Tony71502

Here's the back story. My 91 fox was due for a rear shoe change, I said F it and got a full 4 wheel disc/5 lug conversion. While i was in there, hey wtf I'll change my rear end out too.

I bought a rebuilt rear end from a member on here, with what he claimed were about 500 miles since rebuild. One of the bolt holes on the flange on the end of passenger's side axle tube was bent. Which means some serious force musta have been delivered(ie someone dropped it?). We gave it a little torching and bent it back to normal. (It was so bent the old backing plate bolt was unused and unable to come out without the flange being torched and bent back).

Another thing to consider, we removed the transmission and I had a master mechanic friend of mine replace the speedo drive gear for the new 3.73:1 calibration(the internal gear). The transmission was relatively easy to get back in, everything was lined up.

Also a firewall clutch adjuster and quadrant were bought from Max Motorsports.

Also put on 17x9 rims.

So... There is an extremely unusual noise when the car is being let into 2nd, 3rd, 4th, and 5th.... the noise is also audible when coasting in gear and also giving it some gas in gear. It sounds like a metal on metal grinding noise, to be honest, but anything is possible.

Another thing to note, when the clutch is depressed or the car is in neutral, the noise is inaudible(might be there, might not... we all know how the shifter can act as a tuning fork almost, the only problem is holding the shifter doesn't stop the noise when in gear).

The noise get's worse with higher Mph, which leads me to believe it can not be due to a misadjusted clutch, as the engine rpms in 5th are lower than when in second or third... yet the noise is worse.

I think it's either the gears were installed improperly, the axle tube was bent during whatever damaged the axle tube flange, causing damage to wheel bearing or even causing my brand new axles to not ride true. Or there possibly was something not assembled right when my master mech (he's got about 35 years exp) installed the speedo gear.

I'm not familiar with trans internals so IDK if doing the speedo gear could even affect parts that would cause this noise. Also, since this noise only happens when in gear, that means the shifter has to be in gear for this noise to be audible. The noise may be happening when the car is in neutral, but I can't hear it.

I have no idea what's causing this, and right now I can't enjoy the fruits of my labor.

My only considerations to solving this is putting it on a lift and going through first second and a bit of third, while someone listens to the rearend as the wheels spin.

Any help is more than appreciated!!!

Boss_Hotrod

Basically all you can do is run it on jack while listening to the tranny and rear end. That will help narrow it down. It more than likely the rearend since the speedo gears are plastic.

Tony71502

I'm not considering the speedo gear to be the culprit, but as I said I'm not familiar with transmission internals... so If a bearing removed in order to remove the speedo gear, then i guess there's a possibilty that it could be causing this noise?

Hopefully someone familiar with transmissions can rule this out.

Btw.... My PS axle seal was leaking after the first drive of the car. We replaced that while I was welding up my exhaust to clear the huge tires. Sucks to waste a good couple quarts of lucas.

mjr46

check the axles and axle bearings

Tony71502

The axles are brand new ford racing axls, the wheel bearing seemed fine on the passenger side, which is where the damage was. We had it open tonight checking the bearing, my buddy whos a pretty good mech, although not experienced in years, claimed that the bearing was in good order. But that may not be true. Do you think that the axle tube could possibly be bent?

Or do you mean check the new axle for any scoring caused by a bad bearing and possible bent tube?

I don't think ford would make or even ship out bent axles. But who knows.

mjr46

it's not that they'd ship them out that way , it's the careless ups bafoons that don't give a rats butt about it arriving in good condition.

Tony71502

The ford racing 2300K cobra r disc conversion kit is shipped in a large 2'x4'x2' box on a pallete, inside that pallete is numerous boxes(over 20) containing each individual piece, a very well put together kit. The container was assembled and shipped out by ford, considering the larger outer box had ford racing on it. The boxes containing the axles had paper packaging in them as well. I don't think that they were damaged during shipping.

So, if my rear end is damaged somehow.... How much different is a ford 9 inch than an 8.8?

I realize my DS may need shortened, hell I'll get a new one since it's the only stock driveline part I have. How much different is the brake flanges, how much different would the track length be? These rears can be direct replacements with a fox suspension, whether they are all that way IDK, but many companies will tailor it to fit fox suspensions.

I may just say to hell with it and get a 9 inch if the rear end is F'd.

67mustang302

Sounds like it could be a transmission bearing. Definitely listen to it on jack stands, to rule out a diff/axle bearing. If it's coming from the trans and it only makes a grinding sound in gear that gets worse the faster you go, then it's probably a bearing in the trans.

Tony71502

I'm looking through a manual that was used by my buddy at Rosedale, it consequently uses a t-5 as the subject of a manual transmission tear down and rebuild....

There are no bearings involved in removeing the speedo gear, unless I am somehow mistaken, but I doubt it...

That kind of rulesout a tranny bearing being bad. And supports the fact that the shifter/trans makes the trans amplify the grinding sound in the rear end.

Once again, if I am mistaken, someone please respond.

67mustang302

You have to find out where the sound is coming from first, until you do that everything is really just speculation.