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



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

 

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



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!