[Camaro_Nut2001]

Hello, I took my 78 Malibu to the track Friday and tore it up. I would like some advise on what the problem might be. Here goes, I have a rebuilt 350 .060 over, flat tops with 882 heads with 2.02/1.60. I'm running a Lunati VooDoo cam, Advertised Duration 276/ 284, Lift .504/ .525. I have a Performer RPM intake with a 750 single pump carb. The motor is still new with only about 200 miles on it so I took it easy on it. I have a TH350 with a shift kit, 3200 to 3500 stall, new U-Joints, stock D/S. I pulled the stock 7.5 10 bolt out & put in a 8.5 10 bolt out of a 70 Lemans. It has a 4.56 gear with a spool. I'm running 28.0-10.5-15 M/T Drag Slicks.
I took it down the 1/8th real easy shifting a 5200 but left the line pretty hard. I flashed the stall instead of tacking it up and leaving that way. I brought it back to the trailer and adjusted on the carb. I was going to make my second run and pulled into the bleach box. I was heating my tires up and shifted from 1st to 2nd and the car came apart. It broke the D/S into, busted the bellhousing off the motor. Now my car is sitting down on the left side like I busted a shock or something.
Wonder what caused me to do all this damage? I was doing my burnout when it happened so it was not like I hooked up at the line. If it had done it then I could understand. Please Help as I want to take it back before the season ends this year.

[eloc431962]

Sounds like your driveshaft was to long. not enough slack in the tailshaft. You need to check your mounts also motor and trans.if your driveshaft was to long when you torque it up it pushes it into the tailshaft something gonna break. do you have the drivers side of your engine chained down. most people run a solid mount on the driver side to stop the flex so things wont break or twist so much. Cole

[Camaro_Nut2001]

First off, thank you for your opinion on what happened. My driveshaft was the correct length and no I don't have anything chained down. I'm running factory motor mounts and an after market trans mount. I understand what you're saying though.

[eloc431962]

The rearend hasent shifted has it from when you changed it? Or the pinion angle may be off. Cole

[ericnova72]

It may be just the fact that you were still running the stock driveshaft. I don't remember the exact #, but for most stock shafts the "critical speed" where the shaft bows under power and rpm far enough to become permanently deformed is only a little over 5000 rpm. You may have hurt it on the previous pass and it let go on the next. The stock shaft in the Metric cars is also one of the weakest out there. You may want to look at some of the racing driveshaft companies and do a search on this topic here at Hotrodders, this topic came up a few months ago.

You weren't using a conversion type U-joint at one end of the shaft were you? These are known to cause problems.

Another thing to look at would be the u-joint used, it is not recommended to use a greasable joint in a drag car because the drilled hole through the joint makes it considerably weaker. Solid, greasable only at assembly joints are the type to use.

Third thing to look at would be pinion angle, since you have changed to a rear that was not originally installed in you body type. Did you use an adjustable upper control arm kit to do this install, or an aftermarket kit made for this conversion, or did you just force it in using stock pieces?

[eloc431962]

Originally Posted by Camaro_Nut2001

Hello, Now my car is sitting down on the left side like I busted a shock or something.
Wonder what caused me to do all this damage? I was doing my burnout when it happened so it was not like I hooked up at the line. If it had done it then I could understand. Please Help as I want to take it back before the season ends this year.

Eric i am wondering why his car is sitting down on the left side now. something in his suspension broke or something. Cole

[ericnova72]

Until the OP actually examines his car and tells us what he found, we will have no idea why it sits un-level now, could be as simple as the spring is mis-aligned in the pocket. I was just pointing out things to look for that pertained to the driveshaft. I'd have determined why it sat un-level before it even came back off the trailer.
Edit: Any time you blow a driveshaft with any tire speed, there will almost always be much more damage than just a broken shaft. Usually the trans, exhaust, and rear end pinion yoke are trashed.

[eloc431962]

I totally agree with you Eric. Was just thinking about it and was wondering what your input might be thats all. just i know you are a very knowledgeable person on here and i appreciate that. Last year i busted the bell-housing in my 67 camaro now i am running a solid mount on the driver side no breaks yet in that area anyway. Cole

[ericnova72]

I hear you Cole. Broke my share of stock driveshafts (3) before I got smart. I figure the un-level problem has to be spring or airshock related as the suspension in these cars doesn't hold anything up, just front to back and side to side location of the rear axle.

After measuring run-out on several stock driveshafts, I came to the conclusion that they are the most poorly made pieces in the entire stock driveline, typically made with seamed tubing(muffler tube) and to terrible run-out specs(some more than .050") and that is why they have weights at both ends--to balance out the poor assembly and materials. The race shafts I use typically run out less than .005" and have no weights! They are not needed if the shaft is straight. www.dennysdriveshaft.com and there are others just as good.

[Camaro_Nut2001]

Hello Guys, Thank ya'll for the great information. I checked and the left spring is knocked of it's perch. The rearend has shifted over to the right about 3 inches. When I put the rearend in I just cut the two stabilizer bars and over laped them and welded them back together. I did'nt use an adjustable kit or anything. The rearend is 2 inches longer than the factory one that came out of it.

[ericnova72]

Camaro_Nut, If you can finance it you will be much farther ahead to get the adjustable upper control arms made for this swap. This is because the bushing centerlines on the frame and on the axle housing are not aligned in the same plane using the 1970 rear. Are you sure it is a 8.5" and not an 8.2"? GM didn't start using the 8.5" in coil spring cars until 1972.

Without the correct upper arms I think you are going to have nothing but problems, both with alignment and location, and with pinion angle. Did you set the pinion angle correctly before welding the upper arms together?

FYI, shifting the trans in the water box is the hardest thing on the parts. Proper procedure is to start off in high gear, but without a manual valvebody you will be unable to do this. If you do have to shift, get the tires rolling at an easy pace, shift, and then spin them hard. Always let off the gas before the tires hook coming out of the water, that hook causes more broken trannys than any other thing.

[Huanhuan]

Now that is a lot of brass air fittings ******************************* there is just about every type
of air fitting that you could want. Wholesale prices too. I guess these could be used as small water pipe fitting also. I
used some of the parts to make my babington wvo burner.

[Camaro_Nut2001]

You are right, it is an 8.2. I am going to check with Summit on those arms and go that route. I really want to thank everyone for there input as it has really helped me.