So to all the naysayers who said the 5 bolt is a weak transmission and will never last...... You guys were right The car lasted 3 weeks and the transmission shit the bag. Started making a horrible grinding noise going down the street, followed by a snap and the rear wheels locking up. The car was sitting on the side of the road with a 30 foot trail of gear oil behind it and a big puddle under it when we went to pick it up. It has no second gear at all anymore, and the transmission case is broken. Back to the drawing board....
Sorry to hear the outcome. There are any number of good alternative transmissions BUT only one I can think of that will work with the torque tube. That would be the heavier duty 6 bolt cover from Century/Roadmaster/Limited series. Since you are obviously a talented fabricator, perhaps conversion to open driveline would be worth considering. I am doing that to my '40 Super. Using Stock Car Products 'truck arms" (same as '60 thru '72 Chev/GMC pickups) and an opendrive rear axle assembly. The original Buick rear end is, in my opinion, no prize either and I am a Buick fan. I plan on using the original spring mounts and track bar and build mounts for the trailing arms up in the "X" member. Whatever you and the owner decide, best wishes. Ray
So.... you all ready for an update? I mentioned to the owner the chevy trailing arm idea Hnstray mentioned in the beginning, and it just so happens he had one, already taken out of the truck and waiting to be installed... It would have made sense to do this from the get go, but the customer really wanted to try the adapter idea and use the stock drivetrain, and I kind of wanted to try it also just to see if we could do it. We all know the outcome of that... Anyways here some new pics Here is the 5 bolt transmission... It blowed up good! Chevy truck rear end Even though the chevy rear end is 2.5" wider, it fits real nice. Even with the stock buick rims. So the front of the trailing arms line up dead on with the X member, however I don't want to mount them like this. I'm worried about scrub line issues. This car sits real low already, and the owner is talking about air bags now since we have the rear suspension all apart anyways. My first though was cut the perches off the rear end and move them in to narrow up the trailing arms. I would need to move them 2.5" in on each side for a total of 5". This would allow the trailing arms to fit nice up high inside. However with them that narrow, it only leaves about 3.25" for a driveshaft to squeeze through. So then I though about shortening them. If I shorten them 15" they will tuck up nice, and have lots of clearance. Thats where I'm at as of now. Any suggestions on the trailing arms? Shorten them? Narrow them? Both? Have your own idea? Oh and the 5 bolt is being replaced with a rebuilt Saginaw 4 speed.... I tried talking him in to a TKO 600, but he wouldn't go for it....
Looking good! A couple of thooughts come to mind. I am assuming the port-a-power is holding the front of the arms at the stock seperation distance. It might be possible to angle cut the arms near the axle pads to swing them in a bit to tuck inside the "X" member. 3 1/2" ought to be enough for driveshaft clearance since the front of the arms will not narrow any further with suspension movement. A bit more complicated method would be to modify the web of the "X" member with a 'boxing' plate(s) to anchor the truck arm between the upper and lower flanges of the "X" and still retain the "X" member strength. Personally, I would not wish to shorten the truck arms as their length is one of the attractive features of the whole setup. The main benefit is reduced changes in angularity in the pinion as compared to the driveshaft U joint. Ideally, the pivot point of the truck arms should be the same as, or very close to, the front u joint location both fore and aft and when viewed from the side. You have displayed excellent fabrication skills so I think you will figure it out. Keep on posting the progress........I love seeing this come together. Regards, Ray
I was thinking originally of pie cutting the arms to swing them in, but I think it's easier just to move the perches them selves in on the rear end housing. Tomorrow I'll mock up a driveshaft in there and check my measurements again. I would rather narrow them than shorten them for the reasons you mentioned.
Pretty interesting thread and a very cool swap. Just a question; If you and the owner had a crystal ball, and knew the trans would fail so soon...would both of you had wished the motor was not set back so much now? I am guessing it would be way too much in labor costs to move the motor forward now?
Yea it would have been so nice to set the engine further forward. Would have saved a ton of money on labour not having to make a new firewall and transmission hump. But it's staying where it is now. It doesn't look bad where it is, and the exhaust clears everything so nice with it that far back.
Did you have any problems getting the wheels on and off with the extra width of the rear end? Even on my stock setup it was a bitch to slide the tires out.
The wheels still go off and on with out deflating the tires, although they just barley squeeze in and out now. You have to hold your tongue just right.
My mind says to cut the X, pie cut it about 12" back, and move it out to align with the truck arms, then gusset, fishplate, and box it into something stronger than the factory X. It would allow you to retain the proper gemoetry on the arms, as well as give you the proper angle for the mounting bolts,,, and at the same time, the additional beef you would be adding to the frame would ensure that things stay where they're supposed to and nothing bad happens if Mr. Customer thinks it a good idea to do any hard launches or power shifting.......... He already has a reputation as a tranny killer. LOL By the way, how's about an engine shot with all them purty carbs mounted and everything buttoned up?
Isn't that suppose to pivot at the same place as the front U joint? So the driveshaft and arms swing through the same arch,
OK, first things first, I apologize for the long wait for an update. I actually finished up the rear end swap quite a while ago, just never had a chance until know to update the thread. I cut the old trailing arm mounts off and moved them in 2" on each side to allow the trailing arms to fit inside the X member. I then fabbed up a new piece to bolt into the original X member for the trailing arms to mount to. And here is how it sits in the frame The driveshaft is a tight fit, but it does fit. The width between the two trailing arm bolts it the same as the width of the X member where the torque tube originally slid through. I drilled a large hole in the X member to be able to get the but off and on, and then used a total of 10 Grade 8 3/8 bolts to fasten the mount to the X member For the rear coils I just used some 2X3 rectangular tubing welded to the rear of the trailing arms and the stock coils bolted up to tubing. The transmission swap was simple, the saginaw bolted right up to the SFI bellhousing, as it should. The stock buick transmission mount was even in the right place. Just needed to drill two holes for the bolts to go through the new transmission. In the end it took about 30 hours to do everything, including running new brake lines, replacing the brakes, getting the shifter hooked up and working etc... I still have to figure an emergency brake out, but it should be pretty straight forward.
First rate job. That should hold up even with the transmission killer at the wheel. I have a 48 convertible that is in the same phase of construction. I have opted to use a New Process 4 speed and Chevy bell housing with adaptors to the Buick straight 8. In the rear I am using a Ford 9" with disc brakes and adapting the existing trailing arms supported by air bags. Your design looks as if it were much easier to fab compared to mine. Great job!!! Dale
Hey, would your adapter now be useful for someone who wants to replace his straight eight with like a 250 Chevy six?
Go for it! I don't know if I would trust the buick trailing arms, they may not be strong enough. I know with fords if you split the rear bones and run open drive it will break the wishbones for sure, unless a torque arm is added. I recommend the chevy truck trailing arms, they work slick! Yea, I think it would work!
Very nice work! This project will really help me out when I change my '54 Buick to an open driveline in the future. Thank you for sharing. How about some video of this bad-boy in action when it's back on the road?
Maybe in a while I can get a video of it ripping around. In the mean time, it's back in the shop for more work. The owner wants to do a dual resevoir master with a power booster now, and put a locker in the 12 bolt. Everytime I think this car is getting close to leaving the shop, the owner gives me a new list of stuff he wants done and another cheque!
I STRONGLY agree with Jalopykid that the stock Buick torque tube braces are not up to the task of controlling the rear axle. In the stock Buick application they do not take ANY torque whatsoever. The torque tube controls the axle 'wrap'. Similar to torque tube Fords, those angle braces keep the axle housing braced to the torque tube fore and aft. Without them, and no leaf springs (like earlyier Chevy cars/trucks) the axle housing could bend or break the torque tube due to chuck holes, uneven traction or braking. The best component for this application is what Jalopykid used, stock GM "truck arms" or, as I have purchased, Stock Car Products replicas of the GM arms. There is a very long thread on the subject of these arms that goes back maybe a year or so. To be effective and not damage the arms themselves, they need to be able to twist, which is why GM designed as them as they did, in an "I" beam configuration (actually two "C" channels back to back). Ray
glad you got it up and running, wished I got on this post earlier, I'm going to open drive on a 39 Buick myself. Not quiet the same setup as yours but close. I can use some of your mods. I have the truck wishbones and mounts. The setback of your engine should help with weight transfer and handling. The hard work is done and if you want in the future you can easily install any type of trans and rear end, . There is lot of Buick info in the HAMB, Team Buick, Webrodder, and AACA.
Thanks Jalopy Kid & Hnstray for the heads up on the Buick trailing arms. It's not too late that I can't use the Chevy trailing arms with a little modification. That's why I firmly believe the HAMB is a great place for information for amateur builders like myself. Thanks again, Dale
Uhhh Dale, we already went thru a Buick trailing arm failure discussion here on the HAMB and it was'nt pretty. The chevy arms were designed for trucks by GM engineers, and were also used by nascar baknthday. I didnt want to hijack this post but felt I had to say something when it could be dangerous. That failure was partly becuz of poor fab,ignorance along with the Buick arms. Checkitout. http://www.jalopyjournal.com/forum/showthread.php?t=587135&highlight=buick+trailing+arms
Thanks 39Cent...I just finished reading the post and dang glad that my project had not gone down that road yet!!! Thanks to all for the tips. Dale
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