Clunking under the car??

ERA 626 · #1 (**permalink**) 10-04-2003, 08:13 PM

I did a fairly hard launch tonight then afterwards I felt a clunking sound under the middle to the rear of the car (ERA)
I put the car up on a lift and gave it a quick inspection.
Checked the u-joints on the half shafts, drive shaft all bolts, turned the wheels, I did not see any thing abnormal.
Then on my way home I noticed it again.
The sound does not sound like a gear sound sounds like a motor mount or a tranny mount or possibly one of the spax coil overs, any Ideas??
My ERA should be able to handle my little 427 right??
I am still getting wheel hop after tighten the rear coil overs and turning in the dampening screws how do I get rid of this wheel hop?? If anything my BFG's should just spin...

decooney · #2 (**permalink**) 10-04-2003, 10:22 PM

Mike,
possibly a few other thing to check:

- a failing u-joint in R/L 1/2 shafts?
- stub axle going out (the part the 1/2 shaft bolts, goes to diff)?
- loose bolt in forward arms/rods on either end?

move fore/aft a few times from 1st to reverse to see if you can recreate it and have someone stand to the side of the car to see if you can locate which side it might be on. Good Luck.

REDSC400 · #3 (**permalink**) 10-05-2003, 05:21 AM

Possibly a blown exhaust mainifold gasket?

CJ428CJ · #4 (**permalink**) 10-05-2003, 03:47 PM

Mike,

I don't know about the clunking, but how many clicks in did you turn the adjusting screws on your dampners? I had wheel hop like you and I turned mine in only about 4 clicks and the wheel hop went away. I could be off by a couple on the total number of clicks though since the first 1, 2, or 3 are really hard to feel. Not sure if I felt a click or not. In any case, I'd just turn them in another click or 2 at a time and try again.

One thought on the clunking sound. The speedo cable is run really close to the drive line. It's not hitting by chance is it?

Chris

ERA 626 · #5 (**permalink**) 10-05-2003, 06:15 PM

not a speedo cable problem,the clunking sound is major, after looking again at the car I have ruled out anything in plain sight bieng loose or broken.
I think it has somthing to do with the posi in the rear dif.
I can drive the car in a straight line and for the most part it is OK.
However when I drive the car in a circle it bangs & clunks violently.
The front end seems like it is binding (the posi sticking) then it will clunk again then the front end seems normal...
I will have to Call Putnam in the AM...

CJ428CJ · #6 (**permalink**) 10-05-2003, 06:50 PM

Mike,

Take a look at page 122 of the assembly manual. It tells you what to do if the rear end posi unit is sticking (replace the gear oil and add an additive).

Hope that does the trick for you.

Chris

ERA 626 · #7 (**permalink**) 10-05-2003, 06:54 PM

I can turn the rear wheel with one wheel in the air and one on the ground. I tried adding additive. I broke somthing. I will speak with bob tomorrow.
I will let you know.
I hope ERA will help me. This should not happen to a new rear end with street tires.

grumpy · #8 (**permalink**) 10-06-2003, 07:51 AM

mrMike,

With the kind of torque/HP and the tires you have, most third members (stock) will not take dumping the clutch on certain type of surfaces. A friction modifier is not a modification, but a "slicker" for the traction clutch pack, since most all hypoid lubricants do not require it without friction plates.

That's why the 8.8 guys change center chucks from stock FORD when clearing 450 HP or 400 ft/lbs torque.

grumpy

PatBuckley · #9 (**permalink**) 10-06-2003, 08:51 AM

I did the same thing you did - what broke was the inner stub axle. It ended up costing about $2K.

I had to replace the left rear caliper, disc, new chrome moly stub axles from CWI (who are out of that end of the business now, I believe) and posi unit.

I don't think you can say what should or shouldn't happen when you make a "hard launch"....stuff happens when we play.

Good luck to you!

Pat

ERA 626 · #10 (**permalink**) 10-06-2003, 10:44 AM

Pat,
I spoke with ERA this morning, I agree I think I broke the stub axle & posi unit.
Why did you have to replace the caliper & disk??
I certainly hope ERA stands behind this rear I purchaced.
I paid $4000 for this rear. The car only has 1500 miles on it and I have street tires. If I would have known that the rear could not handle a mild 427 (550bhp) than I would not have purchaced it. Even Doug at ERA said it should not have broke.

ERA is supposed to call me back this afternoon I will let you know.
So far they have been exellent to work with and I have had a few minor problems and they have propmtly taken care of them, this problem is major so let's see

PatBuckley · #11 (**permalink**) 10-06-2003, 03:21 PM

Mike,

Did you upgrade the stub axles to the chrome moly ones? The stock ones are a failure waiting to happen and I am glad it was the inner one that failed on ERA535. If the outer axles go it is a bigger deal what with the resulting fire and all.

I built my rear end myself and did not go with upgraded axles....it did cost me more in the long run.

You asked why the caliper and disc? Did I say it was a hard launch?

The Goodyear Eagle race tires did not help the situation.

Pat

John 550 · #12 (**permalink**) 10-15-2003, 04:31 PM

Mike , I know this will not help but '
I did the same thing , I did not realize just how much traction is built into these cars .
I let my cousin drive , and told him to "get on it " Dropping the clutch at 5 grand ,
one axle snapped the other bent .
On a good note , I can remove the sub frame in an hour, two bolts two nuts
gas line / brake line . I then brought it to get fixed . This became usefull for when
I did in the spider gears (second break). I then went to a 354 instead of the 331 .
I found out later some good pointers . I no longer drop the clutsh but let it kook some .
Or I let it out , then mash it . The next time I will go for the upgraded axle stubs
I wish your car a speedy recovery , let me know if I can help .

ERA 626 · #13 (**permalink**) 10-15-2003, 08:45 PM

Yes the subframe will come out in an hour if you have a lift.
I broke the spider gear. I am going to send it back to the people who built it (Reider racing in Michigan).

Ant · #14 (**permalink**) 04-28-2005, 02:40 PM

Grumpy,

What is the center chuck the Ford 8.8 boys are changing?

Pat, regarding changing the outer hub axles to chrome moly versions where can these be obtained from? I remember coming across a website (not cobraracing as they never reply to inquiries) with heavy duty Jag stuff!

Mike Bontoft · #15 (**permalink**) 04-29-2005, 11:46 PM

On the heavy duty Jag rear ends I've been building lately I've started using the Auburn pro locker with my 30 spline stub axles. The Auburn unit has a stronger case, It only has 2 spider gears but they are bigger than the jag spiders and I have yet to break one. This unit is a cone style locker and you must use the supplied additive to keep it smooth.
Outer stub shafts 31 spline availability, maybe in the near future, there is not a big demand for them, the inner stub axles are much more of a problem.
Mike Bontoft
cwiinc.com

Ant · #16 (**permalink**) 04-30-2005, 01:35 AM

Mike,

I have several outer Jaguar coarse spline hub axles with big twists in them lying around my workshop!

They were with a 9" IRS and it was locked so that may have contributed to their demise!

Currently either going to use an alloy 8.8 I have with Eaton posi and beef up the outer CV's and axles to 31spline, but from reports they dont give any problems with the inner plunge CV!
My car is coming setup for Jaguar so its going to be some work to change and I not sure I want to reinvent the wheel - so to speak.

Mike Bontoft · #17 (**permalink**) 04-30-2005, 09:14 AM

If I can get 3 people commit, then I will run them. The minimum run is 10 axles.
Mike

Snakebit · #18 (**permalink**) 04-30-2005, 05:48 PM

If you wanted to go drag racing then an IRS set up was not the way to go. These are high performance sports cars with race car suspension. That is why drag racers use a solid rear axle. If you race and abuse your equipment then be prepared to pay the price instead of crying to ERA.

GeeDoubleYouSee · #19 (**permalink**) 05-01-2005, 02:58 AM

To all SPF owner's

I found my clunking noise, it was the clevis mount on the rear of the differential. The 8.8 12 mm bolt snapped at the end and the rear of differential was hoping up and down. The bolt was a hard to find critter 8.8 12 mm 6 or 7 inches long. The clunk happened when I let off the gas pedal and when pressed on it, but as long as i kept tourqe on it there was no clunk. This might happen to other Cobra's also, any with IRS. Hope this helps.

GWC

ERA 626 · #20 (**permalink**) 05-01-2005, 08:48 AM

Snakebit,
#1 I was not "drag racing"
#2 who was crying?
I ended up fixing it my self all is good.