So one of my clients I sold a condo to last year works for a reputable Porsche shop in Bellevue, WA that has many cars go to be set up for track stuff. One of ther people there had a guard taken out of their car to be sent out. Long story short... he decided he doesn't want it and I get it

Ok, maybe I'm a noob, but what kind of "guard" did you receive?

It is a limited slip diff. Better than a Quaife too.

Nice! Well in that case, congratulations

I have never heard of the Guard brand, but I have heard of the one that sounds like a dirty girly noise...

Lucky bastard! I want one......

Don't mean to burst your bubble but if he owed you $300 then it wasn't free. If you never planned to get the money back then it was better than nothing. Good deal tough for 300 clams.

Which guard differential is it?

They make several including a spool, a torque biased (same as a quafe) and an actual limited slip.

The spool is full lock.

The limited slip is locked under acceleration and braking.

The torque biased is locked under acceleration as long as both rear wheels are able to handle torque (both on the ground).

So post a picture already.....

That's why I said...well kinda. Generally when I lend people money I don't plan on getting it back. If they do pay it back it is kind of a bonus. I can't wait to pick it up and install it. I like free things


I will post a picture when I pick it up tomorrow.

Can I borrow $ 30,000 buddy?

You're funny. If you buy a $2,000,000 using me as your agent I would be happy to lend you 30k.

300 dollars for a guard diff. Nice score!

That will help for next season AX

No doubt!! That won't move you up in class will it?

what GT diff are you talking about?.......

Maybe... Paul Guard makes a Torque biasing unit, a limited slip, and a spool that is for drag racing I think. The TB unit is best for autocross.

This is why everyone keeps asking you which unit it is Jon... If it is either the TB or the LSD you scored very big... Minimum $1200.00 part before install.

No... it won't move me up a class.

It is the LSD version.

OH U scored

Excellent work, Jon.

I don't know about their lsd's but I live by torque biasing diffs.

My 356 has a quaife, which I would like to upgrade to a guard. HP loss at the wheels is 2/3 what a quaife is.

But lsd's are better anyway for hp loss, and spools are the best. You'll do very well with it.

SO I just got back to my office. I picked up the diff to find out that it is a Guard torque biasing differential. The owner of the shop talked to me about it for a while and I must say I am excited to see what the difference will be with this. Hetold me that this is the BEST for AX that you can get. I would trust his word very well as he preps lots of cars I wish I could get my hands on. I will take pics when I get home

Which trans? 901 or 915?

Ours is in our 915 box. When we selected our torque biased differential, we didn't realize that we really should have opted for a limited slip. We do only track work.

Even with the torque biased GT differential, the lap times improved and wheelspin has been eliminated. The inside rear would get light and could be made to spin with enough throttle input. No more.

After reading several articles after the fact, I found that a limited slip provides lockup under BOTH acceleration and braking even if the wheel is off the ground. The torque biased only works under acceleration with both wheels on the ground.

I'm sure you will love the way the car hooks up with it installed.

The spool would be good too as there are no moving parts and they would be the strongest solution, but they are 100% locked 100% of the time.

It is for the 901. That is exactly what Chris was telling me. He said it is ideal for AX as it does only on accel and not brake. He said for the track it will be good as well, but the LSD is better for the track but not AX.

Hahaha..


John is funny. But misinformed.

The Torque biasing differential selectively gives power to the wheel with the most resistance. Well. More or less. They are tunable, but both wheels have to have some load or the diff wont work properly. This means that the outside tire in a corner gets the most power to it, as opposed to an open diff, where the inside wheel gets the power.

A limited slip is just a clutch that connects both axles together. The idea is that the LS have less friction than the wheels against the pavement. So that going down the straight, you've got lots of power to the pavement, but when turning, you aren't compromising cornering like with a .... spool.

Or a locked differential- called a spool because it looks like a spool that thread or string would go on. It's just a solid cross piece that connects both the axles together. Great for drag racing, terrible for the track, unless you'd like to break the tires loose every corner, just to turn.

Braking is the same mechanism with a torsen. The wheel with the most traction gets the most power from the engine.

That was what I understood. Whether that is what I said or not may be different Or were you talking about the other John?

So here are the pics of my wonderful score

Confucious say.... Crowded elevator smell different to midget.
Concucious also say.... Laugh when Alpha says you are misinfoooooamed.

That is exactly what I do.

Here is a pic of mine:

Click to view attachment

Yeah. Well.

Whatever you do, Jon.

And John, you can feel free to do this whenever you feel like it.

Don't take it apart.

Why would I take it apart? I would rather just send it back to Guard if something was wrong.

Although the commonly heard internet dialog states that torque biasing are better for autox and that lsd is better for the track.... I wouldn't accept that as gospel.

Paul guard himself told me that the above is true for a 911 but that in a mid engine car it could be possible that the TB diff is still better on the track.

Plus what I consider to be one of the premier 914 race shops also believes that the TB is faster than the LSD on the track

I think the descision has a lot of variables. For example what amount of HP are we talking about?

(I'm confident I would use a spool if I had 350+hp... and this because I have used a locked diff already in a 914 with 130 - 160hp)

so the type of tracks
the car set up
and the car's hp all factor into the answer of what diff is the best for a track.

When I had my last transmission built I felt that for my use/car (track only) that the TB was the best choice and ultimately faster. So thats what I went with.