LSD oil
 

1971 911E with LSD….would Swepco 201 be the best oil?

First, there is some ambiguity with the term LSD. If you have a clutch or drum type limited slip differential, you probably need a lube with a friction modifier intended for an LSD, or at least an additional additive “Friction Modifier “. Swepco 201 not have a friction modifier. Swepco 203 does have a modifier blended in and is recommended for LSDs. Torque Bias Differentials don’t need the modifier. The term LSD is used by many as any differential that has anything in it to control traction. I have no practical experience with 203. I personally have a Wavetrac torque biasing and use Swepco 201.

Kendall with the friction modifier is my choice. The LSD will chatter on low speed turns without the additive, assuming it is functioning properly.

The friction modifiers cause the clutch LSDs to slip and not work as intended. Swepco 203 should never be used with a clutch LSD.

Choose a mineral (dino) oil SAE90 GL5 as specified originally by Porsche. With a LSD choose such an oil equipped with additives to support the LSD.

Careful not to pick an oil that favors your LSD but that isn’t right for the early Porsche synchros i.e too slippery.

Why people on open roads need an LSD?

The whole point of an open diff is to make turns.

The whole point of a close diff is to go fast.

rolling my eyes emoji.........:rolleyes:

Limited slip
 

Porschedude996,
Thank you for your reply. The car came from the factory with LSD. I don’t know much about diffs…..here is a picture I took when it was getting rebuilt. Clutch or drum ??

http://forums.pelicanparts.com/uploa...1732111433.jpg

Limited slip
 

2.7 RS,
With all due respect,
I don’t “need” LSD. That’s just how the car was built. I’ve owned it since 1978 and just keep it as a bought it
Mark

That's ZF 40/40 clutch type lsd

Sweco 201 is a perfect choice to use in 901, 911 and 915 transmissions used thru 1986 w/ or w/o lsd.

friction modifiers are only recommended if you want the diff to be less effective

Do you have some objection to the way the diff operates? if so, maybe fiction modifiers are ok, if not, not.

Limited slip oil
 

Thanks for all the input.
I’m gathering that a mineral oil that is SAE90 GLS would be best as suggested by Schulisco ?

Bill,
Thanks for the reply. I’m good with the way the LSD operates. It does chatter a bit on slow tight corners when I accelerate…..but no big deal.
I just had the trans rebuilt because it was grinding in second gear. Mechanic replaced all syncros and checked all bearings. It is now making a grinding/wining type sound on acceleration that was never there before. I know my car well and have owned it since 1978. I am trying to start with the simplest solution……thinking that maybe it has the wrong oil.

That sounds like something wrong, and no oil will fix that. Remember, an lsd only moves internally in a corner when the wheels move at different speeds. In a straight line the lsd is just spinning on the bearings with no internal movement at all.

If it’s in a straight line, you have a bearing issue or a ring and pinion set up problem. That’s most likely. A gear could also be the culprit, but less likely.

Ps. Might be a good idea to make sure the shop actually filled it. I have seen “professionals “ rebuild and install a gearbox, and then let the customer drive off in a dry gearbox.

You don’t actually understand the function of an lsd.

I don't have to fix them or build them. I just drive them. I'm on the user side

I'm glad the OP got the answers he was looking for

Definitely a Clutch LSD. I would say Swepco 201 with a Friction Modifier would meet the needs, or the 203, which as stated before, it has the modifier. The modifier helps eliminate the clutch chatter during low speed turns. It feels like a wobble in the seat to me. And an odd coupling and uncoupling

I have never looked for a vendor the carries 203, so maybe using the 201 with the FM is the thing to do.

Some say you can add too much and effect maybe accelerate wear elsewhere in the gearing, read bobistheoilguy.com. Great site that will open your mind.

I would use the 201, drive it and see if you get a chatter. If you don’t, drive it. If you do get a chatter, add some. Your transaxle will fill with 3 liters. Consider that when reading the MF manufacturer’s instructions. Most American performance cars of yesteryear had a 1-1/2 liter, so if you serviced your 3 liter transaxle like yesteryears American Car with a clutch LSD, you would be putting in an altered ratio.

If you are rebuilding and the clutch packs are new, I would imagine that they are more likely to chatter than the your original clutches. Due to the new surfaces that bite.

I don’t think you will damage your LSD with a 150 hp driving on the street without the FM. Try it without and add an ounce at a time until you don’t feel the chatter. Just don’t add too much FM, it does reduce the lubricity and you have alot of other surfaces in the transaxle. Syncro-Rings, Bearings, ect.

What does your transaxle rebuilder say. Maybe call Roger Brown at California Motor Sports and ask what they recommend. I think they are one of top rebuilders in the world.

http://forums.pelicanparts.com/uploa...1732113397.jpg

Limited slip
 

Matt,
Thanks for the input. You’re probably right on ring and pinion.
During the rebuild, the mechanic pointed out a small stress crack on the ring gear. He asked me if it was making any noise. My reply was no…..the trans sounded fine (I’ve owned this car since 1978, so I know it well)…., it just ground in second gear. Now, after the rebuild, it’s making this humming/wining sound on acceleration….which it never did before. Do you think that the small crack would now be the culprit? I don’t know much about transmissions, but I was reading about pinion depth, preload and backlash ect. It’s sounds pretty intricate to me.
So I guess my question is:
Is the noise possibly from a miss alignment or is it most likely because of the small crack. I know it’s hard to tell without tearing it down again and you would just be speculating.
Thanks for you help,
Mark

Porschedude996,
Thank you for the detailed information. I’m trying to learn as much as I can…..I was a car painter by trade and never learned much about mechanics.
I explain to Matt (below post) what my concern was. I was just starting from the beginning by making sure I had the correct oil in the trans. The main problem is that the trans is making a grinding /wining noise on acceleration that it wasn’t making before the rebuild. The mechanic pointed out a small stress crack on the ring, but it didn’t seem to be creating any problem or noise before the rebuild ……but now it’s noisy
Thanks again for your input,
Mark

The short answer is that a single tooth isn't the likely culprit, but it raises all kinds of alarm bells of it own.

So let's get a little theoretical to aid you in your diagnosis. I want you to think about the function of your gearbox as a variety of things all spinning in a circle, going various directions and speeds. The two you start with are wheel speed and engine speed.

Pay attention to the noise exactly when it happens. Does it go up with wheel speed and get worse the faster you go? If so, it's likely somehow related to the ring and pinion.

Or, does it synch up more closely to the revs of the engine? If so, it's likely a bearing running either on the mainshaft or on the pinion. Furthermore, does it happen in all gears or just one or two? This helps you determine exactly where on the length of the shaft you might have a problem.

Personally, I would have never rebuilt a gearbox with a crack in the ring gear. The job stops being a rebuild right there, and unfortunately for you, doubles the price, at a minimum. I also don't know that I would go back to the prior mechanic with your problem. While the idea of a warranty and some of the work being free is enticing, I seriously question the competence of this "professional" A crack in a tooth is NEVER acceptable.

Limited slip
 

I will do as you say today. I will take it for a drive and pay close attention when the sound occurs.
In all fairness……it’s totally my fault. The mechanic pointed it out and was going to look through his parts pile to see if he had a good used one. He didn’t….and since it wasn’t making any noise I made the decision to continue. I should have educated myself or got on this forum to ask experts such as yourself before I made a decision. I guess I’m learning the hard way.
I’ll report back after my test drive.
Thanks for your input so far,
Mark