thanks for that info .. looks like when I have the extra cash a TH 350 will be going in

 

Everyone told me that T350's are not as strong as T400's, and that the beefing up of the T350 will bring it to T400 cost levels.

 

well that may be true but is the th350 like 40 pounds lighter then the th400??

 

I'm (quietly) considering this same swap (going with a built 350). I was curious too... A quick search on the internet shows this:

TH 350...126#s
TH 400...139#s
All these transmissions were weighted dry, on the same day, with no convertors AND on my "official" bathroom scale.
(end paste)

Hmm, is the 13# savings worth the extra cost? Hmm... I dunno, I'll still probably go the TH350 / Ultrabell / TH400 drum & sprag route...

 

its generally accepted the TH400 is 15lbs heavier the the 350 - but 95% of that is rotating weight. The ultrabell is pretty heavy and an ultrabell + TH350 will probably be heavier then a stock TH400.

It takes a few parts to make the TH350 not blow up, but most can get away with just the intermediate race/sprag upgrade. The new sprag/drum/race from TCI is 350.00 so that plus the 2.75 1st gear and things start getting expensive. After a year of hard use the TH350 will need to be taken apart and looked at most likely - they start to fail in a pretty linear fashion so its pretty obvious when its 'that time.' Plus there are hundreds of local guys just about everywhere that will rebuild them or build you a nice one for reasonable cost - same with a TH400. I'm stingy with my HP though and I want to get as much to the wheels as I can

Over 500rwhp or a nitrous/turbo car I would probbaly go with a TH400 or if I wanted to run a brake for bracket racing.

 

i got TH350 with 4000 stall nonlockup with TH400 sprag/drum (4000 to 6000 miles street driven and racing it every friday nights never had a proplem yet ,,i think its the best combo

 

Whats wrong with the Yank Pro Sportsman 4L60E with transbrake? Looks to be a stout transmission designed for up too 700ft lbs of torque.

 

i broke mine with 300 miles on it at street racing and lost 700$
don't have the transbrake

if u want a build 4l60e go with FLP a friend go one and no proplem yet

 

how is the highway driving with a 3spd tranny? what kind of rear gear are you guys running with this?

I am about to get a conversion from a local guy but he said he hated it on the freeway, he has a 3.73 rear gear, and said the tranny was at like6k when going 65 on teh freeway

just wondering
thanks
ed
firebird455@onebox.com

 

yeah a 3 spd def. needs a 323 or 315 gear if u plan on driving it. if u plan on RACING the car deal w/the 373 gears, and just drive slower...hell I did it and it took me a lot longer to get to the race spots...but my motor and tranny held...

 

My turbo 350 is great now.

After the 2 times I broke the 2 gear sprag. At the Super 10's(HRP) and the Thunder Shootout. 2 weekends in a row.

I went from a M6 to a Turbo 350 for bracket racing. I have a 4800 stall converter and she is holding up pretty well now.

If I had to do it over again I would put a power glide in her!

Good luck to ya.

Coach

 

With 3.42s and 27" tall tires its not that bad on the highway, I think 55-60 will be max cruising speed with the 3.70s though. 3000rpm doesnt sound bad on my stock motor and th blower makes almost no noise there. When I had heads/cam with a noisy valvetrain I dont know if I could have taken the 2500rpm cruise rpm for long - mine sounded like it was going to explode at 2500.

I also expect oil consumption to go up quite a bit (if GM is right on the ring flutter thing) keeping the egine up that high all the time but thats how it goes..

 

What kind of rwhp loss between the TH400 and TH350??? I have a TH400 that I was going to run but if I will be lossing a bunch of hp compared to the TH350 then I may just sell it.

 

A few things to consider. If you are worried about the weight of the rotating parts, get an aluminum drum. If you drive it on the street, have the aluminum drum hubbed with a steel liner. Rossler Transmissions did this for me. That will bring your rotating mass down substantially, for a cost.

A TH350 or TH400 will certainly hammer your perceived HP measurements on a dyno. If you are interested in running a dyno queen, stick with a six speed. If you are interested in picking up some nice ET and a couple MPH the TH400 with a proper torque converter will beat the M6 hands down. I was shocked when I did the conversion at how much the car picked up.

You can also get different 1st gear ratios. If you are concerned about the high initial 1st gear you can actually get a lower gear to help you roll out nicer. I have not done this with my transmission, but I'm debating it!

 

hey derty im very impressed with your times man your car is flying. If you dont mind I was just curious as to what your dyno numbers look like with th th400 and you weight when you ran the 9.5 and how much spray and what convertor. thanks in advance

 

Replied to your other post.