TH 350 Shift Improvement Kits?
 

Firstly what is the best one? Trans-Go, B&M, or ?

I dropped the pan today on a 1972 TH350. Looks to me like that's never happened before or that it's been a very long time since it was. Tons of crap and sludge and I think rust residue. Likely needs to and will be gone through in the near future. Separator plate gaskets broke apart in places and I will have to scrape a good portion off of the one that is attached to the upper transmission attached valve body portion because it is basically glued on toward the middle of it.

I found no check balls though which is my biggest concern. Would this have ever happened from the factory? What would no check balls cause? Where do I get new ones and where should they go in the valve body?

Re: TH 350 Shift Improvement Kits?
 

I have always left the brand of a Performance Kit up to the tranny rebuilder, if they are worth their salt they use one they are getting good results from. A performance kit basically firms up the shifts.

Re: TH 350 Shift Improvement Kits?
 

Over the years, I have used a few of the Trans-Go 350-1&2 kits. "1" is for street and towing, and "2" is for much firmer shifts. Even the "1" kit parts will increase shift firmness, but not to a bang-bang level. The difference is the regulator pressure spring and maybe another part or two. But you should tell them what you're looking for and get their recommendation.

https://transgo.com/product-details/350-12/

I'm not sure why they say the kit is for professional mechanics. When I did my first one, I was clueless about auto transmissions, but the kit was easy to install. Actually did it in a driveway in a few (or maybe several) hours. Learned a lot, too.

Very good instructions here: https://res.cloudinary.com/transgo/wbiss/rk/35012.pdf

Re: TH 350 Shift Improvement Kits?
 

I put a B&M Shift Improver kit in my K20 more years ago than I can remember. Did it in my carport, followed the instructions and had no problems. Still works well, shifts are definitely right-now FIRM!

I recall moving and/or removing some of the check balls. Whatever kit you get, the instructions will tell you what to do. OP, I have no idea why yours doesn't seem to have them, or where to get some.

Re: TH 350 Shift Improvement Kits?
 

Do you or anyone else recall if it’s better to set up for street/strip or rv/heavy duty? I was able to source 0.25” check balls from summit racing. Pack of 10 <$6. I’m wondering if not having any check balls may be the reason for slow reverse engagement?

Re: TH 350 Shift Improvement Kits?
 

I don't know, and I don't recall having that option when I did mine. Hopefully, someone else here will know.

Re: TH 350 Shift Improvement Kits?
 

It's been awhile since I've installed a shift kit, but IIRC, they come with new balls, and they are steel. I've removed some pretty pebbled balls made from whatever GM used in their transmissions. Some kind of plastic. Trans-Go kits were more involved, while the B&M kits were pretty basic. But I could get 3rd gear rubber when I put a B&M kit in a Vega panel truck I had. It had the 3.36 performance axle and a GT (progressive 2-bbl carb and a bigger cam) engine. Surprised a lot of people at stoplights. It being a panel truck, it was also a lot lighter than the regular Vegas. I put a 305 SBC in one. That thing surprised a lot of people, too. :lol:

Re: TH 350 Shift Improvement Kits?
 

Not sure how I missed them falling out but I did find 4 check balls. I don’t believe the pan has ever been off until I just took it off. I reinstalled two of the 4.

Re: TH 350 Shift Improvement Kits?
 

I will second the Transgo kit. I put one in a turbo 350 in my Chevelle I had years ago, and I really liked it. It was firm under heavy throttle, but pretty normal under light throttle. Likely was the 1st. step.

Re: TH 350 Shift Improvement Kits?
 

Was that per the B&M kit instructions?

Re: TH 350 Shift Improvement Kits?
 

Yea I've done two installations long ago and used 2 check balls in both.
One is still doing just fine in my truck 30 years later.

Re: TH 350 Shift Improvement Kits?
 

A V-8 in a Vega. That's pretty cool!

Re: TH 350 Shift Improvement Kits?
 

That was after Chevrolet came out with the 305 in a Monza, but I did it the hard way.

Re: TH 350 Shift Improvement Kits?
 

I had forgotten about that. Now I remember the 305 Monzas competing in a road race series.

Re: TH 350 Shift Improvement Kits?
 

Street/Strip, will be a faster/firmer shift than a HD/RV. Years ago ? Decades ago ? With 3spd AT's for my driver's. They usually got B&M shift kits.

With 700r4's, when I rebuild them. They get a trans-go kit.

The best thing to do. Is just research the kits you're interested in. They all won't come, with the exact same parts. So you can choose between kinda basic, or more involved. Depending on your interests/needs.

They say for " professional use only ". To limit their liability. From backyard mechanics that do not install the kit correctly ( or are incapable of installing it correctly ) and damage their transmission/vehicle.

The " plastic " check balls do not damage the separator plates, like the steel ones do. The plastic check balls are dirt cheap compared to a new separator plate.

Re: TH 350 Shift Improvement Kits?
 

Good to know about the steel balls causing damage over time. Doesn't help that some kits have springs for raising the pressures.