I drove to Chi-town today to pick up MKIV Seats, an R154, and a MKIII front driveshaft.

The MKIV seats yield the proper head room for a 6'3" male and the proper seat height for a sport coupe. The weight drop is an added bonus for sure. I also hate driving the car in the Supra seats without having a stick. This should only speed things up.

This is a horrible photo as it was dark and rainy by the time I got the camera. But, it is an R154 in a V8 SC400:


Given the layover time on the five speed kit and the C's short shifter from Japan for the JZZ30 trans conversion, I am hoping to make the car manual during my fall break in November. These one of a kind mods take time more than anything.

This schedules the supercharger assembly accordingly for spring break in March. That way, when everyone busts out their Camaros, Mustangs, and Firebirds as the weather breaks, I can start my trail of tears.

 

I thought you had decided to stay auto and just get a TC or something instead... So you did decide that you were going to go manual?

 

I got around to installing the differential today. By yourself with only jack stands, expect the operation to take the better part of a day. Fortunately, the weather was perfect and the assembly went pretty much to plan.

The car needs to be jacked up. S10 suspension and 26's anyone?


Use the parking brake to allow yourself to break free the 10mm hex bolts around the circumference of the axle stubs. My car has only seen half of a winter in its life. There is no oxidation whatsoever: I love it.


Unbolt the exhaust from the midpipe back to the mufflers. There are two 14mm bolts at the midpipe, two 12mm bolts on each side near the resonators (mine are deleted), and four 17mm bolts on the muffler mounting bracket.


Get a 12mm allen wrench and an 18-24" piece of 1/2" steel pipe.


The 12mm allen wrench is for the three bolts that secure the differential to the rear cross member. The steel pipe section is for extra leverage. These bolts are TIGHT.

A special thanks to Scott for giving me this tip. Tightly secured 12mm hex bolts are the definition of akward and unneccessary: "Thank you Toyota."

Before removing the ears (19mm) and the companion flange bolts that connect to the driveshaft (17mm), secure the differential with a jack to prevent a greasy mess as the iron housing is sure to break upon meeting the concrete.


I used a piece of wood to help balance the diff, and I used top soil (fertilized no less) to surround the jack and break a fall in the event the diff got a mind of its own and fell off.


As the diff drops, the male ends on the axle stubs will become loose by way of geometry. I went down VERY slowly so as not to damage my pristine stock diff. Once the stock diff was out, I set it aside.


Moving a 90lb differential is not easy...unless you pawn a skateboard off a neighbor kid. I shimmed the diff at an upward angle with a sweatshirt to better accept the driveshaft. I used a small piece of wood to not damage the skateboard and subsequently ruin the neighbor kid's day.

 

Feeling connected to the car after allowing me to borrow their skateboard to mate the diff to the driveshaft, the neighbor kids put their stuffed animals on my trunk hood. If this is not JDM tyte, I don't know what is.


Getting the 90lb diff from the skateboard to the jack was tricky and required a little strength, but I just sucked it up. I reinstalled some of the axle stub bolts now to make sure that the ascent was a clean one.


The diff is well more than half way home at this point. The cross-member bolts are the next to get reinstalled.


With the cross-member bolts installed, the jack and jackstands are useless. The 4.27 Torsen differential is home.


Make sure you put 75w90 or 80w90 gear oil in the differential before driving away. On level ground, the higher of the two 10mm hex plugs should be removed and the diff should be filled until the oil starts evacuating through the hole. At that point, the oil level is sufficiently high.



Since my Torsen diff center is BRAND NEW, I am going to go through with a 300 mile break-in period. I drove for 20 miles tonight for the first phase. My initial concern was to get to a vacant parking lot to do a dozen or so figure eights at full wheel lock both forwards and backwards at idle speed to wake the LSD up. During the entire break in period: the tach stays under 3k, the speedo stays under 55mph, no hard launches, no sudden stops, and no sharp corners.

Given the limited time with the diff tonight, I am very pleased. The operation is whisper quiet. Turning is more true from the Torsen unit. The car feels 200lbs lighter from the gearing, and the diff is buttery smooth from the new gear oil.

After my 300mi of hell are over (I set the trip to know just when I can punch it), I will definitely do 0-60 and 45-65 runs to monitor the progress of the car.

 

Blizzy,

You are the man!

Where did you say you got that LSD?

Your reccomendation on my thread and your write up here have got me thinking....

KC

 

KC-

Thanks for the compliment. I just love this car too much to not take it all the way.

I got the LSD from Supraforums brand spanking new for $400. It was a great deal. If/when my stock diff sells to offset the cost of the salvaged SC300 a/t diff, I will be $400 in the hole for a pretty sick rear end.

The LSD is really a must with your stall converter upgrade (in my opinion)...even if you keep the stock gearing. Hell, if you would like a donor SC400 diff in MINT condition, I would help you out and give you a great deal on the one I just removed.

-Mark

 

Nice write up Mark! This will come in handy for others.

 

From a forum vendor or from a classified?

How much? Are you willing to ship it? It's a 3.916 correct?

I had considered an SC300 manual diff (4.083), a bit more umph without screwing with the speedo as much as the 4.27.

I'm still not really convinved that I need it for my normal driving habits. Might change my mind if we get snow this winter though, and I have to admit it would be nice to have when I decide to get throttle happy.

KC

 

KC-

The LSD was found on the classifieds. But, I hear Titan will get them in used on occassion and fire sell then for $200. You might give them a call.

Yes, the gearing on my diff is 3.92. The shorter gears will definitely help performance at the expense of snow traction. I would perhaps investigate the companion flange on the SC300 m/t because that model may well carry a different rear driveshaft completely.

4.27 is definitely very aggressive in the speedo-error department. I will correct the error when the R154 goes in.

-Mark

 

thanks for the help. you have been instrumental with the progress of my car from day one.

I hope this thread can help many SC guys in many ways. I will make a table of contents on the 1st posting one of these days to make weeding through the thread rubble more easily accomplished.

 

I just got back from time trials with the 4.27 LSD. Recall my baseline averages are 6.78s for 0-60 and 3.57s for 45-65.

I ran five trials for each. Again, I used the digital camera and trimmed the files using a video editor. For this iteration, I was careful to account for the speedometer error from the different gearing.

Here are the times...

0-60mph:
(1) 6.50s
(2) 6.44s
(3) 6.50s
(4) 6.43s
(5) 6.37s

45-65mph:
(1) 3.23s
(2) 3.17s
(3) 3.16s
(4) 3.23s
(5) 3.23s

This generates new averages...
0-60: 6.45s (-0.33)
45-65: 3.20s (-0.37)

It is noticeably more difficult to hook up off the line with the shorter gearing. However, the LSD does do a nice job of a "chirp and go" launch. I think more practice launching with the LSD could trim perhaps another 0.1s from my 0-60. But, these numbers really give an excellent indication.

Theoretically, the LSD is not giving me any kind of a boost from 45-65 over an open differential. Thus, for $150-200, a salvaged SC300 a/t differential with the 4.27 gearing could net a very nice result for not a lot of dough on an otherwise stock SC400.

 

good stuff man. in to keep an eye on this thread.

 

great mods please keep posting!

 

Good stuff Mark! BTW Mark, My Clutch is here!

 

a few things... first off... torsen lsd's= very weak. clutch packs... wiht metal clutches... much stronger. torsens are very smooth, but cannot handle shock loading for ****... so dont even think about clutch dropping on that diff...