TH350 Clutches / Modifications

[Chad E532]

I am attempting my first automatic transmission rebuild and am wondering what clutch/steel count I should use in the various clutch packs for my application.
I will be running Red Alto clutches with Kolene steels along with a manual valve body with no band.

From my research I have found a few modifications I am going to try like enlarging the direct clutch cooling holes (and adding a few more) along with adding bushings to the sun gear and running a wider direct clutch/drum bushing. Any other tricks I should implement?

The application is a 3400 lb small block car running 11.30's
Thanks in advance,
Chad

[Alan Roehrich]

If you're drag racing, you don't need the extra holes in the direct piston. They won't hurt, but they won't help anything either.

If this is a bracket car, 5 low reverse, 5 forward, and 5 direct clutches, with no cushions will work fine, and 3 intermediate clutches, with no cushion, will be fine there. Replace the wavy cushion plates with flat steels.

[Bob Mulry]

Hi Alan,

Got to be careful about not running the wavy steel on the intermediate clutch pack because sometimes the flat steels interfere with the apply piston return spring retainer. This will also give you an incorrect clutch pack clearance...

Just a heads up,
Bob

[Daran Summerton]

I read a company made a 700r4 low work?????

[Alan Roehrich]

Originally Posted by Daran Summerton

I read a company made a 700r4 low work?????

Daran, what they do is take the ring gear off of the 350 rear planetary, then cut the ring gear off of a 700 rear planetary, and weld it on the plate of the 350 planetary, they also weld a plate on the 700 planetary carrier to set the end play for the thrust bearing. Then they take the rear piston for the 350, and turn the ID in a lathe to clear the 700 ring gear.

That's how you get a 2.75 low gear for a 350. I just put one in the Super Stock Camaro, because we can't get the right rear gear to run a 2.52 low.

[Alan Roehrich]

Originally Posted by Bob Mulry

Hi Alan,

Got to be careful about not running the wavy steel on the intermediate clutch pack because sometimes the flat steels interfere with the apply piston return spring retainer. This will also give you an incorrect clutch pack clearance...

Just a heads up,
Bob

Bob, it may be possible to have that happen, but I've been building them that way for about 25 years, and never had a problem. I usually get 400 passes out of one of my 350's, and that's in the AA/SA car. I just replace the wavy with a flat steel.

[Daran Summerton]

Alan I really could use a 3.06 low T-350

[Alan Roehrich]

Originally Posted by Daran Summerton

Alan I really could use a 3.06 low T-350

Daran, I think Coan can get you close, but the price and the RPM drop will both probably be ugly and painful.

You'd need to change the front planetary out with something, and you'd end up with somewhere around a 1.75 to 1.8 low gear, a 1.2 to 1.25 drop in gear ratio is a lot, especially for an engine you think needs a 3.06 low gear. My big complaint with the 700 R4 is the low gear is too low, and the drop between 1st and 2nd is too big.

[Chad E532]

Alan,
Thanks for the info on the clutch/plate counts and also the tip on replacing the wave plate with flat steels.
What is the theory behind drilling the holes out on the direct clutch? It is just a cooling enhancement for street driven cars?

This is a race only car that is slowly inching it's way to I/SA as I save up the funds to replace the bracket engine with a legal stocker.
Thanks again.

[Daran Summerton]

My latest brillant idea, 1966 Impala SS/NA 283/220 low budget!!!! 5.86 gear stocker radials, footbrake stock t-350 with 8" converter approx. 4500.
60 ft 1.86
1/4 12.80 on a 12.15 index
mph 106

My U/SA left harder

Car will never be a killer, just looking for consistancy 2-3 under.