Brit dex

Hi all,
I’ve done some searches, but not finding quite what I’m after.. so apologies as this is very new for me..
As title suggests just wondering if anyone is running with the std auto box?
I was thinking of factoring in cost wise a rebuild of the box, but just using it and see what happens!!

I have a 99 Auto, and considering a pro charger or similar ( so no bonnet mods)
Car is a pure pleasure, fine weather weekend fun car, it will not be going down the strip, It will not be
Used for track days etc, its purely to open up once in a while for that added grin factor.. and nice to make a point
To people when they buzz about your car trying to push you!! ;-)

Been talking to a few people on their opinions, but no one has any real experience.. I’m getting responses such as
It will go and break straight away, or might never go at all.. to if intended use is as I have stated, should be OK.. main pressure point comes
Dumping all the power through in style of quarter mile.. if its fed in not as bad..??

I have no experience of these things, I love my car currently, and its great fun but there are times would like bit more grunt..
But not excessive. I think what a charger will give is about the max I would like to go to.. I’m not chasing HP figures, just driving fun..
I guess it boils down to how you drive it ultimately.

Is there any advisory things to do if I did this…
extra cooling on the auto box? ( if that’s possible, think I have seen threads on this)
maybe a trans temp gauge to keep an eye on it?
Or other things that might help?

I’m in the UK so access to experts and actually seeing a charged one close up is difficult..
There is a local company who do know C5’s willing to fit the kit, and I do trust them as they have done lots on my car, and have a lot of experience with Vettes, and I’ve used them for a good few years
The box would be another job for a specialist if it needed doing

Forcedvert

What rear gears do you have? A 342 feels like a sc (kinda) if you are at 283 and it's cheaper and safer. You could always go sc after that if you want more. My auto lasted 3 mo of drive time with sc but I was not easy on it.

Brit dex

Hi forced vert
Thanks for the response... I'm not sure what I have it's a stock trans..
Is there a way of checking?

So are you suggesting upgrading the trans first and get some gains from that? Interesting !
Never thought of that.. Car has custom exhaust.. Full system, upgrade throttle body, air intake etc.. So it might be a good first step addition?
Is it a big job to do?

Thanks

Forcedvert

I was talking rear differential gears, theres a tread that explains how to check on highway at 70 mph... I think on a4 the rpm in 3rd gear at 70 is gear ratio? Most a4's have 283. A 342 is a great upgrade.....better still with a little stall converter.

donald4972

OP,
If you have A4 transmission, you probably have the 2.73 or 3.15 gears in the rear differential. Unless a previous owner changed them, that is. There is a list of options on your car, on the glove box door which will tell you by code, which differential your car came with, from the factory.

Many have SuperCharged C5's, and run many thousands of miles, with no problems with A4 transmission; myself included. I just got new fluid, filter, and installed a transmission cooler.

You can find guys with built transmissions, who 'lose' them when racing. There's always that risk. You can also find guys who did not SuperCharge, who break things too. Just is what it is....

I installed the SuperCharger, and went from 2.73 gears to Z06 3.42 rear differential. Along with the transmission cooler. No problems, no regrets. If something breaks, I'll just get it fixed.

You will love the power, of a SuperCharged C5 Corvette though, I assure you of that !!! If you've never driven a SuperCharged Corvette, you can not imagine the power and torque these things have.

Don

Forcedvert

I'm such a dork.... I meant 273 ^^^^^ he is correct, but you can check them in 3rd gear I'm sure I read that somewhere. I would never talk anyone out of a sc that has money to spend, I would love to know just how many break as apposed to how many that hold together? And I would agree driving style has a lot to do with it! .....That gear (342) ratio is a good choice for the centri supercharger or just for driving stock... it's a big difference in quickness. I know because I did that first. I don't think you can go wrong doing that first imo. But hey, if you got the cash, do it all at once. Just be warned... its hard to keep your foot out of it.

Ps I took out motor also, all on the street, but I was not afraid to push it knowing I could be in for major expense, to me it's all part of modifying these cars, having fun. Just look around on this forum you will find all the answers you want. Great guys with lots of knowledge, like Donanld4972 correcting my mistake about the stock gears.

Brit dex

Thanks Don / forcedvert
Really appreciated.. As I say over here we gave limited options.. I'm really lucky to have local guys.. Who do great work and love vettes.. I wouldn't tackle this work myself..
I think I have more thinking to do.. I do think my car will be totally stock but I will check..
Interesting that changing this has such an impact.. Maybe I do this first then SC next!

So what rough cost is it for going to 3.42 gears and a cooler? Is it a big job?

Thanks again..

Forcedvert

Labor I'm not recalling but differential (whole pumpkin complete) was about $1600 plus freight and core from tranzilla, you will also need something to calibrate shift points as all that will change, I did a asto van stall converter at same time (little higher stall speed). My car went from not being able to spin tires from a stop (Michelin ps2) to being able to spin all the way through first and well into second gear at will. Coolers are cheap.

Brit dex

Ok thank you ... Need to try to find someone over here to do that!
Did you put upgraded shafts in at the same time ?

Cutlassmaster

There are a lot of variables to consider on your question. Miles on the transmission, prior services to it, how its been driven and so on. There are many people that have not touched their trans and been fine. Many that broke it and needed to be rebuilt. I have had my supercharger on for just under 2 years and about 10K miles. Car currently has 74K miles on it. I bought it with 41K miles and replaced filter, added a cooler, another screw on external filter and started car to pump remaining fluid out while adding it to the pan. Probably replaced in the 90+ % of it by doing that. I run the amsoil fluid and noticed a difference right away in the shifting. I then modified the shift pressures and time for a quicker and more solid shift. I have been to the track and ran it maybe 5 runs. A couple of runs over 130 mph and some spirited driving here and there. Besides amsoil fluid in the differential, that is untouched. So far no issues and I will wait until the day comes when it stops working. It could be tomorrow or it could be 10 years from now. Hope you the best of luck in your decision on what to do.
Chris

Forcedvert

I did not and maybe should have but have had no problems so far, when I did upgrade to 342 I was not sure I wanted sc. If I did it over I would have went that way. Also Poly couplers and good aftermarket torq converter, I wasted money on stock couplers and astro van tc. But who knew I would become obsessed.
Good luck!
Adam

Brit dex

Thanks Chris
Mine is actually like yours! Bout at 45k miles, currently under about 60k.. Have trans fund replaced..mind do open her up when out.. But don't thrash all the time... I guess what I don't know is how she was driven up to 45k.. I have an SCT chip which moved shifting points and did make a difference.. Certainly a cooler wouldn't go amiss and maybe a trans temp gauge to keep an eye on it..

Brit dex

Thanks Adam
May check costs on shafts, if it's already apart maybe worth looking at then..

Cutlassmaster

Does yours not show trans temp? You should be able to scroll through oil pressure, oil temp, coolant temp, trans temp..... using the buttons near your gauges.
Chris

Brit dex

Cheers Chris

alxltd1

So after you determine what differential gear ratio you currently have, here is a link to upgrading the internals of the differential to C6 Z06 parts:
https://www.corvetteforum.com/forums...-z06-guts.html

Now if you find that you have the stock 2:73 gears and want to upgrade to say 3:42 and also upgrade the internals, then a better option would be to purchase an entire completely assembled differential in 3:42 from one of the forum vendors. You can have it built with all the upgraded options and any gear ratio that pleases you. The point being that it takes knowledge, skill and special tools to change the ring and pinion gear in your existing differential case and have it function without whine or wear issues if it is not set up correctly. Good luck.

Brit dex

Many thanks for the info