although i dont yet know my gearing, will the stock buick rear differential for a 69 wildcat hold up to the 650-700 hp that im building my engine to? how about the driveshaft? thans
This will be your biggest hurdle yet. If your '69 looks like my '67 underneath, you'll notice that the stock floorpan was kept fairly low & flat by the use of a two-piece driveshaft with a center support bearing and constant velocity joint...this helped increase leg/foot room in the big cars, but is a weak link under big power. To succesfully plant your heavy car with that kind of HP I think you'll be looking at a custom conversion to a one piece driveshaft which will probably require extensive floorpan mods. This would also require a rear pinion angle change, but you'll probably have to go with a custom Ford 9" or GM 12 bolt (Chevy style) with aftermarket internals and a custom housing anyway, so the angle can be dialed in based on the requirements. There are no hi-po aftermarket parts out there for the original 9-3/8" rear end. I remember reading about a damn quick Riviera here with similar mods, one-piece shaft & Ford 9" rear end. Maybe a search will turn something up. FYI, I'm still running the two-piece shaft (rebuilt, aftermarket u-joints) and the stock 9-3/8" rear end. It's been fine with my combo so far, but then I haven't tried hard for traction yet. Once a set of slicks go on, I have a feeling I'll be finding the weak link(s) REALLY quick. I wouldn't even try it without installing two driveshaft safety loops first. See if your '69 looks like my '67...you might see that you don't have a straight shot to the rear axle from the transmission (top pic): Devon
Is it a posi? If you decide to pull it, there's some demand for the big posi's... o No: From what I've seen, that 9 3/8" rear end is pretty darned stout. Built by Olds, they're plenty strong enough for most uses...I don't know about that much hp, though. Main problem with them is parts availability = near zero.
i dont know if that picture is inside a big tube, but all i see under my car is tranny, driveshaft straight to the rear it has what looks like a large sleeve over the driveshaft, and drops to the rear about 3/8", not sure what it does, then rear end. it looks like a straight driveshaft to me.
You might be in luck! I just checked my parts book and it appears 1969 was the year Buick switched the Wildcat to a one-piece driveshaft. Devon
Score! So, the one-peice should stand up to the beating, if i take it easy will the rear end also? o No: easy meaning only a few races a month :3gears: :Brow: :laugh:
how about 3/4 throttle races :Brow: would it stand up to any beating at all, or would it just be bam, punch it once and the rear ends gone? its in really good condition right now
In 69 the Cat was a 6000 series car so would have carried the same 9 3/8 gear set as an Electra or a Riv. Someone may have broken one but I suspect it is a rare occurrence.
The 9-3/8" failure modes I've heard about have been broken carrier bearing caps. There's no aftermarket solution, but maybe custom caps could be fabricated (???). Sounds like a pain in the neck. If I bolt slicks to my car my guess is driveshaft failure first, carrier bearing cap second. Devon
Scarry stuff, you ever seen what driveshaft failure does to a car, and tranny....and possibly the car thats beside you when the tube pieces come out from under the car....scared yet?
I've seen it firsthand...that why right now I run two loops in the beast (CV joint in the middle of the shaft = a second potential spot for bad news!). If I try slicks I will probably fabricate short tubes to replace the loops for better containment. Devon
is there any way to reinforce the stock one? and will a GM 12 bolt bolt on or will i have to be welding something?
I don't know, I still get nervous when I beat on mine. 3 rears broke in my buddy's '70 Riv back in high school days. And I had a rear in my '66 Riv break. It was always the spider gears that were toast. All those full throttle 55 mph tire chirping shifts into second we did are surely what did them in. Of course, back then they were a dime a dozen in yards.
You can always use heavy duty u-joints to help the driveshaft, but unfortunately there are no bolt-in rear axles that are stronger. The only possibility would be to have a custom housing set up based on the existing rear suspension configuration. Moser and Currie Enterprises are two companies that come to mind. Devon
looked into them, they only make aftermarket axle shafts for the buick. so, i will most likely be putting a gm 12 bolt in it, probably posi (i want it, others dont because of punching it in a corner and losing control, since it is a street car) Are there any advantages to moving the axle further back or forward any number of inches, or should i just buy the strong driveshaft closest to my length and have them weld the brackets in where it sits? One more thing, will my current brackets have to be cut off? I would like to have the option to put the stock rear end back in for any reason at all. Thanks
A custom 9" housing would be a whole lot easier to fabricate, than to try & adapt a '65-70 Impalla 12 bolt hsg into the '69 Wildcat chassis. The 12 bolt Impalla hsg has no cast in upper control arm mounts, instead it uses two lower control arm mounts & a panhard bar as a track locator. Believe your early 9 3/8 has at least one upper control arm mount. While a 12 bolt Impalla rear could possibly be modded to work, you'd be better off going nodular 9"' route, lot less frame mods & you have a r/e that one can change 3rd members out on. Going to one piece driveshaft & sectioning & raising the floor pan tunnel will not be that hard, esp if the car is gutted. Something to think about... would be nice if the tunnel came out same contour as a bodystyle with readily avail molded carpet. Might look at the floorpan of a '65-70 Impalla. With tunnel mods, expect the rear seat frames to need cutting as well. One question that has not been asked... with 650-700 hp on tap, is the Big block Buick engine "all motor"? If so, my hat's off to you :Brow: On the other hand, if not all motor, & you're planning on spraying a 250 horse shot, are you planning on progressive activation? Similiar deal... have a few more hp on tap with my '63 LeMans "streetcar's" combo. Engine was built for progressive nitrous... lot easier on drivetrain parts than if I'd spent 16K+ on an 800 horse all motor Pontiac. :3gears: Roger
