Ok, so I got the new coil springs (full set), the front calipers, 2 v8 motormounts, the panhard bar, a torque arm (I think) back to the house. The front struts/steering linkage/wheels/brake assemblies and clip (he threw it in anways) Way to go Gabe!!

On thinking about the diff inspection earlier today (and after reading up online and finding pics and such) I think it may actually have the posi. Admittedly I'm not sure of everything I was looking at short of finding the 13:42 marked on the ring gear. In looking at posi unit pics, I do recall seeing a large cylindrical housing with windows cast into it and 2 gears spinning on it's insides...I thought a posi was a sealed unit...

does anyone have an installed posi pic?

When I blocked the driveshaft and turned one axle, the other turned in the opposite direction. Does that mean anything?

 

The difference between a factory style posi and an open rear is the little clutch packs on the outer sides of the spider gears. From your description it sounds like an open rear or a worn out posi. A posi isn't sealed, what you described is a basic diff carrier. Only way to tell you for sure is if you could post some pics of it with the cover off.,,

 

Ok, give me like 15-20 mins, I'll have them up.

 

Ok...here batch #1

 

and a couple more angles if it helps....so what's the verdict?

 

If I've researched the different brands correctly and compared pics this looks like a gov-lock diff. Any confirmations?

 

That's a locker if I've ever seen one. Not factory for any f-body of any year, most likely out of a truck or added by someone. The gears are also most likely not stock if someone took the time to swap in a locker, on a positive note that most likely means it's not nearly as old as 86 and the bearings are most likely newer as well. Also lockers don't wear out as clutch style posi's do. They tend to make clunking noises around turns which can be slightly annoying but it should work just fine for you. Edit did you ever figure out the gear ratio?

 

I looked at your above post, that marking may be a tooth count of pinion vs ring gear, if so you have 3.23's
Edit: Just saw you already figured that out on the previous page.. doh

 

Great confirmations on the locker...visually I believe it's a gov-lok, aka grenade-lok, aka gov-bomb...and I thought it was a passive clutch style, open until slip then engage...but kickass, I'm open to any identification frankly I didn't know the thing initially when I looked at it so, what do I know?...as far as the gear ratio...the ring is marked GM 13:42 (3.23), but admittedly I didn't hand count the teeth on either the ring or pinion...I'm confident the ring is 42 teeth by the marking...the guy was told it was a 3.73 limitted slip and by the ring at least it seems a 3.23...but the performance diff is there, are you sure it's a locker and not the gov-lok limitted slip, the pics I looked at were almost dead on. How can I identify it, I didn't see any obvious id numbers as I went over it?

Is it possible the pinion could be upsized to maybe 11 (not 3.73 but 3.82) or 12 (3.5) teeth without changing the ring and is it possible to investigate without ripping the assembly apart?

 

sorry if I confused you at all, I just said locker as in some type of locker weather it be a detroit locker (which it isnt) or a gov-lock (which is looks like). As far as changing just the pinion gear no that's not possible, gear sets are just that sets, if you tried to interchange ring and pinion gears you'd just end up with a bunch of chunks of metal.

 

I was pretty sure the ring/pinion had to be a set, but I'm not experienced enough to say I know that...so yes...at this point I'm going with the idea that it's a 3.23 gear set with a gov-lok diff. cool..disc brakes, identical gear gearing and a gov-lok...definately an upgrade from the drum/open diff. i've got now, but still left hunting for a higher set and an active locking diff., but a good start anyways. For the price, the discs were worth it.

 

That is a GM G80 locking differential (gov-lok) from a truck. S10 used the same center section as the F-body. There is a spring loaded pawl visible in your last pictures that flips out when there is a 100RPM difference between the wheels. You can imagine the shock those two little pivot pins can see on a dry pavement burnout. Hence the grenade lock nickname. Ice and mud with little throttle input is what they are designed for.

I'm running a trak-loc in mine which is more suited to twisty road courses. For quarter mile and street you may want a true Eaton posi limited slip with clutches. For more dedicated quarter mile is the detroit locker but you get the popping on the street. It works the opposite as your G80 in that it starts out locked up and has to pop loose going around a corner.

 

I figured I'd be looking for an active LSD eventually (locked always, then unlocks around corners)...I'm a little worried about the gov-bomb. I figure I'll chalk the diff upgrade into the 'aftermarket performance' build season. This year and probably next I think I should hit the 'performance stock' area. Good on the confirms for the G80, btw, thx...so id-wise It's a J65, G80 but I missed the G92 gearings(3.43s for that year iirc)...I just won't beat on the drivetrain, not that I really could with the V6, , but once the V8 goes in, I'll have to really start looking for something more reliable before I start running down 'stangs

 

For an actual performance rear you should be looking at something with a bigger ring gear then our tiny factory 10 bolts. They are alright for street driving with limited traction, with a good set of sticky tires they arn't too hard to glow to pieces at all. If this is just gonna be a fun street car chances are you'll be ok, if you're looking for something that can take some real abuse look for a 12 bolt or ford 9 inch.

 

Don't get me wrong, I am, but for the price I got it all for ($125), the disc brake conversion alone was worth it, the locker is a bonus, and the front suspension/brakes/clip/steering completes everything I need to at least safely drop in a 400hp V8. I still have to do the work (a couple weeks once the snow melts and temps rise), but I feel like I've got all the parts for the z28 suspension and drivetrain upgrade for this season. Alot of progress for only a little bill. Gotta hook up a different proportioning valve for the brakes but that's my only forseeable additional, I'll pull out of a yard cheap. Makes me smile.

 

yeah it sounds like you got a good deal for the price. The only suspension parts that are different (from a v6 and v8 car) would be the springs and probably the shocks and struts though I'm not sure on that. There are different springs and shock/struts for differen't models z28, iroc, ws6, etc. Either way if they are new or lightly used they will be an upgrade from your worn stock parts for sure, 20 year old springs and struts/shocks should be replaced anyway. If you havn't already add subframe connectors to your list of must haves. Sounds like you're planning everything quite well, I look forward to reading about your progress

 

Thank you , yes SF connectors are on my list somewhere before the engine. The susp/drivetrain was my chief concern. Thx for the planning props. I'm having fun, I've never done stuff like this before so I'm learning as I go, reading alot. Some things seem more obvious than others but so far so good. All help/input is appreciated. I'm building Lucy with love, not just the manuals. I'm seriously proud of her and she takes care of me on the road.

We even got our first speeding ticket the other day, hoping to beat it. Cop didn't see the semi come up on my a** @75 swerving his trailer over the whites on the pike, the other truck that kept me from just changing lanes, and me speeding up a little to get out of the way. Guess that's what happens when he sits at the bottom of a hill around a corner with less a 1/4 mi. visibility up the road from his radar trap. I'm the bad guy for avoiding a dangerous situation because I hit 82 on a road where the average driver goes 80-100. The state will spend more money to get $170 out of me then it's worth by the time I'm done dragging it all out. Anybody got tips?

 

that sucks what state? Normally best thing you can do is just go to traffic court, don't waste money on a lawyer, not worth it at all. Typically they will reduce or drop the points that you would take on your license if you just paid the ticket and happily collect the fine plus court costs and send you on your way. The situation behind it matters little to them, fact is you were speeding and they gotcha. Good luck!

 

-

 

Tax-*******-achusetts. Hate this f*ing place. Yeah, I intend to fight it. And yes, my driving record is spotless 10 years running. I did what I did because I believed it to be the safest course of action and granted I was over the limit, but it certainly wasn't a mph that would qualify as uncontrolled or racing or something. I'd happily pay the fine all day long if it didn't hit my insurance/driving record for the next 7 years. I intend to drag it out one way or the other. No, no lawyer...once all's said and done they'll spend more trying to get the money than the fine is worth and if they stick me with it in the end, then at least I'll take that in satisfaction. I'll update as the process goes along.

 

It's official!!! Lucy is now truly unique. Today it was 60 degrees out and I just couldn't help myself. Hit the Parts store, grabbed wire, parts cleaner, and electrical tape.

Today I installed the 2.8L higher flowing intake onto the 3.1L motor...would you believe she actually sounds quieter??? it required I extend the air sensor wiring about 3 feet, but it's in it's complete (right down to the MAF sensor, though it's disconnected and being used as a spacer right now since the engine has a MAP sensor) and no "check engine light" so....sweet

Does anyone know If I can take advantage of that MAF without reprogramming?
Or if I would even want to? Are there any pros/cons to one as opposed to the other since as I understand they're doing essentially the same things just in different ways, does one do it better than the other?

 

So a 60 degree sunday became wash and clean day. All the tools got organized, interior got completely vacuumed, paint chips got a quick spray. Even her rims got scrubbed. Lucy is looking all pretty

On to rear end prep next...going to spray out the entire housing with parts cleaner and turn it a couple time to get all the old fluid out. Then the chrome cover has got to be de-rusted and cleaned up, need to get a gasket...looking to paint over the axle in black

 

Oh yes, btw....in prep for the drum to disc changeover I know I need to get a different proportioning valve...short of getting lucky enough to find a junked camaro with 4 wheel disc (not holding my breath) and pulling it out of there, should I be able to pull it out of ANY 4 wheel disc GM of approximately close years? (ie. s10s, blazers, cavs, fieros, fbirds, gprixs, etc.)

Other than the prop valve is there anything else I should be looking for the 4 wheel disc conversion?

 

I got a bunch of cleaning done im my garage as well this weeekend, though it was raining.

MAF: No, you can't just connect it to an ECM that isn't programmed for it. MAF engines still have MAP sensors as well. A speed density tune relying on a MAP only makes guesses about how much air is actually flowing through. A tune for a MAF can better deal with small changes such as a better flowing air intake. The supercharged guys often tune out the MAF because it can have trouble following big booste.

Bottom port proportioning from any Camaro or Firebird will be o.k. I don't think one from another vehicle will be close enough. Consider adding an adjustable proportioning to your existing set up and you can exactly dial it in and keep up with any other brake upgrades.
Might need new rear e-brake cables as well.

 

Ok...so it isn't just plug and go, I figured as much but thought it worth inquiring...in that case, in your opinion, is it worthwhile to try and get the thing functional, and are there any easy/cheap ways of doing so seeing as I don't want to dip to much money into a v6 that's on borrowed time and will only be in for another year or so pending any major failures? If it would improve the thing for cheap I'd take the time to do it, but if it'd be expensive and not really affect operation substantially, I'll just move on.

What do you mean by 'bottom port proportioning'? I thought it was a complete unit called a proportioning valve or combination valve? So they are vehicle specific? Adjustable would be great, know where I can find one on a budget? From the shopping I've done stock=~$75, I found only a single adjustable one =$150... ...is there any possiblity I could alter the existing one to function as required (drilling, porting, etc.)?

The axle assembly I have has all the brake hardware and ebrake setup intact...calipers, rotors, ebrake cable though it's slated for a tear down paint and rebuild, would I still need a new cable?

 

So today's project...as New England winter felt the need to rear its ugly head again, I went ahead and pulled the badly rusted over chrome diff cover for rework. Took the chrome polish and with a little info from the internet a bunch of aluminum foil ***** and got all the rust possible off the thing. The foil worked great! Aluminum is apparently softer than chrome and does not scratch, but it's hard enough to make short work of the worst rust. The bubble and edges shined up perfect, but the trough (with the bolt holes) was so badly rusted that the chrome had been mostly eaten away. Taped up the edges and the bubble and gloss blacked the trough (same color the axle and diff. will be after I'm done going through it). Damn it's pretty and was worth the afternoon

 

The proportioning valve is all one piece. What Acclr8n meant was that you can connect the rear brake hard line to the bottom port on your current proportioning valve. The ebrake cables can be re-used as long as they are in good condition AFAIK.

 

Ok...so there are 3 out ports on the existing presumed factory valve then? (Apparently I have to go do an inspection). One for the front, one for the rears, and a bypass-type on the bottom if I understand you correctly?

Safety issue question then, if I plug it into the bottom port (and it's a bypass) what happens if a brake should fail? does it still separate the front/rears so I could still stop the car without a large blunt object or waiting until it rolls out in neutral if I'm lucky through the light/stop sign/corner or other place where I'd go to use the brakes and if failed they won't work?

I didn't think I could just plug it into the existing PV (even in another place) and it would work as intended/safely/better...I wouldn't mind it having better stopping ability (new england so snow/ice stopping is a consideration) seeing as I'm converting it to disc, remembering that the rear is from an 87 but since it shows obvious modification with the gov lock, I should also check for iron vs. alum calipers...going out later today to prep the diff. to be refilled/resealed, have to hit the parts store first though for cleaner, fluids, and gasket.

I do intend to drive this on the street the majority of the time so when it comes to brakes I really want to make sure I do this right.

 

On older car's (my daughter's '84) the rear brake line went into the front of the valve horizontally. On newer ones ( '86 for example) the rear brake hard line came into the valve from the bottom vertically though still towards the front of the unit.

Theoretically possible to alter the existing porting, but I wouldn't know how to do it. Summit Racing has adjustable ones you would install in the rear hard line after the existing drum proportioning valve from $35-132. My neighbor works on Formula Fords and uses fixed proportioning blocks that can be had for $15, but you need to know exactly what you want. I'd get an adjustable.

If your disc brake axle came with the two e-brake cables still attached to the calipers, your golden.

 

The front brakes each get their own port on the proportioning valve. The two smaller ones closer to the firewall. The larger 14mm x 1.5 bottom port towards the head lights supplies both rear brakes fro a T on the axle. If you hook it up the way it is, the rear brakes will lock up faster than the fronts increasing your stopping distance. But the car will stop.

 

Ok...so, starting understanding from the beginning, this might sound like a stupid question but would I be looking to raise or lower rear fluid proportioning? going from 91 drums to 87 (modification to be determined, so assuming iron caliper rear, aluminum caliper fronts) discs?

Adjustable would be great but I'm concerned I might defeat certain safety measures using a inline aftermarket valve...is that reasonable, remembering I don't know too much about this stuff?

sweet.

 

Increasing stopping distance sounds like a bad thing so I don't think I want to do that, if anything I'd want to decrease that without locking the front or rear too soon and skidding/spinning out.

 

Sorry, haven't had a chance to check back yet(busy day at work). There are 3 outlets on the proportioning valve, 1 to each of the front brake calipers, and 1 larger diameter one running with the fuel lines to the back of the car that goes to a splitter valve on top of the diff. From there it goes to each drum/caliper. Iron vs Aluminum calipers shouldn't make a difference as far as the proportioning valve is concerned. I believe only aluminum calipers were used on the back of our cars though if the diff has been swapped in your new rear, who knows what else he changed?

Having the rears lock before the front is BAD. ESPECIALLY if you will be driving in snow/ice. Ever done donuts before in an empty parking lot? You know, get going to a decent speed, then yank on the ebrake? Lots of fun when you want it to happen, scary as hell when you don't. That's why you don't want the rears locking up first, and that is what the proportioning valve is designed to do.

AFAIK, the proportioning valve on yours would be the same whether it came from the factory with disc rears or drums. Acclr8n can double-check me on that.

The adjustable proportioning valve is useful when the rears do lock up before the fronts so you can adjust the line pressure to the rear down, which would send them less pressure so they would be less likely to lock up. You could even dial the pressure up/down based on driving conditions or your intended driving habits for that trip. Like running to the parts store vs. autocrossing.

Turning the rear brake pressure down too far will increase your stopping distance because the rear brakes won't be helping to stop the car as much. However cars are set up so that the majority of the braking power is in the front brakes. That's why the fronts always get discs these days and the rears can get either. That being said, having the rears lock up won't decrease your braking distance. All it will do is create a dangerous situation like I mentioned above and/or put a flat spot on the tires as they are dragged to a stop.

You won't be able to defeat any safety measures built into the brake system. They are built into the master cylinder. As long as you don't change that, you will be fine. You would be using the adjustable valve after the OEM valve.

 

I should be able to tell that as I go through the rebuild. I read another thread on this board where early 3gens had iron, and then they switch mid-gen to pbr alums and they went into great depth with prop valve concerns about alums requiring less pressure than iron and in some cases they could be swapped over directly without changing the PV...

That much I think I knew...hence my safety concerns. But thanks for the confirm.

That'd be terrific, shouldn't that mean that I can just hook it up and go? I really didn't think I could just do that...two different years to remember 87 discs, 91 discs, 91 PV....I thought drums required different pressure than discs though.

Right...I did get the idea that adjustable means flexible, factory means static.

Got that much too...definately don't want rear lock up, I'd like them to work in proper proportion for the shortest safest optimum stopping distance.

So...If I understand correctly...once I change over...too much pressure will be going to the rear calipers and the adjustable valve inline AFTER the factory valve will be used to dial that pressure down because calipers require less pressure than drums?....or do I have that backwards as in too little pressure will be going to the rears and the adjustable valve will be used to dial up the rear pressure to compensate

what I'm thinking is that if the factory valve is split 45% rear drum and 55% front disc and that's static then the aftermarket inline adjustable valve (of which I would only need one?) would adjust from there just for the rear, and would it do this without changing the front pressure?

 

So after shopping for and reading up on inline adjustable prop valves they appear to only be capable of reducing the inlet pressure from full in to ~57%. Presuming the factory valve puts out the 45% exampled earlier then full would mean 45% pressure and with the adjustable valve I could dial that down to about 20%. So I take that to mean I trying to reduce pressure to the rear because calipers require less pressure overall than drums. So with the adjustable inline valve after the factory PV that would give me bias range from factory (45%/55% in my example, I know that's not a real number) to heavy front bias (20%/80% in my example, I know that's not a real number either)...trying to get the concept here

....basically the rear pressure needs to go down after I change over to discs because calipers require less pressure than drums?

 

Sorry if some of the answers sounded a bit condescending, I'm trying to type this at work so it doesn't have my full attention. I also talk to morons all day long(Internet Tech Support) so it tends to bleed into my posts I think.

To be honest, I'm not sure of the exact pressure numbers required by discs vs drums or iron vs aluminum calipers. I believe disc requires higher pressure, but don't quote me on that. I could see the reasoning behind aluminum being able to tolerate less pressure than iron, but I don't know for sure.

I tried looking up proportioning valve part numbers on Autozone, Advance Auto, and Summit's sites and nobody carries them apparently. I'll try GM's site to see if the part numbers are the same. If they are, then I wouldn't worry about using the one you have.

As far as I understand how an adjustable valve functions it valve would only be able to reduce the pressure, not increase it. In reducing the pressure to the rear, it doesn't really increase the pressure to the front. It increases the ratio braking power front to rear. If you have a 45%rrear/55%front split and you close the adjustable valve halfway, your braking ratio now is closer to 2.5%rear/77.5%front.

Adjusting a valve connected inline between the proportioning valve and the rear brakes won't affect pressure going to the front brakes, no. They are a separate circuit from the rears.

 

You basically just forced me to scrap my whole last post. Trying to work and post again. Anyhow, it sounds like you got the idea. The pressures don't really change in the front brakes, they just do more of the work. The rears see less fluid and therefore do less work.

 

Sorta-kinda. You stomp on the peddle and displace X amount of fluid. The car pitches forward planting more weight on the front, hence bigger better brakes up front. Drums require a higher volume of fluid to operate so a drum proportioning valve sends more fluid to the rear than a 4 wheel disk brake valve. Ideally the brakes all lock up at the same time even though the fronts are doing more of the work. As long as the added in adjustable valve isn't leaking and is adjusted it is not hurting any factory safety features. The adjustable valve is reducing the flow of fluid to the rear so more of your peddle effort can go to the front. The factory valves are tuned within tolerance parameters (not perfect for each car) for the specific vehicle. Rotor sizes, caliper piston sizes, length and size of all the brake lines. Switching from the factory 6mm front to rear line to more common aftermarket 1/4" line (6.35mm) can through off your proportioning. All that said there are plenty of people running drum p. valves with 4 wheel disk conversions. You don't daily drive your car to impending lock-up at each stop I hope.

More stop for less stomp.

 

No sweat...I'm no car expert so assuming I know something in particular is just not giving me info. Professionally, I'm a Server/Network/Desktop Engineer with a degree in Programming....I've done my fair share of support calls starting in helpdesk, though thankfully I get alot less stupid people in Tier III+ working on backend technologies.

That's what I'm trying to get a handle on...does the rear pressure need to increase or decrease? Exactly how much is a whole different question.

That would definately be a plus. I also know of a few junk yard parts cars I may be able to pull different years/stock setups (no 4 wheel discs though)

That's what I got from my shopping...

ok, that's good, now if I can work out whether the rear needs to increase/decrease....

 

Right, I feel like they should be doing the 'right' amount of work. I need to know if I should be dialing it down for rear calipers as opposed to drums...

 

Ok...so I need to dial the rear down because the drums prop valve puts more pressure than the calipers need and If I just swapped it over direct I could potentially put the calipers over the 'rear lockup first line'.

That assuring...I just don't want to do something that'll cause a problem when I least expect it...you don't really know about a brake problem until you're trying to stop and suddenly the car won't, I can't think of a circumstance that I would go to hit the brakes and it wouldn't be a disaster for them to not work.

So without the valve the braking curve will shift to the rear and I want to shift it back towards the front...do I understand that correctly?

No...but I want to make sure that those few and far between occassions when I do...I can...safely...

 

Ok, so now...shopping for an adjustable prop valve for the larger rear outlet port...looking over summit...there seem to be some varying options....
1/8th NPT
10mm X 1.0
3/8-24 in. Inverted flare


Now from ACCELR8N post earlier the outlet port is 14mm X 1.5 (cm?mm?)...none of these seem to match up directly...

I'm presuming the 10mmX1.0 is too small as at least the numbers are in the same format...metric to english conversion on 14mmx1.5cm gives me .55118 in X .59055 in (oval?)...the 1/8th NPT converts to 3.175mm and 3/8th is 17.145mm...or is that some sort of standard line diameter sold based on threading size? and the threading size is what I need to know?

 

gmpartsdirect.com lists the part as "metering valve". From the catalog button, select year etc., brakes, brake hydraulics. $68.99 plus shipping.

 

Ok...well that looks like a whole prop valve...the listing doesn't tell me anything about the part specs though...

 

It would be a stock non-adjustable valve.

 

Ok...that costs me the ability to adjust. isn't that a bad thing as I modify the vehicle, the weight changes from factory stock....in the long run, doesn't the adjustable valve give me tuning ability I wouldn't have otherwise to make it work better as I move away from factory stock?

 

I think I have a new problem now with the rear end rebuild portion of this (still a bit away from actually installing the thing)...I'm having trouble locating the filler hole on the diff. I think I found something that looks like it should be, but it has nothing to stop the diff with and appear to open up into the left axle shaft (is there separate axle fluid involved?) but it isn't threaded for a bolt or anything....if that is the filler hole, then what do I plug it with.

 

that's the fill hole, the differential and the axles share the same lubricant. It should have a pipe thread plug in it, its 1/2 npt I think.. don't quote me on that..

 

the inside of the thing is smooth...no threadings of any kind, I don't want to tap the thing and get metal shavings inside...

 

I believe what you circled is the breather hole. You're missing the breather valve.

The fill hole is on the side, screws in horizontally. Should be a 3/8" square hole into which you put a 3/8" drive extension on a ratchet.