GoatHead

2017 GS 2600 miles. One autocross event and a 2-days HPDE event October 2018

I flushed my brake fluid and replaced with Castrol SRF last October for my first HPDE event. My next HPDE event is going to be in February or March. What do I need to do to my brake fluid? Full flush? Bleed? Leave it as is?

How about transmission fluid. I still have the factory fill. Do I need to replace?

Thanks,

thebishman

GoatHead

Thanks.... so 18 months for SRF with track use. Sounds too good!

How many miles I can go on factory fill transmission fluid, if I am doing HPDEs?

RapidC84B

TKOGTO

You have plenty on time on the trans fluid. With the C6, the manual says "If the vehicle is used for racing or other competitive driving, the rear axle fluid temperatures may be higher than would occur in normal driving. We recommend that the rear axle fluid be drained and refilled with new fluid after every 24 hours of racing or competitive driving." I change the tranny fluid at the same time. Not miles based. Works out to annually with ~ 12 track days/yr.

You're good to go on the SRF as well. I have used it for a full season with only 1 quick bleed and I'm guessing it could have lasted another 4-5 days.

fleming23

I do a full drain/refill annually on trans/diff and flush a new bottle or two of SRF through the lines. My car only has 9500 miles since 2016 but sees regular track use and high heat. Preventative maintenance, just like going to the dentist ever 6 months.

Supercharged111

I do SRF annually on my CMC car but it could go farther. Comes out clear and clean every April. I'm only 260whp and 3250# post race, good to see heavier faster cars go a full season too.

Poor-sha

Straight from the C7 owners manual:

"Manual transmission fluid should be changed after every 15 hours of track usage."

"Axles must have 2414 km (1,500 mi) before being used in track driving. The rear axle fluid temperatures may be higher than when driving in severe conditions. Drain and refill with new fluid after the first racing or competitive driving event, and then after every 24 hours of racing or competitive driving."

RapidC84B

Interesting that the trans is that quick vs. the diff. In my experience the diff fluid takes far more abuse (at least in a C5 race car) than the trans.

RichieRichZ06

You're nuts if you allow the rear diff or trans fluid to go 24 hours of track use before changing. I see what the fluid typically looks like at half that amount of track time and it's full of particles, looks burnt and stinks the shop up. I agree on the annual SRF fluid change, assuming you're doing 6-10 events per year. Figuring about 60-80 minutes of track time per track day, I recommend checking the diff and trans fluid condition after 6-8 track days before assuming it will be OK to go 15-20 track days.

GoatHead

I searched the manual and the Corvette track preparation document, and I couldn't find any reference to "Manual transmission fluid should be changed after every 15 hours of track usage." I know you owned ZR1 and Z06. I own GS

I think it is probably a good idea to change the diff and the transmission fluid once a year or after 12 track days as preventative maintenance.

synner

I prefer a quality synthetic after break-in period to ensure good heat tolerance but I have a large cooler on the trans and diff as well. I only average 5-6ish weekends a year so every other year for trans and diff. I run a heavier vehicle (camaro) so cook the fluid more and do a full flush every second weekend. I've had fluid failures before so am overzealous, I know some will say its overkill. Brake fluid is cheaper than wasting a track day with cooked brakes. I'm not a fan of trackside bleeding when heat has expanded the caliper and you burn your hands horribly. Ducts and proper pads can only do so much for my portly girl. I have vented pistons waiting to go in too but am stuck overseas for a while with the car in storage.

Dan H.

Just had my diff rebuilt by RKT for my C5. They recommended changing the diff fluid after every other event. For my trans I do once each winter and the fluid comes out clean. I do the engine oil after 2-3 events. SRF I do a bleed before my first event of the season, then I do a second bleed around July. I also change the coolant every winter. All this for a C5

RapidC84B

That's if you don't have a cooler I'd assume... most C7s have coolers which greatly extends fluid life. Also, in my racecar I ran 75w120 Amsoil gear oil which was one thickness up from standard.

Poor-sha

That was copied directly from the 2019 Corvette owners manual PDF. I do believe they updated their guidance on this for 2019.

badhabit_wb

What Fleming23 said. I don't use srf I use the AP racing R3 fluid in their big brake kit. I flush it completely once a year. As far as I'm concerned brakes are the most important item in the car. spending less than 100 per year on fluid it good insurance.

RapidC84B

Does the trans fluid guidance distinguish between manual or auto? Seems very conservative for a manual with a cooler.

EDIT your earlier post quotes it as manual trans.