trans, diffs and gears... oh my.

[Whizbang]

okay. so disclaimer: i have really nothing better to do deployed than research, interpret and scheme.

So my rx7 has a miata gearset in the M Type Mazda box. These are:

Mazda Miata Gearbox
1st: 3.136
2nd: 1.888
3rd: 1.330
4th: 1.00
5th: 0.814

the mazdacomp box for the 12a peripheral port engine had this:

Mazda Competition Rx-7 Gearbox
1st: 2.350
2nd: 1.608
3rd: 1.240
4th: 1.00
5th: 0.881 or 0.839

For reference the stock boxes have either a 3.4xx or 3.6xx first gear.

The box works, for know, but if it shit cans, i plan on going T5 since adapters exist for it. Frankly, when the engine goes, i want to go with the 2.0 or 2.3 Duratec engine... So getting a proper T5 is the end goal anyway. Just not sure how long i have on the rotary engine.

now in the rear, i have a reinforced axle housings, with a 4.78 ring and pinion from the mazda influenced kia sportage. same 7" "big bearing" everything and the 3rd member actually just bolts to the rx7 axle housing. doing some measuring... has about 7mm depth and 9mm root. compared to the stock 3.9 at 8mm and 9mm, respectively.

But! im stuck with either a 4x110mm pattern or the harder to find 4x114.3 pattern, OR buying mosier axles, which having seen a set a friend order having the hub pressed on, im not impressed.

So i plan on using something else. Considering the Dana 30 Volvo axles if i can get my hands on one in a 4x114.3 or 5x114.3. But i have found mixed information on when the Dana 30 was used versus the "31".

At the same time i plan to mimic the escort 4 four link and ditch the mazda verson.

So. now that im not sure what im getting at anymore since im over whelmed....


1. What gearset would be optimal for the T5 for a 2.0 or 2.3 duratec,non turbo, engine at say the 180hp mark. (higher would be lovely but that seems realistic from what ive read)

1. How would that gearset compare if i choose a turbo 2.0 (say B6 miata engine) or even a turbo duratec?

2. What final drive would compliment the above when stuck with a 64cm ish 15" rally tire? (brake clearance)

3. What volvo should i look for to get the axle i want? are their 5 lug Dana 30s?

4. why is microwave bacon terrible?

[85rx-7gsl-se]

How is 4x114.3 harder to find?

[Whizbang]

GSLSE axles are drying up and they are far from bulletproof. I have no spares at the moment. Previous owner broke at least two 4x110 axles in two years, (not something to deal with at a rally)

if not volvo, the toyota 8" then machine the truck flange down and tap for the pattern

[85rx-7gsl-se]

Oh you meant axles. I thought you were referring to bolt pattern and wheels for said bolt pattern lol.

[Whizbang]

yea i should have clarified

[mattallac]

180whp ,there's not much shock load to hurt a gslse axel ,unless you're dropping the clutch at 6k.My opinion is 1.if you want axels go to dutchman ,they're axels are made to order and are quality parts.2 if you want bulletproof use a ford 8' ,they are easy to get ,less weight than a 9" and the 28 spline axels can take 500hp of shock load . I'm using a 8"center section rx2 axle tubes and 8"ends with dutchman axels 4x114 . I'm gonna build a rear end once and move on .I hope that helps.

[Whizbang]

rally stresses things...differently... but the wee mazda axles have failed enough times in the past, and a failure costs you the race essentially. with entries at what they are...

im considering the toyota 8" as well. What had the ford 8"? google just keep showing me 8.8"

[FerociousP]

Originally Posted by Gravity Fed

rally stresses things...differently... but the wee mazda axles have failed enough times in the past, and a failure costs you the race essentially. with entries at what they are...

im considering the toyota 8" as well. What had the ford 8"? google just keep showing me 8.8"

Have you considered the B2600i axle? I'm just now messing with it myself but you can see in a recent thread I've made that the Rx8 LSD fits into it, which also opens up the possibilities for aftermarket diffs. Also, the manual 4WD axle is already a highish 4.30. Basically its a straight axle TurboII rear end. It is 6-lug, and drum , which would present obvious issues, but just bringing it into the fray.

It would def keep things in the family!!

[85rx-7gsl-se]

Ford 8" is old school.

[mattallac]

Yes ford 8"and 9" are old school ,nascar does 200mph on a 9"and they were both made in the same years.Ford 8"came in old mustangs ,comet and falcons (most 60's and 70's mid sized fords)The 28 spline axels are the same as a 9" . Parts are easy to find and cheap.Gear sets and posi units are easy to come by.The toyota rear end is good ,but the 4x4 guys suck the axles up .And the b series rear end is good also ,the 6 lug is a pain (same as the repu) and they don't make posi units .To use a posi unit in a b series there is a guy on the repu forum that makes a spacer so you can use a 3rd gen rx7 tensor.I have done that for my repu and it worked great .Ring and pinions are hard to come by. If you need multiple gear sets that are easy to get ford is the best way.

[Whizbang]

the volvo dana 30 is another option im seriously considering.

for the truck axles, like the toyota, generally, there is a wide enough pattern on the 6 lug to drill a 4.5" pattern then mill the rest off to fit a brake rotor.