Q45 diff upgrades

[gottdeskrieges]

I've installed the q45 diff into my 240 a couple of weeks ago. So, now that's it's in I'm wondering how much abuse it can handle. Also to see if there is any LSD upgrades for this particular diff. My car should make anywhere from 600-800rwhp, just give you guys an idea what the diff will be going thru. Thanks for any help you guys send my way as well for the info for others.

[turbo2nr]

underground motorsports s14, is making 800+whp on a a rb and bw s372..
using a q45 diff..

several ka-t guys making over 700whp is running q45 diffs as well..

[gottdeskrieges]

are there any lsd upgrades for the q45 diff? im glad it capable of handling the power, can wait to put my car on the road and see how she responds.

[g6civcx]

Originally Posted by gottdeskrieges

I'm wondering how much abuse it can handle... 600-800rwhp

First, diff wreckage depends on how you drive more than what you have.

Second, torque is a better indicator of abuse than power.

Drivetrain breakage occurs when engine torque is applied but the wheels don't want to turn, like when you have super sticky drag slicks. Something in the middle has to give.

In my experience, generally the stock axle is the weak link. You will blow out an axle before you break the diff, assuming the diff is in good shape and installed properly.

The next weakest link is the propeller shaft. This seems to go next once you've beefed up the axles.

I don't know what gearbox you have, but assuming you have a KA or SR gearbox, these seem to be pretty weak as well.

The last thing in the drivetrain I would expect to break is the R200 diff. These are super strong.

I've been putting 400+ ft-lbs of torque through these diffs and I have never had one break on me. I've had a bunch of stock propeller shafts, axles, and gearboxes break before the diff broke.

[gottdeskrieges]

Im using a r154 transmission. I have a 2jz swap with a BW s374. One piece driveshafts with the q45 rearsetup. Its more of can I get a R/R that is lower than the 3.54 like down to 3.2x's. Im glad to see they old up though, makes things easier on me in that department. Thanks for your input.

[g6civcx]

Originally Posted by gottdeskrieges

can I get a R/R that is lower than the 3.54 like down to 3.2x's.

You're talking to the right person. I'm the only I know with an R200 with 3.1 in an S-chassis.

AFAIK, there is no 3.2-3.4 stock R200 unless you get custom gear set.

The next step up would be 3.5 like you have. There is nothing in between 3.1 and 3.5.

[gottdeskrieges]

Ok well 3.1 is fine. How do I go about getting that done? Your on a v8 setup correct? How do you like the ratio? Is it daily driven?

[g6civcx]

Originally Posted by gottdeskrieges

How do I go about getting that done?

Search for the term "3.133" in the S-chassis subforum.

Originally Posted by gottdeskrieges

Your on a v8 setup correct?

Yes.

Originally Posted by gottdeskrieges

How do you like the ratio?

It's perfect. Anything higher would not be driveable for something with this much low end torque.

Originally Posted by gottdeskrieges

Is it daily driven?

Yes.

[gottdeskrieges]

I read over the thread, looks exactly like what I need to do. I do have a couple questions though. Since I'm using q45 right now can the axles and flange off the q45 be used on a pathfinder or the r/r of a pathfinder into a q45 diff since I don't have any s13 parts in that area? Would u mind pming ur number?

[g6civcx]

Originally Posted by gottdeskrieges

can the axles and flange off the q45 be used on a pathfinder

Yes and yes, with a caveat. You have to check the actual length of the output flange and axles. I want to say yes, but since I have not done this specific combo, I cannot say for sure.

The axles may or may not be the right length as well. You may have to get custom axles in the worst case.

Originally Posted by gottdeskrieges

the r/r of a pathfinder into a q45 diff?

Look in my thread.

Originally Posted by gottdeskrieges

Would u mind pming ur number?

PM me your number and I'll text you mine.

[g6civcx]

Like we talked about, I posted a complete thread with pix for you and everyone else: http://zilvia.net/f/s-chassis/267957...s-chassis.html

[moedigzz]

3.1 FD? what? you like going 200+ in 5th? put big mickey et streets on it and get traction. low FD's are for higher top speeds, not traction.

[g6civcx]

Originally Posted by moedigzz

3.1 FD? what? you like going 200+ in 5th? put big mickey et streets on it and get traction. low FD's are for higher top speeds, not traction.

Yes, I'm geared to do 180mph in 5th gear. I'm running a Borg Warner World Class T5. Soon I will be switching to a Richmond T5 with custom 6-speed gearset.

The OP is putting down well over 700 horsepowers and I'm putting down close to that.

Nobody is talking about traction. We're talking about wasting time shifting gear.

Final drive ratio is part of tuning. High power cars run through the first 3 gears so quickly that a lower final drive is needed to prevent rapid shifting.

If anyone has any question about gearing, please ask me.