Rearend???
 

I was just wondering what kind of rearend is in the mk3 supras? Is it limited slip or posi or neither? Anyone know the gear ratios???? Thanks.

There are several different gear ratio's and some have lsd rearends and others are open(no lsd, no posi). The way you tell is by the code that is on the tag in the drvers door jam. Look at the code that begins with G.
It should be something like G305.
The G is for the diff size so G=8inch diff(all Supras have the 8inch)
The 1st two numbers are the ratio.
They are as follows.
28=4.3
30=3.9
31=3.7
The last number tells if it is open or lsd. If it is an odd number it is lsd, if it is even, it is open.
So G305 is an 8 inch rearend housing with 3.9 gear ratio and is lsd.
Hope this answers your question. I have never heard of a Supra with a true posi in it, would take away from the cars cornering ability to much. There might be more ratio's but these are all I know of.

i dont have a code on my car? 86.5 NA

my 86.5 has an lsd, but it doesnt mean yours does. take a look at your rear end. mine said right on it somewhere that it was lsd.

well, when i spin around corners, or squeel the tires, there is two tire marks, which would probibly mean LSD?

Yes 2 tires spinning is lsd, and the tag is under your hood on the firewall, I forgot that they did not put the stickers in until 1989, it's a big metal tag, you can't miss it.

Just lift your rear end up and spin the back wheels if they both spin in the same direction you have lsd. If you spin them and they go seperate ways then you don't have lsd. It also says on the differential LSD oil only which means you have an LSD.

sorry to jack....

some idiot peeled the sticker off my door, I have an 89 turbo and I do not see the lsd tag on the rear either is there anywhere else they put the id??

I don't know of any other place on the car other that the door jam and on the rearend itself. I remember seeing somewhere in my forum travels that one guy found his sticker on the inside of the car in the hatch area, but if memory serves me correct it was under the interior pannels, I cannot say if that is where the factory put it or if someone just moved it there because they painted it or something. What gear are you in at 75 mph and what rpm are you at? Tell me that and I might be able to tell you what you have for a gear ratio. It's really pretty simple, if you are doing 75 in 5th gear and are at 4,000 rmp or so you have low gears, if you are only at 2,500rpm or so then you have high gears or long gears as some people call them.

at 70 I am at 2100 rpms in 5th. 75 I think 2850

I have LOW gears lol. When im at 70 im at about 3200 or 3500

could someone explain this too me. why, in the same gear and at the same speed, do "low" gears have higher rpms, and "high" gears have lower rpms?

low gears have a small actual gears so it doest take as many rpms to turn it enough to spin the other gear. The high gear has a larger actual gear so it takes more rpm to get it around. I hope this makes sense im really tired. And someone correct me if im wrong. lol.

I've got 3.9 gears in mine and at 75 I'm at 2850 there about so I'd say you got 3.9 gears.

What h8z2luze said is close, the size of the gear is not that different, but the size of the teeth on the gear is. Smaller teeth means more of them and larger ones means less of them. For example, 4.11 gears have 37 teeth on the ring gear and 9 teeth on the pinion gear, so in short the driveline of the car must turn 4.11 times to turn the wheels all the way around once. You get your gear ratio by taking the number of teeth on the ring gear divided by the number of teeth on the pinion gear, 37/9=4.1111111111111. So if you have like 2.83 gears your driveline only has to turn 2.83 times to make the wheels turn all the way around once, thus giving you lower rpm. Hope this answers your question.

maybe i can help
http://img179.imageshack.us/img179/8595/gearsyu9.png
lower gears have small circumferences that allows them to do a complete 360
faster
while the higher gears have a bigger circumference, hence a longer rotation

bcuz the lower gears needs to rotate more to produce the same amount of power as the higher gear does
the higher gears puts out enough power so it does not need to rotate any faster
rpm = rotation per minute

im not making you sound stupid,
but look at it this way
you got the lower gears as a , small guy , really quick but no muscle
then you got the higher gears, big guy, muscular, but no speed

to push a 3600 lbs object
the smaller guy needs to work more harder than the muscular guy

i did my best to explain that, may not have the proper terms but, i think it works,
if not, oh well i gave it my best shot
hopefully it helps

I found mine, its G285 :)

So would that mean that the rearend has 4.30 gears like 4.11's? Cause that would be really low.

Yup, you got some the lowest ones there is, great for in town and racing, shitty for the highway.

thanks for the explination. ive got it all worked out in my head now.

High gears are called high, And have high rpms, Because of the numeric gear ratio. All for example, First, being a high gear, is say, a 3:1 ratio. Meaning the drive gear spins 3 times(high rpms, more mechanical advantage) for one rotation of the driven. At 5th, The ratio is say 1:1, a low gear. The drive and driven spin the same. Which is less rpms and less mechanical advantage as opposed to 3:1. And overdrive means that the ratio is less than one. .75:1 for example. And supra2nr, For your explanation, A smaller guy running faster and a stronger guy running slower pulling the same weight, Are doing the same ammount of work, But one faster and one with more force. That is the important part.

And also, My n/a was at about 3500 rpms going 70 lol. It sucked balls on the highway.