Driveline Support Beam Removal
Thread Starter
Instructor
Joined: Dec 2012
Posts: 105
Likes: 15
From: Ball Ground Georgia
Driveline Support Beam Removal
OK, 87 coupe with automatic transmission.
I recently changed the pinion shaft seal on the differential, which involved removing the support beam and the driveshaft. Once I got the driveshaft out I thought I'd completely remove the beam and give it a good cleaning. How in the world does that thing come out of there? I have a lift, so access is great to the bottom of the car, but I didn't see any way to get the beam down past the transmission or rear end. Is there a trick to it or should I just plan on dropping the rear end to get some room???
Thanks!
I recently changed the pinion shaft seal on the differential, which involved removing the support beam and the driveshaft. Once I got the driveshaft out I thought I'd completely remove the beam and give it a good cleaning. How in the world does that thing come out of there? I have a lift, so access is great to the bottom of the car, but I didn't see any way to get the beam down past the transmission or rear end. Is there a trick to it or should I just plan on dropping the rear end to get some room???
Thanks!
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
OK, 87 coupe with automatic transmission.
I recently changed the pinion shaft seal on the differential, which involved removing the support beam and the driveshaft. Once I got the driveshaft out I thought I'd completely remove the beam and give it a good cleaning. How in the world does that thing come out of there? I have a lift, so access is great to the bottom of the car, but I didn't see any way to get the beam down past the transmission or rear end. Is there a trick to it or should I just plan on dropping the rear end to get some room???
Thanks!
I recently changed the pinion shaft seal on the differential, which involved removing the support beam and the driveshaft. Once I got the driveshaft out I thought I'd completely remove the beam and give it a good cleaning. How in the world does that thing come out of there? I have a lift, so access is great to the bottom of the car, but I didn't see any way to get the beam down past the transmission or rear end. Is there a trick to it or should I just plan on dropping the rear end to get some room???
Thanks!
Tech Contributor
Joined: Jun 2004
Posts: 20,910
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
The first time I tried to remove the C-beam I ran into the same issue. I happened to be on a business trip (in mid project) at one of the GM proving grounds and asked one of the Corvette techs hth do you get the beam out. He smiled and then showed me one of the development cars, and I saw where they just took a crescent wrench and made a minor bend to one of the tunnel panels where the flanges meet/overlap.
I never understood why the flanges needed to be that big, anyway.
I never understood why the flanges needed to be that big, anyway.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
The first time I tried to remove the C-beam I ran into the same issue. I happened to be on a business trip (in mid project) at one of the GM proving grounds and asked one of the Corvette techs hth do you get the beam out. He smiled and then showed me one of the development cars, and I saw where they just took a crescent wrench and made a minor bend to one of the tunnel panels where the flanges meet/overlap.
I never understood why the flanges needed to be that big, anyway.
I never understood why the flanges needed to be that big, anyway.
DUB
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
As Cumbercr mentioned, remove all 4 cbeam bolts. Support the transmission. Push the cbeam as far back as you can until the front clears the tailshaft and output shaft. Pull the front of the cbeam down and slide it forward off the differential.
Advanced
Joined: Jun 2008
Posts: 63
Likes: 1
From: Pittsburgh PA
I'm struggling with this too. I have the c beam pushed back clearing the trans, but if I pull it down to clear the trans so that I can pull forward again, I torque the hell out of the rear diff. Is that OK?
Dale
Dale
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
Advanced
Joined: Jun 2008
Posts: 63
Likes: 1
From: Pittsburgh PA
i got it. After posting, I gave it another try. I slid if forward of the differential pinion and then pulled down. I'm replacing the clutch, and already had the transmission loose (but not out) and I think that helped.
Thanks for the help.
Thanks for the help.
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Advanced
Joined: Jun 2008
Posts: 63
Likes: 1
From: Pittsburgh PA
Another question-
While removing the C-beam, I noticed something along where the c-beam meets the rear end and where it meets the transmission. It is a caulk like substance that was pretty hard - almost like liquid nails.
I saw nothing in the service manual about replacing it. I guess I'm leaning toward not replacing it.
Anyone know what it is or if it needs to be replaced?
Dale
While removing the C-beam, I noticed something along where the c-beam meets the rear end and where it meets the transmission. It is a caulk like substance that was pretty hard - almost like liquid nails.
I saw nothing in the service manual about replacing it. I guess I'm leaning toward not replacing it.
Anyone know what it is or if it needs to be replaced?
Dale
Le Mans Master
Joined: Feb 2005
Posts: 6,485
Likes: 566
From: Clearwater Florida
Another question-
While removing the C-beam, I noticed something along where the c-beam meets the rear end and where it meets the transmission. It is a caulk like substance that was pretty hard - almost like liquid nails.
I saw nothing in the service manual about replacing it. I guess I'm leaning toward not replacing it.
Anyone know what it is or if it needs to be replaced?
Dale
While removing the C-beam, I noticed something along where the c-beam meets the rear end and where it meets the transmission. It is a caulk like substance that was pretty hard - almost like liquid nails.
I saw nothing in the service manual about replacing it. I guess I'm leaning toward not replacing it.
Anyone know what it is or if it needs to be replaced?
Dale
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
Actually I found this to be rather easy, and IIRC this is how the FSM describes the proceedure.
First thing is to support the trans, or the engine if you are removing the trans. Make sure that the park brake is disengaged.
Remove the beam bolts. Using a rubber mallet, push the beam outward until it clears the trans and the diff. Then push it forward until the rear clears the front of the diff. Then slowly lower the rear of the trans, move the brake cable enough to pull down the rear of the beam, and pull out from the rear.
The most dificult part is getting the bolts out. Once they are out, this method took all of about two minutes. It goes back in the same way in reverse order.
Edit: Mine is a 96 with the ZF, not sure if any different on the '87, but I believe the beam is the same.
First thing is to support the trans, or the engine if you are removing the trans. Make sure that the park brake is disengaged.
Remove the beam bolts. Using a rubber mallet, push the beam outward until it clears the trans and the diff. Then push it forward until the rear clears the front of the diff. Then slowly lower the rear of the trans, move the brake cable enough to pull down the rear of the beam, and pull out from the rear.
The most dificult part is getting the bolts out. Once they are out, this method took all of about two minutes. It goes back in the same way in reverse order.
Edit: Mine is a 96 with the ZF, not sure if any different on the '87, but I believe the beam is the same.
Race Director
Joined: Feb 2003
Posts: 16,475
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From: Kingman AZ
Cruise-In VII Veteran
Cruise-In VIII
St. Jude Donor '06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16
Here are some pics I took at Carlisle a few years back. I took these to help with visualization of the C beam and how it attaches:
Melting Slicks
Joined: Jan 2009
Posts: 3,482
Likes: 196
From: folsom california
inspect the c beam mounting holes to ensure they have not become oversized or egg shaped; if so repair or replace as necessary;
Consider installing beam plates, not only do these make installation / tightening of the top nuts much easier, they spread the clamping load over a larger area making a more secure connection between the C beam and where it mounts on the tailshaft housing and differential;
DO NOT over tighten the c beam mounting bolts; you will only distort the c beam and crush the mounting webs on the tailshaft housing and / or differential;
lastly use, as the factory did , an adhesive; my favorite ? LIQUID NAILS, contractor grade.
Race Director
Joined: Dec 1999
Posts: 10,230
Likes: 885
From: Alexandria, Virginia, USA VA
The C beam transmission interface to the tailshaft housing and differential is a weak point; do everything you can to limit movement in these areas;
inspect the c beam mounting holes to ensure they have not become oversized or egg shaped; if so repair or replace as necessary;
Consider installing beam plates, not only do these make installation / tightening of the top nuts much easier, they spread the clamping load over a larger area making a more secure connection between the C beam and where it mounts on the tailshaft housing and differential;
DO NOT over tighten the c beam mounting bolts; you will only distort the c beam and crush the mounting webs on the tailshaft housing and / or differential;
lastly use, as the factory did , an adhesive; my favorite ? LIQUID NAILS, contractor grade.
inspect the c beam mounting holes to ensure they have not become oversized or egg shaped; if so repair or replace as necessary;
Consider installing beam plates, not only do these make installation / tightening of the top nuts much easier, they spread the clamping load over a larger area making a more secure connection between the C beam and where it mounts on the tailshaft housing and differential;
DO NOT over tighten the c beam mounting bolts; you will only distort the c beam and crush the mounting webs on the tailshaft housing and / or differential;
lastly use, as the factory did , an adhesive; my favorite ? LIQUID NAILS, contractor grade.
I just deinstalled the c beam and it helped to support the tranny and diff level and the bolts came right out
wrestle the cbeam to the side and shove it all the way back, you can now flex the diff just a bit and pull it down and straight out
the "factory goo" is there I guess for noise isolation. the c beam plates for sure "fix" a key flex point and make the car track straighter under power
watch that diff flex around a bit and you'll understand why one wheel gets loaded more than the other causing the car to step out
Heel & Toe
Joined: Apr 2018
Posts: 19
Likes: 0
C-beam goo is Poly urethane epoxy. It is for added stiffness for the C beam flex issue. ZF doctors C-beam plates are the best choice. The FSM for 1990 does state to use the epoxy on the beam. The correct product is called WINDOW WELD.
Mike
Mike
Melting Slicks
Joined: Jul 2005
Posts: 2,649
Likes: 863
Speaking as someone who has taken transmissions out of more than one C4 - I use a different way. I've tried the pushing the "C-Beam" both forward and back as far as it would go - and there are times - It just doesn't want to see to go far enough to disengage.
So - what I now do is to put a jack under the rear diff, and pull the two bolts that hold the "batwing" in place. All of a sudden the diff is free floating, and can be lowered Substantially - thus giving a lot more clearance for "C-Beam" removal. Give it a shot - see what you think ....
So - what I now do is to put a jack under the rear diff, and pull the two bolts that hold the "batwing" in place. All of a sudden the diff is free floating, and can be lowered Substantially - thus giving a lot more clearance for "C-Beam" removal. Give it a shot - see what you think ....
Heel & Toe
Joined: Apr 2018
Posts: 19
Likes: 0
The one's Bill sells are kind of like an H beam configuration. I wasn't able to use his on my re/re. Bill was out of stock and I need too get the car back together. Looks pretty good. I am sure it will give some additional stiffness.
