Clunk from Driveshaft

Dale B · #1 (**permalink**) 03-31-2011, 10:32 AM

Hi Guys,

I'm looking to buy a Daytona and have found one but the owner has told me that he gets the "occassional clunk" from the Driveshaft and says that this is because when the car was built (quite recently) the builder lined the rear end of the tranny is lined up directly with the differential in the back axle and it should have had a 3 degree difference.
Could this be the case or is it more likely to be a problem with either the tranny or final drive?

Cheers Dale

Z-linkCobra · #2 (**permalink**) 03-31-2011, 10:42 AM

could be a number of things. Generaly speaking if the pinoin and yoke on the tranny are ever line up perfectly you get a vibration not a clunk. If it has IRS then I would think it would always be a problem. If its not IRS then you might be able to change the pinoin angle and fix it if indeed thats whats causing the noise.

No info on when the clunk is...acceleration, deacceleration, turning, braking.

blykins · #3 (**permalink**) 03-31-2011, 10:44 AM

Could be excessive backlash, or even a failing u-joint. I'd take it for a drive and pay attention to when it occurs.

Dale B · #4 (**permalink**) 04-01-2011, 01:12 AM

Cheers Guys ... wont be able to test drive I'm in the UK :-)

It has a Ford 8.8 rear end .... so would it be an easy fix to change the pinion angle?

RICK LAKE · #5 (**permalink**) 04-01-2011, 04:27 AM

DaleB Dale I can give you a quick list
Bad universal joint
posi rear carrier locking up or unlocking
loss control arms or bushings have play, same for solid metal bushing
play in the trans internally
back lash in the rearend.
output shafts twisted in the rearend
play in the hub bearings
Transmission angle and rearend angle off, cause binding
Yoke on the trans binding
no lube in the pivot joints out universals
Heim joint binding from no oil or the grease is gone from joint
The frame could have a bad weld and be cracking

The list can go on for another 15-20 lines, I think you get the problem
If the car is abused, any part of the drivetrain or suspension could cause the problem. You need to find a mechanic to isolate the problem. They have chassic ears to help locate the problem for couple hundred dollars.
It could also be nothing more that the body on the frame at one opf the mount locations. Bottom line, I don't know the price of the car but would want this problem FOUND if not fixed before buying. The car has you in love with it and a problem that could kill you. Cracked frames do happen. I am not trying to scary you but this is real. Get some one to look at the car.
Also get in writing from owner that this car is solid built with no problem. If owner doesn't do this, I would walk away and look for another prize. JMO. Rick L. Ps it's like a box of cracker jacks, you never know what the prize wil be.

Dale B · #6 (**permalink**) 04-01-2011, 05:10 AM

The car is on Cobra Country ... second one down in the Daytona section (NAF car).

It's only done 300 miles and the tranny / rear end were new when fitted. Talking with the owner (who seems a real genuine guy), he's just lost interest in the car with it taking such a longtime to get built.
I cant imagine it being a frame problem (unless you guys can tell me NAF built rubbish cars), so that leaves the drivetrain.
Is it more likely to be a fault with a mechanical item rather than the pinion angle? ... I mean to say, can a poor /wrong pinion angle cause a clunking sound. I think I'd prefer it to be a mechanical problem because I can simply replace the defective item.

Clois Harlan · #7 (**permalink**) 04-01-2011, 05:50 AM

Quote:

Originally Posted by blykins

Could be excessive backlash, or even a failing u-joint. I'd take it for a drive and pay attention to when it occurs.

My vote is for excessive backlash. I saw this problem on my brothers 69 Camaro resto.

RICK LAKE · #8 (**permalink**) 04-01-2011, 06:44 AM

DaleB Dale need to break down when this problem happens. With 300 miles, I am guess all new parts. This doesn't mean the there is not a problem with back lash in the rearend or trans problem. When does the noise happen? Hot,Cold,Speed, Accel, Coast down to stop, Brakes applied, car just sitting.
It is possible to get a clunk noise if the driveshaft is too long and the pinion angle goes from neg to pos. The drive shaft could bind when the angle reaches "0". Any thing is fixable. i will look at the ad when get a change. Find out what posi carrier is in the rearend. Rick.

Dale B · #9 (**permalink**) 04-01-2011, 11:55 AM

Cheers Rick appreciated

Dale B · #10 (**permalink**) 04-01-2011, 03:24 PM

Apparently the rear end is a four link with watt? ... I assume you USA chaps will know what that is :-)

Dale B · #11 (**permalink**) 04-01-2011, 03:25 PM

This is the reply to an email ....

The rear end is a 4 link with watts. Achieving the offset is just an adjustment of the nuts

tcrist · #12 (**permalink**) 04-01-2011, 03:55 PM

Good on you Rick for helping this guy out a bit.

Could also just be loose or ill fitting bolts. If you can't fly over to look at it yourself , then you might want to pay a qualified mechanic (that has no ties with the buyer) to look it over (as was mentioned before).

lovehamr · #13 (**permalink**) 04-03-2011, 06:30 AM

Dale, the 4 link with a watts refers to the rear suspension being a live axle with 2 trailing arms on each side which locate the the rear end fore and aft and through virtical movement. These 4 links are also responsible for the pinion angle.

The watts link is a pair of rods located on each side of the car's frame and attached to the back of rear end housing by means of a rocker (link) which will allow virticle movement of the rear but stop any lateral movement.

http://www.youtube.com/watch?v=blDJ-...eature=related

Lots more going on there but these are the basics. And for what it's worth; if the pinion angle is the cause of the noise (which I doubt) and it's so easy to fix (just a turn of the nuts) then why hasn't he already done it?