TH350 Clutches / Modifications

Daran Summerton · 05-15-2011, 07:57 PM

Alan I really could use a 3.06 low T-350

Alan Roehrich · 05-15-2011, 08:02 PM

Quote:

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 · 05-15-2011, 08:24 PM

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.

Alan Roehrich · 05-15-2011, 08:40 PM

Quote:

Originally Posted by 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.

Chad, I've seen that modification done, but not seen any real gain.

Honestly, the transmission for Stock will be very different. In fact, for your car, in I/SA, I'd be looking at a 200 Metric from McClay or Arnett. To convert your 350 to a class transmission, you'll need to replace both drums with aluminum drums, as well as having some other stuff lightened. The difference between what you're building now and what you'll need for Stock is about a tenth.

Daran Summerton · 05-19-2011, 07:51 PM

http://www.truckinweb.com/tech/0510t.../photo_03.html

What do ya'll think???

ss3011 · 05-19-2011, 08:19 PM

One of the reasons for drilling out the "cooling holes" in the OD of the clutch housing is to allow trapped oil to escape. The oil could build up on the OD of the clutch plates, when the housing spins and drag the clutch on. By drilling holes in the correct areas of the splines, the oil will exhaust and won't apply the clutch. Usually this trick only is done on the direct clutch housing.

Alan Roehrich · 05-19-2011, 08:48 PM

Quote:

Originally Posted by Daran Summerton

http://www.truckinweb.com/tech/0510t.../photo_03.html

What do ya'll think???

Daran, that is exactly what I described up thread. It yields a 2.75 low gear, because the front planetary remains unchanged.

That photo is merely a picture of a stock TH350 rear planetary carrier next to a stock 700 R4 planetary. That's not what it looks like when ready to install.

Daran Summerton · 05-15-2011, 08:27 PM

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.

Mark Yacavone · 05-20-2011, 02:07 AM

Quote:

Originally Posted by 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.

Daran, You're way under geared and about a thousand short on the stall speed for openers.

Alan Roehrich · 05-20-2011, 02:15 AM

Mark, I was thinking 6.17 gears, if it's a 12 bolt, and about 6000 stall, if he's got a Super Stock engine that will spin anything like it should. Not sure a 2.75 low will work because of the drop between 1st and 2nd. That extra point and a half of gear is a big deal to a small engine with no torque, especially in a heavy car.

Going from 2.52 in 1st to 1.52 in 2nd is not the same as going from 2.75 in 1st to 1.6 in 2nd, even though the 1st is low, the extra 0.15 gear drop makes a bigger difference than some think, because they forget the car is going SLOWER when it comes out of low gear with a 2.75 than it is with a 2.52, that amplifies the drop.

05-15-2011, 07:57 PM	#1
Daran Summerton Senior Member Join Date: Jun 2003 Location: Las Vegas nv Posts: 600 Likes: 18 Liked 66 Times in 37 Posts	Re: TH350 Clutches / Modifications Alan I really could use a 3.06 low T-350 __________________ 72 cutlass

05-15-2011, 08:24 PM	#3
Chad E532 Member Join Date: Jul 2008 Location: Lindstrom MN Posts: 156 Likes: 7 Liked 54 Times in 7 Posts	Re: TH350 Clutches / Modifications 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.

05-19-2011, 07:51 PM	#5
Daran Summerton Senior Member Join Date: Jun 2003 Location: Las Vegas nv Posts: 600 Likes: 18 Liked 66 Times in 37 Posts	Re: TH350 Clutches / Modifications http://www.truckinweb.com/tech/0510t.../photo_03.html What do ya'll think??? __________________ 72 cutlass

05-19-2011, 08:19 PM	#6
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 909 Likes: 70 Liked 239 Times in 114 Posts	Re: TH350 Clutches / Modifications One of the reasons for drilling out the "cooling holes" in the OD of the clutch housing is to allow trapped oil to escape. The oil could build up on the OD of the clutch plates, when the housing spins and drag the clutch on. By drilling holes in the correct areas of the splines, the oil will exhaust and won't apply the clutch. Usually this trick only is done on the direct clutch housing.

05-15-2011, 08:27 PM	#8
Daran Summerton Senior Member Join Date: Jun 2003 Location: Las Vegas nv Posts: 600 Likes: 18 Liked 66 Times in 37 Posts	Re: TH350 Clutches / Modifications 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. __________________ 72 cutlass

05-20-2011, 02:15 AM	#10
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,126 Likes: 1,583 Liked 1,882 Times in 423 Posts	Re: TH350 Clutches / Modifications Mark, I was thinking 6.17 gears, if it's a 12 bolt, and about 6000 stall, if he's got a Super Stock engine that will spin anything like it should. Not sure a 2.75 low will work because of the drop between 1st and 2nd. That extra point and a half of gear is a big deal to a small engine with no torque, especially in a heavy car. Going from 2.52 in 1st to 1.52 in 2nd is not the same as going from 2.75 in 1st to 1.6 in 2nd, even though the 1st is low, the extra 0.15 gear drop makes a bigger difference than some think, because they forget the car is going SLOWER when it comes out of low gear with a 2.75 than it is with a 2.52, that amplifies the drop. __________________ Alan Roehrich 212A G/S