SC3 5spd to 6spd swap

[neurot75]

I asked this on club lexus but i still didnt get a clear responce. The responses i got were the typical dickhead: its too pricey forget it, or why do u really want to do this? whats your main reason, blah blah blah.

Thats up to me to decide.

He'res the deal, im looking for an SC3 with a 5spd in good shape to buy in the very near future. I would deff. not go the route of getting an auto and swapping. My question is simply how hard would it be to swap in a 6spd out of a supra in place of a 5spd. I am planning on turboing the SC3 when i get it, and most likely going into 500hp territory.

Why id want to do it is simple.
The 6spd can hold more power.
It is a True 5spd, with an overdrive.
I like the gearing in comparison to other trannies.
Seems like a worth while thing to do if one is serious about their car (and i am; would be when i get it)

I heard that pre 95 SC3's have smaller subtunnels and have problems with having a 6spd in there? and post 95's have a bigger tunnel? is this true?

How hard is it really to do this swap, and how much am i looking to spend. Money is not a huge issue, but then again i am not a multi millionare. I know a lot of things would be involved, i.e. custom drive shaft, changing to a 6spd rear end, maybe even modding the tunnel and/or mounts?

I would really like to hear from ppl familiar with this, people who have done this or have had experience with this mod.

Thanks,
Vlad

[Bean]

Yes thats correct, the pre-95s have a smaller tunnel and causes the transmission to bump into the tunnel from what I've read and been told. Manual transmission cars are much easier to swap over.

As with any transmission swap, you're going to need the flywheel to match it and then the right clutch to mount onto the flywheel.
In the 5-speed to 6-speed swap case, you'll need the 6-speed slave cylinder too since the clutch mechanism works opposite of what the 5-speed does.

On the SC300, you'll need a custom driveshaft, powerhouse racing offers a custom 1 piece and Toyomoto (if you can ever get ahold of them) down in Miami can build you a twopiece (has less vibration).

And you'll need a different differential. The stock gearing on the SC300 is too short at 4.08 and you'd be switching gears so fast it'd be crazy. And if you're going to be making the power you're after, you'll need a LSD anyways. So just swap out for the 6-speed TT differential too. It is a 3.13 ratio and properly geared for the 6-speed. To swap that differential you will need both of the axle shafts too (the driver side is a different length than stock, and the 6-speed versions are way beefier than the stock Lexus part)

All in all you're looking at around $4000-$4500 for the whole swap for just parts.
$2500 for the tranny
$50 for the slave cylinder
$200 for resurfaced STOCK flywheel (do not run an aftermarket one!)
$750 for good TT clutch to handle good power
~$600 for differential and axle shafts
$500 for 1piece driveshaft (possibly more than this)

that comes to about $4600. It'd be less if you can find a decent condition tranny for less, but good conditioned ones market price is $2500
and cheaper clutches can be found for about $500 or so, thats still not much money saved. Its expensive.

Reason people ask you questions over there is because you never stated what your power requirements were. There are other options besides the V160 6-speed. There are a lot of people that don't own the SC300 or Supra yet that come and ask that question over there. It gets asked about 3 or 4 times a month by the same types of people who then NEVER post again. The information is there inside the forum, I know because I've posted answers to the swap questions several times :)

[neurot75]

thank you very much, thats exactly what i was looking for. Seem's like a bit more work than i expected.

Can the stock 5spd handle the power i have in mind? granted with an aftermarket clutch and maybe a lighter flywheel?

I also have another question.
Would it make more sence to use the supra turbo LSD from an auto or a mt car?

[Bean]

I would keep the stock flywheel if I were you. I've heard too many horror stories of aftermarket flywheels coming apart. Though thats for the V160 and not the W58 5-speed that we have.... I'd still be cautious

At 500hp if you dont drag launch it and dont do any big pulls in 5th gear and dont shift super fast (just applying the throttle with control instead of WOT after every shift as fast as you can) then you MIGHT be ok. I say 'might' because some people have had success and some people have not.

If you want an LSD, I'd either run the MKIV TT auto rear end (which is a 3.73 and not a 3.13 like the MT version, and it bolts directly to the stock axles) or the non-turbo MKIV Supra LSD (which is not found on every NA Supra, it varies depending on the VIN number)... that LSD is a 4.08 which matches what you have now.

Just remember, each upgrade you do to the driveline (clutch and LSD and tires) make the transmission the next weak spot. If something has to give with too much load on the motor (ie too much torque or too much top-gear pulls) then the weakest link will give out.

At 400whp if you're careful you should be ok. If not, W58s are a dime a dozen and chances are your clutch and flywheel will be just fine.

[UrBaN cUsToMs]

ive had an aftermarket flywheel and i was lucky for it to be in great condition. The problem is not all flywheels work good with all clutches. you have to get them matched right. the stock ones are much stronger typically and wont wear. if you have the hp to make up for it its not a big loss.

[neurot75]

sounds good, thank you all for the info.

So if i understand correctly, the 5spd's limit is around a little over 400 hp?

if so then thats not too bad, for me at least.

[UrBaN cUsToMs]

5spd is 500whp 6pd is 800whp. thats the guidelines in the books from what i year. have people pushed it? yes. some guy had 750 hp on a w58. and it held up for him. and obviously woon has his supra pushing 1000+ on stock v160.

[Bean]

I honestly dunno about 500whp at all. I know plenty of people that break them around 400whp. I dont know of anyone with 500whp running the stock 5-speed. If you can show me proof then I'll be a believer. We're talking about being able to put 10k miles on a transmission without it blowing up here. there's lots of cars in the NA-T arena that are daily drivers.

500whp has too much torque associated with it for the little W58 to handle. Its not a very big transmission at all... compared to the V160 anyways. And I've seen alot of 6-speed cars handle 1000whp before... actually more hp than that.

[Kirk]

There was a local supra who put down 681rwhp on a 5sp, kbprice put down 476 on a 5sp and hes been na-t for 4+ yrs, scnat on the forums also put over 500 at the wheels... and I will be cutting it close aswell with my transmission and seeing how long it lasts. Depends how you drive the car and the beginning condition of the transmission before you throw the power at it. Of course its not as reliable as the 6SP by any means, which is why I will be swapping over to 6SP the second mine takes a dump :) A guy locally put down 1147rwhp on a 6SP with no problems... :fingersx:

[Bean]

daaaaaaannng... hmm well maybe I was wrong :D I always felt that my 2nd gear would go pretty quickly lol