P.O.S. Racing

Looks like the POS Racer trashed the passenger’s side rear end seal, got oil on the brakes and tire. The race season is over, and plan to do some work to the car over the winter. So was thinking about yanking the rear end out, and replacing the seals and such. Can the LSD be serviced? What items should be replaced?

Thanks,

setzep

I'd like to know also, think the lsd in my -se rear is gone.

On a side note, how do you like the flowmaster muffler on your car? Single, two or three chamber? I know they sound bad *** on a V-8 but never herd one on a rotary.

P.O.S. Racing

setzep, I'm not 100% sure which flowmaster I have on the POS Racer, I'll plan to mess with the car this long weekend, I'll Let you know!

Anyone got any LSD advice, has anyone changed the seals or the bearings, can the LSD be rebuilt, refurbished, or just replaced. How can you tell if the LSD died, it was spinning both wheels from a start, before my clutch started slippin, but sometimes on the track, it sounded like just one wheel was spinning.

Thanks,

yayarx7

I completely trashed a rear wheel bearing coming home from an autocross once. This of course led to R&Ring both of the bearings and seals. I had to pull the axles and take them to a local shop so they could press the new bearings and collars on for me. When i got one of them back and put the thing back together the brake rotor was rubbing aginst the caliper mount????? It turns out here is a spacer that the shop "lost" that goes on the axle before the bearing/collar assy. Well these things never get lost so no one has them in stock so RP had to order one from japan for me.

Just thought I would share a moment with yall

Never heard about replacing/maintaining anything on an LSD!
I do know there is a way to test the things for preload or friction or something like that. They do it at Nationals to the F-body guys to make sure they are running stock LSD's. But I do not know how it is done.

Maybe somebody out there knows?

stinkfist

Yes, you can rebuild them, but it's cheaper and easier to find a good used one in a junk yard or on the internet. these things tend to hold up pretty well. If you get a good used one you should be good to go for a while. Put an add on www.thepartstrader.com in the wanted section. I was looking for a diff a few weeks ago and got several responses. Most are in the $150-$200 price range. I ended up buying a whole disk to disc rear end with calipers and e-brake cable for $250.

Good luck,
Mike

P.O.S. Racing

Mike, a junkyard sounds like the way to go but how do you determine if a junkyard rear end is good?

stinkfist

Yeah it will be hard to tell if it is good but there are a few ways to help. If You can find one behind an auto tranny then you know it will be good because it's never been driven hard. Low mileage cars will have better ones. Look for cars that have no mods. Your best bet would be to find one behind an auto though.
Theres not many out there but they are out there.
Good luck,

Mike

Rich

I was doing some research on Miatas for some parts I made. I ran accross an article on a miata tech site on LSD rear end swaps. IT stated that the lsd diff from an 84-92 Rx-7 would bolt into a later miata rear end with some minor grinding. With that said, I am trying to find part numbers for the LSD housings for the 84/85 GSL-SE and the FC's. If the carrier parts are the same, then the FC lsd will be a bolt in swap for the FB's. This is good for the simple fact that the FC n/a (88-92) were a Viscous coupling, and the others are all clutch packs. Even further looking I found that the 2nd miata ran a torsen (crap in my book, if you want to know why, I will be more then happy to say) which would make it a junk yard swap too. Just something to get the wheels up stairs a turning. Anyone have the part nuber for the LSD carrier from a GSL-SE?

RX-Midget

OK, Why do you think the Torsen diff is crap?

Chuck Clark

If you drive your car in autocrosses or road races, the Miata Torsen is a great upgrade over the RX-7 LSD. They cost about $650 from Mazda Comp, so they're not cheap, but they give the rear end a lot more bite coming out of a turn........especially if you're racing in the rain.

Rich

Disclamer: This is the personal views of Rich. It in no way reflects on the managment, members of this site, or anyone that has heard of a car. It is not ment to start a flame war, or pissing match, just mearly one person's views on the subject

Now, I personally don't like a torsen due to it's ability to act as an open diff when a complete loss of traction is present on one wheel. Back in the day (like a whoppin 3 years ago) I was running an open track day at Laguna Seca. It was a dry dry summer day, the R1's that I was running were very warm, and added to the extreme camber on the car, and hot sticky pavement, I was getting MASSIVE traction. I was heading into turn 7, and was forced into a slow line by another car that wouldn't yeld comming out of 6. As I came into the apex, I clipped the rumble strip bouncing my left side up. Added to this I was just getting on the gas (okay I was smashing it in 2nd) as the tire came up, my torsen diff did what they are designed to do, act as an open diff. For a split second I had all power transfered to the wheel up. In other words, the inside wheel got 100% of the power and it started spinning. When the car came down, the instant onslought of torque from the motor fighting the friction of the tire. Exploding the internals of the torsen (I'll post pics tommrow) Now, I know that it was my fault for being in the wrong line, for hitting the gas so hard at the apex, etc. Sence then I have done the same thing in that same turn with a clutch pack, and NEVER once have I had any wheel spin, or damage to my drivetrain. So now I will only run a clutch pack, and if nessasary a Viscous. I like the viscous, but it takes wheel spin to activate the "lock" where the clutch pack is always there for me. Granted the lag of the torsen is good if you want some hard, fast, exit lines, but the ability to enter a turn under power like an open diff. They all have their place, I just choose to avoid the torsen types.

Chuck Clark

Rich,

Sorry to hear about your problems.

But, allow me to reiterate......if you want to go fast on the twisties, you will have an advantage over guys with LSDs if you have a Torsen......especially of it rains. If you have wheels in the air, it doesn't matter which rear end you have....you're not going fast.

Chuck

Rich

I guess the only other problem with a torsen is the ice issue. IF you have one wheel on the ice, and the other off, you are not going to move much (if you have 0 traction with one wheel) Don't get me wrong, they are great parts, and are VERY good for racing, as well as spanking people in the hills. Just blowing a quafe unit left a nasty taste in my mouth for them. I am sure one day, I will try it again, and if, say, a miata diff lands in my lap, I will think about it. But what I see the Miata Torsen LSD only transmits 20-25% of the torque to the loose wheel. Anyone else hear of this? I have found some good info on diff swaps rx7-B2000-626-323-GLC, and the like. Has anyone else done this research, or am I blazing the trail? From what I see the '84/85 had larger axles then the 79-83, but did they use a different spline diameter, and if so, anyone know this dimention. I will be hitting the junk yards this saturday in search for a cheap upgrade. I might come down to the, shove an 84 GSL-SE axle into the diff of a miata, and FC to see if they fit.

Pele

iTrader: (28)

Can you piece together a rear end? Could you fit the following parts together?

GSL or GSL-SE Axles and housing
B2000 Pinion and ring (4.44)
Miata Torsen Unit

Also why would one want an LSD to act like an open diff? Isn't tht whole point of an LSD to NOT be an open diff?

Rich

sorry double post

Rich

You don't want your LSD to act as an open diff. But with all the great points into having a torsen unit, the downfall is not only the price, but the fact that if you have NO traction on one wheel, the diff will then act JUST like an open unit. Also, depending on the gear sizes used, the torque bias is changable. The miata unit is around 20% torque biasing. Which simply means if you start to slip, only 20% of the torque will be transmited to the slipping side. While 80% will remain on the tire with more traction.

Now, as promised, pics of a blown Torsen (as quafe claims is unbreakable) This diff was removed from a TA Vette. you can see the worm gears are warn almost smooth, and some gears are missing. the spline gear is jammed into it's present locatation (in the center) Like I said, torsen units are GREAT LSD's I just prefer the Clutch type for race applications, and maybe a good viscous.
http://www.geocities.com/sr20_510/im...isc/image6.jpg
Still in the housing
http://www.geocities.com/sr20_510/im...isc/image1.jpg
good shot of the spline gear in it's new home
http://www.geocities.com/sr20_510/im...isc/image2.jpg
if you look at the worm gear at the top, you can see where the gear tooth used to be located
http://www.geocities.com/sr20_510/im...isc/image3.jpg
again, a good pic of the missing chunk of worm gear (upper right) and the spline gear in it's home. It relocated the worm gear there to the inside of the case. You can also see that the splines are still intact. The force of the snap broke the bolt holding the stub axles to the spline gear which sent them out of the carrier. Good thing, hardened 4130 cro-mo stub axles/CV joints are not CHEAP parts.
http://www.geocities.com/sr20_510/im...isc/image4.jpg
good shot of the chipped worm gear, notice that the one closer to the ring gear is in almost perfect shape. That's because the spline gear rotated away from this one. It removed others that were it it's way.
http://www.geocities.com/sr20_510/im...isc/image5.jpg
A good overall shot of the damage. Also notice the lack of wear on the ring gear in all the shots. The color change is the dust that has collected on this part. I keep it like a trophey The whole rear end was only in the car for about 6mo before the damage.

Because Geocities/Yahoo is lame, you can't use the links here. You will have to open a new brouser window, and cut/paste. Or you can just click the link to see the pics.
http://www.geocities.com/sr20_510/images/misc

pineapple racing

To test the lsd, jack up only one tire off the ground, block the car so it cannot move. With the tool you have make, a piece of steel with holes cut in it to fit over the studs (or bolted with lugs) with an old socket welded to it with the 1/2 in drive end out, use a beam type torque wrench and see how much torque it takes to rotate the "wheel" that is off the ground. 85ft.lb. is a tight unit, probably a recient rebuild. 30 ftlb. is common for a used street piece. The hardest part, is putting the ring gear back exactly where is was so the pattern of the gear contact is not changed. This could cause gear noise. In sever cases reducing the life. The friction plates are not too pricey, and they don't all need to be replaced. Even if it costs you a little more than an untested used unit, it would be rebuilt not used. Someone that knows them will probably not charge more that an hour of shop time+parts to freshen just the lsd if you have it out of the car and clean. If you do it yourself follow the book, clean all the bolts/bolt holes very well and use locktite on every fastener. If you use the original ring gear check the back lash BEFORE dissassembly and return it to the same figure. For the bearing preload, check how much torque it takes to rotate the assy. before you diss. then put it back (I usually add a little more drag to make up for normal wear). Don't add to much! Rob

Pele

iTrader: (28)

Oh yeah. Forogot to ask. In all the catalogs, I see the spacers for the pinions. They're all in VERY small incriments. Like hundredths of an inch or something. (I don't have a catalog handy or I'd look.)

If the backlash of the gears is wrong. (I assume that's what's evidenced by the wear pattern on the ring and pinion gears.) and you use the spacers to adjust that, how do you tell which spacer to use?

What if you're adding a different ring and pinion wiht wear marks from another diff or maybe a new ring and pinion?

Do you have to reassemble and teardown for trial and error? Seems kind time consuming and costly to me.

Nobody ever said anything about my Frankenstein diff. So I'm assuming you can't do it.

Also, can you stimulate a torsen if it is in the no traction condition by using the e-brake? Fool it into thinking there is traction on the other wheel? Or would it have gone crunch by them?

Rich

I haven't gone to the yards to start parting one together, I will see about it this weekend and let you know with some pics...