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#1 |
Better late than never
![]() Join Date: Dec 2001
Location: Columbus, IN
Posts: 324
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Missing Trans Crossmember?
Am I missing a transmission crossmember? I used to have a 250/3-speed and now have 350/4-speed. It looks like there should be a crossmember, but there is not one in my parts pile and can't remember taking one off. My floor shifter rattles, maybe this is why?
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1970 C/10 SWB Stepside |
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#2 |
Senior Member
Join Date: Apr 2000
Location: Delta,Pa
Posts: 14,950
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u saying theres no cross member at all under the transmission? if there isnt your asking for major trouble like the motor mounts breaking and the engine falling back not to mention bad driveline angles that will cause broken parts.
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Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member. |
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#3 |
my gas saver
Join Date: Sep 2003
Location: Clarksville, TN
Posts: 2,046
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yeah that could=kaboom time in the future. you can make a mount for these old trucks if you have to.
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85' SWB, 4.3/TH350, getting ready for paint 84`SWB, 462ci./TH400, cowl hood, 15" billet spec., flows, blazer buckets/console, flat black 71`SWB, project ebay feedback |
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#4 |
Better late than never
![]() Join Date: Dec 2001
Location: Columbus, IN
Posts: 324
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Ouch, that's what I thought. Is there a universal mount, or do I need to look for one specific to the 4-speed?
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1970 C/10 SWB Stepside |
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#5 |
Registered User
Join Date: Jul 2003
Location: Mountain Home ID
Posts: 85
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You should have a one x-member under the oil pan that the engine and front suspension mount to and another under the bellhousing supporting the rear of the engine and the transmission behind it. On a factory truck you wont have one under the tailshaft like on an automatic. If your shifter is moving excesively your motor/trans mounts may be shot or maybe you just removed the trans mounts and not put them back in during the swap. They look like the pic below. Just my $.02.
Tim Last edited by mindhive; 11-24-2004 at 08:53 PM. |
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#6 |
Still drivin' a Rat Rod
Join Date: Sep 2004
Location: Monett Missouri
Posts: 4,925
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You should have a crossmember like this one with a 4 gear in it.
Hope this helps
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Rusty Member #13872 Instead of saying.....you are a discomfort in the back of my front.....one should be able to say...... you are a pain in the *a$#* 71 GMC LWB 49 Chevy 85 Chevy G20 Check out my website |
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#7 |
Better late than never
![]() Join Date: Dec 2001
Location: Columbus, IN
Posts: 324
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OK, I do have the bellhousing crossmember in Brainchild's photo, and of course the engine mounts. Thanks for replys. So there is not a crossmember that attaches only to the transmission?
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1970 C/10 SWB Stepside |
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#8 |
Still drivin' a Rat Rod
Join Date: Sep 2004
Location: Monett Missouri
Posts: 4,925
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Nope just the one that bolts the bellhousing in.
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Rusty Member #13872 Instead of saying.....you are a discomfort in the back of my front.....one should be able to say...... you are a pain in the *a$#* 71 GMC LWB 49 Chevy 85 Chevy G20 Check out my website |
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#9 |
Professional Grade
Join Date: May 2003
Location: Fort McMurray, Alberta
Posts: 7,915
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Shouldn't there be a crossmember near the end of the tranny, near the output shaft?
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1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap) |
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#10 |
10/30/19
Join Date: Aug 2004
Location: ottawa kansas
Posts: 5,215
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This is exactly why I love this board.There is a vast amount knowledge and willingness to help.
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#11 |
Better late than never
![]() Join Date: Dec 2001
Location: Columbus, IN
Posts: 324
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Russell, that is my question. It just looks like there should be. There are a couple of bolt holes on the underside of the tailhousing.
kingsolver72, you are right, this board rocks! I would have never done as well on my truck without the guidance and inspiration that I received on this board.
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1970 C/10 SWB Stepside |
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#12 |
Still drivin' a Rat Rod
Join Date: Sep 2004
Location: Monett Missouri
Posts: 4,925
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No,just the one crossmember.The tranny is a newer model.The one in the wrecker has the rear crossmember,it's a 76,and has a huge PTO hanging on it.My 71,and 67,and even the 49 all have 4 speeds,and just the one crossmember bolted to the bellhousing.
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Rusty Member #13872 Instead of saying.....you are a discomfort in the back of my front.....one should be able to say...... you are a pain in the *a$#* 71 GMC LWB 49 Chevy 85 Chevy G20 Check out my website |
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#13 |
Left Foot Functioning
Join Date: May 2004
Location: Duncan, OK
Posts: 348
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KEH,
The factory solution for your '70 truck was the bellhousing crossmember pictured here, or one very similar. The bellhousing crossmembers came on 3 speed and 4 speed trucks, and were slightly different depending on engine config - V8 or I6. Yes, it looks a little strange, but the tranny just hangs out the back. So as mindhive and brainchild told you, you have all the parts that would have originally come on your truck, with no support at the rear of the tranny. Your vibration problem could be in bad motor/tranny mount pads, or a vibration from the other end. Since your driveshaft was probably modified during the swap from I6/3spd to V8/4spd, it could be out of balance, have a phasing problem (u-joints not mounted parallel at opposite ends), bad u-joints, or even a carrier bearing that's going out or gone. Another possible source of the rattle is the lever itself - they have a tendency to break where the hardened tong is attached to the lever itself - it stays together, but will wiggle a lot more. I've swapped 4spds into both 3spd and auto trucks, and preferred to use the auto tranny crossmember (mounts at the rear of the tranny) in both setups. I removed the bellhousing crossmember from the I6/3spd truck. You're right about the holes in the rear of the 4spd, they do work with the auto crossmember and the tranny mount pad. FYI, later model trucks all came with the transmission crossmember at the rear, no bellhousing crossmembers. SSOW ![]()
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69 C10 (#1 son's ride) 72 C20 (Dad's farm truck) 82 K30 (Ex - brush pumper project) |
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#14 |
Young truck fanatic
Join Date: Jun 2003
Location: The wonderful Mat-Su Valley....Palmer, Ak
Posts: 253
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Correct, Your truck should only have and need the bellhousing cross member. However as i have found out, i you put in a car 4 speed or an M21 in my case an auto x-member can be used for support in the rear of the tranny. However this will not work with a truck 4 speed.
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'67 Chevy Longstep 2wd 350 w/4spd manual Muncie M21. My first project. **Proud to be Valley Trash** |
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#15 |
Better late than never
![]() Join Date: Dec 2001
Location: Columbus, IN
Posts: 324
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Stickshift, I will check your suggestions for the source of vibration. Thanks for the ideas. It has to be one of them. I do have a car 4-speed saginaw, and would think that a crossmember would help too.
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1970 C/10 SWB Stepside |
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#16 | |
Sleep-Deprived
Join Date: Sep 2002
Location: Tulsa, Oklahoma
Posts: 445
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4 speed truck tranny with auto cross member
Quote:
sweet n rare67, I hope you were refering to the auto cross member not working with the original sm465(?) transmission? ![]()
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1971 K/10 Long Fleetside 350/350 - 6" Lift 1969 C/10 SWB 292 - Sold It |
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#17 |
Active Member
![]() Join Date: Aug 2004
Location: Canton, OH
Posts: 249
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Not trying to hijack the thread but do I need to modify my driveshaft when changing from a 3 speed Saginaw to an M21 Muncie 4speed?
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69 C10 LWB Project 47 Cushman Scooter Project It is better to have loved and lost than to live with a psycho all your life. ![]() ![]() |
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#18 | |
Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,403
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Quote:
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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#19 |
Active Member
![]() Join Date: Aug 2004
Location: Canton, OH
Posts: 249
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Thanks. Don't suppose I could just swap bearing retainers.
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69 C10 LWB Project 47 Cushman Scooter Project It is better to have loved and lost than to live with a psycho all your life. ![]() ![]() |
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#20 |
Better late than never
![]() Join Date: Dec 2001
Location: Columbus, IN
Posts: 324
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No, you cannot swap the retainers. I can't remember for sure why, but they look alike on the outside but there is something different inside. I tried that and also spent some time looking to have a ring made. End the end I just bolted up the bellhousing like it was and have not hade any problems.
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1970 C/10 SWB Stepside |
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#21 |
Senior Member
![]() Join Date: Jan 2000
Location: Arlington, VA
Posts: 398
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KEH, if you were able to locate the transmission with a 4.684 outside bearing retainer diameter with a 68-72 chevy truck bellhousing with 5.124in diameter retainer hole and you still got the tramsmission located to the engine crankshaft within 0.05in runout, you are one really lucky son-of-a-gun.
Everyone else will eiher need a pressed on spacer to make up the difference, or another bellhousing with the smaller bearing retainer diameter hole. This is necessary for the long term health and longetivity of your clutch, throwout bearing, throwout bearing retainer, transmission input shaft, input shaft bearings, etc.etc. If you change bellhousings, you will then need to locate the new bellhousing to the crankshaft centerline to make sure the new bellhousing retainer hole is concentric with the engine crankshaft centerline. _______________ Oh yeah, back to your original question. You could also use both the bellhousing crossmember and add a truck auto transmission crossmember to go under the rear of the car Muncie transmission. Early Classic Industries make a truck auto transmission crossmember if you can't find an original one easily. Last edited by Willy Prost; 11-28-2004 at 08:42 PM. |
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