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Discussion Starter #1
I read previous posts for an hour trying to figure this out. :roll:
So please don't yell at me. :cry:
Besides the clunk btween shifts and noise from the rear ,I noticed i was passing people i normally don't on the freeway...........mmmm : ???..well i did a little test with my garmin 295 GPS and here is what i found.
ohh by the way........old records show the rear was replaced in 95 at 138k with a "used rear" ....JAS1 was the part # the shop used. the car has 152k now.
info below is from the tag on the firewall
86 MkII P Ma61L-BLMQFA
C/TR/A/TM 8 B4LG86F 283W58
5mge ....................all stock.
The calibration test is as follows........all in 5th gear in MPH

RPM speedo GPS

2450 55 -
2700 60 67
2950 65 72
3100 70 77
3350 75 -
is it the rear or the speedo????...nothing mentioned about changing the gear in tranny
what was the original gears in this car?......i have now idea whats in it now.
but i'd like to replace with a true trak but would like to keep the original gear ratio. Just going to be street driving. maybe the occasional auto x for just forfun.......

Thoughts??????
thanks, Intis
 

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Your car's original diff was an F283, which is a 4.30:1 LSD. If you think it's been changed, the only way to find out is to pull the rear cover off the diff and count the teeth OR spin the tailshaft one revolution and count the wheel revolutions (this is a fairly rough method though).
 

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With the info you gave there is NO way of telling. Are you running different tire sizes? If the rear was swapped out then what good is the firewall badging? The only ways are to count teeth or spin the drive shaft and count wheel revolution.
 

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Discussion Starter #4
just threw the tag up for xtra info ......I'm new here and still learning about the car.............

Thanks.
 

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Intis,

Most of the bottom firewall dataplate information can be found in the cs.com history section. http://www.celicasupra.com/othercodes.htm

The model information can be found here: http://ourworld.compuserve.com/homepages/stepho/newcodes.htm

Since you're still a :n00b: we'll give you a break & help you out (at least I will). So.....

Your bottom firewall codes are as follows: 8B4LG86F283W58

Paint 8B4: Dark Blue Metallic Clear Coat Paint.

Interior LG86: Blue Leather P-Type Seats.

Axle F283: F = 7.5" Ring Gear Diameter. 28 = 4.30 ratio (who knows what's there now however). 3 = 2 pinion/LSD rear.

Transmission: W58 5-speed.

Model Code MA61L-BLMQFA

M = Engine Family = M series, 6cyl, petrol.
A = Platform Type = Celica (-1985)
61 = Model Code. In this case, it would be a Celica Supra w/ the 5MGE. Other examples: 45 = Celica Supra w/ the M-EU motor, 46 = the 4ME motor, 47 = the 5ME motor, 63 = the M-TEU motor. 70 = the 7MGE/GTE motor.
L = Drive configuration = Left hand drive. THIS DOES NOT MEAN THAT IT'S A L-TYPE SUPRA!!!! (big misconception).

B = Model Code based on same platform. In this case, it's Celica Supra.
L = Body Style = Liftback.
M = Transmission Type = 5-speed, floor mounted.
Q = Trim Level or Grade = Highest Level.
F = Engine Type = Twin Cam EFI (Highest Performance)
A = Country Destination. In this case, it would be USA. Canada would be a K.

Hope this answers your questions about the dataplate information.

(Admin's: Some variation of this needs to be a sticky. :D )
 

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I imagine the rear was prolly swapped out w/ a 3.72 differential, those seem like high mph for those rpms, I had 3.72s swapped into my Silpra but I had taller tires on it, so I can't tell exactly, but I know my car certainly doesn't do 77mph @ 3100
I imagine 3.72s would cause the 7mph difference or so, but you can always spin the driveshaft and find out that way, also, you'll want to jack the rear end up and spin your rear wheels, if they both spin in the same direction you have LSD, if they spin opposite from each other, they're non-LSD
 

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he has a 4.30:1 r&p. as to wether its lsd or not, jack the rear of the car up and turn one of the wheels. the other wheel will turn in the same direction if its lsd. my 84 with 4:30:1 did 70mph at 3krpm, so did my brown 85 with 4.30:1, and my mkiii with 4.30:1. with the 3.727 im hopeing to drop the rpms down to below 2500 @ 70mph
william
 

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Discussion Starter #8
Still running the oem tire size. I don't remember seeing the opposite wheel turn fwd when spinning one wheel when i had it up on jacks.weeks ago.... but i did notice while cking the drv line that both wheels spun fwd while turning the drv shft.........I'll chk the ratio this wkend.

seems like Reider racing and River city diffs are the favorites to deal with.
I've never messed with a diff b4 .

Thanks Gang.

Intis
 

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Actually, my bet would be either a 3.91 R&P out of a Celica or a Cressida or the much sought after 3.73. Calculating it out you get:
RPM: 3100
4.30 R&P- 68mph
4.10 R&P- 71mph
3.91 R&P- 74mph
3.73 R&P- 78mph
3.42 R&P- 85mph

Thats about all the gear ratios I can think of that anyone could get for that rear end easily. The cressidas may have a 3.56, or something like that, but I can't think of the exact number off the top of my head. http://www.f-body.org/gears/ Play around with it if you want, it's kinda fun. Tranny ratios are:
1st- 3.29
2nd- 1.89
3rd- 1.28
4th- 1.00
5th- .78
 

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Discussion Starter #10
Thanks for those numbers...............I'll let know the results this weekend.

Intis
 

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Discussion Starter #11
Ok ,...Jacked up the car and this is what i got. When spinning one wheel,either side the opposite wheel doesn't turn. When rotating the DS both wheels turn fwd.

I marked the DS and one wheel. 1 full turn on the Ds got me .25 rotation from the wheel. 2/ .50 3/.75 4/ 1 full rotation. I have yet to pull the cover off and count the teeth.....

Iwould guess i have 4.10's???????????........

Thoughts on this???
 

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Discussion Starter #13
I agree.......i,ve got a 4.30 replacement since this one is a worn out mess.

I'm interested what i'll find when i take it apart.
 
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