TH350 Strength

GUMP · 12-21-2015, 12:02 PM

I wouldn't be afraid of hurting the case at that HP. Poly transmission mount for sure.

Jim Kaekel · 12-21-2015, 12:20 PM

Most TH-350 4WD cases used the special cast aluminum dust cover that helped strengthen the case, but you probably don't need it since you don't have a big, heavy transfer case hanging off the back of the trans. I would use a stock rubber trans. mount with stock engine mounts and a torque strap on the left front of the engine. If you want to help prevent case breakage, make or buy a brace that connects the boss on the right side of the bellhousing to the boss at the rear that's right in front of the tailhousing. I broke several bellhousings over the years prior to installing a brace. That's my .02.

Eman · 12-21-2015, 12:35 PM

Rubber mount for sure. Case will crack near cooler lines if stressed, only case I cracked was with a frt. motor plate and only a trans mount and the case was trimmed of tabs which weakened it. If you pull the pump and the input shaft it's easy to ck for the 36 element sprag if you're concerned. I ran with only a hardened race for years with no failures. Be gentle with 2nd gear and you'll have no problems. Start burnout in 2nd and shift to 3rd quickly. Don't ever come out of burnout in 2nd and shock it by having the tires grab.

ken robinson · 12-21-2015, 01:03 PM

The GM cases on all the glides & TH are not best castings , broke a few over the years . I run solid engine mount & rubber trans mount .1 bolt cross member to rubber mount . The 2-3 burn out works . Tire shake/spin can destroy parts . We run 350s in both cars .Your car has a full frame like Bob kingswood wagon . You'll be ok. Sometimes you just get a pour case/core . Driveshaft balance-ing not to be over looked too . See you at Lebanon ...

impstocker · 12-21-2015, 02:29 PM

Want to thank everbody for great advice. I am going to fabricate that brace today. I will continue to use the solid motor mounts with a poly tranny mount with 1 bolt. Yes Ken full frame also solid body mounts with 8 point roll bar welded through to frame plus some other gussets ect. No flex in frame and body.

Believe it or not I never raced a "real race car" with an automatic so the info on the 2-3 burnouts i never knew.

Will Lamprecht 65 imp I/SA

impstocker · 12-21-2015, 02:33 PM

Yes ken, I will be using the driveshaft which was built and balanced that I had in my 68 Impala. I would spin that to 7200. Had to find a place that would do it, most shops said to long would not do it!

Will

ss3011 · 12-21-2015, 03:08 PM

Another good upgrade is to install a 4L65 lo roller clutch assembly/support. This part is made of nodular iron, instead of a normal 350 which was gray iron , and the rollers were slightly wider. It will handle much more torque than a 350 roller clutch.

12-21-2015, 12:02 PM	#1
GUMP VIP Member Join Date: May 2002 Location: Shelby, NC Posts: 1,832 Likes: 2,198 Liked 2,364 Times in 560 Posts	Re: TH350 Strength I wouldn't be afraid of hurting the case at that HP. Poly transmission mount for sure.

12-21-2015, 12:20 PM	#2
Jim Kaekel VIP Member Join Date: Jul 2002 Location: Michigan Posts: 1,229 Likes: 133 Liked 536 Times in 110 Posts	Re: TH350 Strength Most TH-350 4WD cases used the special cast aluminum dust cover that helped strengthen the case, but you probably don't need it since you don't have a big, heavy transfer case hanging off the back of the trans. I would use a stock rubber trans. mount with stock engine mounts and a torque strap on the left front of the engine. If you want to help prevent case breakage, make or buy a brace that connects the boss on the right side of the bellhousing to the boss at the rear that's right in front of the tailhousing. I broke several bellhousings over the years prior to installing a brace. That's my .02. __________________ Jim Kaekel 3836 STK

12-21-2015, 12:35 PM	#3
Eman Member Join Date: May 2014 Location: E TN Posts: 474 Likes: 16 Liked 133 Times in 76 Posts	Re: TH350 Strength Rubber mount for sure. Case will crack near cooler lines if stressed, only case I cracked was with a frt. motor plate and only a trans mount and the case was trimmed of tabs which weakened it. If you pull the pump and the input shaft it's easy to ck for the 36 element sprag if you're concerned. I ran with only a hardened race for years with no failures. Be gentle with 2nd gear and you'll have no problems. Start burnout in 2nd and shift to 3rd quickly. Don't ever come out of burnout in 2nd and shock it by having the tires grab.

12-21-2015, 01:03 PM	#4
ken robinson Member Join Date: Dec 2001 Location: tomsriver nj Posts: 482 Likes: 75 Liked 225 Times in 88 Posts	Re: TH350 Strength The GM cases on all the glides & TH are not best castings , broke a few over the years . I run solid engine mount & rubber trans mount .1 bolt cross member to rubber mount . The 2-3 burn out works . Tire shake/spin can destroy parts . We run 350s in both cars .Your car has a full frame like Bob kingswood wagon . You'll be ok. Sometimes you just get a pour case/core . Driveshaft balance-ing not to be over looked too . See you at Lebanon ...

12-21-2015, 02:29 PM	#5
impstocker Member Join Date: Dec 2008 Location: Wingdale, NY Posts: 302 Likes: 27 Liked 53 Times in 16 Posts	Re: TH350 Strength Want to thank everbody for great advice. I am going to fabricate that brace today. I will continue to use the solid motor mounts with a poly tranny mount with 1 bolt. Yes Ken full frame also solid body mounts with 8 point roll bar welded through to frame plus some other gussets ect. No flex in frame and body. Believe it or not I never raced a "real race car" with an automatic so the info on the 2-3 burnouts i never knew. Will Lamprecht 65 imp I/SA

12-21-2015, 02:33 PM	#6
impstocker Member Join Date: Dec 2008 Location: Wingdale, NY Posts: 302 Likes: 27 Liked 53 Times in 16 Posts	Re: TH350 Strength Yes ken, I will be using the driveshaft which was built and balanced that I had in my 68 Impala. I would spin that to 7200. Had to find a place that would do it, most shops said to long would not do it! Will

12-21-2015, 03:08 PM	#7
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 910 Likes: 70 Liked 239 Times in 114 Posts	Re: TH350 Strength Another good upgrade is to install a 4L65 lo roller clutch assembly/support. This part is made of nodular iron, instead of a normal 350 which was gray iron , and the rollers were slightly wider. It will handle much more torque than a 350 roller clutch.