Hi guys , I'm having a real tough time trying to assemble the transmission crossmember in a 66 four speed car. Chassis manual is not much help when it comes to the cross member. I'm thinking I have the wrong crossmember. Is anyone familiar with how the cross member gets attached to the frame rails? On the frame rail there is a bracket welded to the frame with 4 holes in it. Is this for mounting the (2 piece) rubber and metal bracket mount that you use with the flat end crossmember? The cross member I got with the car has the bolt holes drilled in the end. After I get the rear rubber transmission mount in line with the crossmember the bolt holes in the end of the crossmember do not line up with the frame rail bracket. Any help would be greatly appreciated. Car has been apart for over 20 years / pile of parts and a chassis manual is tough. Thanks Michael
WOW, my 66 is a Skylark GS and it has a bracket welded onto the inside of the boxed-in portion of the frame with 2 holes that correspond the holes in the cross member just like they did 64 to 66. I know what you're talking about with the one that has no holes at the end of the cross member and rubber isolators with straps that bolt to the frame, I'm not sure what year they started that 67 for sure(if they started that in 66 then mine is wrong). Questions: 1) do you have a boxed in frame? 2) what transmission 300 or 400? 3) what cross member do yo have the stamped out one one that goes straight across or the tubular one that is bent in the shape of a U. Pictures would help. Someone changed the transmission in mine to a 400 and extended the frame bracket back instead of using the correct crossmember.
Hey Thanks for the help ! Yes this car has the box frame, Buicks idea of a handle the torque lol. Interestingly enough the same 4 holes are drilled on the original part of the frame in the same exact location. So you can see how the factory so called improved the frame from the Special and the Skylark. Through hours of web surfing I believe mine to is because of the transmission. Car was originally a 4 speed car but as members have stated it should have a Borg trans. What I got with the car is a Saginaw . I have the straight across cross member . It appears that all of the rear rubber transmission mounts are the same for 66 GM A body cars so I'm now thinking the rear mount is in a slightly different location then that of a Borg. So looks like motor and trans out again and find a Borg. Thanks again !
Yes, the crossmember bolts directly to the frame. The rubber insulators started in 67. Your Saginaw must be a different length than the original BW T-10. Maybe you can just find a different tailhousing for it. My T-10 has the trans mount bolt holes in the tail about 14-1/4" from the front where it meets the bell.
Thanks yeah I measured the distance to the mount from the front of the bellhousing it is 1/2 inch give or take a 1/16 further then the 2 speed automatic trans that I have from a 66 GS. Attempting now to see if tail shaft housings are interchangeable.
Sorry, I missed the 4 speed part. I have some Saginaw's and Muncie's on the self, always thought they were the same, now I'm curious. And I always thought a 300/350 and Muncie's were the same too. Do you have enough material to drill new holes? I had a Borg Warner T10 and a Muncie in my 64 Special and had no cross member issues going from one to the other. I don't know what 4 speed the 66GS came with, I've heard the 65s had top loaders in them because they didn't think the T10 could handle the torque. If it were me, I'd keep the Muncie and re-drill the holes. Does you car have a factory nailhead bell housing or is it a newer bell housing with an adapter plate? That would account for the 1/2".
Yeah its got me guessing too. Its the factory bell housing no adapter plate and yes there is plenty of room to adjust the holes. The problem is the 66 shifter mounts to the crossmember, UGGHHHH . I just found a Saginaw tail housing in Long Island I'm gonna take apart this trans and take the tail shaft housing with me. The housing in LI has holes drilled on the back of it to mount a shifter to the trans then it wont matter where I move the crossmember to. Just gotta hope the tail shaft housings are interchangeable. On top of all this custom stuff there is the fact that a Saginaw is just not built to handle the torque. So trying to see what upgrades can be made to help it out, its not like I'm building a race car. Worse comes to worse I'm just gonna put it on the shelf and go find a Borg or a Muncie and just start over.
I'm 99% sure the tail shaft housings are not interchangeable, The Saginaw bolts directly to the front housing and the main bearing support is part of the housing, the Borg Warner and Muncie have a bearing support plate that sandwiches between the main and tailshaft housings. Sounds like you are using the factory shifter, I'm pretty sure that wont bolt to the side of the tailshaft housing, a Hurst shifter it will. How are your motor mounts? Is it possible that they collapsed and moved back? Would it be a show stopper if the shifter moved back 1/2"? As far as power/torque handling capability, I doubt that the early Borg Warner T10 and the Saginaw are that much different. They say not to put more than 250 HP through a Saginaw but I know people who put way over 300 hp through them with no problem. I blew up an old T10 behind a 260 hp 340. The Muncie will handle much more power especially the M22 and the Super T10 is almost as good.
The 65-66 GS both used the BW T-10. '65 had the shifter mounted to the tailshaft, 66 had it mounted to the crossmember. Both used the same tailshaft, so you could put mount a shifter to the tailshaft of a 66. Does your Saginaw trans have mounts for a shifter? 3 speed transmissions often did not since they were usually column shift. Aftermarket shifters for those had mounting brackets that used the case/tailshaft bolts, and a u-bolt that went around the tail. If you can identify what car your trans was meant for, you can search for an aftermarket shifter. Find the pn on the tail and do a Google or eBay search. I don't know offhand if the trans bolt holes in the crossmember are centered front-rear w/ respect to the frame mount holes. If not, try flipping the crossmember around and see if it fits better.
So turns out the Saginaw Tail shaft housings are interchangeable in the right years. Luckily the 3 and 4 speed trans are the same from 66 to 74. Mine is date coded 66. So I got my hands on a tail shaft housing with the holes in the tail shaft $62.00 in Long Island a bargain and a half. Yes the factory shifter I had can only bolt to the crossmember. Just bought a new bracket for that shifter too from Wild Bill. I had on the shelf a brand new Hurst comp plus shifter which I will now bolt to the trans so I can move the crossmember without any problems. No chance on the motor mounts being bad as they are brand new. I'm going to record the measurement from bell housing to the rear rubber mount so when I run into a Borg T10 I can see what the actual difference is. The pic in my avatar is where I'm at right now. As far as the research data on Saginaw I have 1 groove on the input shaft and the gear ratios are almost identical to that of the M20 so unless the gear material is that much different I'm thinking I might be OK. Stock 401 with a little better camshaft. Its not for the strip is just for some fun on the street. Thanks for all the help guys I love this site !
The one/no line Saginaw is the strongest one they made with 2.54 first gear, which will be fine for your application. Yes, 3 and 4 speed tailshaft housings are interchangeable. I'm in the process of building a 4 speed Saginaw with a 3 speed overdrive unit on the back, all those parts interchange within the Saginaw brand. I've read that some of the one line units had 2.75 first gear but I have never seen one. The top loaders were only used for the 3 speed GS. Sounds like you're on track and moving forward.
Hi, A 66 would have come with either a close ratio T-10, 2.20 first gear, would have a GS cast into the side of it along with a date code, I believe the transmissions were first used in 1963 full size cars through 1966. Or a Ford/Dearborn toploader 3 speed, with similar ratios as a th400. I can't imagine you getting away with mounting a Saginaw tail housings onto a T-10, or even a Muncie 4 speed as both have a shift lever for reverse in the tail housing so not sure how well they would bolt up let alone the reverse internal linkage line up. As for strength the T10 had special high nickel gears, and the 3 speed Ford/Dearborn was used because of strength vs any other 3 speed available from GM, also that trans was used for years in all higher performance 3 speed applications. The Saginaw was mostly used in lower performance cars, 4 speed and 3 speed, late 60's GM dropped the Dearborn top loader and used a HD Muncie 3 speed on all higher performance cars. Attached is a 66 T10 and a 65 Dearborn for reference As for shifter, I'd suggest get a mount for a newer Hurst and a competion plus shifter and ditch the crossmember mount style as the factory Muncie style shifters left a lot to be desired Regards, Jim
Thank You Jim , Lucky man to have those 4 speed trans ! I am def not trying to put a Saginaw tail on a Borg or a Muncie. The guy I bought the chassis from stated that the trans he gave me was original to the car. Of course I just believed him not sure if there is an acronym for "believe " like "assume" but there should be one. Now that I am assembling this ride I could not get the crossmember to line up. Has to be perfect as the shifter bolts to the cross member. My trans had no holes in the tail shaft to mount a shifter so that is why I bought the tail housing to change over, Its Saginaw to Saginaw. He sold it to me with a Saginaw trans. My first four speed trans. I am now almost an expert in identifying 4 speed transmissions lol. Thanks to my honest car salesman. Car has correct factory bellhousing and correct shifting linkage from the clutch pedal to the clutch fork just the wrong damn trans. Its about a half inch or so longer then the holes in the crossmember. I believe once I get the shifter bolted on and the shift rods adjusted properly the trans will be OK. Then I can move the crossmember back a little bit. Then I will just have to deal with the driveshaft I'm hoping there is enough play in the yoke to slide it in. I will keep you guys posted on the outcome just in case another honest salesman rears his head. Thanks again Jim
Hi again, One other thing using a trans other than one that came in that era Gran Sport, the throwout bearing has a smaller ID than what is used on most Muncie and I image any Saginaw transmissions, you'll need to check the front bearing retainer OD to the ID of the throwout bearing as I had to have my bearing retainer turned down, I think 0.030" but don't quote me as was 10+ years ago. (I ran a M20 Muncie for a while and now a new Autogear M22w, both I has to turn down the retainer) Good luck, not sure a 3 speed Saginaw is going to last very long as the Nailheads have lots of torque, you might want to look for a Dearborn if you're set on having a 3 speed as most people sell them cheap were used in early GTO's, 442's and would guess some big block Chevy cars. Last few I have seen on Craigslist a few years ago were under 200 bucks. Also you can use a Muncie M20, M21 or M22, needs to be a 10 spline input/27 spline output, 70 or 71 and older as later ones came with a fine spline input number?/32 spline output were longer. Another thing, the T10 tail housings on the Buicks and believe there maybe a Chevy version had 2 shifter mounting patterns, so if you use a Muncie the shifter will be farther towards the rear of the car as not aware of a Muncie tail housing with 2 mounting locations. Best regards, Jim
