Final Score: LSD 1, Inside Wheel Spin 0

[CrankyOldMan]

So I just took the new gearbox out for a spin around the block. HOLY CRAP! No inside wheel spin on hard acceleration out of the corners, lots more torque in 2nd gear and it now lands inside the power band between 1-2 shifts. I haven't gotten on the freeway yet, so I haven't been able to test 3-4-5, but I'll take care of that once I'm done getting the steering column aligned again. The steering also feels much more responsive, but that could just be a camber change.

For those of you that haven't been following the saga, check out the back story here: http://www.yarisworld.com/forums/showthread.php?t=35999

[CrankyOldMan]

More musings after one 30 mile rural commute and one suburban lunch run.

I'm still getting used to the presence of the LSD, but it makes a huge difference in the corners. I got the tires up going over a railroad crossing, so I felt the difference between open and limited right away. (Helical diffs become open diffs if one wheel has zero traction.) It gets a little twitchy when engine braking, and the steering effort seems more deliberate, but all in all it looks like it's worth the blood sweat and (tears?) money.

The new gear ratios are AMAZING! I can land above 4k RPMs and pull strong in 2nd, 3rd and 4th. The taller 5th with the xB final drive seems to be just right for highway cruising now, and isn't completely useless. I still have the factory governor, so the "lost" top speed is irrelevant.

Long story short: if you have the mechanical aptitude and/or funds for either project, DO EEEET!

Next on the list of terrible ideas? Cat-back exhaust!

[Jason@SportsCar]

Amazing you were able to patch those pieces together and make it work. Congratulations.

[CrankyOldMan]

Thanks! It's been a really fun project, and I've learned a lot in the process. Hopefully someone else can benefit from my adventure, too.

[xnamerxx]

Might have to pick your brain for my coming up build.

How are you liking the quaife?

[CrankyOldMan]

Might have to pick your brain for my coming up build.

How are you liking the quaife?

Sure thing. There's lots of stuff documented in the above link, but I should probably do a consolidated build thread. Most of it was just researching part numbers.

The Quaife is very streetable, and responds well in the corners. I've got an AutoX coming up this weekend, so I can really see what it does on the short course.

[kou]

This is awesome. Any chance for a part # and where you got the lsd from.

[xnamerxx]

So what are the gear ratios you finally ended up with. I saw what was posted on page 1 but I wasn't sure if that's what was used in final assembly.

[Will-I-Am]

Nice mate! Really looking forward to installing my TRD LSD. Cant wait for it to get on the track. Only thing is that i have to be careful of curb hopping because its a helical like you said and it becomes an open diff.

Tell me about your findings when you did an Auto-X

[CrankyOldMan]

This is awesome. Any chance for a part # and where you got the lsd from.
The LSD is a Quaife QDF15E, from THMotorsports. There's a few other distributors, but the price difference is negligible. It's more expensive than the KAAZ but less expensive than the OS Giken (both are clutch-types). If you aren't set on a helical type, the KAAZ would be a good way to go on a budget.

So what are the gear ratios you finally ended up with. I saw what was posted on page 1 but I wasn't sure if that's what was used in final assembly.
I'll have to dig up the piece of paper that I wrote it all down on, but I think it was the ratios listed in this post (http://www.yarisworld.com/forums/showpost.php?p=700737&postcount=13). The following post shows the new gear ratio spreads vs stock, which should give you an idea of why I chose the ratios that I did. There are a few other ratios available for 1, 3, 4 and 5 if you're interested in theorycrafting a gearbox for a specific track or non-stock power curve.

Nice mate! Really looking forward to installing my TRD LSD. Cant wait for it to get on the track. Only thing is that i have to be careful of curb hopping because its a helical like you said and it becomes an open diff.

Tell me about your findings when you did an Auto-X
As long as your mechanic is competent and can follow the repair manual, you shouldn't have any problems with getting it set up. I got into some gravel on a curve today and got the diff to run open, but it hooked right up once it got back to clean pavement. The only issues I really see is the way the wheel reacts to mashing the gas pedal mid-curve: I think it wants to lock the front axle and go in whatever direction you were last pointing in.

Either way, I'll try and post my findings by the end of the weekend.

[sheekeebut]

Helical, so like a Torsen, right? If that's the case, a little feathering of the brake would do to keep diff pulling, yes?

[CrankyOldMan]

Helical, so like a Torsen, right? If that's the case, a little feathering of the brake would do to keep diff pulling, yes?

Yes and yes, but I don't know how to left-foot brake yet. =)

[sheekeebut]

Well if it's any encouragement, it took me 3 months and 5,000 km in two cars to get confident with left foot braking. Not much trouble at all.

No more steering wheel headbutts.

[sheekeebut]

And with your diff, I bet it would be like the REAL Yaris coming to life.

[kou]

Searched for the quaife diff. It is a little pricey so I went with the TRD LSD which I just ordered for nearly half the price at $690.44 its a mechanical diff the same as the quaife which means cheaper maintenance and should be pretty strong.

[CrankyOldMan]

Well, ran the autoX today. Can't really report much as it was a REALLY dirty course and it rained just before our heat. Of the 4 runs, I had one ABS-related error, one cone, one spin/DNF and one clean run. I was still able to break the tires loose on corners--which given the surface conditions might be expected--but overall it seemed to be better behaved. I also didn't spend any time chasing tire pressure, so that may have been a contributing factor. There were also some strange grinding noises when the tires broke loose on a straightaway, but that could just be the noise a helical makes when engaging under low/lost traction.

The final drive mod is absolutely amazing for our car! I launched in 1st and then hit 2nd by the second gate. Kept it in 2nd the rest of the way and had no lack of power or redline conditions the whole course. YMMV, of course, depending on the track.

[cali yaris]

I can beat TH Motorsports every time :wink:

[kou]

Just got my TRD lsd and it is a clutch.

[xnamerxx]

TRD unit should be helical, any chance the LSD has a part number on it?

[CTScott]

TRD unit should be helical, any chance the LSD has a part number on it?

I think the TRD ones are indeed helical, but helical ones still use clutch plates for driving the axles. This is how the bad translation on the TRD site described the LSD and if you look at the cutaway image from the TRD site you see the helical gears as well as the clutch plates.

"Because the limited slip capacity is provided using a number of clutch plates, it exhibits a direct, reliable LSD effect."

http://jpx.responsejp.com/jpx/images/2004/09/09/63544_1.jpg?fit=normal

[xnamerxx]

CT pic only shows hypoid gears, thats a salisbury unit, as you can see the dual clutch packs for drive and decel. If that was a helical unit you would see the helical gears going across the case.

http://upload.wikimedia.org/wikipedia/commons/7/75/Spur_gear_differential_(Manual_of_Driving_and_Main tenance).jpg

[sheekeebut]

if you look at the cutaway image from the TRD site you see the helical gears as well as the clutch plates.

http://jpx.responsejp.com/jpx/images/2004/09/09/63544_1.jpg?fit=normal

Wouldn't the helical gears be spiral shaped? Like so? http://blog.keyeslexus.com/wp-content/uploads/2013/06/torsen.jpg

[CTScott]

OK. So someone needs to pull apart a Yaris one and see what is actually in there. Looking at the TRD descriptions only one of the Celica and one of the Corona ones specifically say helical (or actually "helycal").

[CTScott]

Sorry to Cranky for taking this off topic, but it looks like there were two different types of TRD LSDs for the Yaris/Vitz

The earlier one is: 41301-AE000 (and is helical)
54243

The later one is: 41301-AW004 (clutch type)
54245
54244

[CrankyOldMan]

No worries. It's all relevant for someone looking to install an LSD.

[Will-I-Am]

TRD Diff is in and drove some practice laps and Time Attack this weekend.

Saturday we had a trackday and it was nice and sunny so really could test out the diff. What a difference! No more wheel hopping on fast exiting corners. Much more stable at high speeds during corners and overall more balance. Was really hoping to get some decent laps the next days during Time Attack

Unfortunately the next day it was raining and the track was really wet and slippery, also a car lost his complete oil sump plus content all over the track during his first round so that made the track extra slippery. Fortunately, the fwd cars had much more grip and traction then then rwd cars so we could outcorner all of the gt86's and 350z's. Had a lot of fun doing some battles with bmw's who would just drift trough corners and me taking the inside lane overtaking them, haha

I need to do some proper testing on a dry track during a hotlap to really get the best out of the diff but all in all i'm very happy with it!!

[sheekeebut]

Funny, I thought the wet and ugly conditions would have been the perfect testbed for diff

[Will-I-Am]

Funny, I thought the wet and ugly conditions would have been the perfect testbed for diff

they were. but i never drove in the full wet with oil and stuff on that track so couldnt compare laptimes with another fast lap

[Will-I-Am]

leaving the competition behind haha

https://fbcdn-sphotos-d-a.akamaihd.net/hphotos-ak-xaf1/t31.0-8/1507221_797497750272869_7227969956159579779_o.jpg

[aspro]

Sweet pic. I sure hope you are leading the charge and not actually being over lapped haha jks.

[CrankyOldMan]

I think it's a big improvement in the wet over an open diff. It's been raining quite a bit the last week or so, and I've had much more control over the car--even with UHP Summer tires that are bald in the rear and near-the-wear-mark up front. It does take quite a bit to get used to the way it handles when accelerating too hard in a tight corner, but when you get the line right, it's just power all the way through.