LSD Swap out

[Tomas]

The stock cone gear type lsd made by GKN on the Aisin tranny found on the MS3 is really not that bad. I decided to swap it against a Quaife, which is of helical gear type, after a few messages from Saitek. I believe he is the only other person running one. Quaife Part# is QDF7F/36D . I am not a transmission rebuilding specialist so if you find something blatantly wrong here feel free to comment. Meh.

Mazda sells a transmission shop manual. I don't think it's needed but that does not mean it's not a good idea to get one. I didn't.



Once the transmission is off vehicle with it's oil drained start by removing the shifter plate / lever assembly which actuates the forks. These are all 12mm bolts. It's the part where the shifter cables attach to. Also remove the gear position sensors and centering bolts. There are 5 of them in total. The lever needs to be in the neutral position in order to come out of the casing. If it's not it won't slide out. Pushing down the lever one step will get you into 1st and second gear. Another step into reverse. Pulling up the lever will get you into 5th and 6th and middle position is obviously 3rd and 4th.

Don't force anything. If something doesn't come out smoothly you are fucking up somewhere.

Now proceed to remove all the bolts that hold the casings together. There are are a shit load of them on the outside and about 5 in the hollow space around the throwout bearing. Again these are all 12mm bots.

Place the transmission on the face that looks toward the engine. It can stay in this position till you put it back together.

Now remove the 17mm bolt that sits somewhere on the cover. There is only one 17mm bolt in the whole transmission. You won't get the tranny apart unless you remove this bolt as it secures a gear assembly which I am going to call "idle gear" as I don't have a clue what it does.

Remove the big ass allen plug pictured below to expose the snap rings that hold the layshafts in place. The outer races of the layshaft bearings are grooved to accept the rings. Pull on the cover and separate bond between the casings before opening the snap rings. Once the cover puts upward pressure against the snap rings from pushing it up, take snap ring pliers and open rings. You can open the rings with one hand and hug the upper casing with the other so that the races of the layshaft bearings slide through their seat. Take cover of to expose shit inside.



Remove little steel sheet and plastic piece that, I presume, serve as oil routers. Remove and clean magnet which sits in slot as pictured below.



Remove all the small allen plugs around the outside of the casing you are working on right now. Inside the holes are sleeves that contain springs that press steel balls against the shafts. They serve as centering devices for the forks when they are engaged in each of the two gears the fork / ring slides on (except for reverse which fork goes only one way and is made of aluminum - who the fuck knows why) . IF YOU PULL THE FORK SHAFTS WITHOUT FIRST REMOVING THE STEEL BALLS THEY WILL FALL IN THE CAVITY THAT CONTAINS THE BEARINGS FOR THE FORK SHAFTS. If you put the shafts back in their location with the balls sitting in the bottom of the cavity you will not be able to shift 1st, 3rd, 5th and reverse. I found this out the hard way. The balls and springs look like this. The spring sits inside the sleeve. You will need a magnet for this.





If you feel uncomfortable in that you won't be able to put all the guts of the tranny back together, go ahead and mark each fork to the shaft it sits on as you are gonna start taking them apart now. There are 4 forks with 4 corresponding shafts. I am pretty sure you can't put the transmission back together if you don't get the forks in the right place but marking them won't hurt. Now remove screws and knock out cotter pins holding forks to shafts. There is also a rocker arm that levers one fork to the other on one of the layshafts. It's the one with gears 1 through 4 I believe.






Once the forks are removed, MAKE SURE YOU DON'T SLIDE THE RINGS ON THE SYNCRHOS TOO FAR UP OR THE LITTLE BALLS SITTING IN THE CAVITY BELOW WILL TORPEDO OUT. These little balls are spring loaded against the inner part of the ring. I tell you this cause it happened to me more than a few times and they are a royal pain in the ass to find on the floor.



Now lift the two layshafts and Input shaft out of the lower casing. The layshafts are the two beefy gear assemblies to each side of the input shaft. They should come right out. Then remove idle gear.



The LSD is bolted to the crown gear which you should be able to lift out as well now.



Remove bearings from LSD using bearing puller.



Remove bolts attaching crown gear to stock LSD and swap.



Obviously enough, everything goes back in reverse order.



When putting the casings back together you need to align the threaded hole at the shoulder of the below pictured idle gear to the hole in the casing where the 17mm bolt goes through ( there is only 1x 17mm bolt - remember?) . YOU WILL NEED TO TAKE THE TRANSMISSION BACK APART IF YOU DON'T. Don't put gasket maker on the casings till you are sure the bolt will screw into the hole. This also, I learned the hard way.



Finally, once you have everything back together and sealed, it is essential that you go through each gear position by hand to make sure they all engage properly.

1. Push down lever all the way and move to one side will get you in reverse.
2. Push down half way and move from one side to the other. This will be 1st and 2nd
3. Leave in neutral position and move side to side. This is 3rd and 4th.
4. Pull lever up and move side to side. This is 5th and 6th.

If any of the uneven gears and reverse fails to engage, you probably dropped a steel ball in the cavity of the bearings for the fork shafts.
If any of the even gears fails to engage there is probably something wrong with the gears or synchros on the layshafts.

Fuck - that went way longer than anticipated.
It's really not that hard once you have it all in front of you.

[Lex]

Awesome that you're doing this! I will probably do the same once it's time for a clutch job.

Did you pull the motor or drop the tranny from underneath? How long did the entire process take?

Most importantly, how does it compare to the stock LSD when driving?

[essejkcamraw]

i am also interested to hear the difference between this and stock. good stuff man!

[Tomas]

I dropped the gear box from underneath. Swapping the LSD is prob about a 4-6 hour job. Taking the gear box out and changing clutch took me 12-14 hours working alone. About 4 hours of that was just spent trying to drop the tranny. It's tight down there and you want to slide it out while supporting it parallel to the engine.
I am still breaking in the EM stage 2 clutch so can't say much as far as traction on the Quaife. I can say it is much smoother at slow speed and no noise with Amsoil trans oil. In two weeks is out to the track again so we'll see if I can get better traction out of some of the 3rd gear turns. That's the main reason for the swap.

[drknyte]

Don't leave us hanging...... Do updates when available!

Good work dude bro man!

[Mizzle]

Any consideration given to changing out the diff gear ratio? If not, why not? If yes, why no change? Just curious.

[bewsted]

Glad you decided to dig into this because i would pay someone to install this shit on my car...CANT STAND TRANSMISSION WORK.

[Tomas]

Originally Posted by Mizzle Any consideration given to changing out the diff gear ratio? If not, why not? If yes, why no change? Just curious.

If you want longer gears you got to get a genpoo tranny. There is no way to change the gearing on the Gen1 gear box without changing the bottom two gears of the layshafts and the crown gear where the lsd bolts on to.

I have no idea whether you can buy these genpoo transmission components individually.

[Phoenix Speed3]

This is awesome... good work

[Bucker]

Hey OP thanks. Seriously. Good stuff in here.

[backward_0]

This is why I love MSF right here.

[Tech/Sales@EM]

Nice Man. Hope Everything Works Out.

[Tomas]

Okeedokee.

As with the clutch, the quaife is also holding up well after 1200 miles now.

Traction during track work: it can definitely get you more of it than the stock LSD. The vehicle will plow more however, as both front tires can get to spin exiting a turn instead of the inner tire alone. If that happens it does not matter how stiff your rear end is or how easily you can get it to rotate you will not be able to avoid the plowing. It's not like the car just keeps going straight or anything, but you do notice that the nose is harder to turn in when exiting a corner at high load in 3rd gear.

In my opinion it is not a huuuge difference though. If someone asked me whether I'd recommend this upgrade for a DD my answer would be no. The stock LSD is plenty good. For tracking the car its definitely a good upgrade.

I was thinking of getting an OS Gicken clutch pack LSD once they come out to put on the other gear box I have but I don't think I will. There is just only so much you can do with FWD. Messing with the LSD will only yield limited results.

It is still a great learning experience to take the tranny apart and change the LSD if you are into that sort of thing. Work on the gear box itself is easy as you don't have to bend over or crawl anywhere like you do when working on the car.

[Nliiitend1]

Great writeup! A very welcome addition to the forums.

[PunjabiPlaya]

epic thread is epic

[saitek]

Glad everything went well. Get a chance to get it out to a trackday?

[drknyte]

Originally Posted by saitek Glad everything went well. Get a chance to get it out to a trackday?

Lame readers lame!!!!

"Traction during track work: it can definitely get you more of it than the stock LSD. The vehicle will plow more however, as both front tires can get to spin exiting a turn instead of the inner tire alone. If that happens it does not matter how stiff your rear end is or how easily you can get it to rotate you will not be able to avoid the plowing. It's not like the car just keeps going straight or anything, but you do notice that the nose is harder to turn in when exiting a corner at high load in 3rd gear."

[Wolfgang5884]

Lots of great info. thanks for posting!

[Tomas]

Originally Posted by saitek Glad everything went well. Get a chance to get it out to a trackday?

Hey man, long time no hear!

Yup, took the car to Homestead last week end. There is a thread/vid in the road racing section.

What happened to that noise you were having? Figure out what it was? Still busy with that new job huh?

[saitek]

Good track and great driving, looks like the quaife held up well. I liked the end.

My trans is out of the car right now. Drained the trans oil and it looked fine. My codriver
will crack it open and see if he can figure out the source. If my triple digit work hour weeks ease up, I might do a local track day late september or so. Car should be put back together by then.

[Tomas]

Originally Posted by saitek Good track and great driving, looks like the quaife held up well. I liked the end. My trans is out of the car right now. Drained the trans oil and it looked fine. My codriver will crack it open and see if he can figure out the source. If my triple digit work hour weeks ease up, I might do a local track day late september or so. Car should be put back together by then.

Good luck!
Hope nothing major is wrong. Take pics if you find the problem. Interested to see what it could be.
That dude in the 911 is going to get it next time. With the 3071 I have on now I am gonna surprise his ass. He is a cool guy but deserves to be put in his place. haha.

[qtrmile beast]

I want to assume that since your avatar is of a speed3 that this was a speed3 rebuild? i have a speed6 tranny that i want to crack open sometime soon.. great write up!!!

[Tomas]

^ You assume correctly. It's a MS3.
I believe except for the transfer case and final gear ratio the Aisin on the MS3 and MS6 are very similar if not identical. Check with 06speed6. I think he can confirm.

[06Speed6]

Syncros may be different, i havent looked at the ms3 syncros yet.

[kmac]

Love the write up.

[Tomas]

As much as you love Tokay?

[kmac]

Originally Posted by Tomas As much as you love Tokay?

No that's just crazy talk. He's my one and only, but this is a close second.

[Tomas]

Please stop. You're gonna make my mascara run.

[enganear]

The beauty of the Quaife is that it does not lock the front wheels together under torque like the cone clutch design. It applies equal torque. The cone clutch depends on resistance to create separation forces at the spider gears which forces the hardened steel cone clutches to lock the two axles together through the housing. If you unload one wheel, no slip limiting occurs. The Quaife and Torsen geared designs will not limit the slip of an entirely unloaded wheel, but do a good job up to about a 3:1 torque difference. Most importantly they do not inhibit turn in or promote understeer under power. I have not used the Quaife, but I went directly from an Auburn cone clutch to a Torsen diff on an ESP 5.0 Mustang with terrific results. I would choose the cone clutch over the geared design for drag racing.

[Tomas]

And the clutch packs are pretty noisy too and sometimes require adjustment.
OS Gicken is supposed to be bringing one to the market soon. Probably pretty expensive. Supposedly with over 20 clutch discs.

[Tech/Sales@EM]

I would like to see a wavetrac option for you MS3 guys. Maybe in the future.

[Tomas]

Wow. I learn something new every day here.
That wavetrac lsd looks pretty slick. Prices seem reasonable too.
Almost like a planetary gear design.

Wavetrac® Differential - A torque biasing differential with a difference

[Tech/Sales@EM]

Yeah its the best of both worlds, like a quiaffe and os giken together.

You could prolly send your old lsd in and have them make one. If u still have it ill send u a packing slip and have it sent to my contact there if they are interested in making one.

[Tomas]

Yeah. I still have it and wouldn't mind sending it to them.
Good idea too would be to give them the quaife part number. May be they can cross reference the part number to a unit they have already established. Oh and the Aisin model number for the gear box. I believe the tranny is shared by some other platforms IIRC.

[Tech/Sales@EM]

Yes it is your correct. Ill contant him tomorrow and see ho they want to proceed.

[Ziggo]

Very interesting, I don't really have issues with zero load conditions, but I take it this could eliminate the power on "kick" I feel when getting back onto the throttle aggressively?

My only track experience was on my motorcycle prior to this car and I have always wondered where that kick came from.

[justint5387]

I used this write-up for my OS Giken diff last week. This is a great write up, but here are some tips i want to add.

Something that i want to add is:

1. Make sure the diff you receive has 16 bolts, I received the wrong diff. I found out the hard way.

2. Buy new diff bearings, make it easier and get the right size pressing tool.

3. The allen plug hiding the snap rings in the 2nd pic is either 1-1/16 or 27mm. I couldn't find an allen socket or wrench that fit, so my friend welded a nut onto the plug so that we can turn it with a pipe wrench. Took me a few hours to find a solution

4. A snap ring pliers will be a great help. My friend had it in his garage

5. Remember to line up the reverse gear for the 17mm bolt with the case

6. Remember to make sure all the gears work before putting it back in the car. I found out I couldn't shift to 5th, not sure why because i took it apart and reinstalled it the same way.

[Tomas]

How much did you pay for the the OS gicken lsd?
Please also make a review once drivable.

[justint5387]

Originally Posted by Tomas How much did you pay for the the OS gicken lsd? Please also make a review once drivable.

My price is discounted through sponsorship, MSRP is $1695 IIRC.

I already drove it, it feels great. The faster i go, the more the front want to turn in to the apex when I am on the gas. Of course, car will still understeer if you floor the car too early, nothing can stop that. However, I didn't feel any wheel spin even on tighter auto-x corners, only time that i got wheel spin is when I spun the tires off the line. One thing that I note is that you can expect slightly more turbo lag since you are not spinning the wheels out of the corner anymore.

[Tomas]

How about noise and slow speed engagement when locking steering to either side?