C Beam differences?
Thread Starter
Le Mans Master
Joined: Sep 2005
Posts: 6,551
Likes: 36
From: Jenks OK
C Beam differences?
I've been working on a T56 swap and my bracket doesn't come close to the holes I have in my c-beam. I was poking around through some old threads and other forums and it seems a lot of the guys with '85's have greater difficulty with their C-beam than others do. I'm wondering if the shape of the c-beam changed a bit over time.
Anyone have any evidence of this? I think I'm going to order another salvage car c-beam just for the comparison to make sure I'm crazy.
Anyone have any evidence of this? I think I'm going to order another salvage car c-beam just for the comparison to make sure I'm crazy.
Team Owner
Joined: Sep 2003
Posts: 25,331
Likes: 2,722
I've been working on a T56 swap and my bracket doesn't come close to the holes I have in my c-beam. I was poking around through some old threads and other forums and it seems a lot of the guys with '85's have greater difficulty with their C-beam than others do. I'm wondering if the shape of the c-beam changed a bit over time.
Anyone have any evidence of this? I think I'm going to order another salvage car c-beam just for the comparison to make sure I'm crazy.
Anyone have any evidence of this? I think I'm going to order another salvage car c-beam just for the comparison to make sure I'm crazy.
There should be no reason to buy another just to compare. If you need dimensions supply what yours are and I could maybe substantiate those from one of each that I have.
Can you provide a snapshot of your bracket with your C-beam noting the differences? Whose bracket did you purchase? I seem to recall there was one vendors bracket that required modification. Don't know first hand. Never did one.
The ends of either C-beam should mate to any combination that was originally engineered for a C4. The rear mounting holes are the same whether D44 or D36 and the front would be the same regardless of whether it's an A4 or either of the MT combinations that were production.
Last edited by WVZR-1; Apr 30, 2013 at 12:46 AM.
Thread Starter
Le Mans Master
Joined: Sep 2005
Posts: 6,551
Likes: 36
From: Jenks OK
From '85 to end of production if you have a D44 which would have been in an '85 original MT car the C-beam carries a single part number. An original '84 A4 or MT carried a different part number for that year only BUT in '85 the part number was changed to a part number that was the same through end of production. So there's actually only 2 C-beams D36 or D44. Which rear do you have?
There should be no reason to buy another just to compare. If you need dimensions supply what yours are and I could maybe substantiate those from one of each that I have.
Can you provide a snapshot of your bracket with your C-beam noting the differences? Whose bracket did you purchase? I seem to recall there was one vendors bracket that required modification. Don't know first hand. Never did one.
The ends of either C-beam should mate to any combination that was originally engineered for a C4. The rear mounting holes are the same whether D44 or D36 and the front would be the same regardless of whether it's an A4 or either of the MT combinations that were production.
There should be no reason to buy another just to compare. If you need dimensions supply what yours are and I could maybe substantiate those from one of each that I have.
Can you provide a snapshot of your bracket with your C-beam noting the differences? Whose bracket did you purchase? I seem to recall there was one vendors bracket that required modification. Don't know first hand. Never did one.
The ends of either C-beam should mate to any combination that was originally engineered for a C4. The rear mounting holes are the same whether D44 or D36 and the front would be the same regardless of whether it's an A4 or either of the MT combinations that were production.
I've got an 85 with the 4+3, I'm using the pro-street bracket which originally required some people to elongate the mounting holes, mine the mounting holes are about an inch in front of where the bracket ends.
I know my '85 is an early production car and has some differences from some of the later '85s I'm wondering if they changed the c-beam slightly mid year. I know the mounting holes for a d-36 equipped 'vette are about an inch different.
Team Owner
Joined: Sep 2003
Posts: 25,331
Likes: 2,722
I've got an 85 with the 4+3, I'm using the pro-street bracket which originally required some people to elongate the mounting holes, mine the mounting holes are about an inch in front of where the bracket ends.
I know my '85 is an early production car and has some differences from some of the later '85s I'm wondering if they changed the c-beam slightly mid year. I know the mounting holes for a d-36 equipped 'vette are about an inch different.
I know my '85 is an early production car and has some differences from some of the later '85s I'm wondering if they changed the c-beam slightly mid year. I know the mounting holes for a d-36 equipped 'vette are about an inch different.
Burning Brakes
Joined: Jun 2005
Posts: 1,188
Likes: 13
From: Wallingford Vermont
If you got one of the early "ProStreet" brackets with holes, I would weld up the bolt holes then grind them smooth. A very simple process for any one with a welder. Then mount everything up under the car and mark your bottom bracket hole using your "C" beam as your guide. Make sure your drive shaft u-joints as straight/parallel as possible. Pull the bracket out mirror image your top hole mark, then (re-)drill them out.
Apparently ProStreet had some issues with the correct location of the holes (or they just got lazy
), you remember I had to drill mine. It would be much easier/better to weld in the bracket (holes) than the "C" beam as aluminum can loose some of it tensile after welding. I do not like the idea of elongating the "C" beam holes, that sounds like a recipe for disaster 
Apparently ProStreet had some issues with the correct location of the holes (or they just got lazy
), you remember I had to drill mine. It would be much easier/better to weld in the bracket (holes) than the "C" beam as aluminum can loose some of it tensile after welding. I do not like the idea of elongating the "C" beam holes, that sounds like a recipe for disaster
Thread Starter
Le Mans Master
Joined: Sep 2005
Posts: 6,551
Likes: 36
From: Jenks OK
If you got one of the early "ProStreet" brackets with holes, I would weld up the bolt holes then grind them smooth. A very simple process for any one with a welder. Then mount everything up under the car and mark your bottom bracket hole using your "C" beam as your guide. Make sure your drive shaft u-joints as straight/parallel as possible. Pull the bracket out mirror image your top hole mark, then (re-)drill them out.
Apparently ProStreet had some issues with the correct location of the holes (or they just got lazy), you remember I had to drill mine. It would be much easier/better to weld in the bracket (holes) than the "C" beam as aluminum can loose some of it tensile after welding. I do not like the idea of elongating the "C" beam holes, that sounds like a recipe for disaster
Apparently ProStreet had some issues with the correct location of the holes (or they just got lazy
), you remember I had to drill mine. It would be much easier/better to weld in the bracket (holes) than the "C" beam as aluminum can loose some of it tensile after welding. I do not like the idea of elongating the "C" beam holes, that sounds like a recipe for disaster I was slowed down by one of my u-joints coming apart on me while I was test fitting the driveshaft so I'm going to double check my alignment when I get the new u-joint in.
Thread Starter
Le Mans Master
Joined: Sep 2005
Posts: 6,551
Likes: 36
From: Jenks OK
If you got one of the early "ProStreet" brackets with holes, I would weld up the bolt holes then grind them smooth. A very simple process for any one with a welder. Then mount everything up under the car and mark your bottom bracket hole using your "C" beam as your guide. Make sure your drive shaft u-joints as straight/parallel as possible. Pull the bracket out mirror image your top hole mark, then (re-)drill them out.
Apparently ProStreet had some issues with the correct location of the holes (or they just got lazy), you remember I had to drill mine. It would be much easier/better to weld in the bracket (holes) than the "C" beam as aluminum can loose some of it tensile after welding. I do not like the idea of elongating the "C" beam holes, that sounds like a recipe for disaster
Apparently ProStreet had some issues with the correct location of the holes (or they just got lazy
), you remember I had to drill mine. It would be much easier/better to weld in the bracket (holes) than the "C" beam as aluminum can loose some of it tensile after welding. I do not like the idea of elongating the "C" beam holes, that sounds like a recipe for disaster 
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,214
From: Park City Utah
The T56 defaults to Rev lock out. you can either wire up a switch (like the clutch switch) to open it...or you can do what I did which is nothing. and force it past the lockout every time you go to reverse. It's just a strong(er) spring than the one that you push through for 5-6 in neutral.
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Drifting
Joined: Feb 2006
Posts: 1,423
Likes: 96
From: Magnolia Tx
I pulled the solenoid out and replaced the light detent spring with a
heavier one ( a piece cut from my 4+3 shifter) and put a threaded plug
in the solenoid hole. Reverse isn't locked out, but takes a conscious
push to get into.
Thread Starter
Le Mans Master
Joined: Sep 2005
Posts: 6,551
Likes: 36
From: Jenks OK
I like this idea, I'm hard pressed to imagine a situation where I'm going to be slamming into 5th so hard that I would push past it into reverse.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,214
From: Park City Utah
I don't get it...the T56 is already set up like that, stock...with the solenoid in place. Why did to you do all that work to get to the same result?
Burning Brakes
Joined: Jun 2005
Posts: 1,188
Likes: 13
From: Wallingford Vermont
I wired up a push button switch on the console. Not the most elegant solution as you have to reach over with your left hand while shifting with your right. I wanted a push button on the shifter or shift lever but Hurst didn't offer that in black and I got impatient.
What bellhousing are you using? I'm using the factory Camaro BH. In in the interest of getting you going again (and getting another 4+3 off the streets
) I just measured my Vette. From differential (input) seal surface to T56 (output) seal surface I'm at 31 and 1/8". My guess is ProStreet put the holes in the wrong place. Weld it / Drill it
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,214
From: Park City Utah
If you really want to keep the functionality of the Rev solenoid, wire to the brake light switch. How often are you "going for 5th" and on the brakes? Not often.
Thread Starter
Le Mans Master
Joined: Sep 2005
Posts: 6,551
Likes: 36
From: Jenks OK
Only when I've overestimated the speed of traffic on the on-ramp! Seriously though even then I'm not in a hurry to slam it into 5th.
Drifting
Joined: Feb 2006
Posts: 1,423
Likes: 96
From: Magnolia Tx
break-over. I tried it that way but it was too much for my taste.
I do like the brake light idea, i will likely do that next time its on
the floor.
Thread Starter
Le Mans Master
Joined: Sep 2005
Posts: 6,551
Likes: 36
From: Jenks OK
Next question! on the Dakota Digital SGI-5 box to speedo wiring, I've got an A and B side on the speedometer pigtail that plugs into the t56, which side do I send to the dakota digital box, the other do I just leave routed as is?