TH350 Rebuild Online: Free DIY Post

[jakeshoe]

Originally Posted by Psychonat69

So by the lack of reply I assume you think I'm just another idiot looking for easy answers. well I am not I am just trying to learn. This is what I've found out. there is one check ball for the 1-2 accumulator, one for the 2-3 accumulator, one for the reverse clutch and one between the modulator and detent. the balls are in there to slow down the application of the accumulator by way of a restrictor in parallel with the ball, and when it is released it will be faster by way of check ball. haven't figured out the one in the modulator/detent but I assume that is the one you leave in or you will have low line pressure. you told me to leave in all 5 balls, that got me for a bit before i figured that there is 5 in a lock up 350. I have a non lock up so i only have 4. I might not be exactly right on all of this but as I said I am just trying to learn. but then again If you wouldn't have asked me if i know what the balls are fore I probably would not have researched it so thank you.

My lack of reply is due to the fact I run a full time performance transmission shop with myself and 4 other employees, besides having a family and other responsibilities.

Yes 4 on a NLU unit.

Install all 4 is my recommendation. You can do as you wish but I can run all the stock checkballs and make a nothing fancy Th350 live at almost 700 RWHP for YEARS.

[Psychonat69]

Thank you for the reply. because you are recommending me not do anything I have just read about improving the 350 I now have just a couple more questions. would you recommend the duel feed mod either? and if you leave the checkballs in you wouldn't drill the separator plate holes either I assume. would you change the sprag race to a hardened one on all builds, or just HD ones. In all I think your recommendation to my application would to just leave it stk.

[jakeshoe]

Originally Posted by Psychonat69

Thank you for the reply. because you are recommending me not do anything I have just read about improving the 350 I now have just a couple more questions. would you recommend the duel feed mod either? and if you leave the checkballs in you wouldn't drill the separator plate holes either I assume. would you change the sprag race to a hardened one on all builds, or just HD ones. In all I think your recommendation to my application would to just leave it stk.

Don't read into my reply.
I said I would recommend running all the checkballs.
I did not say I would not dual feed it or not drill the feed holes.

You working with a 4wd application, you don't want to beat the transfer case to death, so you don't want this shifting on the "kill" mode everytime it shifts.
Leave all the accumulators functioning and drill the feed holes to .125" for 2nd and 3rd.
Dual feed it.
It will shift crisply but not overly firm, it will live forever as will the t-case behind it.
Hardened sprag race is a good upgrade.

[Psychonat69]

Thank you for the clarification. Your experience is well appreciated.

[70ss350oneowner]

I am definitely staying out of the build/rebuild tranny game, but tuning components is my main-stream. Your TH350 rebuild article is a beautifuly done craft with great pics. Thanks.

Situation:
Yesterday under WOT (grocery getter low comp small block) throttle stuck. Key to OFF at 3Krpm (I know this had to shock load every piece of tranny - was in second gear at the time) - then shifter quickly into neutral. Fixed problem on road side. (Idiot doing dash work got the air vent cable where it would ride over the the gas pedal link, get behind that link and forced WOT to hang in that position.

Problem:
Parking at home noticed a very slight but definite tranny whine in neutral at idle. Stopped at barely 1Krpm. Can also barely hear the slightest whine in gears moving at very light loads. This trans has never whined or faulted. Note: Trans uses a 2200rpm "hole shot" converter - installed several years ago - always worked/s great. (just a note - don't know if this is important). Trans assembly has never made a noise before. Orig trans rebuilt by very good pro in Atlanta years ago.

Question:
Should I panic now or play "wait & see" (this has never worked for me before, but I had to ask).

This is a one owner 70 Camaro and I would like to keep the original tranny shell if it needs your stage I build - can ship it to you as necessary.

NEED;
Your input on what to do.

Thanks, Mike 256 856 0682

[Cardinal]

IMHO, it will be less expensive to investigate why it is making noises BEFORE it fails = tears up a bunch of good parts. But, that's me.

I hope that Jake pipes in on this one as he's the resident automatic transmission expert.

[falloutboy]

or you could call his shop in Texas if time is of the essence

(ha always wanted to use this term)

[jakeshoe]

Originally Posted by 70ss350oneowner

I am definitely staying out of the build/rebuild tranny game, but tuning components is my main-stream. Your TH350 rebuild article is a beautifuly done craft with great pics. Thanks.

Situation:
Yesterday under WOT (grocery getter low comp small block) throttle stuck. Key to OFF at 3Krpm (I know this had to shock load every piece of tranny - was in second gear at the time) - then shifter quickly into neutral. Fixed problem on road side. (Idiot doing dash work got the air vent cable where it would ride over the the gas pedal link, get behind that link and forced WOT to hang in that position.

Problem:
Parking at home noticed a very slight but definite tranny whine in neutral at idle. Stopped at barely 1Krpm. Can also barely hear the slightest whine in gears moving at very light loads. This trans has never whined or faulted. Note: Trans uses a 2200rpm "hole shot" converter - installed several years ago - always worked/s great. (just a note - don't know if this is important). Trans assembly has never made a noise before. Orig trans rebuilt by very good pro in Atlanta years ago.

Question:
Should I panic now or play "wait & see" (this has never worked for me before, but I had to ask).

This is a one owner 70 Camaro and I would like to keep the original tranny shell if it needs your stage I build - can ship it to you as necessary.

NEED;
Your input on what to do.

Thanks, Mike 256 856 0682

Mike,
Check the basics. Check the fluid level, shifter adjustment, etc.
You might put a couple of easy miles on it to see if the noise continues.
Shutting off the key isn't going to hurt the trans. Not a good idea while at high speed, but you had to do it in your situation, and not really harsh at low speed.

Give me a call.

Jake

[Mrbrey1]

PLEASE do one of these for a 700r4

[Rich Schmidt]

I am looking into doing a full race th350 in the near future. I just puked the planetaries(stock 1.82)in my glide,and have a spare set of 1.76's,and since I just freshened it with all the best stuff last season(blue frictions,kevlar band ect) I am going to put it back together with the 1.76's,and probably sell it. I am looking to gather all the parts and build a th350 myself. I do Powerglides in my sleep,but never a th-350,and I was wondering what some of the hard parts I would really need to withstand about 750HP and a transbrake. I see that it is possible to throw mad money at a th350,but I will need to know where to spend it for durability. I am not looking for low friction rollerized everything,just a long lasting bracket trans for my electronics class/10.90 car. I wouldn't mind spending a few hundred more then what I would on a th400 as long as it wil stay together. I swapped for a th350 to a th400 years ago,and on an 8,000 rpm engine,it cost a solid 3 tenths. The glide was worth nothing better or worse then the th-350. Its a 3500# car with a 7200 rpm 439 big block running low 10's now,but I plan on taking about 400# out of the car,and adding about 150 hp. Whats your take on this?

[Cardinal]

Rich:

Oh, man, I'm not sure that a TH350 will stand up to that much torque without pouring a ton of money into it.

THEE weakest part of a TH350 is the bell housing area. IMHO, spend the money for a J. W. Performance Ultrabell housing that will eliminate that problem.

Jakeshoe can address the rest of the parts that you need to put into a TH350 to make it (hopefully) bullet proof. IMHO, PM, email, or call him to get his advice. BTW, he does build VERY strong transmissions for reasonable prices.

Beyond all of that, I recommend that you read all the replies in this posting. There is a TON of good information in it that you absolutely need to document before building your TH350.

I have built almost a dozen TH350s from mild to wild. My last TH350 was for our youngest son's 83 S10 that he wants to someday replace the warmed over 350 SBC with a 383 stroker monster motor! LOL! I am fortunate that I have a lathe so I can turn down all the pistons to achieve the maximum number of clutches and plates in each clutch pack = more of them means that the trans can handle more HP which I put into this trans along with a HD trans cooler and B&M shift improver kit (which Jake dislikes but I've had good luck with. Like they say, "to each their own".).

Spragues (sp?) are another area that will be spending good money on.

AND follow Jake's oil bypass modification to the case as it definately improves the TH350's performance.

Understand that Jake is (IMHO) THEE person to go to whith any automatic transmission project. You CANNOT go wrong if you follow is advice!

[jakeshoe]

Losing 3 tenths from a TH350 to a TH400 would be caused by either a converter change or something grossly wrong with the TH400 (slippage).

It just doesn't happen and the TH400 although thought to "consume" more HP hasn't shown to do that in any combo we've ever dealt with. We've also gone even heavier (and lighter) without any significant change.

750 HP from a BBC through a TH350 with a transbrake isn't going to be as reliable as a TH400.
The issue becomes the planetaries, that's after you've installed a billet input shaft, good sprag drum, and gone through several cores to get decent parts.

A TH350 although lighter has some parasite losses that a 400 doesn't have.

[Cardinal]

See, I knew Jake would "tell it like it is". IMHO, he walks on water when it comes to his knowledge of automatic transmissions.

[vince150]

I have a link to an awesome trans I used on my Z28 along with some pictures of my restoration on my website. www.bestwaxforcars.com Check it out. I'd love to hear what you guys think