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Are you running a diff cooler?

Are you running a diff cooler?


  • Total voters
    28

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JDee

Ancient Racer
1,797
2,001
Exp. Type
W2W Racing
Exp. Level
20+ Years
5 miles from Mosport
Are you getting axle overheats? I did for a while until I switched to Red Line diff lube and wrapped the exhaust with high heat wrap for about 3' where it goes near the diff. Haven't had a single overheat since doing those two things. If you're not getting warned of axle overheats then you've got no issue.
 
603
1,020
Exp. Type
HPDE
Exp. Level
3-5 Years
Wisconsin
Are you getting axle overheats? I did for a while until I switched to Red Line diff lube and wrapped the exhaust with high heat wrap for about 3' where it goes near the diff. Haven't had a single overheat since doing those two things. If you're not getting warned of axle overheats then you've got no issue.

might be a dumb question but how would I know? Everything seems inline.
 

Dave_W

Cones - not just for ice cream
984
1,277
Exp. Type
Autocross
Exp. Level
20+ Years
Connecticut
I think the S550s have a diff temp sensor from the factory - maybe only certain models / packages. The S197 GT500 may have one, maybe after a certain year; but most S197s do not.
 

JDee

Ancient Racer
1,797
2,001
Exp. Type
W2W Racing
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20+ Years
5 miles from Mosport
Mine's a '16 with only 1 option that being PP1 so it has the torsen diff. I suspect maybe the heat sensor is only on the Torsens? But I'm just guessing. You would think a clutch diff would be more prone to overheating than a Torsen, but I really don't know. I raced a guy's Camaro in Firehawk way back in the late 80s/early 90s and it had a clutch diff and it used to just eat rear ends unless you had the clutches virtually locked solid.
 
1,119
1,110
Exp. Type
HPDE
Exp. Level
5-10 Years
Lenoir City TN
The clutch type LSD's generate more heat than a Torsen or TrueTrac. I don't see a need for a diff cooler if you are running a Torsen and good fluid unless you are endurance racing. For the usual 20-30 minute track sessions seen in HPDE I just don't think it is necessary.
 

JDee

Ancient Racer
1,797
2,001
Exp. Type
W2W Racing
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20+ Years
5 miles from Mosport
The clutch type LSD's generate more heat than a Torsen or TrueTrac. I don't see a need for a diff cooler if you are running a Torsen and good fluid unless you are endurance racing. For the usual 20-30 minute track sessions seen in HPDE I just don't think it is necessary.
WADR, I beg to differ. On a very fast track like Mosport where I get a 93.3 mph average lap speed the heat build up is phenomenal. With no exhaust wrap and using stock Ford diff fluid I was getting axle overheats on hot days in less than 15 minutes of track time. By contrast Shannonville is a very wiggly track with much lower speeds and I never got diff overheats there, the average lap speed is around 75 mph or so. Higher speeds = higher heat. I get that a Torsen makes less heat than a clutch diff does, but it still makes heat and is subjected to heat generated from the car itself from several different sources.

I did endurance racing back in the 90s, drove another guy's Camaro with a clutch type diff, it was an ex-PlayersGM series car and they had many bespoke driveline pieces on them. You could not keep rear ends in those cars even in sprint racing. The only way to make those diffs live back in the day was to virtually lock them solid so there was zero clutch slip, or as close to zero as you could get. Even at that the diffs needed a rebuild every 10 hours. It was funny watching them drive around in the pits, the inside rear wheel would hop trying to keep up with the outside wheel. Those cars had a grand total of 220 hp, less than half what our cars have today, and they still ate rear ends.

Those cars were lucky to see 120mph up the back straight, this car sees 147 mph up that same back straight. They ran 1:41 laps, this car runs 1:33s. Higher speed = higher heat. Torsen or not, there's a limit to the heat they can stand, which is why Ford put a heat sensor in the rear end.

The stock exhaust runs very close to the diff so I wrapped the exhaust for 4 feet around the diff area and that along with Red Line fluid helped a lot. I haven't had a diff overheat for the last 2 years. But I also know what triggers it and I tend to avoid those conditions, which you can easily do when you're just lapping. I had a diff cooler spec'd out but decided it was not necessary, if the driver manages the problem correctly. I've learned how to do that and no longer get axle overheats. The car is heavy enough without adding more to the weight problem.
 
1,119
1,110
Exp. Type
HPDE
Exp. Level
5-10 Years
Lenoir City TN
WADR, I beg to differ. On a very fast track like Mosport where I get a 93.3 mph average lap speed the heat build up is phenomenal. With no exhaust wrap and using stock Ford diff fluid I was getting axle overheats on hot days in less than 15 minutes of track time. By contrast Shannonville is a very wiggly track with much lower speeds and I never got diff overheats there, the average lap speed is around 75 mph or so. Higher speeds = higher heat. I get that a Torsen makes less heat than a clutch diff does, but it still makes heat and is subjected to heat generated from the car itself from several different sources.

I did endurance racing back in the 90s, drove another guy's Camaro with a clutch type diff, it was an ex-PlayersGM series car and they had many bespoke driveline pieces on them. You could not keep rear ends in those cars even in sprint racing. The only way to make those diffs live back in the day was to virtually lock them solid so there was zero clutch slip, or as close to zero as you could get. Even at that the diffs needed a rebuild every 10 hours. It was funny watching them drive around in the pits, the inside rear wheel would hop trying to keep up with the outside wheel. Those cars had a grand total of 220 hp, less than half what our cars have today, and they still ate rear ends.

Those cars were lucky to see 120mph up the back straight, this car sees 147 mph up that same back straight. They ran 1:41 laps, this car runs 1:33s. Higher speed = higher heat. Torsen or not, there's a limit to the heat they can stand, which is why Ford put a heat sensor in the rear end.

The stock exhaust runs very close to the diff so I wrapped the exhaust for 4 feet around the diff area and that along with Red Line fluid helped a lot. I haven't had a diff overheat for the last 2 years. But I also know what triggers it and I tend to avoid those conditions, which you can easily do when you're just lapping. I had a diff cooler spec'd out but decided it was not necessary, if the driver manages the problem correctly. I've learned how to do that and no longer get axle overheats. The car is heavy enough without adding more to the weight problem.
Your S550 may be a bit different. The OP is driving an S197 as am I. I primarily run my car in the Southeast US in temps in the 90's without a diff cooler and have not had any trouble in 20-30 minute sessions on track. I do have a finned aluminum diff cover which holds an extra quart of fluid and have been running Redline 75w140 for years. My exhaust is not wrapped.
 
I only had the diff fluid overheat and spew at Watkins Glen, another high speed track so I would agree with JDee that it depends on the layout and avg speed. I'm installing a cooler now in anticipation of a WG visit next month.
 

1 old racer

Too blessed to be stressed and old track whore,
128
267
Exp. Level
20+ Years
fontana ca.
The last couple of hot track days I ran, been a while ago :'-(, The heating problem was caused mostly by the heat soaking between the sessions. The first session out no heat issue. Then as the day wore on I got less and less time on the track before the dreaded temp warning came on. My exhaust is wrapped, which helps a lot but it was not enough. I turn my diff cooler on on the cool down lap and for a few min. in the pits. that is all it takes for me to keep the dreaded overtemp from occurring. Something else to try before you dive in with a diff cooler. I didnt think about this simple item til after I added a diff cooler, but it works for the guys that do it. Between sessions place a leaf blower under the car to get keep are movement under and around the diff.

Here is a video of the orig. install:
 

Fabman

Dances with Racecars
6,518
8,154
Exp. Type
W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
My car is just a track car and is tracked about 12-18 times per year. I am in the midwest.

Do you think it needs a diff cooler? I have not had one and have had zero issues to this point.
s550 must run a cooler while s197's are optional. Most don't run them.
The top running s197's the last few years at the 25 hr of thunderhill run no coolers (trans or diff) and that's a pretty grueling race.
The s197 dissipates heat through all that mass of axle tubes etc. while the s550 is just a center section and it can't self cool like the s197.
Good fluid and pointing the exhaust away pays dividends here.
 
501
550
Exp. Type
W2W Racing
Exp. Level
20+ Years
Snowy North
Solid mounting the diff to subframe helps in S550 applications....but it causes significant NVH for those who care about interior trim rattles and buzzing if your subframe is also hard-mounted.
 
s550 must run a cooler while s197's are optional. Most don't run them.
The top running s197's the last few years at the 25 hr of thunderhill run no coolers (trans or diff) and that's a pretty grueling race.
The s197 dissipates heat through all that mass of axle tubes etc. while the s550 is just a center section and it can't self cool like the s197.
Good fluid and pointing the exhaust away pays dividends here.
Do you think there is a difference in heat when you have a clutch based diff vs. a torsen or true track? also, my exhaust is very close to the diff, should i wrap it? i ask because on the last track day i noticed a bit of overflow out of the diff.
Edit: i have an S197 with the Ford Performance aluminum diff cover and Eaton true track.
 

Fabman

Dances with Racecars
6,518
8,154
Exp. Type
W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
Do you think there is a difference in heat when you have a clutch based diff vs. a torsen or true track? also, my exhaust is very close to the diff, should i wrap it? i ask because on the last track day i noticed a bit of overflow out of the diff.
Edit: i have an S197 with the Ford Performance aluminum diff cover and Eaton true track.
No cooler necessary. Point the exhaust away if you have turn downs. You should be fine.
 

Fabman

Dances with Racecars
6,518
8,154
Exp. Type
W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
 
Do you think there is a difference in heat when you have a clutch based diff vs. a torsen or true track? also, my exhaust is very close to the diff, should i wrap it? i ask because on the last track day i noticed a bit of overflow out of the diff.
Edit: i have an S197 with the Ford Performance aluminum diff cover and Eaton true track.

yes there is a difference in heat generated, torsen generates more. theoretically of course (all the additional gears in the torsen spinning generate more heat), though in practice as well, I've had both in the same car.
 

JDee

Ancient Racer
1,797
2,001
Exp. Type
W2W Racing
Exp. Level
20+ Years
5 miles from Mosport
So I think I might have lunched my Torsen yesterday, it had been a tiny bit noisier than I remember on the last couple of track days but not horribly noisy. On left turns the noise from the diff is very apparent. It's not a constant noise like you would get with a wheel bearing. I checked the wheel bearings and they seem fine, no play in them.

Hard to describe, sounds like gears skipping or jumping but with sort of a grind, it's just a loud ugly noise that shouldn't be there. Somebody described the same thing in another post from a while back, they called it a ratcheting sound and that's what mine sounds like. It's a Torsen, so it's got lots o' gears. It only does it on left turns and the noise seems to be coming mostly from the middle to the right side of the car. You can make it do it in a parking lot at 15 mph.

This thing had a problem with constant axle overheats way back when I first took it to the track, I used to get the axle overheat warning regularly on hot days. I went to RedLine diff oil which solved the overheats. But obviously that just delayed the inevitable. I drained the fluid today, didn't look too bad but it was somewhat dark. It'd be nice if it just needed a change of diff fluid.
 
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