u-joint replacement

9

95blklsc

Registered
Hey guys, I'm making another attempt to tackle the vibration problem this weekend. I've narrowed it down to u-joints........feeling pretty good about this one due to the fact that the inner plastic cap on the front u-joint is cracked.

I've done some searching and have all the info on how to get the shaft out by lowering the tank and exhaust, but does anyone have any suggestions or tips for replacing the u-joints? I've never done this before so anything is appreciated.
 
RE: u-joint replacement

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... but does anyone have any suggestions or tips for replacing the u-joints? I've never done this before so anything is appreciated.
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You could be in for quite a suprise. :B :+

Seriously, I've not done the u-joints on a Mark VIII, but I've had quite a bit of experience on other vehicles and heavy equipment.

This is a fairly decent introductory lesson...

http://autorepair.about.com/cs/doityourself/a/aa102602a.htm

http://autorepair.about.com/library/faqs/bl755d.htm

It can be a cake walk or one of the worst experiences working on your car. Let us know how it goes.

My first piece of advice is to make sure you have a big 3 lb hammer.
 
RE: u-joint replacement

I've done u-joints enough times to know that it's something i will pay someone else to do from now on. I usually remove the driveshaft myself and drop it off at a shop.

That said, i don't know about your specific vibration problem, but i've never known a u-joint to fail on one of these cars. The driveshaft runs in a pretty much straight line, so there's not much "u" ing for those joints to do. Chances are, your vibration is due to the totally crappy design/manufacturing of the driveshaft, and to fix it you'll probably need an MMC driveshaft.

If you have stock gears, you can probably buy a used driveshaft from someone who went with an MMC shaft with gears. Mine didn't start vibrating until about 115-120 stock, and it's still sitting in my garage. A friend of mine might have dibs on it, though.
 
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I've done u-joints enough times to know that it's something i will pay someone else to do from now on.
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Ha, ha! :7 We all have those particular jobs we will gladly pay to have done rather than DIY. Anything that has to do with the exhaust is my achilles heel. On these cars that's more than you think.

I know guys that will tear down and rebuild a tranny but won't touch the differential gears.
 
RE: u-joint replacement

it IS a metal matrix driveshaft with spicer u-joints. The problem is one of the inner plastic caps is broken, that's why I suspect the bad u-joint is the result. If the cap isn't sealing it all kinds of junk could get in there and damage the bearings. If it's not that it's got to be an issue with the shaft. I've already checked the pinion angle and it's within .5 deg's of perfect. It's not a wheel balance issue becuase it vibrates in jackstands w/o wheels on. No question it's drivline and I'm 99% sure it's something to do with the shaft, either u-joints or somethings wrong with the DS.

I'll give it a try, if I run into problems I'll just bring the shaft somewhere.

EDIT **BTW I have 3.73 gears.
 
RE: u-joint replacement

Have you attempted re-indexing the shaft at the tranny and/or companion flange at the differential?
 
RE: u-joint replacement

I've tried it at the diff, clocked it in increments of 45 deg, no difference. I'm going to do the u-joint because it should be replaced regardless if it's the problem or not. When I do that I'll index it at the tranny. I'll let you guys know how things work out. I'm hoping this will take care of it......x(
 
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could also be the transmission. early tail shafts sucked.
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Sssssssshhhhh... ::grrr::
 
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let's hope that's not the case........................but it didn't always vibrate so I'm hoping your wrong.::nono::
 
RE: u-joint replacement

Regardless, it would be a good time to inspect the tailshaft bushing.
 
RE: u-joint replacement

As far as inspecing are you talking about the amount of play that the yoke has in the trans output? I did look at that and there's really almost nothing, you can just about hear a little play when you tug on it but can't really visually see any movement.
 
RE: u-joint replacement

doing your universal joints are a piece of cake as long as you have a vice that will open far enough to press them in and out I use scockets to press them out one that will fit the exact size of the cap and one that the cap will fit inside of if you don't have a vice its is harder but take your time with that hammer John was talking about just press everything in as straight as possible and don't forget to take out the retaining clips that hold the caps in there
 
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As far as inspecing are you talking about the amount of play that the yoke has in the trans output? I did look at that and there's really almost nothing, you can just about hear a little play when you tug on it but can't really visually see any movement.
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You would need to mic it and compare with the oem specs. 'Almost nothing' isn't really quantitative enough. I can look for the spec later at home. Since it's a tranny part I may not have it if it's not in the FLM specification book.

Too loose will allow vibrations at the tailshaft and eventually failure of the rear seal. Too tight will cause overheating which may lead to seal failure or at worst a complete galling of the yoke and bearing.

You may want to also consider a forced lube tailshaft mod. The fluid film introduced by the forced lube line can play a role as well.
 
RE: u-joint replacement

I don't recommend the forced lube mod. it's a pain in the rear and i'm not sure it provides any tangible benefit. I've driven from MI to FL with 4.10's twice without the forced lube and haven't had a problem.

I'd suggest replacing that bushing, though. Should be $5 at a tranny parts shop (the kind the tranny shops go to for rebuild parts). Ford discontinued it, they want you to buy the whole housing. You'll need to remove the tailshaft housing, press the old one out, and press the new one back in.
 
RE: u-joint replacement

How many miles on your Mark?

The manual says to lube the rear end at 90,000 miles.

Maybe related to your problem?
 
RE: u-joint replacement

Has anyone actually taken a bad u-joint out of a FN10 or MN12 car? I haven't I have changed quite a few ,but never really had a bad one.
Rear bushings and yokes well thats a different story. That has always been a problem with these transmissions. Personally I think you are asking for trouble running a 4.10 gear with no force lubrication. Ya it may be a pain to do for someone who doesn't have the equipment (bridgeport works great ),but I am sure if you ask around you can find someone who will be willing to do it for you.
Alan
 
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Oh, i had the forced lube mod. All it did was leak all over. I pulled it off because it's useless. I talked to Lidio at Alternative and he agrees. He puts 4.10's in Marauders all day long and never does the forced lube mod, and he's never had a problem. That bushing really doesn't need much lubrication, and it gets plenty from the stock lubricating method.
 
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