Revamping the Rx7

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eyesoreracing
Tranny 1: MX-5 5-speed. Basically the same old Miata/RX-7 box with a new bolt pattern. I'm not 100% certain you can just swap bellhousings, but I'm 82% certain.

Tranny 2: MX-5 6-speed. Newish transmission. Only ever used in NC MX-5s and 2010-2012 RX-8s.

Tranny 3: Whatever piece of crap came in a Ranger.

The Miata 5-speed is not the strongest box in the world, but its cheap to rebuild, and there are well established solutions to the few problems it does have. Locked up boxes are usually syncrho/shift fork issues that have snowballed. Not terribly hard to correct.

All pretty crappy ratios when you consider the price and work to get them in.

Ford typ 9 ENDLESS choices from stock--as good as any of the above to ultra close 2.25 first to 1;1 top

T5 GOOD ratios, strong and available gear kits with close ratios---only a bit more than the MX5 6 speed.

The 6 speed COULD be useful skipping 1st, but then you just paid a lot to have a "just OK" 5 speed.

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

I personally was thinking ebayed Renesis engine with some oil mods for a Gr2 car... mainly because I know how to make rotaries do things whereas these piston things irritate me. It would probably be broadly competitive power/torque output with a decent standalone, especially with the sort of rear end gears you could run with a redline out as far as it would spin... and relatively availableish. But ongoing thinking about how goddamn far I'd have to trailer to run any stage event or even rallycross... bleh, kind of torpedoing that, stupid 'forged internals' thread for making me actually calculate that out. Smiles per hour/dollar points to me going roadracing instead.

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mekilljoydammit
I personally was thinking ebayed Renesis engine with some oil mods for a Gr2 car... mainly because I know how to make rotaries do things whereas these piston things irritate me. It would probably be broadly competitive power/torque output with a decent standalone, especially with the sort of rear end gears you could run with a redline out as far as it would spin... and relatively availableish. But ongoing thinking about how goddamn far I'd have to trailer to run any stage event or even rallycross... bleh, kind of torpedoing that, stupid 'forged internals' thread for making me actually calculate that out. Smiles per hour/dollar points to me going roadracing instead.

Yeah gawddam 4 strokes twirl around about half the time doing NOTHING!!!
Wassup wif dat?

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Yeah, and if this belt thingie on the front breaks or slips, or you overrev them the pistons bonk into things... or sometimes go out the side of the engine, or all sorts of other mysterious ways of breaking. And then there's all these weird moving parts and springs and crap. WTF, eh?

Matthew Johnson's RX8 has a T-5 dogbox from G-Force as a spare. Not sure how they were adapting that to the rotary engine but okay. Wait, that's a different direction than we are talking about.

Ford Type 9 is typical as many aftermarket boxes follow that pattern. Selholm, Quaiffe, Drenth and a few others can be ordered with T9 pattern. If you are willing to pay.

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Grant Hughes

G-Force sells all the crap to adapt the T5 up to a rotary; few other places do too actually. But like you said, that's going the wrong way.

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mekilljoydammit
G-Force sells all the crap to adapt the T5 up to a rotary; few other places do too actually. But like you said, that's going the wrong way.

More like, around in circles instead of up or down?

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Grant Hughes

Quote
mekilljoydammit
Yeah, and if this belt thingie on the front breaks or slips, or you overrev them the pistons bonk into things... or sometimes go out the side of the engine, or all sorts of other mysterious ways of breaking. And then there's all these weird moving parts and springs and crap. WTF, eh?

Yeah that's what I say.. Why are cams and followers and "Valves" even in the motor when millions of nicer motors make the power and torque of turboed 16v motors ----size for size---without and of that crap. Why that's solid proof that it isn't even needed, so why do they use them.. (ring ding ding ding...)

And they fiire every time the piston goes up!
More torque at lower rpm.

Ha! (ding ding ding)

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Can you get parts for those things in automotive use? I mean I like 2 stroke stuff too, but got caught by rotary stuff. Only seen one old Saab around here ever.

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john vanlandingham
The 6 speed COULD be useful skipping 1st, but then you just paid a lot to have a "just OK" 5 speed.

2.2 1st, 1.0 4th, .8 5th is just okay now?

That's the 6-speed if you ignore 1st gear. It looks like almost the same ratios as the Mazda Comp box.

Dave - What MX-5s used the 5-speed and Duratec/MZR? If it's the smoothcase, hmm that's interesting. The input is probably longer like the B6/BP engine trans, the tailhousing is probably the same length.

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.

Quote
heymagic
Well don't take my teasing Alex and mostly Matt as bashing , it isn't. Just teasing as usual. I'd likely give up on the rotary nowadays myself. When I raced there was a guy in Bremerton..Doug ???...who built them for very cheap. Dirt floor garage no less. But what a whiz he was and the motors ran...I'd guess he is long retired and I wouldn't pay the prices the actual brick and mortar places charge.

Doug Moe. Back in 1987 he built the rollcage in my first Opel Manta rally car. Ok, it was built from water pipe and wasn't exactly symmetrical and was welded with a stick welder but it exceeded the cage rules at the time and all the joints were 100% welded and he only charged me $350, including tax.
You want Doug Moe stories? I got Doug Moe stories. He had this filthy little hole in the wall shop that made JV's place (or my place) look extremely tidy. Rotary engines and parts all over the place. Greg Fordahl was over there one time and Doug was trying to get something off a shelf and a rotor housing falls off the shelf above his head and damn near cuts his thumb completely off. His thumb is just hanging on by a piece of gristle and he picks up a tube of nearby silicone sealant and spooges it on there and then wraps it up with some electrical tape. He only agrees to go to the hospital because Greg insists on taking him.

Quote
Pete

Dave - What MX-5s used the 5-speed and Duratec/MZR? If it's the smoothcase, hmm that's interesting. The input is probably longer like the B6/BP engine trans, the tailhousing is probably the same length.

Any of the NC MX-5s cars that didn't have a 6-speed. I know, that's a fucked-up answer, but it was an option package thing. If the car had 16" wheels, it was always a 5-speed (unless it was an automatic). I think there may have been some ways to get 5-speeds and 17" wheels too, but I'm not 100% sure of that.

For John, that means ones that look like this:


Or this:

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john vanlandingham

Quote
eyesoreracing
Tranny 1: MX-5 5-speed. Basically the same old Miata/RX-7 box with a new bolt pattern. I'm not 100% certain you can just swap bellhousings, but I'm 82% certain.

Tranny 2: MX-5 6-speed. Newish transmission. Only ever used in NC MX-5s and 2010-2012 RX-8s.

Tranny 3: Whatever piece of crap came in a Ranger.

The Miata 5-speed is not the strongest box in the world, but its cheap to rebuild, and there are well established solutions to the few problems it does have. Locked up boxes are usually syncrho/shift fork issues that have snowballed. Not terribly hard to correct.

All pretty crappy ratios when you consider the price and work to get them in.

Crappy ratios:
5-speed is
3.14
1.89
1.33
1.0
0.8

6-speed is
3.82
2.26
1.64
1.18
1.0
0.79

Price:
beats me. Less than any motorsport box, but still a newish car compared to a X-bricky.

Effort to put it in:
What, bolts? The damn thing comes on the back of a Duratec/MZR already!

-Dave

One of my friends detailed the differences between the different 6-speeds used. Apparently there are three different units, the early Miata unit, the RX-8 unit, and the late Miata/MX-5 unit. I can't find the thread now (it was posted by j9fd3s on the rx7club forum, probably in the 1st-gen section) but IIRC the nutshell is, the RX-8 and late Miata unit are similar and have the same in/out as Turbo II box, the early Miata uses the same in/out as the as the good old 5-speed "smoothcase".

As far as "established problems" with the 5-speed, is one of them the bolts backing out of the center bearing retainer plate?



I've done this twice now. Think it's time to invest in a bolt head drilling fixture so I can lockwire the things.

edit: WTF... I resized that pic to 400x300 and it's still coming up as big by huge. If it's still big in five minutes I'm going to remove it.

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.



Edited 1 time(s). Last edit at 05/22/2012 07:48PM by Pete.

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Doivi Clarkinen

Quote
heymagic
Well don't take my teasing Alex and mostly Matt as bashing , it isn't. Just teasing as usual. I'd likely give up on the rotary nowadays myself. When I raced there was a guy in Bremerton..Doug ???...who built them for very cheap. Dirt floor garage no less. But what a whiz he was and the motors ran...I'd guess he is long retired and I wouldn't pay the prices the actual brick and mortar places charge.

Doug Moe. Back in 1987 he built the rollcage in my first Opel Manta rally car. Ok, it was built from water pipe and wasn't exactly symmetrical and was welded with a stick welder but it exceeded the cage rules at the time and all the joints were 100% welded and he only charged me $350, including tax.
You want Doug Moe stories? I got Doug Moe stories. He had this filthy little hole in the wall shop that made JV's place (or my place) look extremely tidy. Rotary engines and parts all over the place. Greg Fordahl was over there one time and Doug was trying to get something off a shelf and a rotor housing falls off the shelf above his head and damn near cuts his thumb completely off. His thumb is just hanging on by a piece of gristle and he picks up a tube of nearby silicone sealant and spooges it on there and then wraps it up with some electrical tape. He only agrees to go to the hospital because Greg insists on taking him.

Yeah, that guy. Afuckingmazing with rotaries and never charged enough. Shop was across the street from the garbage dump or truck shop or something. Total crap building...and the toilet was even worse than the shop. He did figure out a way to take the 6 port rotary and make it work. Put one in an old Datsun roadsore I sold. Sumbitch was flat fast then.