five7kid

iTrader: (14)

I have a complete set of LS1 brakes, including fronts, rears, master/booster/combo valve that I've had for awhile but haven't gotten around to installing on my '82 Berlinetta. However, I picked up a Moser 12-bolt last year that had been in a '95 LT1 car with factory brakes (he got it to 3rd gen length, for some reason). He was upgrading the rear in his '95 and sold the Moser to me with the LT1 brakes. It doesn't work so well with the '82 factory front disks, as you might imagine.

So I'm finally getting around to installing the LS1 on the fronts using Big Brake Upgrade hubs & brackets (modifying my own spindles). I'm under a bit of a time crunch, though, and was wondering if the LT1 brakes on the Moser axle will play well with the LS1 fronts using the LS1 master and combo valve. Or, should I just bite the bullet and do the LS1 rears while I'm at it.

Up to this point I've only used factory brakes on my 3rd gens, so this is my first venture into bigger brakes.

sofakingdom

iTrader: (1)

Can't see why they wouldn't be... the LS1 rears were pretty much the same as the LT1 ones except that they went to the "drum in hat" style of parking brake. Service brakes are largely the same though.

five7kid

iTrader: (14)

What I figured, but I didn't have piston size, etc.

I also understand LT1 brakes work better if the parking brake is used regularly. I don't have cables for it, but I do have cables for the LS1 brakes (which don't have that issue) - a parking brake is a nice thing to have, in my opinion.

Only other concern is if 15" rims fit over the LS1s. I'd like to stick with 15" if possible, but could go to 16" if necessary.

QwkTrip

iTrader: (22)

I don't know for sure, but I think the LT1 are 40 mm piston while the LS1 is 45 mm piston. A lot of people, including me, find the LT1 rear brakes to be really weak and require a lot of line pressure to make them contribute. I will always wonder what would have happened if I had gotten the Wilwood brakes instead.

A 12 bolt with c-clip eliminators has pretty limited brake options. Might want to sort out what is possible before you order parts because a lot of stuff won't work. That is the main reason I have never changed my rear brakes.

five7kid

iTrader: (14)

Well, I won't be ordering stuff, for the rear it's either the LS1s (that I probably won't be installing right now), or the LT1s that are already on there.

I honestly don't know if the 12-bolt has C-clip eliminators, as I bought it used and assembled (including the LT1 brakes). And I was dealing with "Dad", not the car owner who originally ordered and installed the rear (hey, it was sitting in Dad's garage, he wanted it out of the way...). I just attached it, added fluids, and started running it.

I spent most of this evening rummaging through the storage unit looking for the front brake parts. I thought I knew which pile it was under, but found the box with the rears first. More digging and I found the booster and master cylinder. Then I remembered the car it came from was ABS, no combo valve (same car as the engine & transmission came from - got the whole cradle, and they threw in the master, booster, and ABS unit). Finally found the front calipers and brackets (and 4th gen hubs), but no rotors. What can I say, it was back in 2009 when I got all this stuff - memory is getting fuzzy.

I'm assuming the LS master is the best choice. Now I'm wondering if the 3rd gen disc/disc combo valve will work. If not, I'm probably going to have to go with an adjustable proportioning valve.

Project creep. Oh, well, I have until next Friday to get it together...

QwkTrip

iTrader: (22)

I think c-clip eliminator is visually identifiable by the end flange on the axle tube. I'm not educated on the specifics of that, but I believe my 12 bolt has a Ford flange on it.

daferris

iTrader: (8)

On my car I have LS1's all the way around with the 1NCF2 spring.


https://www.thirdgen.org/forums/brak...e-upgrade.html


The car is very well balanced with only once in the last 2 years of track days did the rears come on too hard compared to the fronts.


That said I think but not sure the only difference between the external size of the LS1 vs. LT1 rear calipers. Is that the LT1's use parking brake mounted below the caliper and the LS1's use a rotor with an internal drum. A thought is to get a re-man LS caliper from the likes of Advance or Auto Zone to see if it mounts up. If it doesn't then you could just return it...I think the rotor thickness is the same again I do not know for sure but I can measure an LS one and post it. The draw back is that you would lose your parking brake. On a stick car that's an issue on an Auto one not so much... Just an Idea. If you stick with LT1 calipers with the smaller pistons the 1NCF2 spring would be a big help. I see no reason assuming the third gen master and proportioning valve are in good shape that you would need to use the 4th gen stuff. The 4th gen uses the ABS brake block as a proportioning valve as well and that causes issues unless you swap in all of the ABS sensors ect...

five7kid

iTrader: (14)

Does that include the LS1 master cylinder?

The car is mainly used in drag racing, although it is driven to the track. More rear brake action is preferred, as we run in footbrake classes, and good rear brake hold helps avoid starting line creep as you go up on the converter. For whatever reason I haven't had much success with an adjustable valve in the past; may be me, though.

Well, I don't have to buy a caliper to do a fit check - I'll just take it out of the box with the rest of the rear LS1 brake stuff and find out...

I'm assuming the LS1/LT1 calipers require more volume than the '82 3rd gen calipers. I may be mistaken in that, as I haven't compared them side-to-side yet. But if the extra braking power comes from the larger rotors, it makes sense that the 3rd gen master & prop valve will work (and mine were new last year when I went from the drum 3rd gen 10-bolt to the disc Moser 12-bolt).

Why would I lose parking brake? Moser makes no mention on their website that stock LS1 brakes won't fit. I have all of the LS1 brake parts - rotors, calipers, brackets, park brake shoes, park brake cables, even the park brake handle. What I recall is that it all swaps over to a 3rd gen.

Yeah, I finally figured that out. Wondered about just putting the block in, but assumed it wouldn't work well without the electronics active.

Thanks for your input. Brakes are not my forte. I haven't been happy with this car's brakes since 1999, about time I get them right.

daferris

iTrader: (8)

I am using all 3rd gen 1988 stuff for the master and proportioning valve.
If the LS1's do have bigger pistons (I do not know as I have never used the LT1 versions) might be worth the upgrade. I bought all 4 (Front & Rear) calipers for less than $200 after getting the core charge back with the TRT30 Advance Auto coupon.
The difference in the parking brake is the LS1 uses a completely separate 8" +- (I never measured it drum brake that is between the axle flange and the rotor surface.
The LT1 parking brake has a lever mounted external to the caliper that contacts one of the brake pads to clamp it to the rotor surface.
I had the old useless iron rear discs on my car before and can tell you that it is UNREAL how much better the car stops now. For rotors and pads I just use the E-Bay Brakemotive drilled and slotted ones and just replace them every year the rears are still fine but the fronts are toast but that's with 3-4 track days and about 3-4000 miles it's like $180+- for 4 rotors and front and rear pads

five7kid

iTrader: (14)

You don't have excessive pedal travel, right?

Assuming there are no big differences between '82 disc/disc and '88 disc/disc other than the SAE vs metric fittings, I should be okay then.

Not having them side-by-side right now, the LS1 piston doesn't look all that big to me, but not sure I could tell the difference between 40mm and 45mm by sight.

Since the question has been brought up, I'm also trying to ascertain whether the LS1s will fit the Moser 12-bolt. Their website for the '93-'02 12-bolt doesn't distinguish between LT1 and LS1, just has "stock" for brake options. So if they'll fit, I'll eventually go for the LS1s I have just because I have all the parts. If for whatever reason they don't fit, I'll stick with the LT1s on there now.

But I don't think I'll have enough time to do both fronts and backs in this shot.

I understand the difference. Just didn't understand your earlier statement that I'd lose parking brakes. I don't have parking brakes now because the seller of the 12-bolt didn't include the cables, and I haven't bought cables for the LT1 brakes because I've always assumed I'd switch to the LS1 rears eventually, for which I do have the cables.

I had '82/'83 rear discs on my LS1/T56 car with 9". I actually got the LS1 rears for it because of a wild idea I had about eliminating the torque arm (which didn't pan out). I later got the fronts when I picked up the LS1/4L60E for this car.

So I've had these LS1 brakes since 2009, just never had enough motivation to get it all converted. I'm finally motivated, as the '82 front discs just don't play well with the LT1 rear discs.

five7kid

iTrader: (14)

The Moser website says c-clip eliminators are optional with 30-spline axles, but required with 33- and 35-spline. I believe mine is 30-spline (probably the reason they were upgrading and selling it - they were getting into the small-tire heads-up stuff), but since it was a race-only car, they may have done the eliminators. However, the Moser site doesn't say anything about non-stock brakes being required with the eliminators.

Eventually I'll pull it apart and look...

QwkTrip

iTrader: (22)

The only thing about a master cylinder that matters is the piston bore diameter. A smaller bore will cause a longer pedal stroke and make the brake pedal feel softer. A larger bore will cause a shorter pedal stroke and increase effort to push the brake pedal.

If I remember right, a 4th gen LS1 master cylinder has a 24 mm straight bore. Can't remember what your '82 has but it is within 1 or 2 mm bore size. Basically, you won't feel hardly any difference between each master cylinder.

five7kid

iTrader: (14)

That's what I was getting at. I've fussed trying to get the right bore diameter on another car with non-factory brakes. Rather frustrating.

Hope so.

five7kid

iTrader: (14)

Oh, daferris, I also ordered 1NCF2 and 1NCF5 springs. Should be here Monday; too late for tomorrow's racing, but I'm not sure I'll get the LS1 fronts on before tomorrow, either. Also thinking the spring change may help my manual disc/drum brakes on the '57, which have frustrated me for going on 3 years now (including the aforementioned MC bore size fussing).

daferris

iTrader: (8)

On my car with the stock 4 wheel disc MC I notice no real difference in pedal travel. As to the parking brake it's more a function of if you used LS calipers with LT1 rotors you would not have provision's for a parking brake ( no internal drum and no mounting boss for an lt style parking brake)

five7kid

iTrader: (14)

Good to know, because that has been my main phobia all along.

No, that's not what I would consider. If I switch to LS brakes, it will be a complete swap. If I can't do a complete swap for whatever reason, I would keep the LT1 brakes (because I already know now that they fit), and get the parking brake functioning by doing whatever needs to be done - the actuation levers are on the calipers, I just don't currently have cables. Haven't seen what is required to get LT1 park brakes working in a 3rd gen, or if anything special is needed to get it done (were any 3rd gen rear discs like LT1 rears?).

Thanks for your inputs. Like I said, brakes aren't my forte.

daferris

iTrader: (8)

I have to think for cables get 4th gen LT1 cables I am running 4th gen LS1 cables on my LS1 rear brake swap. I just made 2 about 10" long cables brazed nubs at both ends 1 went in the equalizer the other I took a sleeve sliced it long ways put both my extension and the new LS parking cable then pinched the sleeve shut so the cable was longer put a small hose clamp just for good measure on the sleeve it's worked great for the last 2 years

five7kid

iTrader: (14)

I measured the one I have this evening and it is right at 1.02", which is 26mm (converts to 25.9mm, but I didn't disassemble it for the measurement).

The MC I have on the car now is one I bought last year when I put the 12-bolt in, which is supposed to be for the disc/disc application (also got a disc/disc combo valve at the same time). So, to measure it, I'd have to pull it off of the booster, which I'm not sure I want to do unless I know I need to.

My son & I FINALLY got started on the front conversion this evening. The directions said to use a Sawzall to cut the stock spindle, which wouldn't have been my first choice for the job, but to my surprise it did it. My HF saw housing broke earlier this year, so I had gone out and picked up a new Porter-Cable unit for this job - good price, high-quality, didn't blink an eye cutting off those three pieces on each spindle. Drilled and tapped the required holes, ground off around the conversion bracket mount bolts, bolted on the brackets, installed the hubs & new rotors - and discovered I didn't cut off enough material from the bottom of the spindle to clear the caliper bracket mount bolt. GRRRRRR!!!!!! That was at 11:15 pm, he has a 40 minute drive home and has to work tomorrow, I have an appointment tomorrow morning; so the car isn't going to be ready for the first race of the season tomorrow evening. He's going to have to run my Vette instead. Oh, well, we should have it done for next weekend, when he really needs it for the faster required ET we need to run for that race series.

86White_T/A305

I thought about changing my mc to newer ls1 but after reading how slight the differences are between my stock 87 mc and the 4thgen I dont think its worth the effort. Im running ls1/lt1 front/rear brake setup with 22lbs prop valve spring. Pedal effort is the same but very well balanced..and if you jam on the pedal..the car will halt and my rears dont lock up with my et streets out back. As for parking brake cables i used the stock lt1 cables and had them shortened for a tighter fit and short travel on the ebrake handle.

I will say the stock gm pads/rotors for my ls1 fronts are ok but leave more to be desired for front stopping power.I feel them fading when the car is driven aggressively..nothing that hasnt been said a million times before on tech.

five7kid

iTrader: (14)

Update: I got a little more work done Sunday, found I still had to trim a little more from the stock spindle to clear the caliper (missed that in the instructions). Finally got both sides mounted up, and the new Earl's SS brake line on the driver side. While hooking up the brake line on the passenger side, I was adjusting the routing of the factory hard line (the Earl's fitting is a bit longer than the factory hose), and the hard line cracked at the fitting - too many "adjustments" over the years (it's a factory V6 car, so wasn't the first time that line has been tweaked). So, that ended that day's activities.

Monday I reacquainted myself with double flares - had the tool, just hadn't used it much. After a few trial runs to try to perfect the process, moved to the real thing. About the hardest part was getting the spring that goes around the factory line trimmed back far enough to get the tool mounted to the line. The line nut was getting rounded with all the cycles over the years, so stole one off a line I had sitting around. Got it hooked back up, did several non-bled pedal strokes that were enough to push the pistons out to clamp down on the rotor, no leaks. Hopefully that's good to go now.

The new proportioning valve springs arrived in the mail yesterday. I had a meeting to go to in the evening, so I didn't get any work done on it. Hope to get the spring installed this evening, and get the brakes bled.

Next step is getting rims that fit. I've been running stock 14" Berlinetta rims, I'm sure their days are over. My son has a set of 15" from his S10 (like what we're running on the rear - after all, he's the one burning the rubber these days, let him use his tires), not sure they're going to fit over the LS1s on the front. If not, I have a set of 16" IROC rims, but the tires on them are old, worn out, and cracked, so if we have to run the IROCs, I need to get tires for them. Hopefully I can find some 225s in 16" locally, don't want to run any wider tires than that on the fronts.

five7kid

iTrader: (14)

Discovered a couple of things tonight: 1) Those springs don't fit my type of proportioning valve; 2) the S10 rims just barely rub the fins on the calipers.

I'll probably go to an adjustable prop valve sometime in the future if the brakes don't seem to be adequately balanced. Guess we'll see.

For now I'll get the skinniest tires I can get on the 8" wide IROC 16" rims. Which I hope is tomorrow so I can finally get it back on the ground and see how the brakes work.

jmd

iTrader: (4)

I missed the reason to run less than 245 on a third gen wheel on a third gen, or I am confused as to what car / wheel / mods are being run.

Adjustable prop. is something we have all gotten by without, but really shoulda gone in with brake upgrades.

five7kid

iTrader: (14)

It's primary use is drag racing. Helps a little with reaction time and ET to have a narrower tread and less rotating mass. And the IROCs are the only 16" 4.75 rims I have (new rims not in the budget right now).

five7kid

iTrader: (14)

I don't know if it proves anything, but last night my son went undefeated. The usual 7 rounds were shortened to 3 by rain, but he won his last run. His report is he can stall up an additional 500 RPM (about 1k below the flash RPMs) without having to "pump" the brakes (after staging, give the pedal a hard stroke, hold the line lock, let the pedal up, give it another stroke, then stall up) like we had to do before - makes it difficult to have time to get to a proper stall speed before the tree comes down. He tree'd every opponent last night for relatively easy wins.

It doesn't toss you into the windshield at the first touch, but it does give more braking with more pedal - a very welcome change.

So, overall, very pleased with the outcome. It might work even better with an adjustable proportioning valve, but for the time being, we're good.

We'll probably address the use of the LS1 rears after the season.

daferris

iTrader: (8)

Is your proportioning valve iron or aluminum?

86White_T/A305

Sounds just like my car feels for braking..doesnt nose dive the car at first touch..but if you put your foot down..it brings you to a good stop.

I think I read someone was able to use the stiffer springs on the stock iron prop valves with some finese.Might have to skim through that thread again.

five7kid

iTrader: (14)

Aluminum.

It's not a 3rd gen unit. It's kind of a generic disc/disc GM piece for SAE threads.