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From that chart it WOULD IT ? be safe to deduce that all mk's either came with a 41 or 43 tooth RING, and either an 11, 12, or 13 tooth PINION? Now.... question... is it possible to take a 4.30 RING and merge it with any old 12 tooth Pinion?? Other than getting the gears meshed properly would this be a problem? Either way that'd get me either a 3.42 or a 3.58, NOT bad ... plus I'd see another 20% on my mileage!! (Though 25mpg @ 75mph & 400hp aint bad, I'd love to see 30mpg)
IIRC, in '85 when the Celica GT-S finally got a 7.5" diff, it used the 3.58.
 

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From that chart it WOULD IT ? be safe to deduce that all mk's either came with a 41 or 43 tooth RING, and either an 11, 12, or 13 tooth PINION? Now.... question... is it possible to take a 4.30 RING and merge it with any old 12 tooth Pinion??
Yes, if that chart is accurate then that is true.

If so then it would seem that we only need the pinion gears to create our own 3.58 and 3.42 gears.

The problem is still sourcing the 12 tooth pinion gear.
 

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From that chart it WOULD IT ? be safe to deduce that all mk's either came with a 41 or 43 tooth RING, and either an 11, 12, or 13 tooth PINION? Now.... question... is it possible to take a 4.30 RING and merge it with any old 12 tooth Pinion?? Other than getting the gears meshed properly would this be a problem? Either way that'd get me either a 3.42 or a 3.58, NOT bad ... plus I'd see another 20% on my mileage!! (Though 25mpg @ 75mph & 400hp aint bad, I'd love to see 30mpg)

it will be awesome if i can get 25 + mpg at least. :zzzzz:
 

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From that chart it WOULD IT ? be safe to deduce that all mk's either came with a 41 or 43 tooth RING, and either an 11, 12, or 13 tooth PINION? Now.... question... is it possible to take a 4.30 RING and merge it with any old 12 tooth Pinion?? Other than getting the gears meshed properly would this be a problem? Either way that'd get me either a 3.42 or a 3.58, NOT bad ... plus I'd see another 20% on my mileage!! (Though 25mpg @ 75mph & 400hp aint bad, I'd love to see 30mpg)
First off, 3.42 and 3.58 matching sets are available-Application was 2wd Toyota truck from 88-95ish, and front pumpkin of some 4x4 trucks from same time range. Ive got a 3.58 in my car from one, and last I heard, they were available new from Mark. Second, the pinions have different tooth pitch and ODs, so they wont mix and match on the ring gear. BTDT. I got my 3.58 from PnP for $30. If the possible Donor Vehicle has a 4speed, its one of these ratios....The Data plate section of the FAQ shows the codes to look for.
 

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First off, 3.42 and 3.58 matching sets are available-Application was 2wd Toyota truck from 88-95ish, and front pumpkin of some 4x4 trucks from same time range. Ive got a 3.58 in my car from one, and last I heard, they were available new from Mark. Second, the pinions have different tooth pitch and ODs, so they wont mix and match on the ring gear. BTDT. I got my 3.58 from PnP for $30. If the possible Donor Vehicle has a 4speed, its one of these ratios....The Data plate section of the FAQ shows the codes to look for.
That's exactly what I was anticipating, different gear/tooth angles. Not a big deal, thanks for the refresher on what vehicles they come in.
 

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whew, I've pinned speedo @ 130 @ about 6000rpms w/ 4.30 gears which appears to be accurate comparing to the chart... I would like to see someone w/ a stock n/a mk2 "officially" top their car out @ redline and see what mph that would be...just can't figure out a way to get a speed check unless you have a cop friend who'll clock you, heh
or maybe an aftermarket speedo that does over 130? I dunno
I think Norbie has said he's done 160mph but that's definitly NOT stock...
all mag articles I read has the mk2 topped at 130mph, so is the car not supposed to pick up even a little more speed if it still has a few more rpms to go?

a tom tom GPS would tell you what speed you are at.
 

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My 1982 with 4:31, W58, 225/65-R14 and standard 5M only made it to 128 MPH, at ~6,750 RPM. Stock weight + 250lbs (I'm a big dude). I was heading down hill at about 10% Grade. The chart just looks a little off. I may be wring though.

just can't figure out a way to get a speed check unless you have a cop friend who'll clock you, heh
or maybe an aftermarket speedo that does over 130?
RE: My father has been an officer for 25 years (get outta jail free card)
I was along side a 2008 Porsche... My speedo read past 85, that was as high as it went. But he signed "1...2...3-5." I took it as 100 + 20 + 3 + 5
 

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My 1982 with 4:31, W58, 225/65-R14 and standard 5M only made it to 128 MPH, at ~6,750 RPM. Stock weight + 250lbs (I'm a big dude). I was heading down hill at about 10% Grade. The chart just looks a little off. I may be wring though.


RE: My father has been an officer for 25 years (get outta jail free card)
I was along side a 2008 Porsche... My speedo read past 85, that was as high as it went. But he signed "1...2...3-5." I took it as 100 + 20 + 3 + 5
6,750 RPM? impossible, my 5m topped out at 6,6xx RPM on the freeway, BLAH BLAH it was at 3 in the morning and no one in site lol, i had to slow down because the wind popped my passenger window out a bit lol.
but my 5m is a late high comp engine, and it's on an 83 with 4:10 gears, all i have done to the car is suspension and exhaust.
 

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Discussion Starter #113
chart doesn't seem right. im at 80 mph in 5th @ 3000rpm W58 and 3.73 lsd gps confirmed 205/60/15
Let me provide some alternate sources:

The pertinent inputs-
W58 gear ratios
5th gear = 0.783

Tire diameter: 205/60-15 = 24.7in

Rear Gear Ratio: 3.73

The formula: mph = (rpm * tire diameter in inches) / (gear * differential * 336)

mph = (3000 * 24.7) / (0.783 * 3.73 *336)
mph = 74100 / 981.3
mph = 75.5

Alternate calulator

IMO, if you feel the chart is off, it's more likely that some portion of the input is incorrect. My bet is that your RPM is inaccurate; next up is that your diff isn't really 3.73. Less likely is that the gps is wrong or, grasping at straws, you don't know how to read what's printed on your tire.
 

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I hope that information is correct. 8750rpms, 17 inch rim/tire = 24.7 (same as 15 inch tire above?????)

(8750*24.7) / (1.00*4.10*336) = 156.88mph

The dyno said 158mph in 4th (R154).

I am just trying to calculate the speed because I have no speedometer.

Calculated 208.35mph in 5th.
 

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hhmm interesting, think I'm going to print this into a sticker and slap it on my dash so I can figure out what speed I'm doing for once. My speedo's out 60+ kmh it fluctuates as you drive.
 

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precise speedo on the MK2!

With the 3.72diff, and its correct speed gear in the W57 and the speedo INTERNAL (all from the same Euro. spec MK2) behind the US standard MPH/kph dash, and 215/65R14 tires on the back, the speed is PRECISE! I clocked it on FEW roadside radars (used in Europe to show your speed so you can correct it) in different speeds, and I was stunned at the preciseness of my speedo!!! The reason I swapped the internal speedo mechanism, was because my original US Spec. one had over 330,000 miles on it and its gears were worn and the arrow would dance around, while the Euro spec. one I had only a bit over the equivalent of 111,000 miles.
So it is safe to say that the Euro spec. MK2s had pretty decent speedo (safe for the larger rear tires I run 215/65R14 vs. 225/60R14).
 

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My 85P has always been a bit optimistic and with 225/60/15's, it's very close. I can't recall the diameter difference compared to the 225/60/14's but I think it's a bit over 4%. Most vehicles tend to read a bit high though. It's not uncommon for some motorcycles to be read way over reality, some by between 10 and as much as 15%!
As far as top speed, my car has always been able to go faster in 4th gear and this is true of many vehicles. Upshifting to 5th and the engine just doesn't have enough power to sustain that speed. I've had mine verified by a friend with his police cruiser at 135 or so and might have had a few more in it but very few.
 

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Hate to continue to revive an old thread, but is there a way i can tell if i have an LSD without getting under the car? it sits relatively low to the point where its hard to get under plus its like 10 degrees out.
 

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This thread is funny, all you guys doing math when there's a calculator made to solve all these problems for you with just a few button clicks! Have you all not seen DeanFun's Tire Speed calculator? It was posted 2 years after this thread started. ANYWAYS, I just solved a huge mystery in the land of correcting Toyota speedometers and magical part numbers, see this post in the aforementioned thread...
http://www.celicasupra.com/forums/showthread.php?25423-Testing-Tire-Speedo-Differential-Calculator-try-it-out!&p=853866#post853866
 
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