Diff Ratios

[sneakyis200]

hey all.

may have been brought up before. cant find the info anywhere including google.

just wanna know what diff ratios the is200/300 use across the different models and how i find out what mine has.

i have a 4spd auto is200 possibly sports model. have looked under the car didnt know what i was looking for. but it has a sticker something something like 06/2005 or something on it. looked like a date. car is 2001 model. so for a start thats odd.

what im looking for is lowering the revs if possible. car is almost all highway. so if i could drop the revs a bit might save me some fuel.

any suggestions on what i might have or how i can find out. then also what fits in?

if there is something i can add in that will say take it from a 4.1 to a 3.1 or something major like that from another car i might also be keen. i know it will be an absolute slug off the line. buts sitting around 3000rpm at 100km/h seems a bit high. silly 4spd.

also... is it possible for an auto to slip? seems like a CVT auto sometimes when i take off from the lights. speed goes up with out revs climbing that much when im at like mid throttle.

[rickylexus250]

hey all.

may have been brought up before. cant find the info anywhere including google.

just wanna know what diff ratios the is200/300 use across the different models and how i find out what mine has.

i have a 4spd auto is200 possibly sports model. have looked under the car didnt know what i was looking for. but it has a sticker something something like 06/2005 or something on it. looked like a date. car is 2001 model. so for a start thats odd.

what im looking for is lowering the revs if possible. car is almost all highway. so if i could drop the revs a bit might save me some fuel.

any suggestions on what i might have or how i can find out. then also what fits in?

if there is something i can add in that will say take it from a 4.1 to a 3.1 or something major like that from another car i might also be keen. i know it will be an absolute slug off the line. buts sitting around 3000rpm at 100km/h seems a bit high. silly 4spd.

also... is it possible for an auto to slip? seems like a CVT auto sometimes when i take off from the lights. speed goes up with out revs climbing that much when im at like mid throttle.

I didn't think it came with CVT, perhaps the transmission is slipping and in regard to the revs, check the manual to see if that is correct, also check that the tyre/rim combination is correct. You can also change the revs by altering this combination.

[plankton007]

The IS200 has really close gear ratios (Final drive of 4.3 I think) allowing it to stay in it's power band so it doesn't fall off in torque. That's probably why when it shifts gears it feels like it hasn't really shifted since it's always in that power band. This is probably why you think it feels like a CVT.

It's also a 4spd in the auto so highway driving is going to make the revs sit really high like you've already stated.

You could try and fit a lower gear ratio diff or change the ring and rod in the diff but that's about a 6-7 hour job.

IS200 Gear ratios

A/T = 4.3

M/T = 3.9

IS300 Gear ratios

A/T = 3.909 (though some models are 3.709 if someone can correct me that will be great)

My guess for the M/T IS200 is that it would have longer ratios similar to the is300. You could also try and fit the IS300 diff housing into your car for the same results. The IS300 diffs come in models m85 and m98. The m85 is the diff without LSD and the m98 has LSD. You can find a used m85 for fairly cheap (under $200) however the LSD diff is more expensive around the $600-$700 region.

However, I think all the IS300s in Australia came with the LSDs... (someone please confirm)

I'm not 100% sure if the diff housing across the 2 models will be the same bolt on and bolt in but some ads on eBay state that they will fit both models

http://www.ebay.com.au/itm/lexus-is200-differential-rear-diff-from-a-manual-car-Australian-spec-car-/121320532293?pt=AU_Car_Parts_Accessories&hash=item1c3f446945

You can try this link. It's from a manual is200.

[sneakyis200]

tyre and rims are right.

yeah still get the feeling the auto slips sometimes.... i might get it serviced just as good measure.

as for diff ratios... seems like its to much effort. i think there is another issue causing my high consumption that i need to address before i try and improve it.

also... what numbers and such am i looking for on the diff to find out what one i have? as im certain its an lsd. it slides just as well to the left as it does the right. no way its a open diff.