TH350 Rebuild Online: Free DIY Post

jakeshoe

Veteran Member
Lifetime Gold Member
Dec 8, 2000
8,925
Republic of Texas
A screech could be from several areas including the roller clutches, sun shell to case contact, bad thrust washer.
If it happens on a 1-2 shift it is a bad torrington bearing in the planets.
 

Mikey18

Veteran Member
Dec 31, 2000
325
Soldotna, Alaska
Thanks for the great info Jake. Ive got a 350c to put back together and was wondering about the differences between it and a regular unit. I know its a lockup converter, and i needed a different shift kit (trans go stage 2 installed). Is this tranny any weaker/ different other than that? Do I need to lock up the converter to prevent damage or is it ok to run unlocked all the time? If so, how do I need to wire it? Also curious about the wave plates... GM instructor had us leave them out to fit more clutches (2 int, 5 for, 4 dir and 4 low/rev) a few years ago, I was thinking this might make it shift too harsh and wear prematurely? And last but not least, I recently read in one of those car rags (forget which, i get so many) about drilling a hole in the pump to increase lube to the gears, opinion? Thanks again for the great tech! Mike
 

Mikey18

Veteran Member
Dec 31, 2000
325
Soldotna, Alaska
Forgot about the tools.... Just wanted to share a cheap version I made for the bench press... Made from 2 shelf brackets for the stand, with a straight arm loosely bolted between the 2 up top. Cut a inch long piece of pipe in half and weld a 4-6" leg to the center of each, using a long nail or bolt to attach this to the center of the leverage arm. Maybe this will make sence to some, maybe not...Ill try to post a pic of mine if i can track down someone with a digi cam. :bowtie:
 

jakeshoe

Veteran Member
Lifetime Gold Member
Dec 8, 2000
8,925
Republic of Texas
The lockup version is plenty stout, most of the parts are the same and many are updated to use torrington bearings instead of thrust washers.

You should have 3 intermediate clutches on a V8 model trans, if you don't you need to get a V8 piston or machine yours for 3 clutches.
ALWAYS leave the cushion plate in the intermediates on a TH350.

You can leave the cushion out of the directs but it may cause harsh reverse engagment. Street applications I leave it in, racing I leave it out. Same on the forward, but the side effect is harsh engagement into forward range, although I haven't noticed it being overly harsh.

I don't drill a hole in the pump, I know the mod, but the gears are surrounded by fluid anyway.
 

seven1camaro

New Member
Mar 29, 2007
10
tucson AZ
I have a couple of question about this Dual Feed Mod to the tranny.
To do this
1. Remove seal on direct drum not Piston
2. Remove second seal from the bottom of the pump
3. Plug hole that you show in the pictures
Is this all

But you mention that a shift kit will also have this option to do it with the "transfer plate and gasket to be added under the support plate" and gasket in the valve body, but you prefer to do it internal (I understand why).

I would like to try this, is this good for a DD and what if I don’t know, that the rebuild kit I bought (TCI Master rebuild w/shift kit http://store.summitracing.com/partdetail.asp?autofilter=1&part=TCI-328800&N=700+115&autoview=sku) has this option, or is it, do one or the other, or can both be done with no issues.

Thanks
joe
 
Last edited:

jakeshoe

Veteran Member
Lifetime Gold Member
Dec 8, 2000
8,925
Republic of Texas
You should do one or the other.
If you are using a TCI valve body and seperator plate, and it has the slotted plate that gets sandwiched between the seperator plate and the support plate in front of the valve body, just install all the lip seals and sealing rings as stock, and install the kit according to the instructions.

On a TH350 this method works OK, but you are adding a gasket. The fluid path is big enough and short enough that it is an effective method to dual feed.

However if you are using just the "Trans-Scat" valve body kit that uses the stock VB and changes springs, etc. Internally dual feed, and use the stock sep plate with the holes I show drilled, and omit the slotted plate.
 

jakeshoe

Veteran Member
Lifetime Gold Member
Dec 8, 2000
8,925
Republic of Texas
This mod works great for a daily driver.

Dual feeding the directs firms up the 2-3 shift without any other mods. There are no negative effects that I have found. I never have understood why GM didn't do it.
You will love the shift to 3rd gear at throttle with dual fed clutches and a limited or blocked 2-3 accumulator.
 

seven1camaro

New Member
Mar 29, 2007
10
tucson AZ
Thanks for answering my question.

On a TH350 this method works OK, but you are adding a gasket
What Other Gasket I'm I adding, the Kit only has to 2VB Gasket A Sep Plate with the slotted plate that come with the shift kit, but there are 3 sets of VB gasket and TCI said to use the one in the package with the plate
Damn know i'm confused :confused:

Since I have the Trans-Scat shift kit I want to go ahead and install it and save this mod for the next one.

Maybe a friend will need his tranny rebuilt soon ;)

Sorry for the hijack
 

camaro71/holland

Veteran Member
Aug 27, 2003
1,664
The Netherlands
jakeshoe said:
Th350pumpstator.jpg

Notice the scraped and split low reverse friction in the intermediate piston cavity. This slightly tightens the intermediate clutch clearance to achieve cleaner 1-2 shift.

Jake, a couple of questions about this mod:

1. Do you have to use a friction plate or can I also use a metal low/reverse plate?
2. If it's necessary to use a friction - do I have to scrape it to a specific thickness? Or can I just use a used one?
3. Can I use emery roll to srape it, like 400 grit?

Thanks, David
 




Latest posts

Top