The actual difference between the OEM USDM/pre-98 JDM ITR tranny (4.40FD), and the 98-up JDM ITR (4.78FD) isn't just the final drive ratios.

First of all the final drive assembly is the combination of the ring gear (it's the big gear bolted around the differential) and the counter shaft (also called pinion shaft) mated together. It is basically the final gear that each individual transmission gear is multiplied by.

What this means is that each gear you shift into is multiplied by the final drive, and thus the ratio of that final drive will have an effect on how quickly you accelerate through each gear. A ratio that is taller will actually have a lower number, and thus, essentially makes it take longer to accelerate through each gear.

A ratio that is shorter will actually have a higher number, and it actually has the effect of being able to accelerate through the gears faster.

Essentially the final drive ratio either raises or lowers the maximum speed achieved in each gear. A transmission with a 4.26FD will take longer to accelerate through the gears than a transmission with a 4.929FD.

A final drive change does NOT affect what rpm drops to when upshifting/shifting through the gears.

It's a common misconception that a final drive "shortens the gears" when in fact it does not change where the rpm needle falls to when shifting into the next gear. the only thing that can change that is changing the actual gears themselves. If one were to keep all gears the same, but change the final drive to a shorter one the maximum mph is shortened in each gear, so you rip through the gears more quickly. ...but if the rpm dropped from 8500rpm down to 6500rpm (just an example I threw out there) when you shifted from 1st to 2nd before the final drive swap, it would still drop the same rpm. You'd just rip through the gears/reach redline sooner.

Play with this Honda gear ratio chart with graphs, etc. and it will illustrate what I'm talking about:

Click Here for M Factory Gear Charts

Okay so now back to the original question about the difference between the 4.400FD and 4.78FD ITR transmissions.

The 4.400 tranny and 4.78FD trannies share the same 1-3 gears, and both have LSDs. The 4.78FD ITR tranny does have TALLER 4th and 5th gears, actually the same gears found in the GS-R transmission. I'm sure Honda did that to keep the rpm drop manageable between 4th and 5th gear, and allowing that taller 5th gear to keep the highway cruising the exact same as the 4.400FD tranny. Again play with that M Factory linked chart and see what I mean.

Hope that helps.

 

Vortex!

 

So taking Libertariat's actual set-up into account, let's do some number crunching.

Since tires have an effect on the cruising rpm in each gear (it's also a sort of final multiplier - shorter tires = like a shorter final drive; taller tires - like a taller FD.) I'm going to use 205/50/16 tires for my math.

Stock ITR transmissions that came with a 4.400FD came with a .848 5th gear. At 80mph let's see what the cruising rpm would be:

80mph = 4200rpm

He is planning on swapping in the taller 94-01 Integra LS 5th gear, which is a .742 (taller) which would be:

80mph = 3500rpm

That's a difference of 700rpm. Might not sound like a lot, but that's a pretty awesome change for such a simple one gear swap.

If he ran that 5th gear in a 4.78FD-equipped tranny with that LS 5th gear:

80mph = 3900rpm

...still lower than a stock ITR tranny.



One last thing - the Accord Euro R/Prelude VTEC tranny has a 4.26FD with a .812 5th gear...cruising rpm in 5th gear at 80mph?

3900rpm

So really you could run the 4.78FD ITR trans with that LS 5th gear and still not be any "worse" off on the highway than the stock tranny that was supposed to be mated to that H23A.

 

Thanks for the info, Tom

Glad to see you back posting a bit.

I'm worried about the 4.78FD being impossible to keep traction on, the 4.4FD will be bad enough, lol.

If I was just drag racing I wouldn't be worried, but too much power in autocross can be rough.

 

i think you will still need a rear t-bracket from a 99-00 si for the b series trans .didn't see it on your list

 

Stout setup. The lower end torque will help and will be a world of difference compared to your current D series. Staying subscribed for updates.

 

I don't know man - won't you pretty much be in 2nd gear for most of the entire auto-X courses? LSD + 4.78 + short 2nd + niiiice torque = bad ***.

I used to try and cram back into 1st when I first began autoXing, but found it far better to try and keep momentum and just stay in second and resist the urge to jam in first and haul *** out of the slow corners. I picked up some speed, saved my trans the strain, reduced the potential for wheelspin, and it helped me stay smoother on course.

That extra grunt down low will certainly serve you well at auto-X.

...now on the street? 1st gear with that kind of torque and a 4.78 might be challenging. It's challenging enough in my car with my less gruntly B18C5 to put the power down in first gear. When you run camber settings that ar well suited for cornering you also give up that flat contact patch that is crucial for launching and having traction in first gear.

 

Yeah, right now it's 2nd gear for the entire course (post launch)

You're spot on as far as retaining momentum you should come out and at least support me this season, heaven forbid you race

And your last statement is my big concern.

Now, do I drop $2,000+ on a custom ITS trans from Synchrotech? Full carbon synchros, MFactory helical LSD, 4.4FD, it's so tempting. Hopefully James@Mainstream can build me one for less. I may need to source a B-series case though, idk.

The swap, as is, is already paid for. I've saved up that money already. I did just get an 18mos no interest credit card from chase, I can pay it off before summer even starts. I've got no debt, period, credit score is 730 or so.

I'm to the point where I'm like: "Man, I would really like to just do this right the first time."

It's awfully tempting.

 

A good friend of mine bought her GS-R swap from JDM source 5+ years ago, it's been beat on for those 5 years now and still working great.

 

Normally I'd say I would not charge any mod-related stuff on a credit card, but honestly in your case it could be used to build even more good credit, and without the added penalties of an interest rate to pay, why not? I'm all for having paid-for modded cars, but there's also a good case for building credit by charging something, and paying it off before the interest kicks in.

I'm just throwing this out there:

I would seriously look at a brand new ITR transmission from an Acura dealership that sells them at wholesale cost to the public. I could contact a few of my dealer friends and see what kind of real, out the door pricing you could get on one.

From that point splitting the case and putting the LS 5th gear in would be an easy job as 5th sits atop both the main and countershafts, and isn't invasive at all. You would not have to unstack anything, and the only true cost would be the 5th gear set and a tube of Hondabond to reseal the trans case.

I'm looking at 2000 Integras' parts here.

The mainshaft half of the 5th gear set is seen here, #8, and is $78.00 on Acura Parts.org - click the picture to take you to the actual page with part numbers and pricing:



The countershaft half of 5th gear is $48.98 at the same website, and it is #5 seen here - again click the picture to take you to the webite's page w/part numbers and pricing:



Also noteworthy is that the 5-R synchro needed for 5th gear is the exact same on the ITR and LS tranny, p/n 23626-P21-335 (can be seen as #10 in first pic on LS and ITR diagrams if you look on MT Mainshaft diagram) which means all you need is the two halves of the 5th gear itself.

So you could add the LS 5th gear for a total parts cost of around $140.00 or so with tax and a tube of Hondabond.

It might sound scary breaking apart a brand new ITR factory tranny case, but again 5th gear is atop the stacks, so all you need to do is pull three bearings (one that sits on top of the mainshaft, and the two stacked on each other on the countershaft) to access the 5th gears, swap the two gears out, press/tap the bearings back in place, then reseal the tranny casing.



Just sayin!

 

will you be going WOT in second gear at any point and holding it for more than just a split second?

 

Thanks for all the info, and I would appreciate you looking into that.

If the trans is anywhere near $2,000 though, I'll be awfully tempted still to go with the Synchrotech setup with the full carbon synchros, LS 5th already installed, and MFactory helical LSD. I'm already budgeted in my swap ~$1300 for the ITR trans from HMO, and $150 for the gearset from Synchrotech. Another ~$600 seems like a steal for a basically new tranny ready to go.

On a tight autocross course I imagine I'll never leave 2nd. If we do a course with a good sized straightaway or a long slalom 3rd gear might get used.

 

Congrats Adam!!! Similarly to what Tom said... I am 83% tempted to do this with my ITR setup as well.

We need to line them up so I can see how hard you pull on me, I need that 17% bit of motivation to go find my own H23 beast.



-Walter

PS=let's meet up soon! Tom?

 

Definitely, Walter

Next Sunday I've got my first Autocross race of the season(points 1) in Stone mountain.

Perhaps we should eat Vortex after? ~2-3pm? Or if you guys don't like delicious burgers and good beer we could go elsewhere.

 

I'm down to meet next weekend, I'll start an email thread with you and Tom so we can plan something.

 

 

Ordered my custom anodized mounts Will match the Volks nicely



Also ordered the H22 A/C d-series bracket thingy.

 

Lovin the mounts!

 

Motor looks very clean!

 

So far today I've ordered:

Bronze Anodized Innovative mounts
Innovative 96-00 Civic h22 A/C bracket
Kaizenspeed Balance Shaft Eliminator kit
Kaizenspeed Timing Tensioner
2.5" metal core vibrant cat
18"x6"x2.5" Thermal muffler with Thermal R&D tip welded on
And Kteller is trying to work out a deal with the supplier for my High End header. Paid for it, though Customer service at Kteller is amazing though, was on the phone with the sales guy for 30mins talking about exhaust.

 

Do you know what durometer poly those Innovative mounts utilize?

 

I went with 75a (track) http://www.innovativemounts.com/Prod...uctCode=B10050

I need your help!!

I'm so lost as for what to do for a transmission!!

1st Choice: ~$1300 for ITR trans from HMO + $150 for LS 5th + $150 install = ~$1600

2nd choice $400 b16 trans, $750 MFactory LSD, $275 Synchros, + $150 LS 5th + $250 labor = ~$1800 (James at Mainstream said I could do this as an option)

3rd choice: Fully reconditioned and rebuilt ITR trans with new bearings, MFactory LSD, full carbon synchros, + LS 5th already installed, for ~$2200.

The last option is the only one with new bearings and reconditioned gears. Synchrotech transmissions has made me the offer and it seems like a killer deal. Bullet proof transmission, lol. It's basically new with a better LSD and GOOD carbon synchros, not some carbon coated Honda ones.

 

Go for the gold. Also, of you were going to get an LS 5th, save yourself the $150 and do it yourself seriously, transmissions are easy.

$2200 isn't that much more you'll be happier. There's nothing worse than not putting up that little bit extra and then never being happy with what you bought. Trust me I know.

 

This is the direction I've been leaning. Do it right the first time and I'll be happier in the long run.

 

Yep, look at Tom's hatch. He went all out on that, striped down to nothing. But he's still got it and still happy with it a decade later.