Would this be a good idea? I kinda like the automatic with traffic and this will be my DD for about 2 more years. I don't like the "rats nest". I also don't want to have to get a aftermarket ECU because i enjoy the cars Hold Mode. I'm not trying to go any faster and i'm happy at 10psi of boost. If anyone has done this let me know how it went: Is getting the car going really "that bad"; how's the drivability, how's gas mileage, etc.



Thanks,

C.T.

i dont know how your transmission computer will accept the increase in revs with the increased gearing.



your gas milage will suck even worse for sure because of the change in revs, but your car will sure accelerate faster

I know alot of auto owners do the 4.33 gears and don't have any problems with it (besides the speedo being off). I've read into it and no one has regreted it.

I'm going to be little critical here..



1. If you don't like the rats nest and don't want an ECU.. you don't have much options.. and this is also with Manual FD.. Unless you want to splice in resistors and such..



2. Why would you want 4.33?? First, you do know how much it costs? Unless you have the parts cheap and willing to drop and do all the work yourself, I don't think its worth it so that you might get slightly faster acceleration.



3. If you are satisfied of owning an auto and its power... and there is no problem with it, Just keep it how it is and enjoy the drive.

1. From what i understand keeping the car around 10psi you won't need a ECU.



2. From what i've heard it's about $1000-1500 and that's not that bad. The 4.33 gear would help out with the auto lag combined with the non-sequential.



3. The non-sequential isn't a power mod for me. The Non-sequential mod is for reducing the 100 points of failure in the sequential turbo system (i belive there's about 50 hoses down there).



Any more input is appercated. Thanks for those who responded. I don't mind any critical input as long as it's helpful.

Just like to point out that this isn't always the case. If you can get the 10psi more efficiently (ie. cooler intake air charge) you run the risk of running lean as well. I also note in your sig that you have intake, intercooler, downpipe, and cat-back, but running stock ecu. You're running the edge of what the stock ecu can handle already.



Taking the 1100-1500 you're looking at spending on the diff may be better used on picking up a power FC or similar...could save you at least double that down the road.

I never heard of the car leaning out at 10psi; that's pretty interesting. I know that i'm pushing the limit as far as mods go on the rx7 without a ECU but Pettit assured me it was okay. I even asked them if i needed a boost controller and they assured me i didn't as long as i wasn't playing boy racer all the time. If i get a aftermarket ECU i'll lose the hold feature and i like to have it when trying to merge into heavy traffic or whenever i need it.

get a downpipe, leave the stock midpipe and keep the 10psi, then add a pfc and then you wont need the gears, you will prob gain near 20hp just doing that and your acceleration would be a lot better and you would spend less than 1500 dollars... and if you need a ecu i have a pfc and commander for sale for 600 bones!!!

Again, As stated before, if you eliminate your rats nest, you would have to put resistors and such to use Stock ECU! Also, I don't have an AUTO and never done non-seq with auto car.. Even for manual, you need an aftermarket ECU to go non-seq as stock ecu relies on other solenoids for seq. system.. Learn about how the car works and you will realize what you've heard might be wrong!



Also, I never said anything about not able to run 10psi.. your car will just go into a limp mode as ECU gets feed back from all your solenoids and such. Its in your factory service manual about how solenoids are connected to the ECU.



If you think ECU and such isn't necessary and you think I'm wrong, just go do what you wish to do.. I personally think its a waste of money to put 4.33 gearing.. unless you are some hardcore racer and needed for specific track you might benefit from it.. Otherwise, there are better ways for you to spend that money.. But hey, its your money and time..



And regarding non seq cars.. do you know what it takes to do non-seq? have you riden in a non-seq stock turbo cars? Again, do some research about them and think really really hard and see if what you wanting to do with 4.33 and non seq turbo make sense to you or not.. because it doesnt to me..

Isn't the tranny controlled by a separate ECU? If not then get a piggy back ECU so you don't lose the HOLD function or anything else.

I'm not into building auto FDs.. but I got into a discussion about PFC working with Auto FDs. There is a way to do it.. not sure if its worth the efforts..



Do a search here or the 7club.

If he loses the HOLD function, can't he just select the gear you want and leave it in until you don't need it and throw it back into drive?

Herblenny, you're gernerally a nice guy at rx7forum.com but in this thread you seem to be have a short fuze. I never said i was right about anything. All i wanted was some direction, to know if my suggestions were possible, and the reasons why it would or wouldn't work. As far as i've known this topic hasn't been covered three thousand times . . . at least at the 3 years i've been at rx7forum.com. Regardless of your "internet tone" i still appercate the answers https://www.nopistons.com/forums/pub...IR#>/smile.gif



The power FC doesn't retain the hold mode. There is some crazy way to wire it but i'm not able to do it and the way to install it to retain the hold mode hasn't been discussed on rx7forum.com. All that i know is that, "it's possible". I've searched awhile back and found nothing. Maybe a recent search will give me some answers.



I found another auto guy from rx7forum.com who i pm'd about his hp automatic setup. He said he could retain the "HOLD" mode with it. Since i can retain the "HOLD" feature now i have no problem with an ECU. Here's his setup . . . . .



"This is what I`ve don`t... I don`t know what you're budget is like so do it at your own pace.



1st, Go single, use a Turbonetics turbo T60-1 or T66 with a .70 or .81 turbine housing. (you can port or leave the motor stock for now). HKS BOV 18 psi spring and a 50mm HKS wastegate only because the flow the exhaust gases very well. Microtech LT8S ECU. 4 - 1600cc injectors (top feed) 2- 98 supra fuel pump (Y it off in the tank) Greddy 3- row intercooler if you can afford it or if not get a isuzu NPR (the larger one). Koyo radiator to keep things cool and lastly, 3 - MSD 6A boxes to run the ignition with 2nd Gen leading and trailing coils.



The 4.33 gears are good but i noticed a minimal loss of top end on the Dyno... if you like the seat pushing your back of the line then get it but overall I'd rather the 3.90 rearend. Remember, turbo loves load so it can spool up, Don`t worry about lag for now because you can use NOS or Alcohol injection to take care of that.



Dyno @ 19 psi was 437

@ 23 psi 469

@ 28 psi 531





You definitely need your tranny rebuilt if your building power over 400 RWHP. For that I went to Mike at Level 10 in New Jersey. (3700.00)

The Stage 3 packages comes complete with valve body upgrade, clutches bands, stall convertor etc. Alittle over price but to me it worth it."



I don't need 437 HP but this gives me a ECU that retains the hold feature (a later PM he sent me comfirmed he still has his hold mode). Thanks to those who replied. Good way to break into the NoPistons.com forms https://www.nopistons.com/forums/pub...IR#>/smile.gif

Also, for those wondering why i thought a 4.33 gear would be a good idea on the auto rx7, here is a article on fd3s.net. Lightning in a world of thunder https://www.nopistons.com/forums/pub...#>/biggrin.gif



From: Rick Zehr (rzehr@pacbell.net)

Date: October 25, 2000



I just had a 4.30 gear set installed in my `93 Touring Automatic, and thought I'd report on the results. Sorry for the long post, but I thought I'd cover the topic once and for all...



Warning - Personal Opinion Follows:



Opinion ON



IMHO, this should be the first mod for any Automatic FD, for reasons I'll describe below. Opinion OFF



OK, now the facts - compare the gear ratios and rear-end ratio in the 5-speed, vs. the automatic.



Higher numbers are 'lower' gears, smaller numbers are 'higher' gears.



5-speed Stock

Manual Auto

Diff. Ratio 4.09 3.91



Trans. 1 3.48 3.03

Gear 2 2.02 1.62

3 1.39 1.00

4 1.00 0.69

5 0.72



So to get the overall gear ratio (ratio of engine revolutions to rear-wheel revolutions), we multiply the ratio of the gear times the ratio of the differential, and get the following table.



4.09 3.91 4.30

Manual Auto Auto



Gear 1 14.2 11.8 13.0

Ratio 2 8.2 6.3 7.0

3 5.7 3.9 4.3

4 4.1 2.71 2.98

5 2.94



If you graph this in a spreadsheet (See below), it is very obvious that the stock automatic suffers compared to a 5-speed in several ways:



* Its lowest gear (first) is much higher than the manual - almost 20% higher a ratio. This makes for a slow start, because the engine is fighting too high a gear for first.



* Its highest gear (4) is almost 7% longer than the highest gear on a manual. While this makes for relaxed and quiet cruising, it also makes for mediocre acceleration on the highway.



* Second and third gears are each much higher than the corresponding manual gear at any given speed. This means the car is sluggish in traffic.



The alternative for an automatic (or for a manual, just less change) is to replace the ring and pinion gears in the differential with a different 'lower' ratio set. Mazda supplies a 4.30 gear set (43 teeth on the ring, and 10 on the pinion), and all the usual vendors carry this gear.



This lowers the ratio of all four gears by 10% (4.30/3.91 = 110%), and has the following effects:



* First gear becomes much closer to that of a 5-speed, giving better acceleration from a stop.



* Second gear becomes excellent in traffic - it fits just between 2nd and 3rd on a 5-speed. It only goes to 65 mph at 6000rpm instead of to 72, but it is much more useful (second was too high), and, being lower, works well to allow third gear to be useful, instead of just another sluggish gear that goes to 120mph. Third now fits in the middle of 3rd and 4th on a 5-speed, and is more useful than it was for suburban driving.



* Fourth gear is 10% lower, and this gives better acceleration on the highway, at the expense of more rpms at any given speed. With the stock diff, my car ran 2800 at 80mph. With the 4.30, it runs 3100rpm at 80, compared to a 5-peed, which is closer to 3050.



The top speed of the car is probably not affected, since fourth gear still gives 26mph per 1000rpm, and so it should still be able to reach the same speed, since wind resistance is the major retarding force, and it would be running 6000rpm at 156mph - still right in the peak power band.



* Overall, the car feels much 'lighter' - the stock automatic just isn't very peppy, and most performance improvements are only effective at high rpms, which you can't use because of the high gears - you can't often go fast enough to hit 6000rpm in third...



* Compared to other performance options, this is effective even at low rpm - you get 10% more torque even at 1500 rpm. Compare this to 'breathing' performance enhancements, which often reduce power at the low rpm you really use in 99% of real-life driving.



* And then there is the single negative: my speedometer now reads 10% high - at indicated 80, I am really only going 72. But hey, this makes you feel like you are even faster, and when you drive down the road at 80 all the time, your girlfriend will be impressed 6^)



Installation requires that the diff be removed, because you have to re-shim and adjust the bearings, even if you don't replace them. This requires special Mazda shims, of course.



Prices for the gearset range from $474 (Racing Beat) to $563 (Mazdatrix). I believe that these are all the same Mazda part, which will work in either manual or auto cars of any year.



This would be a really good opportunity to replace the bearings and the seals, at a cost of just under $200 at Mazda prices. You could also replace the diff bushings at this time, if there is any slop in them (I didn't).



I had the work done by C2 Automotive in Oakland, CA, and am pleased with the results and the service. William drives a CYM R1, tells me that he has done alignment on M2's racing cars, and he obviously works on a lot of FDs (two in the lot when I was there). (510-272-9869) He charged me for 7 hours at $70, located the needed bits and pieces and istalled it all in one day (aside from the ring and pinion which I supplied).



So, for me, the bottom line is that for comparable money I could have got a couple of other performance pieces - say an intake and catback, but probably would not have got 10% more peak hp and torque, and certainly not 10% at all rpm ranges, and no way 10% more on top of any future performance improvements I make later.



Further, this is the only available performance tweak that makes NO additional noise. Even a downpipe adds to the noise level, and an intake unleashes a whole barnyard of new noises under the hood.



So, for all automatic FD owners, I suggest making this your first performance tweak. For 5-speeds, it's harder to justify - only a 5% difference, but it is 5% times your total torque, however high that might someday be...

I am a nice guy:).. Maybe the internet doesn't show the niceness I normally show. LOL!