taqwache

I have decided to pull my 6speed in favor of a TH400 i have laying around. i have read about needing a special torque converter, adapter plate, flywheel, and crossmember. after trying some stuff in the garage, i found out that the tranny bolts right up to a LS1 block (less one bolt). i also read about plenty of people doing this with sucess. why do i need a adapter plate. it is perfectly centered already. also, why is there a need for a special torque converter? i have a flywheel out of a 6.0L and it bolts straight up to my SBC converter. also the center hub of the converter fits in the center of the flywheel centering it up perfectly. i then read that the 6speed crossmember works fine for the TH400. now i found out that the lenght of boths trannys are very close. so what i am really getting at, is that, if everything goes as planed, i can just remove the T56, install the TH400, swap the yokes (not to positive on that one), get a body mounted TA, put in a shifter, install a tranny cooler and thats it. what am i missing.

Steve.

Fast SS on TNT

iTrader: (1)

You have to shim up the rear of the tranny, even with the M6 crossmember. I used a bunch of washers from the local parts store. Use an aftermarket tranny cooler, install a sending unit in the pan for a temp gauge, cover the original M6 shifter hole with some sheetmetal. Use the shifter of your choice, and enjoy. And I do believe you will have to change yokes. I would change out driveshafts as well. A transbrake will eat a factory aluminium one.

I never did understand why companies tried to sell you all kinds of crap for that conversion. I bought washers, a TH400 rear tranny mounts, TCI Flexplate. Everything else came in the kit I got from Madman, and that included an M6 tranny crossmember. He has dipsticks that are Fbody conversion specific. This is an easy swap. Everytime I see somebody whoring an adapter, special this or special that, I just laugh at the unadultered greed of some shops.

Talk to Brian @ Madman and Co. Racing. He knows what all you need for a proper conversion. He sold me his kit, and I'm very happy witht he results.

taqwache

cool. i just ordered a torque arm, tranny cooler, and dipstick. i should have everything else laying around somewhere. i will let yall know how it goes.

Tim98TA

iTrader: (7)

I basically did the same thing, but I went from A4 to TH400 and I didn't use the POS adapter. I used my STOCK 98 flexplate, moved my tranny mount pad rearwards 2" on the crossmember, ordered an ATI tranny, and convertor, which they built to fit my flexplate. Used my STOCK shifter, STOCK cooler lines. I already had a body mount TA. Used Madmans dipstick, which fit perfectly.

grooves12

Isn't the spacer on the flywheel necessary, because the depth of the bellhousing on the Gen III motors is different from the SBC??

I know FROM THE FACTORY GM uses a spacer on on vehicles with the 4L80E. The 4L60E does not require one because apparently GM changed the design of the Bellhousing on the tranny to match the GEN III engine.

I beleive everything will bolt up without the spacer, but then you are pulling the yoke of your torque convertor further out of the transmission than it should be, and there is the possibility it can disengage and cause disastrous results.

I don't know... a $20 spacer from GM is worth it for piece of mind in my book.

kp

iTrader: (34)

I bought my whole 350 setup complete so I didnt have any choice, if I was able to get rid rid of the Yank adapter (.600 thick so the driveshaft and crossmember wont work if I get rid of it) it would have been in the trash months ago. Not to mention I never could get a straight answer from Yank why HIS converter, HIS flexplate and HIS adapter was far enough off that the converter wouldnt engage the front pump..

Only problem I have seen is the converter hub on regular converters not going in the crank at all when the 'pull out' of the converter is set right. Some converters are set up for motor plates and the snout is a little longer so thats probably why some work and some dont. Either way its simple enough to make it work without all the adapter plate crap..

taqwache

thanks for all the replys. i will be doing this swap sometime next week and after i fugure everything out, i will be able to give a little bit more research to this conversion.

RobZ

Hey Taqwache how did it go with th400 swap?I also soon will be doing the swap,but I had question regarding the driveshaft.I heard that you could use the stock drive shaft as long as you have a th400 with an 9" inch tail shaft.Is this true?

taqwache

i am not sure yet, it will be going in the car next week or so. i will let you know.

taqwache

latest update, the sphon torque arm was on back order and i couldn't wait much longer so i ordered a torque arm adapter for the TH400. it is made by hurst and cost $130. i thought that was kind of high but it came with a whole transmission crossmember for a 3gen camaro with a TH400. unfortanatly, all i can use is the torque arm mount and the rest of the stuff is extra. it looks pretty sturdy though and alot cheaper then the $400 body mount torque arm i was going to buy. i also ordered a lokar extended dipstick tube and 24000gvw cooler from speed inc that should be here tommorrow. next i bolted up my SBC converter to the 6.0L flywheel and it fit perfect. the center hub of converter fits in perfect. now, my parts list looks like this.

BnM TH400 $500 (bought it brand new 3 years ago from freind that had it in garage)
3800-4200 converter $100 (bought it from same freind)
hurst torque arm mount $130
lokar extended dipstick tube $70
24000gvw cooler $50
BnM prostick $150 (bought it 4 years ago and had it in 3 cars already)
6.0L flywheel $freebee (had it laying around)
6 speed crossmeber $freebee (my car is already a M6)

looks like all i need is cooler lines (i going to get custom steel braded lines locally) and a driveshaft. not sure on the shaft, my local source when out of buisness last year. maybe the old one from the 69 might fit. its worth a try. if everything goes as planed. i will have a TH400 conversion for just a bit more then $1000. not bad if you ask me hehe.

KRAZY K 2000 TA

iTrader: (5)

I am pretty sure that on the LS1 block there is .600 less material on the block where the transmission mounts to the block which makes the crank stick out that much further.It is not really an adapter plate,more of a spacer.Therefore if u try to bolt the transmission up with the torque converter in place and no spacer it will drive the converter to FAR into the front pump,causing damage to the transmission.Also there is no bolt hole in the LS1 block for the bolt on the top right of the trans to bolt to.Do not try to drill and tap the cylinder is right there.I think YANK sells that spacer .You have everything else.Cheetah shifter alll the way.

NA$TY-TA

iTrader: (21)

Lookin good Steve..... let me know how it turns out and how hard it was... i am wanting to go TH-400 also and im going to need some help later down the road.
Kyle

Gold Phoenix

iTrader: (1)

There is something else to consider. If you go too fast at the track, the safety officials will want to inspect the car in more detail. The NHRA Rulebook states that tranny swaps are allow as long as all of the bolt holes are used. If not, an adaptor plate needs to be used. The TH400 does bolt up to the LS1 except that the LS1 has a bolt hole at the 12 o'clock position and the TH400 does not. Also the TH400 has a bolt hole at the 2 o'clock position and the LS1 does not. This is why these companies make and include the adaptor plate. Also, they provide more accurate adapter for the torque converter. You could be shoving the TC into the front pump or not engaging the splines enough. You also don't have a speedometer. The crossmember can be purchased or made.

john kilgore

lf you guys running a th 400 a 3/4 1 ton truck is the best core. if a trans brake is not used the electric kick down MUST be used, if nothing but a switch. lt will tell your trans that you at full throttle and it will shift latter and firmer.

taqwache

true but i dont have to worry about that where i race. SAR. they never check. also, before i bolt it down i will check the convertor very closely.

taqwache

i never used that electric kick down. the tranny has it on there but i never hooked it up.

taqwache

OK, latest update. today i bolted up the TH400 and everything went in perfectly. i was using the 6.0L flywheel with spacer for the 4L80 and it was perfect. i tried without the spacer but the converter was way to far. so i just reinstalled it and it was perfect. i did not measure it but it was like 1/16 or so away from the flywheel. also the starter motor engaged the flywheel perfectly so there was no problems there. the 6-speed crossmember was also fine but i am going to have to use like a 1" spacer. also the hurst adapter fit fine after some minor fabbing. honestly, i dont think it is worth the $130 they ask for it considering how simple it is but it is the only company that offers one. i did measure the driveshaft and it is going to have to be 44". the stock LS1 shaft is 42". i meausred the driveshaft that came out of my 69 camaro and it is 46" and already has the TH400 yoke on it. so it looks like i will just get that one shorten up to save even more money. the only thing i have left is to get the driveshaft cut and cooler installed. the lokar dipstick is really nice but i have not figured where to mount it just yet. i will let yall know how everything else goes when i get some more time to work on it next week.

toxic99

Curious, why would you want to use a power robbing th400? Sure, it is stronger than all else but, th350s are very strong as well, and can certainly handle the power of a LS1. JMO

taqwache

mainly because i already had one and with the N2O i want to use i dont trust a 350. i will loose a little bit of power with the 400 but hopfully i can just make it up in nitrous.

toxic99

This is what I figured, but th350s are plentiful and cheap. As is aftermarket parts for them.

When built right, they can easily handle 9 sec. cars. Ask me how I know.


Understandable. Good luck.