SCCA CAM-C Thread

[NightmareMoon]

Think he has 3.15s since it's a V6 yeah?

if he does have a 3.15 then going to a 3.73 would drop him from 71.5 to 60.4, which is IMHO too short for national courses. But again, when you dont need to shift, lower gear is better.

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[CobaltFilly]

If your 296 tires are 295/35 then going to a 305/30 or 315/30 will also reduce your top speed as well. If you look up the tire revs per mile you can calculate how much.

Roger.
Fastest I have gone on autocross track (one I was told was a "power" course) was 62...but I have not gone competitive.

What is your advice @NightmareMoon, you always make sense. Let me phrase this way, what would you choose?

Yes I have base model 3.15s

 

[NightmareMoon]

Roger.
Fastest I have gone on autocross track (one I was told was a "power" course) was 62...but I have not gone competitive.

What is your advice @NightmareMoon, you always make sense. Let me phrase this way, what would you choose?

Yes I have base model 3.15s

Well a Torsen is a good diff, and I think you could do worse then starting there. OS Gilken is probably preferred, but its also more money when you can get a perfectly good torsen used.

I worry that a 3.73 won't give you the reach w/o shifting to 3rd. 331=68mph, 355=63.4, 373=60.4, but you'll loose a mph or three once you go to shorter diameter wheels. Picking a gear ratio is a strategic choice you'll have to make for yourself.

 

[Biggsy]

This is the best calculator I have used. You can save transmission ratios. I use it to compare speeds and RPM with different ratios and tire sizes. It has prompted me to move from 3.73 to 3.55s. Hope it helps whoever needs it.

check "Compare" box to dd a second value to be compared against.

https://www.blocklayer.com/rpm-gear

 

[shogun32]

so my local Customs shop that does my track alignments

Do they have a history of building diffs though? There's a bit of a knack involved.

 

[CobaltFilly]

Do they have a history of building diffs though? There's a bit of a knack involved.

They have a history of building SN95 race cars and custom work on semi-trucks, lamborageehees...
Long story short I am pretty sure yes.

But if Nightmare says 3.15s mean no shift in autocross is best, then I just need to be driving faster.

 

[Biggsy]

in my opinion(which could be wrong)...the easiest way to go about swapping a rear diff is to get a driveshaft that mates up to the transmission and diff. This prevents having to rebuild or do anything extra to the diff pinion flange. I am not sure of the bolt pattern of a v6 MT82 but if it is the same as a 15-17 GT and you get 3.73 complete rear diff from a 15-17 car then just get a 15-17 driveshaft for $100 which will come out less than a new pinion flange and the labor or rebuilding it. 18+ use different diff pattern. If the v6 trans has a different bolt pattern then just get a custom driveshaft which should still come out less than the labor for rebuild anything AND you drop weight.

Just my thoughts

 

[CobaltFilly]

in my opinion(which could be wrong)...the easiest way to go about swapping a rear diff is to get a driveshaft that mates up to the transmission and diff. This prevents having to rebuild or do anything extra to the diff pinion flange. I am not sure of the bolt pattern of a v6 MT82 but if it is the same as a 15-17 GT and you get 3.73 complete rear diff from a 15-17 car then just get a 15-17 driveshaft for $100 which will come out less than a new pinion flange and the labor or rebuilding it. 18+ use different diff pattern. If the v6 trans has a different bolt pattern then just get a custom driveshaft which should still come out less than the labor for rebuild anything AND you drop weight.

Just my thoughts

V6 6r80 auto. It is sounding to me like I need to learn how to drive the socks off my 3.15s before I start changing them.

Makes sense, but I believe the V6 driveshaft everything was different due to the transmissions being different shape and size and bell-housing (mounting points stayed the same).

And I am afraid to go custom or single piece driveshaft because I heard that recent driveshafts from multiple large companies were coming not balanced properly. Was debating keeping OEM 2 piece and upgrading this:
https://www.jxbperformance.com/prod...eshaft-center-support-bearing-carrier-upgrade

 

[Biggsy]

V6 6r80 auto. It is sounding to me like I need to learn how to drive the socks off my 3.15s before I start changing them.

Makes sense, but I believe the V6 driveshaft everything was different due to the transmissions being different shape and size and bell-housing.

And I am afraid to go custom or single piece driveshaft because I heard that recent driveshafts from multiple large companies were coming not balanced properly. Was debating keeping OEM 2 piece and upgrading this:
https://www.jxbperformance.com/prod...eshaft-center-support-bearing-carrier-upgrade

ahh okay but same rules apply. I believe a proper company can get you sorted but I understand your concern. I plan on going with that JXB part when I change my diff

 

[CobaltFilly]

ahh okay but same rules apply. I believe a proper company can get you sorted but I understand your concern. I plan on going with that JXB part when I change my diff

Current upgrades for July through November are:
Rear Brakes to GT Vented from Powerstop
JXB Carrier Bushing Upgrade
Steeda 'Stop the Hop' Enthusiast Kit, per HoneyBadger's rec. I have been dealing with decent (though not loss of control inducing, just rpm loss/shift speed loss) wheel-hop at 7k+ shifting 1-2 and 2-3.
Seat time, seat time, seat time.
And more cooling after that.
Most important of these, more seat time.

 

[shogun32]

Pretty sure one of the diffs I have is a 16 gt350. So that may be helpful

 

[kz]

Btw - Jay (who's JXB) is an autocross who's basically on every national event in this part of the country. The most important person in autocross currently, supplies ice cream for everyone at the event. For free.

I'd buy this carrier bearing thing just because of that (ideally planned QA1 driveshaft but I was too hesitant to spend that money even though it comes with weight savings and reduces some rotational inertia).

@CobaltFilly - with auto shifting is less of an issue - not sure how fast that transmission shifts but you shouldn't lose too much time and it's much harder to fumble 3rd -> 2nd downshift. I'd just avoid gearing when you'd have to upshift and downshift multiple times.

Fastest car/driver in my region is F Street 1/LE Camaro with 10 speed auto (driven by multiple times national champion, last year won XP at Nats) - he's basically always top pax and at times top raw (!!!) and we have competent drivers in much faster cars than F Street 3,800 lb Camaro. He shifts multiple times on course ->

 

[CobaltFilly]

Btw - Jay (who's JXB) is an autocross who's basically on every national event in this part of the country. The most important person in autocross currently, supplies ice cream for everyone at the event. For free.

I'd buy this carrier bearing thing just because of that (ideally planned QA1 driveshaft but I was too hesitant to spend that money even though it comes with weight savings and reduces some rotational inertia).

@CobaltFilly - with auto shifting is less of an issue - not sure how fast that transmission shifts but you shouldn't lose too much time and it's much harder to fumble 3rd -> 2nd downshift. I'd just avoid gearing when you'd have to upshift and downshift multiple times.

Fastest car/driver in my region is F Street 1/LE Camaro with 10 speed auto (driven by multiple times national champion, last year won XP at Nats) - he's basically always top pax and at times top raw (!!!) and we have competent drivers in much faster cars than F Street 3,800 lb Camaro. He shifts multiple times on course ->

With MPT tune, my shifting is much quicker than stock V6 ecu tune. Love the paddles. Downshifts are silky smooth, upshifts far quicker than I could ask.

JXB can have my money. I will buy his bearing.

Will watch the vid, Alessandro (Flyhalf) is the guy I am looking up to currently as the track god of mustang 10r80 auto…so I will do my best to build my TT3 track car and enjoy autocross as it is. Since this is a TT3 build after all I feel…

Thanks for all the input guys!

 

[WItoTX]

Btw - Jay (who's JXB) is an autocross who's basically on every national event in this part of the country. The most important person in autocross currently, supplies ice cream for everyone at the event. For free.

I'd buy this carrier bearing thing just because of that (ideally planned QA1 driveshaft but I was too hesitant to spend that money even though it comes with weight savings and reduces some rotational inertia).

@CobaltFilly - with auto shifting is less of an issue - not sure how fast that transmission shifts but you shouldn't lose too much time and it's much harder to fumble 3rd -> 2nd downshift. I'd just avoid gearing when you'd have to upshift and downshift multiple times.

Fastest car/driver in my region is F Street 1/LE Camaro with 10 speed auto (driven by multiple times national champion, last year won XP at Nats) - he's basically always top pax and at times top raw (!!!) and we have competent drivers in much faster cars than F Street 3,800 lb Camaro. He shifts multiple times on course ->

That's a fast, cam friendly course right there!

 

[mavisky]

That's a fast, cam friendly course right there!

My thoughts exactly.

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