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73-87 Chevy _ GMC Trucks => Brakes, Frame, Steering & Suspension => The Lows (Lowering/Drops) => Topic started by: team39763 on April 03, 2011, 10:55:50 pm
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A couple years ago I bought an ebay axle flip bracket. At the time it seemed like a sweet deal and seemed to work great with no problems. Today I was racing at a airstrip near the border and ended up smashing one bracket into the shape of a "W". The other one appears to have ripped the leafspring mounting pad right off the axle tube. I'm guessing this caused my pinion to angle up severely then I lost my driveshaft.
I was two races away from being the track champion when it happened. I was racing against a 80's mustang with a 351(I don't know if he sprayed but he had a kit). Since my truck can't do a burnout, I just pulled up to the line with wet tires...as expected, the mustang beat me off the line. About second gear I had caught him and was passing him then boom...engine hits the rev limiter and no more gears. I was heartbroken, but while being towed back to the pit area the crowd cheered for me and gave me a round of applause...it was really cool. Tons of people came up to me to tell me how good the truck ran and that they liked it...it was a real underdog. All through town, people kept giving us thumbs up and telling us "good job" while stopped at the traffic lights. It made me feel pretty good...good enough to not be sad about ruining my truck. Looks like the trans may be broken in half, the leafspring mounts are garbage, diff housing will need to be checked for sure, driveshaft needs to be checked for straightness, I haven't checked the motor yet(was on the 7200rpm rev limiter hard).
Sorry for the long story, I just don't have many friends or family to share that with. By the way, I ran 12 flat(that's with bad gas, crap tuned carb, and spinning nasty). I got a lot of work to do to get that 10sec slip.
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Sorry to hear about your truck. Glad no one was injured, truck can be repaired, perhaps this time with race quality parts.
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Yeah, I think I found a place that makes race quality spring perches...big hefty ones. I just need to make sure to find somebody who can weld them in correctly. I'm hoping I can save some of the trans parts...it's only 3 weeks old.
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I got my perches from a axle shop come to find out mopar made them I think it was only 20 bucks. If you where around me in MD or de I could help out with the welding.
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For want of a nail, the war was lost...
Bummer about the truck, man. Nice thing about these, though. They're real good at the comeback.
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Again, sorry to hear about the truck, but get it back together with the right parts and go show that mustang who's boss. 8)
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If you are running a flip kit on a leaf spring set up make sure you are using good quality U-bolts evenly torqued. Have you looked into Cal-tracs or a 4 link set up? Got pix of the damage?
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Yea I dont think the quality of a flip kit would really vary too much steel is steel. No moving parts really. Sounds like your truck has some serious power though.
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not all steel is made the same, I guarantee lot's of people on this site can attest to that, me included. Any pics of the damage?
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Like vile stated it probably started at the u bolts. If they stretches or bracket off any you will have a break
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I'll get pics tomorrow.
Vile, I have caltracs on there already. Thankfully they weren't damaged.
I don't think I have that much power...it's probably just something I did wrong. For some reason I can't manage to do a stationary burnout. My truck makes all this noise, but the tires don't spin...so I'm guessing all that power is binding up in the suspension somewhere since the tires ain't turnin'. That's probably where the damage started.
The U-bolts were new from Oreilly's(don't know the brand though) and I tightened them up evenly. They seem to be undamaged. My trans is surely screwed. I got under there to take a look and the case is cracked around where the pan rail meets the tail housing. I wanted to puke...I just had it built 3 weeks ago.
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Sounds like you have major issues...Can't do a burnout, cracked case, ripped out your rear end... definitely use a different builder for your trans and check your pinion angle when you get the rear end reinstalled. The good thing is, parts are plentiful and pretty cheap. So what let go if the U-bolts are still good and everything was torqued evenly?
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From what I can tell one spring perch let go and let the pinion rise up. The flipkit bracket on the other side flattened into the shape of a "W" allowing even more movement.
I'm not sure what to say about the burnouts. I think it's a brake problem. When I press the brakes lightly it won't hold the truck back. If I press the brakes good and hard, it won't let the back tires spin. I also have a linelock setup on my rear brakes and it still won't work. I'm confident in the trans and builder...it's me that's doing something wrong.
EDIT: I just figured out why my linelock wouldn't work. It'll be fixed in the morning. I'm gonna go buy the spring perches and do it right(like I should have the first time). I just need to find a good welder down here who won't warp my housing or blow holes in it.
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Airbagit/chassis tech/ whatever name they're going by this week saddles are notorious for collapsing. That's most of the eBay kits.
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I was warned on this site way back then, but I couldn't make myself spend the extra money for a good quality kit. I may have also screwed up the install of a few things too...I'm still learning the "do's and don'ts" of wrenching.
Pic of the collapsed saddle
(http://i46.photobucket.com/albums/f143/team39763/th_100_1031.jpg) (http://s46.photobucket.com/albums/f143/team39763/?action=view¤t=100_1031.jpg)
Pic of the broken perch.
(http://i46.photobucket.com/albums/f143/team39763/th_100_1030.jpg) (http://s46.photobucket.com/albums/f143/team39763/?action=view¤t=100_1030.jpg)
Can ya'll tell me what happened here? How did the cover bolts get knocked out of the housing? Those things were in there stupid tight. The wheels still roll freely and the pinion turns easily. I'm hoping the housing isn't messed up.
(http://i46.photobucket.com/albums/f143/team39763/th_100_1032.jpg) (http://s46.photobucket.com/albums/f143/team39763/?action=view¤t=100_1032.jpg)
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Do you have caltracs for a flipped axle? Do you have the line lock on the front or back brakes?
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I saw that too vile was kind of hoping I misread it.
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Caltracs are the flipped models. The linelock is on the rear brakes. Plenty of racers have done this and it works pretty good when done right...but I did mine wrong since I didn't know the "trick" to it.
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i thought the locks were for the front so you can do a burn out
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Locking the rear brakes to do a burn out will help NONE. You want the least amount of friction on the rear brakes as possible. You want to have the front tires locked up to stop foreward movement and your rears free to spin. If you want some mean burnouts, empty the brake lines and resevoir for the rear brakes and use just your fronts. You could line lock the rears, rev the engine, hold the front brakes, then release the rear line lock still holding the front brakes and gas. Releasing the line lock with all of that rotating force would brake the tires loose like no other.
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Team, I see several "flaws" in your plan. First, the basic design of a flip kit is poor for what your trying to do with your truck. The axle is trying to rotate upward on the launch & the only thing holding it is the ungusseted vertical sections of the "U" which are pushed against the unsupported/weakest area of the original perch. If anything, the lower flip part should have some support in the triangle areas so the front & back can't bow/buckle like they did. Second, the upright portions should be angled inward somewhat so they are hitting closer to the axle tube...it's still a poor plan, but would be much better than what you have. You really need the bottom perches welded to the tubes with high angled supports holding the ends in place...there is allot of force going on there when the engine turns the drivetrain & the tires have 100% bite.
I'm concerned with the shim in the first picture. I don't exactly understand what is going on there. Is that the center pin of the spring pack behind the perch (beside the stone)? Did that stuff all get moved around or was the shim only half way under the flip part when you put it together? By the bend in the flip part...I'm thinking it was allways that way. What was holding your shim, flip plate centered? Did you drill a new hole in the shim? Was the center pin long enough to to into the hole in the flip plate? I suspect that some issues here maybe what started the whole thing going south. Please answer & I'll explain.
Here's a picture of mine...they are the original tubes/perches just turned upside down, but the simple boxing on the ends supports them from folding. Remember, the front side isn't doing anything on the launch (I guess you can tell that by the your second picture ;) ) The back is what is keeping the housing from turning...it is driving downward into the spring. On your setup, the unsupported item (the top perch) is now trying to do the job. I have built a couple rearends for high powered, leaf spring cars that I made the perch out of 2 flat triangle flat plates (with holes to slide them over the axle tube) & a flat plate for the bottom & a piece of strap to box the triangles the whole way around the tube. This works well, but is un-needed for any "normal" amount of power/traction.
(http://i163.photobucket.com/albums/t285/HAULINIT/truckrearsuspension018.jpg)
Several years back I broke the right side, main leaf on a launch...the outcome was quite similar to yours.
On the linelock thing...Doing the back works fine, installed/operated correctly.
By your last post Team...I'm guessing you have it figured out now? Was the in/out backwards? Any Questions, Just ask! Lorne
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Thanks for the reply Lorne. Yeah, I had the linelock in/out lines backwards. I put the linelock on the rear brakes to block the rears off during the burnout so I could have a little better contol.
Everything just moved around. The shim was on correctly(centered under the saddle) and the pin was in, but I guess it sheared off. The pin was long enough to go through the saddle and the shim. That wasn't it in the picture.
I'm gonna get me some high quality spring perches whenever I do fix the truck. http://www.ballisticfabrication.com/Leaf-spring-perch_p_1485.html
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How much power are you playing with and how wide are your rear tires?
A guy I know has an old AMX with about 600hp in it and really wide tires (dont remember how wide) and he had to get billet spring perches on his car. he twisted and broke even the best stamped perches. his car would pick up the nose however high you wanted it to go though when he stomped the gas.
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I was told that my motor should make around 400-430 and my slicks are 29x12. I don't have enough power to rip things apart. I'm 100% sure it was something I did(didn't do correctly) that caused this.
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Why would you put the line lock for doing burnouts on the rear? You got it backwards.
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i think maybe to burn out the clutch ??? im still confused about this part but seams others have done this, I thought a line lock was to free up one foot so you can use the clutch and gas at the same time
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Vile & others, Quite a few guys have the line lock hooked up in the rear brake line. What you do, instead of having the valve hold fluid/pressure IN the front brakes...it's hooked up so it keeps the fluid/pressure OUT of the rear brakes. Now you use the brake pedal to work the front brakes while doing the burnout. Instead of letting off the button when your done, you just lift off of the brake pedal, then the switch before the next time you want rear brakes...most guys still use a momentary button I believe.
I'm not sure who/when this idea started...the first guy I knew of that did it was running in the F.A.S.T. series (Factory Appearing Stock Tire) where the vehicle must look stock & have many correct dated, ect. parts. Having a line lock set-up hanging under the master cylinder was a no-no. He had his tucked up in the kick-up above the rearend...the line goes back, into the line lock then out to the rubber hose & down to the rearend housing. Lorne
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now that makes sense. you flip the switch before you apply your brakes to cut off flow to the rear. then you use the brakes it will only go to the front.
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I didn't quite get that this is how he has his set up from his posts. I understand the concept you are saying Lorne but for someone who is looking to do a burnout setting it up conventionally seems to make the most sense here no?
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I was aiming to do it exactly as Lorne said. I had a reason for wanting it that way rather than the traditional way, but I can't remember what it was.
I looked over the damage today and the trans is beyond repair, the driveshaft will need a new end welded on it, the rearend is fine(except the spring perch). It could've been worse.
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the first pic shows the angle shim is moved...
Unless it's late and I am missing something, All the cover bolts are in there? Looks like some of the brake support straps were bolted down.
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Haha...I left those bolts loose when I was changing the gasket/fluid in the diff a few days before the race. I just forgot to finish tightening them. Hopefully we can find a decent welder to do the rearend work...I don't want to have to order a new rear axle or ship this one out of state.