CamaroRS385hp

i need something to tide me over until i swap out my engine for a vette engine/tranny this summer. i'm all about acceleration, dont really care about top speed. what's the highest gears i can put in my car and still have it be able to drive on the highway fine? i'll prob. get 3.73's, but if i can get higher gears and still be able to do fine on the highways then i'll get those. i drive 560 miles about once a month on the highway (from college to home and back), average about 75-80mph. what should i get??

Nixon1

4.11's will do ya fine on the highway. I have a 4.10 rear in my V8 and it does fine on the highway, just turns quite a few rpms in top gear..between 2500 and 3000 normal speed. BUT 4.11's suck gas pretty bad so be aware of that! 3.73 is a great compromise rear end.

Just re-reading that...don't get the 4.11's if you're doing that kind of highway miles a month...that's too much to justify having gearing that deep. 3.42 or 3.73 sounds like the ticket to me.

89' RS/blue

I would go with 3.42 or 3.73 gears. there is not much difference between the two, but noticeable. If your car is a stick you've already got 3.42 gears, if its an automatic you've got 3.23 gears. yeah 3.42 or 3.73 are good, anything deeper than that would be bad considering how much you drive on the highway.

CamaroRS385hp

thanks for the input..i got automatic, and i guess i'll be goin for the 3.73's, thanks yall...also, what's the best/one of the best brands to get if a couple places make them?

Keoki_Firebird89

i'd like to know how much those gears cost?

V6camaroman

i have an automatic in my bird and ive got 3:42 gears. im eventually gonna have the rear end rebuilt. is it worth swaping from 3:42 gears to 3:73's. will i feel a difference or should i swap to 4:10's. can someone look at my mods in my sig and help me make a choice. which would be better for my car? 3:73's or 4:10's

pontiacguy1

If I were you, I would go with the 3.73 gears, or I would just leave it alone. The change from 3.23 to 3.42 isn't that big of a step and won't produce that much change for the amount of money it will take you to swap them out properly. The Automatic tranny has a .7:1 overdrive, which means that with a 25 inch tall tire, you will be turning approximately 1850 RPM in overdrive with your current 3.23 gears at 60 MPH. With the 3.73 gears, you will be turning approximately 2100 RPMs in overdrive at 60 MPH. I don't think that 300 additional RPM at 60 MPH is going to make that much difference. That won't be but a 400 RPM difference at 80 MPH in overdrive. It may cut a mile per gallon off of your car, but I would think that won't be too much of a price to pay for a little extra oomph down low.

redraif

Automatic cars should not go past 3.73s...it is too much gear. I have a 3.42 drum brake rear in my Auto now and I am swapping to a 3.73 disc brake rear...used, but it will give me some oomph down low which I need with the cam...If all goes well it will be in this weekend!

Nixon1

red....it's a posi right? I haven't heard recent times on your ride...put up a post after you run it with the rear in, I'd love to hear what it runs now! Did you get all the kinks worked out? Last I heard you were having some issues, although I can't quite remember what they were.

redraif

I swear my car is a rolling issue...timing was the problem. It was at 22...we changed the balancer and believe it or not my old one was fine...rubber a bit cracked up, but dead on...so on to Joe's theory...spark scatter. Well It turns out I did have too much endplay in the distributer. twice as much as I should...so fixed that with shims... Put ti back in the car set the timing and pop blaew out the rear main seal (we think) So tranny is coming out. Shift kit is going in & a new higher stall torque convertor! Alsdo got a performance chip...

The rear end we were going to build, but there was no time and Hawks had a 3.73 disc brake rear at his place. We are getting it. Its not a posi though. That can be fixed, but instead of building the rearend to find out it was not worth while enough, we figured this would be better. The gears I had for the other disc brake rear were 3.42s. Money & time worked out better to get this rear and not to have to build the other just yet! Depending on how things work out...Raif will get a 3.8 turbo TA motor, (when we find one) and the LT1 will go in the 82. So now I will have a spare discbrake rear. Now we just have to decide if the turbo motor will be better suited with which gears (3.42s or 3.73s) and that is how we will build the other disc rearend...

AGood2.8

I must be the only one to go down in gear. Went from a 3.42 down to 3.23's and gave me alot better power range in 2nd and 3rd gears. Car drives much better for mild to hard street use. I am putting out more power than stock though. Remember before yopu make any changes that the V8 cars are running 3.08's and 2.73's from the factory- why- because they have more power to pull the gears. Going up in gears makes the straight line exceleration barely quicker but you loose gear range in cornering and such- the car becomes more twitchy in and out of gears causing potential traction loss.

TomP

Actually I think you mean a lower gear... 3.73 is lower than a 3.42 gear.

When I went from 3.42's to 3.73's, it made a hell of an improvement. Never even noticed if I was spending more money on gas or not... but then again, I've never paid attention to that unless I'm driving from state-to-state. My car's always sucked on gas around town.

Red, remember that the 82-88 rear discs were recalled. You'll need to put the recall kit in to use those calipers; search the suspension/chassis/brakes forum for 'rear disc recall' for the messages and part #s.

Cost-wise; if you guys are tossing around the idea of having 3.73's and a posi put in, or, swapping to a disc rear from 82-85, have the new parts put in. I spent over $600 getting my rear axle to work correctly; including the purchase of the axle, m/c, and prop valve... not to mention all the time wasted on getting a bad m/c, fighting trapped air, and gallons of brake fluid. Plus, the '84 posi is really an Eaton gov-lock locker, and likes to blow up. I thought I was safe because I had a v6... nope... the locker died it's usual death. So I'm back on a junkyard 88 v6's 3.42/open/drum ... which means I have to buy a posi, and if I get a posi for 28 spline axleshafts, I have to buy 28 splline axleshafts (90-up). It's one big money pit.

redraif

Hey Tom 2 quick questions for you... I'm not supposed to be on the computer at work so I'm sneaking this in...

When you swapped rearends did you change your proportioning valve or master cylinder?

Also did you correct your speedo? If so what color is the gear and how many teeth?

TomP

LOL... if this wasn't the v6 board, I'd have a quick answer of "Yep, changed the m/c and prop valve, and didn't change the speedo."

But since this is for us V6 guys, I won't say "do a search!", and I'll go deeper. (But do a search anyway on the suspension/chassis/brakes board, you'll find a load of messages by me on this.)

J50 is the RPO for rear drums, J65 is the RPO for rear discs. These are written on the bottom of the master cylinder's base. Early m/c's were cast iron; later models were aluminum- aluminum won't let the m/c rust due to water absorption of the brake fluid, but, you can't hone out an aluminum m/c to repair a gouge; it has a protective coating.

Anyway, the J65 master cylinder was used from 82-88 for rear discs. The J50 master cylinder was used from 82-88 for rear drums. The J50 was used from 89-92 for both brake systems. Apeiron dug up an old service bulletin for us that addressed customer complaints about "brake pedal too hard to push". GM said that the J50 m/c could be installed in place of the J65.

The J65 has an inch diameter bore, the J50 has a 24mm bore. GM used the J65 to give "performance drivers" a better pedal feel for the brakes. Of course, the idiots that complained didn't want better pedal response; they just wanted easy brakes. (Should've been driving volvos, I suppose.) So GM said it's 100% okay to use a J50 on a 4 wheel disc car- so you don't Have to swap m/c's.

The prop valve is different, I swapped the one in from the donor car. You can buy them new, too, from GM, for $80. There's a difference between 82-84 and 86-92 prop valves. (I'm not sure where '85 falls.) Early prop valves had the rear brake line enter from the front of the prop valve. Later 86-up valves had the rear brake line enter from the bottom. I had an '84 prop valve, and no way was I going to re-bend that line to try to make it stretch to the front of the prop valve. So I got a front-to-rear brake line for $5 out of a junkyard, and swapped the whole sucker in.

People take the prop valve apart and replace springs and stuff to "fix" the 82-88 rear discs, but they're fixing it improperly. The 82-88 discs should have the recall parts installed to get the correct fix.

I didn't correct my speedo; with the effect my old larger tires (P275/60r15) had on my effective rear gear ratio, my speedo came closer to being correct. Now I'm on normal tires, P245/60r15's, and might have to correct the speedo when I put the 3.73's back underneath. I might not, though... it'd be good insurance against speeding. (Speedo will read faster than what I'm actually doing.)

redraif

Cool thanks...believe it or not my boss walked out the door to leave early about 30 min after I posted. Sooo, I have spent the day looking at "search" posts.

I'm gonna grab that prop valve when I get the rear and keep my current disc/drum MC (J50). After all I polished the darn thing! Also, even if this prop valve is bad, I have a spare prop valve from the other 84 disc rear I got last year. Gears were shot or it would have been in by now.

We are going to get the VIN and see if the rear was fixed by GM if not we will either fix it with the recall or replace with the 4th gen disc set up on. Time and $ will play that factor.

Thanks for the info! You rock!

Chevy dealer does list that Recall kit. They have to order it from MI... They said they have never had an order for it if you can believe it?

AGood2.8

The prop valve( actually labeled as: combination valve) that you want is #14089496 1LE combo valve for pre-'89 vehicles with 4-wheel disc. I did this convertion a few years back from drum to disc and have driven with both the J50 vlave and the J65 valve (both with the J50 M/C). The J65 combo valve performs much better.
P.s here's a pic of my rear axle with Auburn posi, 3.23 gears and preloaded alum diff cover.

redraif

Cool. Thanks for the info! I just wanted to know what to expect since we are doing the swap tomorrow & have to have it to the track on Sunday for our club event.

CamaroRS385hp

just wondering...

did all 3rd gens come with drums? if they did, (or if my 92 rs has drums), would switchin to disc brakes make less brake dust? my front wheels collect break dust FAST, and it's a pain to go out there every couple days and spend like 30 min. cleanin out every little crack and crevice the dust got in.

AGood2.8

Not if you run Minimal Dust Street/Track brake pads. Most of the guys on this forum seem to run EBC Green stuff pads. Stillen sells carbon Metal-matrix pads on there site which are still alot better than standard over the counter brake pads and EBC pads.
Try Tirerack for EBC pads.

CamaroRS385hp

Thanks, yeah those are pretty good prices. I got stock front replacements for $60 at a dealership, and these are just a little more.

TomP

Wow... $60... just paid $30 or so for my set of Bendix MKD-154's for the front.

CamaroRS385hp

oops, the brakes were only $19.71...I guess they gave me pretty crappy brakes. Labor was $120 though for 2 hours, but it was covered under a brake warranty I had. woulda done them myself just so i could learn how to do them in the future, but i didn't have any jack stands and since it was covered by the warranty i just brought it there.