OEM Plus (or OEM+)

[SuperBuick]

Getting back into the game this past year and reading a ton of back posts on the forums - I feel this is a valid topic that may even belong in FAQ.  I'm also trying to make things as current as possible here because the drivel and fractured nature of facebook info is so god awful.

What are the best OEM Plus modifications for the 1st gen w-body platform?  And do they just bolt on, or need modifications to adapt.  

 

For starters if you arent familiar with what OEM+ is, here's a primer: https://www.hagerty.com/media/advice/piston-slap/fan-of-oem-plus-but-didnt-know/

Things I think I have read about 1st gen W bodies are that some parts from the 95-97 monte carlo/lumina z34 are desireable on first gens - radiator? brakes? swaybar? Can they simply be bolted on?

Another is that oem gen 2 adjustable control arms can be used on 1st gen cars with modification.

I think later 3.4 fuel injectors on earlier motors is another one.

And there is an oem plus starter upgrade also I think?

If this thread is useful Im happy to update here and organize the best oem+ mods by category and ease of install.

And also perhaps we may end up with one for 1.5 gen and 2nd gen too.

 

Permanent Magnetic Gear Reduction Starter - part number XXXXX - no modifications necessary

Grand Prix GXP Rear Trailing Arms - GM 25990164 - no modification necessary

Cutlass Convertible Strut Tower Brace - part number XXXXX - no modifications necessary if using 3.4 DOHC Bar

Rear Calipers - Part number XXXXXX - modifications?

 

 

Edited January 23 by SuperBuick

[Amanita]

I don't think there's a real reason to not run a cutlass supreme convertible strut bar on your car if you want to improve handling. The bars are different between the 3.1 and 3.4 cars, the 3.1 can take either, I have used both on my Grand Prix. From what I am aware of, the 3.4 cannot use 3.1 bars but I do not have an LQ1 car to test that.

If the 95-97 Monte Carlo got a larger front sway bar than 1st gen FE3 cars I haven't tried it out, but the rear bar is different. I am running a thicker rear sway bar from a Monte in my car, but it is approximately a half inch wider so I had to cut into the bushing on one side to get it to fit. I've been considering swapping back to stock, I cannot tell you if it made an improvement to the handling. My front sway bar is from the same Monte and was the exact same as the stock one.

Edited January 16 by Amanita

[Schurkey]

Permanent magnet gear reduction (PMGR) "Mini starter" works great on my Euro 3.4Ls.

Lotsa guys seem to think the later rear calipers are an upgrade; I disagree but I'm in the minority.

About the same for front struts/brake rotors.  Yeah, the later struts allow slightly-larger-diameter rotors which has the potential for increased braking power...but the REAL problem with braking power is the vacuum booster used on first-gens.  Once the booster is replaced with one that works properly, and the brake fluid is flushed every two years or at least every time pads get replaced, the brake problems are pretty-much done.  Rebuilding calipers is relatively easy, and often successful at restoring proper operation.  The 2-piston calipers are harder than the single-piston calipers, and aluminum calipers often need to have the corrosion dug out of the seal grooves, or the pistons are "stiff" because the rubber seal is overly-compressed.

I like the idea of scrapping the CS130 alternator used on '93--older (?) engines in favor of the CS130D used on newer engines--but in the case of the 3.4L, anyway, it takes an entirely-new front accessory drive mount.  I haven't done this on my cars.

[Amanita]

4 minutes ago, Schurkey said:

Permanent magnet gear reduction (PMGR) "Mini starter" works great on my Euro 3.4Ls.

Lotsa guys seem to think the later rear calipers are an upgrade; I disagree but I'm in the minority.

About the same for front struts/brake rotors.  Yeah, the later struts allow slightly-larger-diameter rotors which has the potential for increased braking power...but the REAL problem with braking power is the vacuum booster used on first-gens.  Once the booster is replaced with one that works properly, and the brake fluid is flushed every two years or at least every time pads get replaced, the brake problems are pretty-much done.  Rebuilding calipers is relatively easy, and often successful at restoring proper operation.  The 2-piston calipers are harder than the single-piston calipers, and aluminum calipers often need to have the corrosion dug out of the seal grooves, or the pistons are "stiff" because the rubber seal is overly-compressed.

I like the idea of scrapping the CS130 alternator used on '93--older (?) engines in favor of the CS130D used on newer engines--but in the case of the 3.4L, anyway, it takes an entirely-new front accessory drive mount.  I haven't done this on my cars.

Is the improved booster the one that they started using during the second facelift for the Grand Prix/Regal/Cutlass? Genuinely curious about OEM+ brake upgrades that I can use for my '96 since I actually track the car and the brakes are where I think I can improve the car the most currently.

Edited January 16 by Amanita

[Schurkey]

In my case, both of my Luminas ('92 and '93 Euro 3.4) had really-poor braking power--stand on the pedal with both feet, and the anti-lock still didn't need to engage.  Both cars got a plain ol' ordinary "rebuilt" booster from Carquest, and it was a HUGE improvement over the faulty original boosters--but the replacements were nothin' special.

For the record, both original boosters passed all the usual booster tests.  They held vacuum, they didn't make odd noises.  They just didn't boost much at all.  I don't know what was wrong with them, but they sure did not work.

 

Perhaps there are bigger/better later-model brakes that can be adapted to a '96.  Keep in mind that your front rotors are already somewhat larger than mine.  I would be sure your current brakes are actually working to their potential--calipers not sticking on the slide-pins, caliper pistons not sticky or seized.  Park brake working properly.  ABS PROPERLY BLED using a scan tool, 'cause otherwise you're only bleeding about half the ABS unit.  Use pads with the highest alphabetic rating available--"AA" is horrible, FF is adequate, GG better, I think you might be able to find HH.  First letter is cold friction, second letter is hot friction.  Usually they're the same, but they wouldn't have to be.  You might find a "FH", for example.

The letters are generally ink-stamped on the friction material, so don't expect to be able to read them on used pads--and don't expect the ratings to be advertised.

Example of "FF" letter markings on Ford Focus brake pads:

Edited January 16 by Schurkey

[SuperBuick]

20 minutes ago, Amanita said:

Is the improved booster the one that they started using during the second facelift for the Grand Prix/Regal/Cutlass? Genuinely curious about OEM+ brake upgrades that I can use for my '96 since I actually track the car and the brakes are where I think I can improve the car the most currently.

I recall @55trucker doing a writeup and this being a huge project.  Probably beyond OEM+, but maybe that was just cuz its a 3.4 DOHC?

[GnatGoSplat]

Here's a strange one, for Cutlass coupe the door sill plates were fancier on '88s.  It was a 2-piece thing and the screws were hidden.  Still black plastic, but it looked more premium than the 1 piece one in my '89.  The '94 had a one piece one as well that was different (more ribbed).  Neither looks as nice as the one in the '88.

The booster on the older cars is definitely quite a bit smaller than the newer ones, I don't remember what year they changed.  I have the booster out of a 96 Monte Z34 on my parts shelf that I never got around to swapping into my '89, it's visibly quite larger.  Just a FYI for anyone wanting to do the swap, I've heard the big booster can't be used on manual transmission cars.

[Bake82]

12 hours ago, GnatGoSplat said:

Here's a strange one, for Cutlass coupe the door sill plates were fancier on '88s.  It was a 2-piece thing and the screws were hidden.  Still black plastic, but it looked more premium than the 1 piece one in my '89.  The '94 had a one piece one as well that was different (more ribbed).  Neither looks as nice as the one in the '88.

The booster on the older cars is definitely quite a bit smaller than the newer ones, I don't remember what year they changed.  I have the booster out of a 96 Monte Z34 on my parts shelf that I never got around to swapping into my '89, it's visibly quite larger.  Just a FYI for anyone wanting to do the swap, I've heard the big booster can't be used on manual transmission cars.

Correct.  They will not allow the clutch master cylinder to fit.

 

Upgrades I can think of

 

- 94+ rear brakes on 88-93

- 96 + front knuckle (for bigger front rotor) 

- 3.4DOHC cars have a 34mm front sway bar 

- 95-97 monte carl rad(1in thick version) 

- 95-97 monte carlo rear sway bar (22mm I think) 

 

Will add more if I think of anything.  Good add with the GXP trailing arms

[SuperBuick]

So I tried the 96 monte 22mm swaybar this weekend and it is too wide by about 3 inches for my 1992 grand prix - so maybe it has to be a 1995? but I can validate that it will not fit a 1992 grand prix.

[Amanita]

27 minutes ago, Bake82 said:

Correct.  They will not allow the clutch master cylinder to fit.

 

Upgrades I can think of

 

- 94+ rear brakes on 88-93

- 96 + front knuckle (for bigger front rotor) 

- 3.4DOHC cars have a 34mm front sway bar 

- 95-97 monte carl rad(1in thick version) 

- 95-97 monte carlo rear sway bar (22mm I think) 

 

Will add more if I think of anything.  Good add with the GXP trailing arms

I'm not going to say all because I'm not sure about the earlier cars with this RPO code, but I think later 1st gens with FE3 have the 34mm sway bar. My SE has it with the 3.1. I don't remember the specific year it came from, but the Monte Carlo rear sway bar I mentioned earlier was from a 1.5 car and it did not fit without having to cut into a bushing.

[GnatGoSplat]

3 minutes ago, SuperBuick said:

So I tried the 96 monte 22mm swaybar this weekend and it is too wide by about 3 inches for my 1992 grand prix - so maybe it has to be a 1995? but I can validate that it will not fit a 1992 grand prix.

I've also read the Monte rear sway bar doesn't fit the leaf spring cars.  Some have been able to mod it somehow, but it's not a direct bolt-on.

[Amanita]

10 minutes ago, GnatGoSplat said:

I've also read the Monte rear sway bar doesn't fit the leaf spring cars.  Some have been able to mod it somehow, but it's not a direct bolt-on.

I'll have to dig through my old phone to see if I took pictures, but the bar itself mounts where it needs to, It's just too wide. There are large collars circling the bar where it would meet up with the stock rear bushings on the knuckle for the Monte, if you grind those down or cut a notch in the bushing you can make it work. My car has been using it for years but I don't know if it made a difference. Next time I have the rear wheels off I'll show a picture, but it isn't pretty lol.

Edit: The 1.5 bar really is the exact same shape as the first gen one, you just need the monte carlo bushings. If it was a slight amount narrower it would be a perfect fit.

Edited Monday at 06:15 PM by Amanita

[rich_e777]

If going with a larger radiator then you need to pay attention to the fans going back on. I swapped to a larger one in my 3100 CS and one of the fans sat too close allowing the hub bolt to work a hole in the radiator. A few washers to space the fan back a touch work perfectly.

Would a 3400 LA1 swap be considered OEM+ as well?

[White93z34]

I'd add and this may be controversial, but own a 88-92 car as starting 93' they started doing heaps of cost cutting measures that just got worse over time. a 90' GP has noticeably thicker sheet metal then a 96'

91-93 LQ1 cars had factory oil coolers this was later removed

Earlier cars also tended to get transmission auxiliary coolers far more often as a matter of course and is basically a bolt on modification

Thicker radiators on earlier cars

TGP main cooling fan can be sourced from a 94-96ish 4 cyl Grand Am and has a quieter SPAL or however you say it blade.

34mm front sway bar / slightly bigger rear sway bar off LQ1 cars

Cutlass strut tower brace

96' front knuckles for slightly larger discs

Better brake boosters starting in about 94' they made it different and seems to be more reliable - unfortunately not compatible with manual transmission cars.

94+ rear brakes from a "it just works" point of view

later fuel injectors as a whole are more reliable

the gear reduction mini starters most 3100/3400 cars got later on

TGP Steering racks are the thighest ratio ones offered on a gen1 w car 2.25 turns lock to lock if I recall correctly.