rx 4 automatic to manual conversion

[dr50376272]

ive got an auto rx 4

i want to throw in a manual gear box, what fits in with no troubles?

what do i need?

does a series 4/5 13b turbo and 5 speed fit straight in? no need for cutting anything? no new exhaust manifold needed?

Living in Japan, finding Mazda Rotary Car Parts, from Cosmo to RX-8.
Delivery by EMS or Japan Post, registered and insured.

David Robertson
JAPAN 899-4332
Kagoshima Ken
Kirishima Shi
Kokubu Chuou 1 Choume
12-11-1
TELEPHONE: +81 995 47 1195
email: dr50376272@gmail.com

[bumpstart]

firstly your auto tailshaft is the wrong length for any manual conversion
the only direct fit for the rx4 OEM clutch, stick position and a stock manual tailshaft is the s1 rx7 "M" box
or the rx5 5 spd "R" box

if you wish to change the clutch and flywheel to auto counter weight and custom flywheel
the FC turbo " R " boxes become good choices,, needing different tailshaft to earlier "R" boxes

for any turbo R box,, or any s2/3 and s4 NA manual M boxes will require cut shut mod to the shifter assembly to match the rx4 floor

typically,, in most markets,, and since you will need a custom tailshaft already is to secure the FC turbo R box and do the mods
for this
you can get " changeover " or " crossdown" custom flywheels in australia that allow use of common 8.5 inch pressure plates and misubishi/ ford escort clutch disk with the FC turbo starter

these flywheels bolt to your stock auto counter weight already on the engine

[Ray]

for any turbo R box,, or any s2/3 and s4 NA manual M boxes will require cut shut mod to the shifter assembly to match the rx4 floor

I can confirm, I\'m running an S3 box in mine, it drops straight in once you have done the shifter cut mod, it\'s pretty straight forward and uses the standard RX-4 mounts and no cutting of the transmission tunnel.

[dr50376272]

ok, and tailshaft? will series 1,2,3 rx 7 boxes fit with the rx 4 manual tailshaft?

[Ray]

ok, and tailshaft? will series 1,2,3 rx 7 boxes fit with the rx 4 manual tailshaft?

My car was originally a 12a RX-4, but now fitted with an old school 13b, and I just did the shifter mod, and retained the standard 2 piece 12a propshaft, and I think I just used the standard RX-7 gearbox mounts, which bolted straight up. Of course this is only a good option if you are using an old school (small flywheel) motor. Also remember the 13b axle is different to the 12a, which is yours?

If you wanted to go the 13b s4 turbo route, you would need to change the front cover to old school style or fabricate some centre mounts, you would also need the turbo gearbox (R-type as bumpstart said) and a custom prop. Not sure whether the same shifter mod can work with R-type, or whether you may need to look at R-type pickup gearboxes, which should have the stick mounted further forward, bumpstart can perhaps give you more advice in that area...

Ray

[dr50376272]

daily driver so im sticking with the 12a. i have a twin dizzy model so will try to source a 12a single dizzy. i need to just be able to swap motor/box because i cant cut anything. so ill try to source a series 2/3 rx7 12a and 5 speed box and just swap it over. probably do a wire job in the engine bay and throw a weber on it.

[bumpstart]

the manual rx4 tailshaft will fit s1/2/3 s4 NA and the rx5 box
the auto tailshaft will not

there is no external differences to note in the main dimensions between rx4 4 spd all the way to s4 NA,, asides that shifter position

all these gearboxes are the same length , and bolt over the 8.5 and 9.0 flywheels
( which use the same starter, despite what you may read elsewhere,,, i swap them all the time )
[ the exception is the bulky rx4 4 speed starter ,, it only fits that rx4 box ( or rx5 ) , whilst all the M box ones fit rx4 and rx7 ]
ie,, the M box starter is reverse compatible,,,but the rx4 starter is too wide, with solenoid in the wrong position  to fit against the  M boxes

and all of them use the same input and output spline

the odd man out is the turbo R boxes ( s4/5 ,, and the s6 )
thse have different splines out and in than the other boxes , and have unique starters suit this ring gear
( but is still the same length )

[bumpstart]

does a series 4/5 13b turbo and 5 speed fit straight in? no need for cutting anything? no new exhaust manifold needed?

the answer to the question about the entire motor package is much more in depth

short answer= not quite directly if you drive on the left hand side of the road

traditional long answer *= sorta ,,

 you will still have to front mount the engine ( SD 12a timing cover + 13b GSL-SE sump  )
and make the slot mods to the plate and under the rubber mounts to allow for the 13b\'s extra length of 20mm  ( if yours is a TD 12a rx4 )
and then you would fit the s5 turbo,, with its manifold flipped over, sometimes with studs removed
( depends where you add the spacer plate below )
-- two holes are ovalled on the turbo foot pattern with a file
you can then space the turbo out 20mm with spacer under turbo,, or between engine and manifold
IE
the turbo is relocated forward adjacent the front rotor instead of the rear,, and it just kisses the inlet manifold with the turbine cover
= needs the spacer or a light grind ( or two )
note spacer at manifold to turbo join needs to retain the split entry
whilst old extractor plate on the engine that is refaced is ideal,, but all these methods require longer bolts to replace the studs and a custom drain pipe added to the turbo ( and fitted into the timing cover )

- conversely,,, add a custom manifold ,,, or a custom turbo and manifold package instead ( still needs the drain mods )

*
non traditional new answer = retain the s5 engine as is with belly mount and timing cover  , move it forward just a bit to help that turbo clear
-- and weld mounts to the front of your current steering cross member
most purists will not do this to a genuine already front mount method rx4 !
instead its a very easy route for those with piston 929 doing the swapsy

[bumpstart]

PS
and yes the shifter assembly externally is very similar for the R boxes to the mods required on s2/3 and s4 NA boxes
( the s5 internally has a thicker bottom cup ball,, without the nylon up, different to the rest but irrelevant )

the magic number you need is 103 mm on the dot for the  cut shut on the selection shaft and the pin tapping relocation
the outer assembly is cut so as to delete the forward set of mounting holes
the locating dowel is pulled
and grind the remaining stub on the gearbox so the detent spring cover on the underside of the shifter assembly can just clear that redundant mounting stub

[Rivalrx]

I\'m liking this thread! I am in the middle of changing my 1975 rx4 sedan from auto to manual...thanks for clearing up about the tail shaft...bugger.

I have a s3 12a and a s1 box and it all looks like it\'s fitting nicely. The rx3 pedal box wasn\'t a good fit (brake booster in the rx4) but luckily the car came with another pedal box...maybe old school 626 or original rx4. not sure..anyway it fitted in perfectly. Just added the new clutch master today...all I need is a new clutch slave and jobs a goodin.

So..the rx4 auto tail shaft is too short or too long? Are there any others that fit?

Manual console wanted for rx4 sedan.

[Rivalrx]

I just saw previously in the thread that a s1 or rx5 tailshaft will suit. Any s1 tailshafts out there?

[dr50376272]

this is what i know so far:

rx 4 starter, rx 7 starter will fit in nicely.

rx 7 series 1,2,3, boxes fit nicely

8.5inch clutch is the best option

rx 4 manual tailshaft is needed but a custom on is ok also.

the biggest trouble for me is here in japan there are no wreckers: they just ship all their old junk cars to benin, nigeria, mali or some other impoverished african country. i would have loved to go size some old mazda vans tailshafts to see if any would bolt up.

mine is all original still running twin dizzy 12a auto. my goal is to without cutting a thing, have it a single dizzy 12a 5 speed by next year. i also need a new front seat, steering wheel, then she is complete.

but i must be able to bolt in the original parts when needed. tough huh?

if i was world dictator, anyone who does not recognise a classic rotary, and pay hommage, would receive the death penalty.

//www.kagoshimaenglish.com/rx4.htm

[Rivalrx]

Are S1-S3 tailshafts ok to use in my sedan with a S3 12a and S1 box?There is currently a std auto tailshaft there.

I MAY have a old school 626 tail shaft in my pile of bits...anyone know if that will fit?:cool;)

[bumpstart]

rx7 s1 -3 is a shorter , single piece shaft ,, your rx4 one should be a long two piece unit
IIRC only the rx5 is going to be compatible ,, and then you must match 12a to 12a,, 13b to 13b
as there is a different uni at play,, and a different pinion flange for 13b tailshafts

ie,, if you have the 12a rx4,, only the 12a rx5 ( japan market only rx5 ! )
is going to be close unless you ship the pinion flange from the 13b diff with a 13b tailshaft

( i would still measure them to be sure,,, i am running on recall that the pans underneath are mostly the same basis )


as is,, i think the OP has taken a different route,, instead finding a rare 12at engine and box as a drop in fit
( aside tailshaft lengths and shifter mod )
-- which,, all those years back,, was my very first mod rotor project ,, a 12at into a rx4 13b LE coupe
( circa late 1991 )


-- very straight forwards, near drop in fit, and a great engine to boot for streetable power
( its all down low with that tiny turbo and hits a wall at 6500-7000 rpm )

normally,, for most the 12at isnt on the radar for options
( being a very tricky engine to source intact out of japan )
but IMO,, probably the easiest option with a very good result for the effort
( if you live in japan ! )

[Rivalrx]

Sorry for the questions and potential thread hijack...would a piston 808 sedan prop shaft be of use for me and the RX-4 auto to S1 gearbox conversion? Not many RX-5\'s here if you get my drift:chat

Cheers for the help