[brianb]

Sorry for the sidebar everyone. I'm giving myself 2 demerits for this. FWIW...Castrol's PDS claims to have friction modifiers already but maybe someone can expound on that for Jpar.

 

[Jpar]

Sorry for the sidebar everyone. I'm giving myself 2 demerits for this. FWIW...Castrol's PDS claims to have friction modifiers already but maybe someone can expound on that for Jpar.

I talked to my son and he is a what I call modern mechanic..(never worked on carburetors doesn't have a timing light..) and he said he was having trouble with his truck and finally had to use a modifier to make it stop acting up.. even though the oil they have at his work was supposedly for limited slip...

 

[Jpar]

Has anyone tried to cut a silver dollar size hole in the passenger side inner fender well at the #8 spark plug and used a plug?...

 

[brianb]

If you did that on your car, would you have to lift that side and let the suspension drop? Would you have to remove the wheel?

 

[Jpar]

If you did that on your car, would you have to lift that side and let the suspension drop? Would you have to remove the wheel?

When I got it the other night I dropped it off at a friend's house he has a self storage business. He also has a lift. I've got Tuesday and Wednesday scheduled with him to do the fluid changes and I bought the NGK spark plugs as well. Going to buy some wires too..
I'm not a purest in any sense, I'm a customizer for sure.. I absolutely love doing things that the factory should have...

 

[Injuneer]

As I recall... when my car was still basically stock (no headers) the passenger side plugs were easier to access from the bottom. Never poked a hole.

= = = = = = = = = =

As far as the limited slip additive - as noted, 1) GM recommends 80W-90 GL-5 + the GM additive. Also mentioned above, the Auburn limited slip used in the 95 F-Bodies is a cone clutch type, and 2) Auburn recommends their own brand 80W-90 GL-5 plus either the Auburn brand LSD additive, or GM or Ford LSD additive.

That tells me you can't go wrong with the differential manufactures recommendation, nor the auto manufacturers recommendation. The engineers aren't a bunch of dummies, at least not until the accountants get involved. Many other manufacturers (or re-packagers) of 80W-90 GL-5 offer a product that includes the friction modifier. I suspect that is a decent alternative solution, but I never tried it. And it's going to be very easy to tell if they work or not. If, when you do the change you start getting "chatter" in the turns you know they don't work. Otherwise, all is well.

Additional info - neither Auburn or Eaton recommend synthetic lube.

From Auburn FAQ:

What is clutch chatter?

Clutch chatter occurs when the clutch cone engages and disengages rapidly in the differential case. It causes no damage and can be cured by using the correct oil and friction modifies. Clutch chatter is caused by the difference between the static (non-slipping) friction coefficient and the dynamic (slipping) friction coefficient. When the difference becomes too great, the clutch cone cycles between the two (sticking and slipping), which creates the noise. Friction modifiers bring the static and dynamic friction coefficients closer together to minimize chatter. Auburn recommends using Auburn limited-slip additive (#504102) with a high-quality non-synthetic 80W 90 hypoid oil.

What kind of oil should be used with an Auburn limited-slip differential/ Auburn Select-A-Loc differential?

Non-synthetic 80w90 GL-5 oil treated with Auburn Gear friction additive, part #504102 (also known as a friction modifier). See Catalog page 32. Three (3) ounces of additive will treat one quart of oil. GM or Ford limited-slip additive may be used. We do not recommend synthetic oil. Auburn limited-slip additive is packed in every box with the differential.

From Eaton FAQ:

What kind of oil should I use in my Posi? Can I use synthetic oil? Do I need friction additive/modifier?

• A quality, petroleum-mineral based, GL5 rated 80w-90 gear oil should be used.
• It is necessary to add a four-ounce bottle of friction modifier for optimum performance (if friction modifier has not already been added to the petroleum-mineral based gear oil that the customer selects).
• While some customers have found that synthetic oil works well in this application, Eaton has not confirmed under test conditions that all synthetic oils (with added friction modifier) are compatible with Eaton Posi applications.

I upgraded to a Strange Engineering 12-bolt on my 94, with an Eaton HD disc-clutch limited slip. While they recommend a heavier weight oil to accommodate the higher torque applications, they still recommend the LSD additive:

Gear Oil Type & Amount

SAE 85W-140 non-synthetic gear oil is recommended S60 & 12 Bolt require 2 quarts of gear oil

Differential Friction Modifier

Differential friction modifier is required for clutch-type limited slip differentials. One entire bottle (4 fl. oz.) is required in addition to the 2 quarts of gear oil. GM or Spicer brand is recommended. Additive is required even if gear oil manufacturer states oil is compatible with limited slip differentials. Additive reduces clutch chatter in differential providing smoother more consistent operation.

 

[Jpar]

As I recall... when my car was still basically stock (no headers) the passenger side plugs were easier to access from the bottom. Never poked a hole.

= = = = = = = = = =

As far as the limited slip additive - as noted, 1) GM recommends 80W-90 GL-5 + the GM additive. Also mentioned above, the Auburn limited slip used in the 95 F-Bodies is a cone clutch type, and 2) Auburn recommends their own brand 80W-90 GL-5 plus either the Auburn brand LSD additive, or GM or Ford LSD additive.

That tells me you can't go wrong with the differential manufactures recommendation, nor the auto manufacturers recommendation. The engineers aren't a bunch of dummies, at least not until the accountants get involved. Many other manufacturers (or re-packagers) of 80W-90 GL-5 offer a product that includes the friction modifier. I suspect that is a decent alternative solution, but I never tried it. And it's going to be very easy to tell if they work or not. If, when you do the change you start getting "chatter" in the turns you know they don't work. Otherwise, all is well.

Additional info - neither Auburn or Eaton recommend synthetic lube.

From Auburn FAQ:



From Eaton FAQ:



I upgraded to a Strange Engineering 12-bolt on my 94, with an Eaton HD disc-clutch limited slip. While they recommend a heavier weight oil to accommodate the higher torque applications, they still recommend the LSD additive:

My duster has a spool so LOL...
I certainly and sincerely appreciate your experienced answers and I take them to heart.. at this point I'm just going to get a little bit of the GM lube and add it in there...
And no way am I trying to out think the engineers. It was just what they had on the shelf in the 80 90 weight... I'll check and make sure it's not synthetic because that $10 a quart I'd be glad to take it back I kept my receipt. I'll have it on the lift Tuesday so maybe if I just can see it from underneath or I doubt if I'll see it but feel it I can get that number 8 spark plug out... One thing about me I don't have a lot of give up in me...

 

[ZumpTA]

I haven't looked at pricing, but is it even worth it to get the oil w/ friction modifier? With Antifreeze, the 50/50 jug is $13 and 100% is $18. $5 more for the 100%, but you get twice as much. Saving $8 minimum "mixing" it yourself. The premium seems to be in the convenience, not the product. I can only imagine that holds true for the oil.

 

[Jpar]

I haven't looked at pricing, but is it even worth it to get the oil w/ friction modifier? With Antifreeze, the 50/50 jug is $13 and 100% is $18. $5 more for the 100%, but you get twice as much. Saving $8 minimum "mixing" it yourself. The premium seems to be in the convenience, not the product. I can only imagine that holds true for the oil.

Not a huge Walmart fan but their fluids seem to be much more reasonably priced. I got their knockoff concentrate for $10 and change and they're 50/50 was seven dollars and change... I got 5w/30 weight mobile one synthetic for $29 and change and a jug of their house brand dexron 2 dexron 3 for 20 bucks and change.. they didn't have the right weight of rear end gear oil but they had Valvoline and kind of those bag style bottles. That you can squeeze... Again just the wrong
weight..
Ended up at the parts store and got the spark plugs the two quarts of Quaker State limited slip 8090 the right stuff 1 minute gasket (which I love that stuff\I put that s*** on everything>>LOL...).. hey k&n oil filter and a knockoff brand air filter because that's all they had.. just going to go to the parts store and get some factory style spark plug wires as I have no performance aspirations at this point besides suspension renewal...

 

[Jpar]

Speaking of suspension renewal I'm dancing between buying just a custom suspension with all the bushings in it or looking at just taking everything apart and using my harbor freight press and pressing in and pressing out in the bushings and buying new ball joints or whatever it needs and replacing those. Obviously all the a arms and stuff like that I would wire wheel clean up and repaint. Also new shocks and or possibly new springs as well... I don't need anything completely custom but I'm not opposed to it either. I like the way the car drives as is and it's my daily I don't want it to be too stiff... Just well cared for...

 

[Jpar]

Also the E break is INOP... Gotta get that investigated...

 

[Jpar]

Okay finally today was the day! Got the TA up on the lift and we got a good look underneath and it wasn't quite as bad as we thought. Just the cast iron stuff the lower control arms the rear diff the rear end some of the arms were a bit Rusty but nothing that was terminal and definitely nothing on the frame. Maybe a little under the battery box.
We went at the rear diff first and it still had fluid in it as it was dripping and it didn't look horrid. Got that all cleaned up repainted and glued back on. We'll let that dry overnight and refill it. Emptied the transmission fluid and it didn't look too bad and refilled it up. Emptied the supposedly new oil change and it was not new lol. Filled that with five quarts of mobile one 5--30. And took the fram filter off and put on a k&n.....
I went directly at that number 8 spark plug and the wires. Everything appeared original.. AC plugs and numbered wires... It didn't look bad for $75,000 MI...
As I went at the spark plug wires on the passenger side I liberated the car of its tension pulley for the serpentine belt that was lol and pretty damn rough condition. Could have been another original piece LOL.. what's that tension pulley in the belt was out of the way we went ahead and pulled the battery which I need to get into that low coolant sensor anyways and we loosened up the alternator and pulled hit up out of the way for access to the number two spark plug. So we got the passenger side plugs out and new ones back in. Tomorrow I plan to go right at the plug wires on the passenger side and then start on the driver side hoping that'll be a little less traumatizing...

 

[Jpar]

Well wrapped up all the service work yesterday again new differential fluid tranny fluid oil change and filter spark plug wires and spark plugs fuel filter air filter look new and a new serpentine belt. Took it today it passed emissions took it to the DMV and got new plates. Put about 50 freeway miles on it and everything seems to check out pretty good....
Probably start a thread on getting some of the interior knick knack plastic cheap stuff replaced. Then I'll go back to mechanicals and maybe get a new radiator new water pump new Opti spark flush out the system. Then I'll be on to brakes rotors shocks and springs. After that I'll just drive it for a while and see what else comes up...
Thank you for all the help and guidance here on this thread..

 

[ZumpTA]

...maybe get a new ...Opti spark ...

Do NOT open that can of worms. If you have an OEM unit on there, you maintain the Cap and Rotor like any other old-school distributor. The "optical" portion of the OEM OptiSpark uses a Mitsubishi sensor that is damn near bulletproof and rarely the point of failure. The OptiSparks available on the Aftermarket these days regardless of Manufacturer or price are 100% Chineseium and as such are extremely unreliable. I've never gotten more than 10,000mi out of one. Try to locate a Reman-OEM or buy the unit Petris Enterprises custom makes. Petris Enterprises is now the only exception to OEM.

It certainly doesn't hurt to have an Opti on the shelf. If you have an Aftermarket Opti on there now, you'll need one soon enough. ...but, if you have an OEM OptiSpark now, there is no greater mistake to be made with this vehicle than replacing it "because it's old". It's basically a Laser Pointer; it doesn't wear out. The non-OEM units electrics are poorly designed and built; and the sensors provide unreliable and/or erratic information to the ECM/PCM.

The OEM OptiSpark was rated to 100,000mi. That was actually the life expectancy of the Cap and Rotor, not the OptiSpark Unit itself; 65,000-80,000 miles is a more realistic service schedule, but then GM couldn't claim the LT1 as a "100,000 miles to the first tune-up" engine.

Think of an OptiSpark like a Gremlin, and never get it wet. That's the #1 rule. It's really not hat bad though. Basically avoid "under-carriage" car washes and service your radiator hoses before they burst. When servicing those hoses, cover the top of the OptiSpark to prevent coolant from intruding into it through the harness connector. Consider tapping the weep-hole of the water-pump and attaching a tube that runs away from the Opti. That's all. You can confidently drive in the rain and through puddles, just try to avoid puddles that come up past the rocker panel. The Opti can get wet. Splashes here and there from any direction are not a problem; it's saturation that kills them. ...certain types of car washes, chugging through deep puddles, the entire cooling system dumping on top of it. All easily avoidable.

The OptiSpark isn't the nightmare it has been made out to be. Misdiagnosis right from day one when caps and rotors failed was to blame for the first half of it's bad reputation. Unreliable Aftermarket units entering the market more and more over time finished it off.

There's a lot to say, and there are several options, but for now; just wait on this one.

Buy a Cap and Rotor kit instead, and when you're replacing it you'll be able to determine if it's an OEM, Aftermarket, or counterfeit-OEM unit. That will give you direction on this one. If you want a spare, by all means, start looking for that Reman unit or give Petris a call.

 

[Jpar]

Do NOT open that can of worms. If you have an OEM unit on there, you maintain the Cap and Rotor like any other old-school distributor. The "optical" portion of the OEM OptiSpark uses a Mitsubishi sensor that is damn near bulletproof and rarely the point of failure. The OptiSparks available on the Aftermarket these days regardless of Manufacturer or price are 100% Chineseium and as such are extremely unreliable. I've never gotten more than 10,000mi out of one. Try to locate a Reman-OEM or buy the unit Petris Enterprises custom makes. Petris Enterprises is now the only exception to OEM.

It certainly doesn't hurt to have an Opti on the shelf. If you have an Aftermarket Opti on there now, you'll need one soon enough. ...but, if you have an OEM OptiSpark now, there is no greater mistake to be made with this vehicle than replacing it "because it's old". It's basically a Laser Pointer; it doesn't wear out. The non-OEM units electrics are poorly designed and built; and the sensors provide unreliable and/or erratic information to the ECM/PCM.

The OEM OptiSpark was rated to 100,000mi. That was actually the life expectancy of the Cap and Rotor, not the OptiSpark Unit itself; 65,000-80,000 miles is a more realistic service schedule, but then GM couldn't claim the LT1 as a "100,000 miles to the first tune-up" engine.

Think of an OptiSpark like a Gremlin, and never get it wet. That's the #1 rule. It's really not hat bad though. Basically avoid "under-carriage" car washes and service your radiator hoses before they burst. When servicing those hoses, cover the top of the OptiSpark to prevent coolant from intruding into it through the harness connector. Consider tapping the weep-hole of the water-pump and attaching a tube that runs away from the Opti. That's all. You can confidently drive in the rain and through puddles, just try to avoid puddles that come up past the rocker panel. The Opti can get wet. Splashes here and there from any direction are not a problem; it's saturation that kills them. ...certain types of car washes, chugging through deep puddles, the entire cooling system dumping on top of it. All easily avoidable.

The OptiSpark isn't the nightmare it has been made out to be. Misdiagnosis right from day one when caps and rotors failed was to blame for the first half of it's bad reputation. Unreliable Aftermarket units entering the market more and more over time finished it off.

There's a lot to say, and there are several options, but for now; just wait on this one.

Buy a Cap and Rotor kit instead, and when you're replacing it you'll be able to determine if it's an OEM, Aftermarket, or counterfeit-OEM unit. That will give you direction on this one. If you want a spare, by all means, start looking for that Reman unit or give Petris a call.

Yes from what I've gathered the original Optus spark is the best thing to have. Again the car has 75,000 miles on it and I'm sure it can't last forever. My idea was to put a summit one in the summer while sending my original out to be rebuilt and the following summer putting it back in.... If rebuilding it is possible? I will check out this Pertris in the meantime and I appreciate the advice and the lead on this rebuilder...

 

[Injuneer]

GM sells rebuilds, but they are hard to find and rumors are they no longer use the preferred Mitsubishi optical module. But they don't rebuild your unit. There was someone on eBay who was supposedly rebuilding and guaranteeing…. something like the “Opti Doctor”. Haven’t seen anyone mention him in maybe 4 or 5 years.

As I mentioned before, if it ain't broke, don’t fix it. Consider replacing the cap/rotor, but as mentioned above, if you have an OEM part and it's not setting diagnostic codes, keep it. The good ones can go past 100,000 miles. But the cap/rotor is a maintenance item, just like any other distributor. Even a Summit Opti is “hit or miss”. The failure rate is inverse to the cost - the cheap Chinese stuff (under $100) can be bad right out of the box.

The one exception on high cost - the MSD complete unit is high $$$ but has NEVER been problem free. Fix one problem, another shows up. I was actually able to provide a Scan9495 data log to MSD that showed the effects of a problem that apparently had to do with the dielectric epoxy in the cap breaking down, allowing the arcing to insert spurious pulses in the output signal that told the PCM the engine was turning 7,000 RPM.

 

[Jpar]

GM sells rebuilds, but they are hard to find and rumors are they no longer use the preferred Mitsubishi optical module. But they don't rebuild your unit. There was someone on eBay who was supposedly rebuilding and guaranteeing…. something like the “Opti Doctor”. Haven’t seen anyone mention him in maybe 4 or 5 years.

As I mentioned before, if it ain't broke, don’t fix it. Consider replacing the cap/rotor, but as mentioned above, if you have an OEM part and it's not setting diagnostic codes, keep it. The good ones can go past 100,000 miles. But the cap/rotor is a maintenance item, just like any other distributor. Even a Summit Opti is “hit or miss”. The failure rate is inverse to the cost - the cheap Chinese stuff (under $100) can be bad right out of the box.

The one exception on high cost - the MSD complete unit is high $$$ but has NEVER been problem free. Fix one problem, another shows up. I was actually able to provide a Scan9495 data log to MSD that showed the effects of a problem that apparently had to do with the dielectric epoxy in the cap breaking down, allowing the arcing to insert spurious pulses in the output signal that told the PCM the engine was turning 7,000 RPM.

I probably will go at the cap and rotor now that I know there's one in there...
I looked up Petris and for over twice the amount of summit they still give the same one year warranty. I don't know whose parts are better but I do know from experience with my Mopar stuff there's the pliers out there who talk up a big game on their Internet site... The car has 75,000 miles on it now but I put 20,000 miles and my wife's new car which I'm trying to avoid by buying this old car and using it for my daily driver so 100,000 miles could come in two and a half years quite easily... Well like you said I'm not going to fix anything that's not broken I do want to try and be ahead of the maintenance game that's for sure... ..

 

[Injuneer]

The reliability of the Petris Opti has been documented by users on multiple LT1-oriented sites. It is not perfect, but I have only seen one user with a problem. Petris attributed it to a bad batch of optical modules, and shut down sales until they could replenish with a reliable stock. Petris was actually very popular with the Corvette LT1 owners several years before the F-Body crowd discovered it and jumped on the bandwagon.

 

[Jpar]

As of now ...
Diff oil changed..
Trans fluid changed..
Motor oil changed.. + filter..
Plugs and wires..
Serpentine belt..
Fuel filter..
Low coolant sensor...
Replaced rear hatch shocks...
Replaced old alarm with new alarm and now have keyless entry.,
Repared under seat wiring for lumbar and bolster airbags...
Removed power antenna awaiting new one tomorrow...
Change fuse on horn and now it works..
Awaiting shifter boot bracket and drivers door locker, should be here today or tomorrow..
I have a rear brake cable to fix the parking brake and a skip shift bypass plug but waiting for my friend with the left he caught covid last week and it'll probably be another week before I get on the lift...
Possibly today install my score of the set of 98 to 2002 tail lights...
That's all I can think of right now but there's got to be more LOL....

 

[Jpar]

The reliability of the Petris Opti has been documented by users on multiple LT1-oriented sites. It is not perfect, but I have only seen one user with a problem. Petris attributed it to a bad batch of optical modules, and shut down sales until they could replenish with a reliable stock. Petris was actually very popular with the Corvette LT1 owners several years before the F-Body crowd discovered it and jumped on the bandwagon.

I just quoted this post to see if I could pick your brain a little bit on something else. I know somewhere I can't find it where I think you were talking about my 95 trans am having an ob2 connection but I have to read the ob1 ?.. I know you addressed it a little bit but my fans coming on right away and starting to make me think something's not right. My idol seems a little high except.. my low coolant light came back on again today which it was on when I bought the car and I replaced the sensor which turned it off but a week ago it came on for one drive and then it went back off again. Now that could just be my cheap Amazon part.... I do want to flush the system or at least what I can get out of there for now maybe fill it back up start it and drop it again... I remember when I looked in there it looked pretty muddy... I'll take a look at my relays as well on my fans... Any direction or opinions would be appreciated..