a shot

Re: Racing differential oil [Re: Fastcompany] #4413543
05/24/17 07:27 PM
05/24/17 07:27 PM
Joined: May 2017
Posts: 105
Pittsburgh, Pa
Fastcompany Offline OP
Fastcompany  Offline OP
Joined: May 2017
Posts: 105
Pittsburgh, Pa
And on the note of inspections I have yet to wear anything out in one of those rear ends. It's always fine until total failure. I will say I have had the most failures in the car with the dog box. No clutch shifting shock loads in pretty hard. The other car has a Richmond 5 speed and can usually make 2 or 3 events without failure. Both cars making approximately 200 hp with solid hub clutches

Re: Racing differential oil [Re: Fastcompany] #4413576
05/24/17 07:58 PM
05/24/17 07:58 PM
Joined: Apr 2009
Posts: 221
Reno, Nevada
Langanobob Offline
Langanobob  Offline
Joined: Apr 2009
Posts: 221
Reno, Nevada
I don't think a lube failure is causing a tooth to break off of the ring gear. It sounds more like a metallurgical,or other issue with the ring gear. Can you take the new gear to a heat treating shop, have them test the hardness and possibly re-heat treat it? Just clutching at straws.

Re: Racing differential oil [Re: Fastcompany] #4413591
05/24/17 08:16 PM
05/24/17 08:16 PM
Joined: May 2017
Posts: 105
Pittsburgh, Pa
Fastcompany Offline OP
Fastcompany  Offline OP
Joined: May 2017
Posts: 105
Pittsburgh, Pa
I can have it tested for sure. Was just discussing this today. Typically if you are to have a part heat treated you do it right before finish machining. And I've already talked to the big manufactures out there and they won't give up any of the heat treating numbers. I am not good enough to say what rc to what depth. My guess right now based on how they wear is very hard and treated to far down at that hardness. Maybe even thru hardened to one spec. I know one had the bolt holes slightly messed up and I ruined a carbide tap trying to clean it up.

Re: Racing differential oil [Re: Fastcompany] #4413605
05/24/17 08:36 PM
05/24/17 08:36 PM
Joined: Sep 2004
Posts: 7,514
Marshfield , MA
andyd Offline
andyd  Offline
Joined: Sep 2004
Posts: 7,514
Marshfield , MA
Old BMW racers had a diff cooler. IIRC it was belt driven off an axle.


'16 Camry LE STP synth 0w20 and STP filter. the Fridge

1994 Ranger ,the Rat, 5w30 dino, STP filter

'16 Camry SE, Valvoline HM 0w20 and OEM filter
Thick oil is better grin2
Re: Racing differential oil [Re: Fastcompany] #4413627
05/24/17 09:07 PM
05/24/17 09:07 PM
Joined: Oct 2010
Posts: 7,002
Michigan
A_Harman Offline
A_Harman  Offline
Joined: Oct 2010
Posts: 7,002
Michigan
Originally Posted By: Fastcompany
I can have it tested for sure. Was just discussing this today. Typically if you are to have a part heat treated you do it right before finish machining. And I've already talked to the big manufactures out there and they won't give up any of the heat treating numbers. I am not good enough to say what rc to what depth. My guess right now based on how they wear is very hard and treated to far down at that hardness. Maybe even thru hardened to one spec. I know one had the bolt holes slightly messed up and I ruined a carbide tap trying to clean it up.


Pretty typical heat treat specs for gear material are usually Rc 57-62 surface hardness with an effective case depth of about .100" to Rc 50 hardness. Core hardness of the material would be Rc 30-34 or somewhere in that range. Are you using low carbon alloy steels that are carburized, or medium carbon steels that are induction or flame-hardened? I would recommend carburized low alloy steel (9310 or 8620) for the more ductile core and better controlled case properties. (But it would be more expensive.)


1985 Z51 Corvette track car
2002 Camaro Z28 LS1/6-speed
2001 Dodge Ram 2500 diesel
1972 GMC 1500 shortbed project truck
Re: Racing differential oil [Re: Fastcompany] #4413632
05/24/17 09:17 PM
05/24/17 09:17 PM
Joined: Oct 2010
Posts: 7,002
Michigan
A_Harman Offline
A_Harman  Offline
Joined: Oct 2010
Posts: 7,002
Michigan
Originally Posted By: Fastcompany
And on the note of inspections I have yet to wear anything out in one of those rear ends. It's always fine until total failure. I will say I have had the most failures in the car with the dog box. No clutch shifting shock loads in pretty hard. The other car has a Richmond 5 speed and can usually make 2 or 3 events without failure. Both cars making approximately 200 hp with solid hub clutches


If you start talking about shock loading of the drivetrain, all bets are off in component fatigue life. If the dog box car fails in every race, and the Richmond 5-speed can go 2 or 3 events, that at least shows a significant difference. Is there an option to put sprung hub clutches in to try to dampen shift shock?


1985 Z51 Corvette track car
2002 Camaro Z28 LS1/6-speed
2001 Dodge Ram 2500 diesel
1972 GMC 1500 shortbed project truck
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