My rear end went BOOM!

[RocsMerc]

About 30,000 miles ago I had 4.10 gears put in. I bought used ford racing gears because I didn't know any better at the time and I thought that the fact that they were ford would be enough. Big mistake. I also had a brand new eaton posi installed at the same time. About 10 minutes after I picked up the car from the shop, the gears started to whine a little and stayed that way ever since. Three years later, as I'm driving to a job interview, the gear whine suddenly changes tone and got way louder and I felt a viberation. My judgement was telling me to pull over but I didn't want to miss the interview and I was only about 5 blocks away. When I got out of the interview I drove around the parking lot and the unusual noise seemed to have subsided, so I figured I would just drive home and order new ford racing gears right away. As I was pulling out of the parking lot the noise came back so I started to look for a place to pull over. I was sitting at a stop light and as soon as I hit the gas, BOOM! It felt like I hit a huge pot hole at speed enough to break a rim, but the car was barely moving. I look back and there is no pot hole. Now I notice a new noise comming from my rear, a thud every 5-10 feet or so. I imediatly pulled into a parking lot and I'm sitting in the cab of a tow truck as I type this.

Update: My car is repaired. Click here for pics of the damage.
http://www.mercurymarauder.net/forums/showthread.php?p=959527#post95 9527

[Mr. Man]

Bummer!! Hope you had better luck at your interview.

[Egon Spengler]

Sorry to hear man.

This thread is full of dirtiness. I'll let Casey have a field day on it!

[RR|Suki]

That sucks man, the gears were installed improperly from the get go.

[BAD MERC]

I bought used gears too. Completely silent and perform flawlessly. I think your installer has the tolerances too close.

[ImpalaSlayer]

I bought used gears too. Completely silent and perform flawlessly. I think your installer has the tolerances too close.

something wasnt set up right. gears are gears unless they had visible signs of wear they should have been fine.

[RacerX]

CBT's rear goes BOOM! too. He needs Beano though, not gears...

[Hacklemerc]

CBT's rear goes BOOM! too. He needs Beano though, not gears...

As mush as I've heard about CBT, I dont think his rear goes BOOM. I think its been wallered out enough to just go "swoosh"

Sorry about your gear issue... Good luck with the interview.

[fastblackmerc]

That sucks man, the gears were installed improperly from the get go.

You hit the nail on the head.... gears installed wrong.

[sailsmen]

The "whine" is because they were not set correctly.

What are you mods, looks like you have a Trilogy?

[johnnyrauder]

hey roc are you still at baums. hope you got the job. i know a good ford mac. he did my s/c and built about 100 mustangs pm me if you want his name he's in islip.

[Blackened300a]

This thread is full of dirtiness. I'll let Casey have a field day on it!

How about more helpful info and less bulls--t to help him out in this thread? That so hard to do lately?

The guy who set up my rear lives out in Suffolk and can do it at his house , but you'll have to have it towed. Hes a perfectionist so I assure you it will be done right.

[RocsMerc]

The "whine" is because they were not set correctly.

What are you mods, looks like you have a Trilogy?

I have a trilogy kit sitting in my garage, but it's not on the car yet. The only relevant mods are the used ford racing 4.10's, a new Eaton posi, and 255/55/18 nitto 402s on the rear tires with stock width rim.

I had the car towed to my house. I got a good deal on towing through my insurance policy. First 5 miles are free and $5 for each additional mile. So what do you guys think I'll end up replacing? Is it likely the posi is destroyed? Bearings?

[RocsMerc]

hey roc are you still at baums. hope you got the job. i know a good ford mac. he did my s/c and built about 100 mustangs pm me if you want his name he's in islip.

Yea, I'm still at Waldbaums. I find out if I got the job or not on Monday.

[Ms. Denmark]

Rocco, I have no words of wisdom on this topic except to say I am so sorry to hear this :(.......and I got my fingers crossed that you get that job!:beer:

[Blackened300a]

So what do you guys think I'll end up replacing? Is it likely the posi is destroyed? Bearings?

If you had a whine that got worse then it gave out on you completely, I'd imagine a new ring and pinion are in your future. Chances are they are destroyed.

[Krytin]

Now I notice a new noise comming from my rear, a thud every 5-10 feet or so. I imediatly pulled into a parking lot and

That's the ring/pinion gears. If you pulled right over the spider gears in the diff should be ok put the potential exists for damage to the spiders fron gear fragments. Good luck with this and the job interview.

[Bigdogjim]

NO short answers however when you pull it apart all your question will be answered. I hope it goes in you favor. And best of luck with the job hunt, hope the interview went well!

[SpartaPerformance]

I hope you get the job. Trust me go with Paul's gear guy there is no better!

[musclemerc]

Hey Roc, there was a recent post on a place with new FRPP 4:10's for 139.00 shipped. You cant beat that!

Good Luck on the repair but I would look for a new carrier as well. Look like Paul has the hook up on the labor.

[blazen71]

Expect to replace everything, but you won't know for sure until the diff cover is removed.

[babbage]

At first when the 4.10's were installed - did you take it easy for the first 500 miles?

At this point you likely need: New ring and pinon kit (frpp is good quality) plus a new carrier and spider gears. The Axle bearings and seals are cheap too so you might as well do those too. Break in new gears with dino oil. Go easy for first 500, flush rear end out, refill with a good quality synthetic - THEN go for burnouts and hard driving.

Good luck with the Job.

[RocsMerc]

At first when the 4.10's were installed - did you take it easy for the first 500 miles?

At this point you likely need: New ring and pinon kit (frpp is good quality) plus a new carrier and spider gears. The Axle bearings and seals are cheap too so you might as well do those too. Break in new gears with dino oil. Go easy for first 500, flush rear end out, refill with a good quality synthetic - THEN go for burnouts and hard driving.

Good luck with the Job.

When I got my gears, I did take it easy for the first 400 miles but I didn't know your suppose to immediately change the oil again. It was filled with Amsoil synthetic once when I first got it and that was it. Also, the guy who installed it didn't say anything about a break in process. I took it upon my self to take it easy in the beginning.

[GreekGod]

... I didn't know your suppose to immediately change the oil again...the guy who installed it didn't say anything about a break in process...

A properly set up rear gear set does not require an oil change or break in. Of the 100's of thousands of Marauders, Crown Vics, and Towncars Ford built, none of them were required to have a break in period, or a break in period oil change.

========================

[RocsMerc]

Thank you to everyone who's been giving me advice on where to bring it. I have a good friend who's a mechanic at an Audi dealership who will be helping me fix it. He lives less than a mile from my house and I won't find a better deal on labor anywhere else. He came over just now and listened to the noise. Chances are there is something with the spider gears and the damage is not just limited to the ring and pinion. That thud I here at regular intervals changes intervals when in a turn. I'm going to bring my car to his house on Thursday and he will open it up and tell me what parts to order. He's going to let me leave the car at his house till it's fixed.

[MM2004]

A properly set up rear gear set does not require an oil change or break in. Of the 100's of thousands of Marauders, Crown Vics, and Towncars Ford built, none of them were required to have a break in period, or a break in period oil change.

========================

What^^^He^^^Said.

Drive it like you stole it!

:burnout:

Mike.

[MercNasty]

I hope u get the job man. when u get the new gears installed make sure they dont make any noises when u first leave, if so, instantly turn around and take it right back to the installer. It had nothing to do with them being used unless they were bad before they were installed. Bad gears are easy to identify tho

[Marauderjack]

At first when the 4.10's were installed - did you take it easy for the first 500 miles?

This makes absolutely no difference.......EVERY FORD tech I've asked about this just laughs at me!!!:shake:

[Chevyguy]

You hit the nail on the head.... gears installed wrong.

Used gears have to be set up EXACTLY the same as they were previously. Even if set up "correctly" they won't mesh correctly

Also, who is to say those gears were not messed up before you got them, one thing to remove your own gears and re-install, marking the pattern really good before pulling them out etc..

[SpartaPerformance]

This makes absolutely no difference.......EVERY FORD tech I've asked about this just laughs at me!!!:shake:

I agree I'm a believer of drive it like you stole it right from the start. Hell I did a two block burn out in front of the dealership when I picked up my Stang. Bob even laughed. :D

[Blackened300a]

I hope u get the job man. when u get the new gears installed make sure they dont make any noises when u first leave, if so, instantly turn around and take it right back to the installer. It had nothing to do with them being used unless they were bad before they were installed. Bad gears are easy to identify tho

The gears will have a hint of whine around 60-65mph Thats considered normal for the FMS gears


A properly set up rear gear set does not require an oil change or break in. Of the 100's of thousands of Marauders, Crown Vics, and Towncars Ford built, none of them were required to have a break in period, or a break in period oil change.

========================

Correct, right after my install I had to test them out.

[babbage]

A properly set up rear gear set does not require an oil change or break in. Of the 100's of thousands of Marauders, Crown Vics, and Towncars Ford built, none of them were required to have a break in period, or a break in period oil change.

========================

Factory does things a little better than people. Can you say robot? All major gear manufacturers recommend changing the gear oil after break in. There will be metal particulate in the oil after first 500 miles.

[Marauderjack]

Factory does things a little better than people. Can you say robot? All major gear manufacturers recommend changing the gear oil after break in. There will be metal particulate in the oil after first 500 miles.


Check the fill plug magnet first to see if there is any metal then drain and refill if you feel like spending the $$$'s!!:cool:

[RR|Suki]

zero noise is normal

[GreekGod]

Factory does things a little better than people. Can you say robot? All major gear manufacturers recommend changing the gear oil after break in. There will be metal particulate in the oil after first 500 miles.

It certainly wouldn't hurt to use regular 80W90 for the 1st 500 miles, & then use synthetic.

==========

[ledzilla]

CBT's rear goes BOOM!

That's what she said!

Anyway, I feel your pain. Blew out my diff last fall, chipped the spider gears. Made a nasty thumping sound as I went down the road, but it was a fairly rapid thump. Local shop found a few too many pieces in the gear oil for my comfort, but managed to get the car somewhat comfortably mobile with fresh oil (changed the oil, thump went away; rather odd). Luckily Blackmobile was selling the entire rear end out of his MM, and it had a brand new 4.10 and new axles. Had it purchased, shipped, and installed for $630 plus a beer and a burger. Anyway, best of luck getting the fix and on your interview!

[fastblackmerc]

It certainly wouldn't hurt to use regular 80W90 for the 1st 500 miles, & then use synthetic.

==========

I had Redline 75w140 in the rear since the 4.10's were first installed. I changed the oil at 2k miles and there were no particles in the oil.

[RocsMerc]

My car is repaired and I now know why it broke so easily. It turns out I was scammed by the guy I bought my original used 4.10's from at Carlisle. What he claimed to be selling were used 4.10 Ford Racing gears. What they actually were was used Motive gears in a Ford Racing box. :mad2: I just counted the number of teeth to check if I was even running a 4.10 gear ratio. At least that much was true. When I went to install these gears three years ago, Mustang Magic was the first shop I went to, but at that time, they discouraged my business because it wasn't a mustang. At first they outright refused, and then they wanted an additional cost to work on it. Disgusted with how I was turned away, I ended up taking it to a different guy that specialized in Camaros and Firebirds. Since then Mustang Magic has dropped their Mustang exclusivity issues. Probably due to the economy if I had to guess. I ended up getting my repairs done at the same Mustang place and they did a very good job with it. When they worked on my car they looked like they did it so many times before that they could do this job in their sleep. Completely silent at all speeds and I even got a one year warranty on my rear end with them. If only they didn't make a big deal about it not being a Mustang three years ago, all of this could have been avoided. They would have noticed that they were not Ford gears and I would not have put them in. It makes no sense to me. Why would anyone turn away money even if the economy was good? To be honest I kind of felt like I was swallowing my pride as a Marauder owner by taking it there after the way I was treated last time. This time around when I asked about having my rear end worked on by them they said "no problem" and "We install 4.10's on Marauders all the time."

Now that that's out of the way here's the pics of the damage. As a point of reference here's what a ring and pinion are suppose to look like.
http://www.streetperformance.com/ART/PRODUCTS/101703/ford-racing-M-4209-G410A.jpeg

Now here's my pinion gear.
http://www.mercurymarauder.net/gallery/data/500/medium/P9220217.JPG
http://www.mercurymarauder.net/gallery/data/500/medium/P9220211.JPG

My ring and posi.
http://www.mercurymarauder.net/gallery/data/500/medium/P9220208.JPG
http://www.mercurymarauder.net/gallery/data/500/medium/P9220210.JPG

This his how they knew it wasn't a Ford part.
http://www.mercurymarauder.net/gallery/data/500/medium/P9220213.JPG

[Blackened300a]

Ouch!!

BTW, they aren't called Mustang Tragic for nothing. I have heard way too many horror stories about that place and their business practices.

[Krytin]

For what it's worth the problem was the initial install.
I've changed out Ford gears that looked like those.
I've never heard of long term success w/used gears installed in a different differential - you will never get it to match the fist wear pattern.

[computertech]

Hey Roc.......I`m glad to hear you got your Marauder fixed up,sounds like its ready for the trilogy install now, talk to Johnnyrauder or Paul
Krytin for help with a local ford mechanic.... there great guys and know the right people for the job:burnout:

[johnnyrauder]

i guess i lost track of this thread otherwise i would have sent you to madden auto in islip billy installed my s/c really knows his stuff built alot of mustangs a real ford guy. that mustang magic guy has all the charm of a dock strike.....

[RocsMerc]

Hey Roc.......I`m glad to hear you got your Marauder fixed up,sounds like its ready for the trilogy install now, talk to Johnnyrauder or Paul
Krytin for help with a local ford mechanic.... there great guys and know the right people for the job:burnout:


I'm waiting till next year to install the Trilogy so I can pay off my car and get a daily driver first. Right now I'm just keeping an eye out for a place to get it dyno tuned after the install.

[tjl006]

When your ready to put in the trilogy let me know. We can do it in a weekend if we have too. Glad to hear you got your gears sorted.