Question about BB 4speed crossmember

Ohio427 · #1 03-23-2006, 05:46 PM

I have a 68 Camaro that I put a BB 427 in last year.The car was a roller but the previous owner had a BB 454 in it. My question is I was told that the crossmember under the transmission is a small block one because of the oval opening instead of the well known square type. The holes are offset to the passenger side in the oval opening instead of being centered in the opening. I just talked to a restoration parts person who said that he has seen GM numbered crossmembers with the oval opening. Has anyone else seen this? I used the BB motor mounts and didn't have much trouble bolting up. Is it possible to even bolt up correctly if I'm using the wrong crossmember?

nuch_ss396 · #2 03-24-2006, 01:26 AM

Good question. I've seen plenty of fake BB 69 Camaros with
the oval hole X-member. However, every real BB 4-speed I
have ever seen has the squared-off hole.

I actually never did get a real good answer as to why the
BB 4-speed X-member exists anyway. Aside from the hole
difference, and the large dimple on the upper passenger
side, they appear to be the same. What is the actual
positional difference of the transmission in conjunction
with each of these X-members? Surely someone here used a
SB X-member on a Camaro once.

Steve

**mnyenko** · #3 03-24-2006, 01:35 AM

If you use small black frame and motor mounts. The small block cross member works fine. If you swith to big block fram mounts. The motor moves up and over to pass side. Then you will need a big block cross member to line up trans mount. I found out the hard way. Earl

Ohio427 · #4 03-24-2006, 02:23 AM

Steve, I'm not really concerned if the crossmember is original GM although the guy I talked to said that he has seen them with GM numbers on them as much as I just want to make sure that it is a BB Xmember. Were the oval hole ones that you have seen aftermarket ones? This one has the original holes (slots) in it with no other holes so it isn't modified. Does anyone know if the holes in a SB Xmember centered in the oval opening? These holes in mine are about 1/2"-3/4" offset to the right like a BB should be. This crossmember has been in the car at least 17 years or more so I can't picture anyone having an aftermarket one out then since most of this aftermarket Phenomenon as being more current. In fact, I don't even recall anyone manufacturing a BB 4 speed Xmember at the present. I may be wrong.

Z28DZ · #5 03-24-2006, 03:06 AM

The only BB 4-speed X-members I've seen have the square hole/diagonal cut and the offset trans mount holes. Earl explained the reason for the offset on the mount holes. Attached is a topside pic of a Camaro BB unit. I believe Heart Beat City reproduces these.

Can you post pics of the top & bottom side of the one you have?

acelr8 · #6 03-24-2006, 03:36 AM

The exhaust is also laid in at an angle in the BB.Where it is straight on a SB.Jeff

nuch_ss396 · #7 03-24-2006, 04:08 AM

Yes,

HeartBeatCity does sell a reproduction. I looks quite
nice too. They are on eBay constantly as repro's &
originals. Just be careful that you don't get a Firebird
X-member by mistake. They have the mount holes in a
different location. I found that out the hard way....

Steve

nuch_ss396 · #8 03-24-2006, 04:12 AM

[ QUOTE ]
Steve, I'm not really concerned if the crossmember is original GM although the guy I talked to said that he has seen them with GM numbers on them as much as I just want to make sure that it is a BB Xmember. Were the oval hole ones that you have seen aftermarket ones? This one has the original holes (slots) in it with no other holes so it isn't modified. Does anyone know if the holes in a SB Xmember centered in the oval opening? These holes in mine are about 1/2"-3/4" offset to the right like a BB should be. This crossmember has been in the car at least 17 years or more so I can't picture anyone having an aftermarket one out then since most of this aftermarket Phenomenon as being more current. In fact, I don't even recall anyone manufacturing a BB 4 speed Xmember at the present. I may be wrong.

[/ QUOTE ]

Darrell,

To help, see if you can get the engine frame mount part
numbers. These are stamped on the flange surface between
the upper two bolt holes. If big block mounts, then you
need the BB X-member. Again, repro's are on eBay.

Steve

nuch_ss396 · #9 03-24-2006, 04:14 AM

[ QUOTE ]
The exhaust is also laid in at an angle in the BB.Where it is straight on a SB.Jeff

[/ QUOTE ]

Jeff,

On the X-member, what about the exhaust issue are you referring to?

Steve

Ohio427 · #10 03-24-2006, 05:24 AM

Ed & Steve, The only picture that I have is one taken from under the car showing only the oval opening and the two transmission bolts offset to the passenger side of the opening. I tried to accessing my web picture hosting site but keep getting an error message. Either they are down or kaput. Steve, If the part numbers on on the top of the flange, I don't believe that I'll have access to see them with everything being in the car. I know for sure that the engine is on BB engine mounts and is offset by about an 1" to the passenger side of the engine compartment. I just can't see the engine lining up to a SB Xmember with the engine in that position. I'm still waiting for someone to tell me if the two holes in a small block Xmember is centered in the oval opening or offset towards the passenger side like mine. If you think that the picture that I have of the oval opening would help, I can email you the picture. By the way thanks for your help. much appreciated.
Darrell

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