Tranny crossmember question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jlaird · 10-26-2007, 07:55 AM

does anybody know if this crossmember from performanceonline.com can be used for either an auto or manual trans? It says its for an auto, but I was wondering if the mount is the same for both trans, but with different bolt hole mounting locations??

http://www.performanceonline.com/sto...cat=461&page=1

sneakysnake · 10-26-2007, 09:39 AM

Stock manuals mounted to the bell housing up close to the back of the motor, as the autos mounted on the tail of the tranny.

sneakysnake · 10-26-2007, 11:25 AM

Here is another pic of man mount from another post.

jlaird · 10-26-2007, 12:16 PM

Thanks for the pics!

SCOTI · 10-26-2007, 01:20 PM

Early manual trannys (3spds) were short & used the crossmember that was located immediately behind the back of the engine. Later manual trannys (that are longer/heavier) would need the same auto-trans style transmission crossmember to better support the additional length/weight.

jlaird · 10-26-2007, 02:38 PM

scoti,

I thought I read something like that. So would the later style manuals use both the crossmembers or just the further back one?

SCOTI · 10-26-2007, 02:46 PM

Quote:

Originally Posted by jlaird

scoti,

I thought I read something like that. So would the later style manuals use both the crossmembers or just the further back one?

Just the rear-most crossmember would be needed.

IIRC, the original truck bellhousings had provisions for the original style man trans c.member that went just behind the block. Aftermarket bellhousings (or those from a HP application) won't have these provisions.

71tahoe · 10-26-2007, 05:05 PM

dimensionally the 3spd is the same or almost the same as the TH 350 (uses same driveshaft and yoke). There is also a spot on the three speed where a mount could bolt but I don't know if it is in the same place.

SCOTI · 10-26-2007, 06:08 PM

Quote:

Originally Posted by 71tahoe

dimensionally the 3spd is the same or almost the same as the TH 350 (uses same driveshaft and yoke). There is also a spot on the three speed where a mount could bolt but I don't know if it is in the same place.

Dimensionally, yes they're similar. But 4spds & autos have more weight/bulk toward the tailshaft vs. the input shaft.

I know you can bolt a 4spd up to the bellhousing & not use any trans c.member @ all. But it's going to cause issues sooner or later.

71tahoe · 10-26-2007, 06:23 PM

Yeah, a lot of weight cantilevered will put undue stress on the bellhousing. I suspect the opposite to be true of the 3spd with no support at the bellhousing might sag in the middle. I also notice the bellhousings designed for rear xmembers (no provision for the mounts) have deep fins for added strength and a lot if not all are aluminum which saves weight. An older 3 on the tree nova probably had a saginaw with the rear crossmember so getting that bellhousing setup might be a way to go. I know there are some car guys on here too who will know

CHRIS67GMC · 10-26-2007, 10:05 PM

Bowler Transmissions builds a awsome tubular cross member that works on both

10-26-2007, 07:55 AM	#1
jlaird Senior Member Join Date: May 2004 Location: johnstown, NY Posts: 2,393	Tranny crossmember question does anybody know if this crossmember from performanceonline.com can be used for either an auto or manual trans? It says its for an auto, but I was wondering if the mount is the same for both trans, but with different bolt hole mounting locations?? http://www.performanceonline.com/sto...cat=461&page=1 Last edited by jlaird; 10-26-2007 at 07:56 AM.

10-26-2007, 09:39 AM	#2
sneakysnake It's a catastrophic success. Join Date: Jan 2003 Location: Oklahoma Posts: 2,077	Re: Tranny crossmember question Stock manuals mounted to the bell housing up close to the back of the motor, as the autos mounted on the tail of the tranny. Attached Images

10-26-2007, 11:25 AM	#3
sneakysnake It's a catastrophic success. Join Date: Jan 2003 Location: Oklahoma Posts: 2,077	Re: Tranny crossmember question Here is another pic of man mount from another post. Attached Images

10-26-2007, 12:16 PM	#4
jlaird Senior Member Join Date: May 2004 Location: johnstown, NY Posts: 2,393	Re: Tranny crossmember question Thanks for the pics!

10-26-2007, 01:20 PM	#5
SCOTI Registered User Join Date: Apr 2001 Location: DALLAS,TX Posts: 21,946	Re: Tranny crossmember question Early manual trannys (3spds) were short & used the crossmember that was located immediately behind the back of the engine. Later manual trannys (that are longer/heavier) would need the same auto-trans style transmission crossmember to better support the additional length/weight. __________________ 67SWB-B.B.RetroRod 64SWB-Recycle 89CCDually-Driver/Tow Truck 99CCSWB Driver All Fleetsides @rattlecankustoms in IG Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive. It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar..... *Cubic inches is like Indiana Jones with a cheap pistol.* Last edited by SCOTI; 10-26-2007 at 01:23 PM.

10-26-2007, 02:38 PM	#6
jlaird Senior Member Join Date: May 2004 Location: johnstown, NY Posts: 2,393	Re: Tranny crossmember question scoti, I thought I read something like that. So would the later style manuals use both the crossmembers or just the further back one?

10-26-2007, 05:05 PM	#8
71tahoe Registered User Join Date: May 2006 Location: Jonesboro, AR Posts: 916	Re: Tranny crossmember question dimensionally the 3spd is the same or almost the same as the TH 350 (uses same driveshaft and yoke). There is also a spot on the three speed where a mount could bolt but I don't know if it is in the same place.

10-26-2007, 06:23 PM	#10
71tahoe Registered User Join Date: May 2006 Location: Jonesboro, AR Posts: 916	Re: Tranny crossmember question Yeah, a lot of weight cantilevered will put undue stress on the bellhousing. I suspect the opposite to be true of the 3spd with no support at the bellhousing might sag in the middle. I also notice the bellhousings designed for rear xmembers (no provision for the mounts) have deep fins for added strength and a lot if not all are aluminum which saves weight. An older 3 on the tree nova probably had a saginaw with the rear crossmember so getting that bellhousing setup might be a way to go. I know there are some car guys on here too who will know

10-26-2007, 10:05 PM	#11
CHRIS67GMC Registered User Join Date: Aug 2007 Location: Tiffin Oh Posts: 299	Re: Tranny crossmember question Bowler Transmissions builds a awsome tubular cross member that works on both



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