I was leaning towards getting a sc400 diff based off what I have read so far, Funny thing is I was at a junkyard today pulling a driveshaft off a sc400 because I wanted to see the differences and the measurements looks like ill have to go back tomorrow for a round 2 battle with the diff. While searching around I also ran into this thread about auto mkiv transmissions ( https://www.clublexus.com/forums/per...-in-sc300.html) . Idk if this is true but comment #8 says that introducing a new fluid to the tranny causes a acidic reaction and kills the gears. Can anyone confirm this? because my tranny came out of a junkyard solstice and the junkyard drained all the fluid etc
Wait, what? Supra TT Auto transmissions are just beefier versions of the common A340E 4-speed found in the SC's. It's a much stronger version so it isn't exactly the same but the overall design and architecture is within the A340E family. I've never heard about this issue or that keeping old and worn Toyota Dextron ATF in a transmission is somehow better than flushing with new fluid.
His experience sounds more like the GTE-spec A340E he got was in need of a full remanufacturing treatment from a good company (ATF Transmissions, etc.).
This is a question best cleared up by one of one of the other members here who have experience with swapping in Supra, Soarer, Aristo and other A340E's from factory GTE cars. That post gives me pause but only because it's new information to me and because I have no personal experience with swapping A340E's.
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By the way, if you are planning to stay automatic and swap in a GTE-spec A340E then just know that original factory gear ratio for a stock Soarer (2.5L turbo) was 3.916 (3.92). But all factory 2JZ-GTE Automatic cars originally came with 3.769 final drive ratios.
no I didnt mean that I wanted to stay automatic lol I thought this was a common issue with all transmissions and fluid. I would take manual over auto any day
People say that with high mileage automatic transmissions when replacing/flushing the trans fluid, however, it is still generally recommended to do it along with the filter before you have issues.
You are not supposed to power flush it though, just drain and refill a couple times will do the trick. some people have problems afterwards but its not the fluids fault.
With torque converters being sensitive and extra seals in there holding fluid in various places, its a different animal than a manual transmission and should be fully serviced eventually.
With manual transmissions, it is best to keep fresh fluid in them. I always use synthetic gear oil in mine.
If it has been sitting in a yard, I fill it with some regular gear fluid (cheap stuff is fine), shake it all around, go through all the gears etc... check for leaks, and then drain it out.
You want to know if there is leak before it is installed.. sometimes people pull off parts to inspect inside and then put it back on, they will leak if not cleaned and rtv'd back on etc..
If the fluid looks good and no foreign debris, leaks etc... then you are ready for installation unless you were planning on rebuilding.
If you do see some stuff come out, I may then open up the case and have a look inside, clean it up and seal it all back up to be ready for install.
If you do open it up you can inspect inside, but you have to be careful and pay attention cause parts may fall out that you have to put back in place.
Fill it with new fluid AFTER you install it, it will be much heavier and probably leak out the tail shaft on you while you are installing it if you try and do it before.
Alot of people use the redline gear oil, I usually just use whatever synthetic is locally available, shouldn't make a huge difference unless the trans is worn out.
I know that the GM T56 uses DEX automatic transmission fluid instead of gear oil (thought it was odd also when installing that one) so just double check since AR5 is the GM version that it should have regular gear oil in it. I think AR5 uses gear oil but I haven't used one of those personally yet. there should be a sticker on it somewhere also if that is the case.
Today was a really good day in terms of research progress. I was viewing the 7m supra mania swap thread ( http://www.supramania.com/forum/thre...olution.25024/ ) and the op of the thread limesquat mentioned removing the whole output cv assembly itself. Behind the assembly is the spline output shaft and the output seal. Limesquat also says that the splines are 1.5" deep so that does bring up a little concern regarding if a slip yolk would be secure on the shaft but if the cv shaft was able to be secure on the transmission why wouldn't a slip yolk. I can confirm that the cv joint assembly will fit on a lexus sc400 rear driveshaft splines. I cant remove my driveshaft out of the sc300 just yet to do some tests since its my daily but I will update this thread with info when I do the swap. This swap is now tremendously more affordable since the driveshaft is the biggest expense and more options on how to connect the driveshaft are avaliable.
I have already thought of some ideas with the driveshaft:
1.
This could be the easiest way I could see is if the slip yolk is removed from the lexus driveshaft and replaced with a gm 27 spline yolk. This does come with some limitations as I dont know the stock driveshaft would fit without shortening or lengthening yet.
2.
A member name fried_rice from a thread regarding the Ar5 mention a stock f body t56 driveshaft being a solution for the ar5 aswell. If the transmission measurements are the same it should work but this is not confirmed here is the thread his post is #49.
3.
This is not really a option but a mk3 driveshaft could work now that the cv joint is removed the mounting point is pushed backed.The length of the transmission tailshaft without the cv could be the same length as the r154 mounting point.
I cant confirm any of these solutions so if any members could chime in with some extra info that would be great.
T56 measurements probably wont be too helpful for an ar5 swap.
I would probably keep the cv part and have a custom driveshaft made, that spline section might be technically long enough but I don't think its long enough for a slip fit situation, they are usually bolte on with a rather large nut so they do not move like on the V160 or toyota transfer cases etc... maybe you can even use one of those flanges if they are the right spline and then use a toyota driveshaft.
The driveshaft in SCs don't move a whole lot but they do move a little bit, I wouldn't just use a slip in drive shaft if planning for more power.
It might also be nice to have a connection there that you can unbolt in the future.
See if you can find a local driveshaft shop and maybe ask them, there is one by me I have used like 3 times now cause they do good work and is very reasonable.
I usually just take them what I have and tell them the length of what I need and the ends I need on it and they make it happen.
sometimes they can't weld certain toyota drivshafts that have the baloon ends (trucks usually) etc.. but they just use a new pipe then.
And the one time I messed up my measurement and they had to redo one shaft, they hooked my up with a better driveshaft then I came in with on the house.
If there is a bolt on solution that works then great, but when going custom talk to your local shops, those guys know everything there is about driveshafts.
and the turn around time will be alot better than custom stuff over the internet... well maybe after all this stuff going on gets better.
I also agree I didnt actually think about how questionable the spline length was at first. I will probably have to get a custom one made or the stock modified unfortunately. It just sucks that the IS platform and MK3 supras have found a oem replacement, I bet there is a toyota driveshaft out there just hasnt been found. Its just weird why gm decided to use a cv flange on the Pontiac solstices Ar5 but not the coloardos.
you said this " I can confirm that the cv joint assembly will fit on a lexus sc400 rear driveshaft splines."
do you have those parts, can you post a picture of that side of the cv joint assembly for me.
Also the sc400 has one of those bolt on rear flanges but they are 3 bolt.
You might be able to take one of those flanges off a sc400 automatic and bolt that to the ar5 in place of the cv stuff and then use a sc400 driveshaft.
I dunno if the lengths are exactly right, but changing the length is something any shop can handle.
Also I am seeing online a conversion adapter from the cv joint pattern to the u joint which would work also.
This seems like it is just replicating what is on the 400, i would see if you can get one of those outputs and see if it can bolt on to the ar5.
I have a bunch of extra flanges that came off transfer cases that are splined and go to a 4 stud flange which attaches o the driveshaft via u joint, but these are usually used on the trucks.
this is what the sc400 one looks like, if the ar5 one slips on the sc400 maybe this one slips on the ar5 and bolts in place.
you can also use a gte flange but its a different size slightly... if you can get it bolted in place a sc400 driveshaft might work or just need a length adjustment.
On the supramania thread limequat says that he was able to find a junkyard out of a 88 to 89 toyota pickup that he was able to bolt. As for the IS300 guys I was wrong about a bolt on solution but they are able to use a driveshaft out of a toyota sequoia and shorten it if i am not wrong to make it a one piece driveshaft.
As for the cv flange I was able to attach it on to the rear end of the sc400 drivehshaft however I believe the CV has a 26 spline pattern and the sc400 has 23. Someone had already took the sc400s tranny and cut the driveshaft but I was still able to get the rear and cut end from the junkyard.
I attached some more images of everything to a imgur album since I didnt want to add alot of images to this reply. I think if the diameter of the SC400s flange is the same it should fit I will take some measurements later.
looks like it is the GM 27 spline, I think the flange I have is a 23 spline. Not sure about the sc400 but I would guess it is 23 also.
I think easiest is to get one of those adapters from the 27 spline to a U joint, and then just take your old driveshaft and have them change the front tube to the right length with the U joint on the end, like the truck driveshafts are, which is probably why they used the sequoia one it has that u joint end on it.
Ya it looks like thats what I am going to do once I get the tranny all bolted up. I want to reseal the transmission before I get anything on but I cant find any oem gaskets for the gearbox to the tailshaft Is this normal? if it is do you think Permamax RTV gear oil sealent would work just as good?
Does anyone know if its safe to cap off the automatic tranny coolant nipple on the auto radiator? My radiator is super new less than 3 months old so I would hate to get rid of such a new radiator
Most people use RTV to seal the cases there is no actual gasket you can buy, the RTV black or the specific one for the job should be fine.
You can cap both of them, should be 2 lines, or you can cut the 2 hoses and run them together with a connector.
Does anyone know if its safe to cap off the automatic tranny coolant nipple on the auto radiator? My radiator is super new less than 3 months old so I would hate to get rid of such a new radiator
Just leave it alone you dont have to plug them, coolant doesnt run through those nipples
While searching around I also ran into this thread about auto mkiv transmissions ( https://www.clublexus.com/forums/per...-in-sc300.html) . Idk if this is true but comment #8 says that introducing a new fluid to the tranny causes a acidic reaction and kills the gears. Can anyone confirm this? because my tranny came out of a junkyard solstice and the junkyard drained all the fluid etc 
