Tonight I was working on getting the rear end wrapped up to swap out in the 51. It is a 10 bolt GM with a locker and disk brakes. Bought the spring kit for the 51 to bolt it up. Kit had new perches that were about a 1/2 inch higher than the ones on the axle. This would be a 1/2 inch lower rear end. The kit uses U-bolts instead of the studs that came on the axle (larger diameter = stronger). Everything sorted out and I noticed there are no pads for the spring perches. I've always been told to have something between the springs and the perch as metal on metal will eventually squeak and make noise. Is this how most of you do it? I bought the replacement spring rubber spring pads. They were a little too wide, so I ground down the edges so they fit right. With them between the spring and the axle, the axle is still 1/4 inch higher than if I used the supplied perches. The factory pads did not come with a pad for the retaining plate. So I used a piece of old heavy duty nylon cargo strap. That should provide cushion without too much compressibility. I want the axle to have just a hint of cushion as it fighting well above it's weight class. The 10 bolt will be trying to hook about 750+ hp to the pavement. Once i had everything mocked up, the next question was how much tire can I fit under it. Currently it has 205 60R15s on it and there is 1.4 inches of clearance between the fender and the side wall. The axles are the same width flange to flange. The 205s protrude 4.1 inches from the flange surface. I put my 26X10.5 15 slicks on the axle and measured flange to side wall depth. Slicks were 4.6 inches. That should leave me .9 inches between the sidewall and the fender. The slicks also had a 4.25 backspacing and I had over 4 inches of clearance to the springs which means I can go with more backspacing and wider tires still. The jury is out until I get the axle under the car, but I'd love to hear your comments and opinions on the spring pads: Use them or not? I'll edit this post and drop the pics in from my phone once it posts.
I've always put leaf springs directly on steel spring perches. Is that what you're wondering about? but you do have to retighten the U bolts after drive a little while, then check them again occasionally, so things don't get loose and move around.
Yes. That is exactly what I was talking about. I was always told to put a pad of some sort that wasn't too soft between the metal surfaces to stop squeaks, rattles, and vibrations that could work the bolts loose. But, since the kit didn't come with pads, it makes think that I wasn't taught correctly all those years ago or I (heaven forbid) have forgotten something I was told about when not to do it.
There are many vehicles built in factories that don’t have anything between the springs and perches, if the u bolts are tight nothing moves, if nothing moves then nothing squeaks
I have never seen rubber on a conventional leaf spring perch. Some very specifically designed ones have rubber, and that ain't one of them If you have squeaks, rattles, and vibration, your u-bolts are dangerously loose, just as they would be with rubber in there.
750 horses to the pavement, Ten bolt, Todays tire technology ,Two springs, no traction enhancement. Something is going to break.
Are you going to weld the spring pads to the axle? Just the U bolts will not keep it from turning with over 700 HP. I have never put anything between the spring and the axle. Never had one squeak either.
2nd gen Camaros/TA came with rubber pads on the rear axle. The first fix we did on those cars was replace it with a piece of 1/2 plate welded to the mount. That 10 bolt won't last long even if you keep the car from hooking the least little bit. Just keep letting the tires down and you will find out. Lets see some photos of your set up .
I see your photos now, if you use the aftermarket spring pad you will be good to go. If my memory serves me correct the factory mount is to shallow and the centering pin won't go deep enough into the mount because the head hits the axle tube. So you either switch perches or weld in a plate to make up the difference for the rubber pad which needs to be removed. All that rubber does is add to wheel hop.
I'll join the peanut gallery calling for a 9". I've got a 10 bolt in my '48 F1 that I've abused terribly, but with 400 less horsepower.
1st gen Camaros had them as well. But it seems they aren’t needed so I’ll replace them with steel plate. Might use old leafs and weld 4” pads into the original pad. As mentioned the centering hole won’t be deep enough without a plate of some sort. And yes, I will add some form of traction bars and I am concerned about too much traction. The original build was going to be around 600 hp from a 383. That engine was crap so I grabbed one of the boat engines and it is getting the 505 BBC now. It dynoed just shy of 650 at 6400 at 8.5 compression but was too lean. To fix the lean issue (heads too big to get air velocity to pull fuel) I’m stealing the 871 from one of the other boat engines. Changing from 37% over to 12% under driven which will put me at 5 lbs of boost. That means way more HP than the plan originally called for. A 9” is a 10 week wait from Performance Works. They will build it to use the same rear disk setup as their 10 bolt that is going in now with 35 spline axles. The tires slipping is what I’m hoping will keep the rear end alive long enough to get a 9” under it. I have thought about borrowing my 76 Bronco’s 9” as it is the right width and has 31 spline Currie axles with a Detroit locker. The 4.56 gears would be too much though, so I’ll put it together as originally planned for now and baby it a little. I want to see how much I’ll like the car when on the road and then decide if the 9” is the answer or what will fix it. But, will the 9” get narrowed and tubs added to the car? Do I go 4 link? If I build it to use all the HP it will need a cage, fuel cell, and other safety features that I’m not thrilled about adding to a mostly cruising car. For now, I want to get it on the road and try to keep it together. The 700R4 might get swapped for a stronger electronic trans when I change the rear end as it will be the next point of failure.
Record the first few passes with slicks. might be fun to watch. squeaks with 750hp? Why worry. The exhaust should fix that. Never had a spring make a noise at the rear end nount. Thay got bushings in each end for that.
The kit spring pads allow you to set the proper pinion angle before you weld them to the axle. U bolts have been used by manufactures for years.
Friend of mine snapped a 10 bolt axle with a 350 and a shot of NOS. Stoped it before it came completely out.
Thanks for all the comments so far. The 10 bolt is definitely the week link right now. Running the 10.5 wide slicks will help it not hook as hard. I've twisted many an axle off roading so I know what happens when you have too much power and too much grip. But, I think it will work to get it on the road yet this year. If I'm mindful of it and don't hit it too hard on the line, I will be able to take it down the track hopefully once or twice and see how it behaves. The 700 is built as strong as they can make it, but won't promise life above 700HP if I abuse it. One has been reported to be living for years above 900hp. Don't know the guy or the car, but it does give me hope. And it has a manual valve body, so no unexpected shifts to shock the trans. Again, hopefully for now the tires will spin before I really hurt the transmission. The Torque converter has a 3 stage and it is good for big power. It will also work in a much stronger overdrive transmission but they require electronics which is why I didn't go there first. So based on what I'm reading, the rubber pads will be gone. A flat plate will get welded to the factory spring pads which are at the recommended pinion angle the 51 mounting kit came with. I checked it by leveling the spring pads with a level and using an angle finder that we use to check prop shaft angle on V-drive boats. I have removed the factory studs from one side of the spring pad and test fit the new plates using the heavier u-bolts. This will help if when I go with traction bars of some type. I like the CalTracs setup, but the jury is still out if that is the best option when I go to a 9 inch. Still deciding on some things. Do I go 35 or 31 spline axles, and do I"ll narrow the stronger rear end to get more tire under the car. How serious do I want to get to make a car I want to drive go down the quarter or eigth mile? The goal is to drive the wheels off of it, now blow them up.
Never Have I Ever run on a track, but Two cars I've had with ten bolts, failed the durability test. The Olds cracked the center carrier. The Chevelle liked to drop C clips. Another SS Malibu, with 12 bolt stood up to my abuse.
I have never used any cushioning device on my rear installations, steel on steel. Torque them up, re-check as Jim suggests.
You can buy a new Strange60 with 35 spline axles and a spool , assembled with your choice of a gear and the housing ends with the yoke for $2375.00 . Which is not a bad deal.
Local guy got banned for the season running a 10 bolt without c-clip eliminators. Made a mess on the track. Luckily it happened at the lights and not further down the track.
When we were young and broke we had a Camaro with a 12 bolt and it was good for 3 passes and it would need a right axle. LOL we finally got a Dana from a Challenger . Those were the days !
Remember going to the local salvage yard and just grabbing another rear-end and throwing your parts into on a Saturday and out cruising that nite ? Or another 4-speed trans ? Ahh the good Ole days when salvage yards were our parts warehouses!! ...
The built 9” isn’t a bad price and changing the 3rd member for short tracks takes way less room compared to tall and short slicks. Only down side is the build time. And the 10 bolt is already eliminated so no worries about c clips. The eliminators don’t do anything except keep your wheel with the car if you break an axle or loose the c clip (don’t think I’ve ever seen a c clip fail). But I’ve hammered on 10 bolts in the past. As long as they don’t grab too hard they do ok. No I’m not saying I will leave it in with the engine making strong power, But for now the grab on the launch is controlled by the skinny right pedal.
I carried in my wallet a cheat-sheet of Ford and GM axle codes, I could identify a rear at the 'yard quickly. Break it on Friday nite... still had to be at work Monday...
With the stock cars, I ran a Ford 9" rear in my Nova. The guys who didn't use the eliminators... oh boy.. I'd smell gear oil cooking and would look for the car with the axle shaft going in and out, give them lots of room.
You don't have to use anything between the perch and the leaf, but you can slip some thin nylon strips between them if you'd like. Many stock vehicle have similar isolators like that, but it's not really needed. Beating the dead horse, but that 10-bolt will not survive with that kind of power. Like, at all. You can get an Explorer 8.8" with disc brakes and LSD for cheap. Narrowing is easy if you need to. And it will handle 750whp easily with the stock 31-spline axles. Add a rear cover with cap girdle for a little extra strength. There are plenty of 8-9 second street cars running basically stock 8.8's with 31 spline axles.
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