r31 diff converion

[lchilds82]

hey guys im look at doing an r31 diff converion to my Gb galant just wondering if anyone can help with the following informationIf - housing/axles shortened need lengths, what ratio would best suit considering it is going to be set up for street/drag, what axle spline is require i think it was 28 from memory but i know there alot of guys on here that know there stuff, cheers guys. Also looking at doing a gearbox upgrade soon as well anyone know anything about the t5 geaboxes, was going to go auto bt most of the auto look way to big any help would great

[HEMI26]

hey man i can't help with the lenths but i know the skyline diff's are 28 spline same as vlt/vl v8-vt but the pintara's come with 25 so just take notice when u buy one, also from wat i know you can get 2.87, 3.08, 3.45, 3.7, 3.9, 4.11 ratio's with ease and same getting the lsd centre's or even getting them reco'd at a good price.

Been thinking the same thing for my scorp as i got 5 r31 diff's laying around due to a freind thats r31 nut. he has'nt snaped a axle yet n been running 250+rwkw for a few yrs, so they hold up for the job

[mic_77]

If the budget permits build it with a Kaaz lsd 28 spline billet axles and a TA performance diff girdle to stop the crownwheel going out the back of the diff. If you can get a Kaaz centre with 31 spline do that just for added security I am not sure on what they have available.

cheers Mic

[amgis_obrut]

If the budget permits build it with a Kaaz lsd 28 spline billet axles and a TA performance diff girdle to stop the crownwheel going out the back of the diff. If you can get a Kaaz centre with 31 spline do that just for added security I am not sure on what they have available.

cheers Mic

lol thats a fine example of over kill, that would be well good for 800hp

[A112H]

^^ agree, I wouldn't even be dead set on looking for the more expensive 28 spline. The 25 splines out of a Pintara will be much cheaper and you can still get VL ratios for them, only the V8's and I think turbos were 28 spline. Any 6cyl Calais will have a 25 spline LSD as do the XD-EA Fords

[lchilds82]

thanks for the feed back guys, so the budget is not massive, everything has been done by me and on the cheap well sort of, any way what i need to know is the best ratios for street/drag setup, i have no idea when it comes to ratio and stuff like that, may be ill just take it in to the local diff guys and tell them what i need and see what they come up with and what price they throw at me. Anybody have any deas about the t5 gearboxes, size wise etc, they are cheap and from what ive heard a fairly strong and should be heaps strong enough for a light weight car with a descent amount of power

[A112H]

For a street drag mix I would be looking around 3.9 maybe 4.1 if you don't do any driving over 80kph
No idea about T5's but if you are keen on an auto you can buy good kits for the 904's

[lchilds82]

i havent seen a 904 advertised anwhere, how would i find one of these

[lchilds82]

nah there wont be much highway driving, just to the dragstrip and back but part from that 60km zones only

[geezer101]

Scorpion autos are T904 transmissions. Way better than borg autos - nice and strong in stock form and will be near bomb proof pushing around a lightweight GB. if you're going down the 2.6L conversion path take the whole drivetrain from a Scorpion, plus the T-bar assembly from the centre console and connecting rod (first gen scorpions were 2L astron 1's) You'll need a modified transmission x-member and a cut down tail shaft (which you'll need to get made up anyway if you're fitting a different rear end). I doubt it will go in if the shell is a manual, the 904 is a big hunk of metal...

(This 904 hasn't got the kick down fitted to it, normally next to the starter motor housing - sorry... )

The auto kick down is rod actuated so you will also need to keep in mind it will need the matching actuator link on the carby for it to work (if you get the lot from a donor scorpion, no worries. Fuel injection...? )

With this drivetrain combo I think it will be punchy as to drive, if you can get power to the ground!

[amgis_obrut]

if you want manual for drag racing that will be an easy conversion id suggest a corona 4 speed, these things take an absolute beating

[mic_77]

You may think it is overkill but wait until you load it up for a decent launch and you snap the resplined axle as they are not hardened. One axle will have to be resplined when you do the conversion this will be the weak link.

cheers Mic

[mic_77]

If you are considering a baby 904 it will cost you more to get it upto a decent rating then converting a c4 into the car with a mild valve body and a half decent converter all depends on what you want to do. The 904 will be fine for a very mild set-up over that budget 4k to get you in the ball park of a half decent set-up that will be good for 11's before spitting out the input shaft and then realizing I should have put a c4 into it in the first place and this is coming from first hand experience.


cheers Mic

[A112H]

Or you could spend this money on suspension and brakes and make it a real race car that isn't afraid of corners

[amgis_obrut]

drag cars arnt afraid of corners, they just require more driving talent to get them around
ya just steer with a right foot

[A112H]

[lchilds82]

so what involved in doing the c4, are parts available( ie. adaptor plate) i have looked into this already but havent come up with much, i might be asking the wrong people though, hopefully you guys can help

[mic_77]

As far as conversions go it is reasonably easy once you know how. It involves an adaptor ring for the bellhousing, modified adaptor for the flex plate you will also need a reinforced flex plate as you will rip the guts out of it the first time you stall it up for a decent launch throw in some arp bolts and you won't get much change out of $1000. You will then need a custom converter budget upto $1500 depends on how far you want to go and who you trust to build the converter. You can build a nice C4 for $1500 but once you go with a trans brake and rollerize the trans expect $3500 for the trans build once again it all depends on how serious you are. You will also have to get the bellhousing and bits from a auto sigma should cost about $30 from pick a part if you do it yourself.

Cheers Mic

[lchilds82]

As far as conversions go it is reasonably easy once you know how. It involves an adaptor ring for the bellhousing, modified adaptor for the flex plate you will also need a reinforced flex plate as you will rip the guts out of it the first time you stall it up for a decent launch throw in some arp bolts and you won't get much change out of $1000. You will then need a custom converter budget upto $1500 depends on how far you want to go and who you trust to build the converter. You can build a nice C4 for $1500 but once you go with a trans brake and rollerize the trans expect $3500 for the trans build once again it all depends on how serious you are. You will also have to get the bellhousing and bits from a auto sigma should cost about $30 from pick a part if you do it yourself.

Thanks for the info more then helpfull, what about other autos like the GM ones that they make the adaptor plates for from a few different places in the states, or are these transmissions way to big, i have been spending alot of time researching this lately, i dont think im quiet as serious as some are, im a chef thats building a car on the side and want to get some fun out of it, and drags is what i like if you know what i mean. I have seen a few Corolla getting around with 4g63 and Gm transmissions doing very quick times and yes understand that they would have thrown money at these boxes to have them built strongly as well but tryn to find the best conversion to suit me. ill keep looking and asking questions c4 does look like a good option though.
Cheers

[mic_77]

If you want to cut the tunnel out and half your firewall as they base all those kits off the GM V8 style tranny, as they did not have the 2 speed with the removable bellhousing like we do that is also another option like the set-up in RX22NV's wagon but still requires all the parts that I have listed the V8 style set-up is good as you can still run the V8 of the shelf converter flex plates and all that. The choice is yours.


cheers Mic

[astronturbo77]

sorry geezer but a 904 and a astron isn't going to be 'punchy as' it will be a snail.

[lchilds82]

Just want to say thanks for being such a massive help i know you have been there and done that and its great to see someone so willing to help and give info on all these things to guys like me who have barely an idea (learning as i go), so what im really seeing here is auto although way supperior are quiet an expensive conversion to get something built strong, i think for me trying to pick up a baby 904 might be the best option as the car will not be a dedicated drag car this might be the best option for my budget or maybe just go w series manual??? would be cheaper i think.

[mic_77]

You will still need a reinforced flexplate and you will need to find out who it is in melbourne that machine's the pump on the baby 904 to suit the BW35 snout otherwise you will snap the tangs of the oil pump drive everytime they were a weak set-up from the factory these are just some of the things that need to be done to get these boxes to live with a bit of power I have seen these issue's even behind standard scorpions.


cheers Mic

[A112H]

Just want to say thanks for being such a massive help i know you have been there and done that and its great to see someone so willing to help and give info on all these things to guys like me who have barely an idea (learning as i go), so what im really seeing here is auto although way supperior are quiet an expensive conversion to get something built strong, i think for me trying to pick up a baby 904 might be the best option as the car will not be a dedicated drag car this might be the best option for my budget or maybe just go w series manual??? would be cheaper i think.

I would be going for the W Toyota box if I were you, and will be myself in the future. Send Bill Hincher a PM and he will send you a quote. I know superscan just got one of his bell housings and is very happy with it.

http://www.billsautofab.com

[lchilds82]

hey its going behind a 4g63tdohc narrow block but yeah if they are that weak then i wont bother with it, and im thinking that a w series will be heaps easier to, ive spoken to bill via emails quiet a bit. thanks for all the help, let you know what i end up doin. Here is were its at, standard 4 speed hooked up, microtech wired in, just gotto finish intercooler piping and the water piping.

[webby]

With the W box you want the JZA80 W58, as compared to the earlier MA61/RT142/MA70 W58. Given that it'll be in a 900kg GB with, at a guess, 200-odd kw at the wheels either would be fine, but the later version's a bit stronger.
If you were putting it behind a 500hp 1JZ in an MX83 or something of a similar weight it'd be a different story, I hear they have a habit of twisting themselves to pieces around that power level

[amgis_obrut]

I'll say it again CORONA 4 SPEED

1st on on this page http://users.tpg.com.au/users/loats/tec ... boxes.html

[webby]

I've got one of those boxes, it's sitting in an RT118 Corona wagon down the paddock

[lchilds82]

I'll say it again CORONA 4 SPEED

1st on on this page http://users.tpg.com.au/users/loats/tec ... boxes.html

im a gonna look into this, who will make ellhousing for this

[A112H]

Unless you are planning on driving like a tool you will be fine with both the Mitsu box and diff.