Driveshaft problem?

[Calabrio]

I just visited a place with my '93 Mark VIII claiming to be a "custom exhaust shop" though my impression was they were really just a place that could weld mufflers into place. They didn't mind removing the 3rd Cat and resonator, but I was "informed" that it wasn't possible for them to install 2.5" dual exhausts without it hanging low and rattling.

Then I showed them that great full length photo Geno took of his double-x set up, and... they didn't know what else to say.

I'll have to find another shop.

Anyway, when the car was up on the rack, I did get a good look at the driveshaft. It was a little alarming.

1. It looks like there are score marks, etches that go around it in a few spots.

2. there's a noticable BULGE in the middle.

It doesn't look twisted, but the middle is bulging and there are some lines carved into it.

Should I be concerned?

 

[Calabrio]

I was just told, privately, that this was the normal appearance of the '93 driveshaft. Does anyone have a picture of one?

 

[gangstaMK8]

the scores that u r seeing in the driveshaft is from a wiring connector that is very close to the shaft.. this happened to mine also it will throw ur balance off a bit mine i can feel when im doing betwen 75- 90 then it goes away

 

[ONEBADMK8]

That little bit would never affect the balance at all.
It is totally normal the way it looks. They are junk.

You need this if you have vibes.

If you don't then leave it alone and you will be fine.

Heres the stock 2 piece shaft.

 

[gangstaMK8]

That little bit would never affect the balance at all.
It is totally normal the way it looks. They are junk.

You need this if you have vibes.

If you don't then leave it alone and you will be fine.

Heres the stock 2 piece shaft.

[/QU

i agree with the stock ones being junk but scores in a driveshaft depending how much there is will and does affect my driveshaft. By the way if my mk8 is running at about 500 rwhp will this denny's driveshaft work for me also there will be a 125 shot on top of the hp mentioned above?

 

[MrWilson]

Did fomoco even ballance the driveshafts b4 they put them in the cars, or did they just go to home depot and grab some fence posts and stuff em on in?

 

[ONEBADMK8]

That little bit would never affect the balance at all.
It is totally normal the way it looks. They are junk.

You need this if you have vibes.

If you don't then leave it alone and you will be fine.

Heres the stock 2 piece shaft.

[/QU

i agree with the stock ones being junk but scores in a driveshaft depending how much there is will and does affect my driveshaft. By the way if my mk8 is running at about 500 rwhp will this denny's driveshaft work for me also there will be a 125 shot on top of the hp mentioned above?

If you look at the car in the upper right on the Dennys page, thats a 6 second 220 mph car with well over 2800 hp.
I think you will be fine.

Those scores are radial in nature meaning it has removed the same amount of material all around. It will not affect the balancing. It could affect the sctructural rigitity of the unit if it went on long enough and deep enough.

 

[mespock]

I just visited a place with my '93 Mark VIII claiming to be a "custom exhaust shop" though my impression was they were really just a place that could weld mufflers into place. They didn't mind removing the 3rd Cat and resonator, but I was "informed" that it wasn't possible for them to install 2.5" dual exhausts without it hanging low and rattling.

That is big time BS... You can run 2.5" with no problems and no rattling and with out them hanging low..

Bring it up hear and I'll get it done for you with no problems... We'll clip off the 3rd Cat then take it in. After that you are set

 

[Calabrio]

I know it's nonsense.
And the look when I showed him the photo of Geno's set-up was priceless. I found a place that despite being called a "custom exhaust shop" was really just a place that can weld mufflers in. Nothing more.

I just discovered that a modular engine speed shop exists real close to my home, so I'll go check that place out and ask around there next. I should also post in the South East chapter forum asking there as well.

"Exhaust Shops in the Tampa Bay area."

 

[Calabrio]

About the Driveshaft, I have a '93 so it looks like I have the one piece unit. The bulge seemed to look like it was flaired in the middle, like an internal bulge...

I'd better get it up on ramps tomorrow and take a picture...
Well, not tomorrow. There's a tropical storming blowing around trees outside. But sometime this week.

 

[Sergmark]

I too have 2.5 inch exhaust ( LMS XX) from the cats back and have no rattles at all.... Check my pictures out in the photo gallery.

 

[driller]

From my '93...

The 'scoring' is from loose tunnel insulation. Should be nothing to be concerned about. The bulge is factory spec.

I sold mine to a Gen2 owner who had bad vibrations and it cured his problems. Meanwhile an MMx shaft cured my vibrations from the 4.10 gear install. Go figure.

 

[Calabrio]

From my '93...
The 'scoring' is from loose tunnel insulation. Should be nothing to be concerned about. The bulge is factory spec.

I sold mine to a Gen2 owner who had bad vibrations and it cured his problems. Meanwhile an MMx shaft cured my vibrations from the 4.10 gear install. Go figure.

Thanks. I figured that if anything was really wrong, the Mark VIII would vibrate like crazy, but it did look a little alarming. I'd never really noticed the driveshaft before. Those pics were incredibly reassuring. Thanks again.

 

[gangstaMK8]

That is big time BS... You can run 2.5" with no problems and no rattling and with out them hanging low..

Bring it up hear and I'll get it done for you with no problems... We'll clip off the 3rd Cat then take it in. After that you are set

what is this 3rd cat talk i know on my mk8 there was a total of 3 cats one main one and 2 small ones what i did was removed 2 small ones and replaced the main one with a high flow cat

 

[Calabrio]

what is this 3rd cat talk i know on my mk8 there was a total of 3 cats one main one and 2 small ones what i did was removed 2 small ones and replaced the main one with a high flow cat

Sounds like you removed the two cats and replaced the resonator and 3rd cat with a high flow cat?

 

[gangstaMK8]

Sounds like you removed the two cats and replaced the resonator and 3rd cat with a high flow cat?

the main cat which was 2 inlet 1 outlet i replaced with a high flow cat and then up front there was 2 identical nerf football size cats and the resonator was near the main cat. all i have for my exhaust is a resonator ,1 high flow cat and 4 inch tips thats it

 

[rmac694203]

Actually the two cats up front are the main cats, and the third cat (2 in 1 out) is just a secondary cat. The two front ones are the main cats because they are the ones monitored by the O2 sensors.

 

[Roadboss]

I went 3" all the way back from the headers, including a 2 in 2 out Magna Flo
resonator with 3" Magna Flo race mufflers in the rear. Clearance was not a problem, and road clearance is fine at stock ride settings.

 

[Calabrio]

I went 3" all the way back from the headers, including a 2 in 2 out Magna Flo
resonator with 3" Magna Flo race mufflers in the rear. Clearance was not a problem, and road clearance is fine at stock ride settings.

I remember reading a thread, and in essence it sounded like exhaust size could be viewed like a Goldilocks and the three bears.

2.25 too small
3.00 too big
2.50 "just right"

I don't know how true that is, but that was the impression I've gotten from all the reading.

 

[MediumD]

I think Roadboss car can make good use of dual 3."

The statement you made is true for near stock cars, but not when you're making serious power.