Damn. Sorry you are going through this. Seems you have bad luck with them. I’m no expert but it seems like you are on the right path with the axles. My Qp 3.89 doesn’t make any noise as far as I know. I have their axles and stock style housing as well. My car was pretty loud though.

 

A portion of my bad luck with QP was of my own doing. I ordered online without talking to a salesperson on 12/30/2020 to avoid a first of the year price increase that didn't happen until March or later LOL. Don't order something like that without talking to a salesperson with so many variables on how you intend to use the car. I assumed and they assumed different things I guess and the front office did try to make things right. I think QP was just too busy because of the Covid thing and short handed and mistakes happened. I was being rushed this week at work and hamburgered the end of my left index finger and I'm left handed. Didn't work out for them or me!

I'm just trying to figure this out. I would be happy to have an expert look at the center section but I doubt they would tear into it because it looks ok. My car makes a lot of noise and the gear noise has gotten a bit louder with the new suspension because the upper link mounts to the top of the center section and I expected that, but not the clunk.

 

They were definitely behind when I ordered mine. Said 5 weeks and it took 9. As you know, I have the same suspension. The only difference in our setup (besides your fabbed housing) is that I didn’t check or have my housing straightened after welding. Maybe in my case that little bit out of true stopped it clunking? Don’t know but I hope you can get it figured out. Maybe run it a season and check out your splines?

 

Pinning this thread for when I have a minute

 

Juggling three or four things at the moment, so pardon the sporadic posts:
1) how did you preload the pinion?
2) how did you preload the carrier?
3) the black goo doesn’t concern me
4) I’d put the lash at .007-.008. That’s where I run my stuff, and I flog the sh*t out of them

 

QP assembled the unit not me.

Have you isolated the clunking as actually coming from the rear end and not the driveshaft, a u-joint, the front yoke, transmission mount or ???

Right off the bat one thing I could think of is a binding front yoke due to the increased length of the 9 inch pinion and yoke over an 8 inch.

Anything is possible but I’m using the same driveshaft with new ujoints with 1/2- 3/4” showing at the tail shaft of the new-ish T5z. Trans is 3.4 down and and pinion is 3.1 up with the driveshaft spitting level. No vibration other than pinned motor mounts.

 

How much pinion shim? It could need more depth (less shim) but tell me about the preloads before we make changes

 

Have you isolated the clunking as actually coming from the rear end and not the driveshaft, a u-joint, the front yoke, transmission mount or ???

Right off the bat one thing I could think of is a binding front yoke due to the increased length of the 9 inch pinion and yoke over an 8 inch.

 

Also those axle splines sound suspect.
Another possibility, although a long shot, is check your wheels/lug nuts. If the lug nuts run out of threads before clamping the wheel, that could be your source.

 

I was thinking that looked like clutch material on your finger, but it looks like you have a true trac, Is that correct? I think I would buy some marking compound and one of these (Adjustable Pinion Yoke Tool). That tool is $23, but you can remove your driveshaft and bolt that to your yoke and it will give you the leverage to pop the rear end in the drive or reverse direction with some leverage and you should be able to hear your noise sitting static, with the rest of the driveline disconnected.
You can accurately check your wear pattern with compound if you wanted, but generally, a bad wear pattern will make a continuous grinding or howling.
I think your clunking is either in your differential unit or your axle splines, although your yoke splines could be it, but doubtful. I wouldn't think .010" backlash would make that much noise, especially when coated in gear oil.
If you make or buy a large leverage tool to bolt to your yoke and pop it back and forth a few times. you should hear your problem. Depending if you have a good rig to hold the chunk on an engine stand, you could have 2 friends hold the axles and pop the yoke back and forth and narrow it down pretty quickly, if its inside the rear end.

 

I think I have probably found the smoking gun, the axles may be too short. I went out and inserted the axles into the Tru Trac all the way 2" and there was no play. I then noticed the witness marks left by the lithium grease I put on the end of the axles when I assembled the rear end and measured that they only engaged 1" so I inserted the axles only 1" and there was a noticeable clunk. I then measured the new axle lengths and the old Moser 28 spline axle lengths out of the 8" and the 8" axles were a 1/2" longer. Moser 26 1/4" vs QP 25 3/4" and Moser 30 1/4" vs QP 29 3/4". So I inserted the QP axles 1 1/2" into the TT and there was almost no play. Unbelievable how much difference that extra half inch made! I am running stock track width and the 28 spline Moser axles that I ran in the 8" also work with the 28 spline 9" so it is an apples to apples comparison.

Anybody know what the minimum engagement of Ford 9" axle splines is?

I was thinking that looked like clutch material on your finger, but it looks like you have a true trac, Is that correct? I think I would buy some marking compound and one of these (Adjustable Pinion Yoke Tool). That tool is $23, but you can remove your driveshaft and bolt that to your yoke and it will give you the leverage to pop the rear end in the drive or reverse direction with some leverage and you should be able to hear your noise sitting static, with the rest of the driveline disconnected.
You can accurately check your wear pattern with compound if you wanted, but generally, a bad wear pattern will make a continuous grinding or howling.
I think your clunking is either in your differential unit or your axle splines, although your yoke splines could be it, but doubtful. I wouldn't think .010" backlash would make that much noise, especially when coated in gear oil.
If you make or buy a large leverage tool to bolt to your yoke and pop it back and forth a few times. you should hear your problem. Depending if you have a good rig to hold the chunk on an engine stand, you could have 2 friends hold the axles and pop the yoke back and forth and narrow it down pretty quickly, if its inside the rear end.

Before I disassembled everything I did set the parking brake and turned the yoke with a pipe wrench and heard an almost triple clunk when going back and forth. Backlash and 2 axles maybe?

1/2" to 3/4" showing with the rear suspension hanging? I wouldn't consider that enough.

Thats at ride height. Really only 4" of suspension travel with the bump stops.

Any loose bracket bolts to body?

I don't think so, I'm OCD on such things and did this on a lift and put the suspension with the springs removed way past anything it will ever encounter unless it is flying through the air and landing really hard. Oh wait I allowed for that possibility also! I did.

 

Any loose bracket bolts to body?

 

Likey internal gears of the truetrack. You DO need to move the pinion in deeper ( by my eyes) from your first picture. Too shallow could also cause the noise. Black stuff is no concern to me either.

 

The rule of thumb is if you have a 1” splined shaft you need 1” of engagement for 100% strength. 28 spline axles are about 1.2 at the splines, so 1.2 of engagement would suffice. It seems your shaft is just a bit too short.

 

So with my 1.33" 31 spline axles I would need almost 1 3/8" for full strength? So QP's shaft is a bit short, don't drag me into it! I would think if I were to order custom axles and I have 2" of spline in the TT I would think I would want get toward 1 3/4" knowing the aftermarket splines everything to 4" so I could cut a bit off if I erred on the long side?

 

With the third member removed, stuff both axles into the housing and post a pic. That will show us how short they are and give us an idea of how much room you have to work with.

Id want all the spline engagement I can get.

 

Dogbone

 

Dogbone

View attachment 835587

OK, I'll bark, I mean bite. What does that do for me other than lightening my wallet even further?

 

Just my two cents . I Have a 9 in. axle in my 65 fastback that came out of 77 F150 . I took the Housing to Moser Engineering . Told them what I need done . They narrow the housing and cut and resplined the rear axles and welded the ladder bar brackets on the housing . I had this all done in 1980 .. I think I spent 250.00 dollars at the time . I still am using the housing and axles to this day .. Runing 456 gears with a spool . I beleive there was 1 inch clearnce between the ends of the axles when they were installed and tighten in the housing . I don't know if they still do that today .. I live in southeastern IN. so I took my housing to them . If I remeber correctly it was about a week turn around at the time ..

 

You know Mike you have me thinking, I get a clunking sound from time to time with mine, but it tends to be when Im entering a parking lot and turning. I cant duplicate it all the time, and when I accelerate in a straight line and then let off the gas and accelerate again I don't hear it.

When I called QP, they suggested looking at the drum brakes(which I have not done yet) as I heard the TruTrac had some issues early on with spider gears losing teeth.

Although my rear end is standard width for 65-66, maybe my axles are a bit short too?

Looking forward to your final solution.

Chris

 

IIRC 1-1/2” is pretty damn close to spot-on. Do you have equal engagement with both shafts?

 

This is on Dutchman’s site, closer to your Moser axles.

 

Yes I saw that also. I noticed that the big bearing big block 67+ cars with the 2" wider rear end assembly were exactly 1" wider than the small bearing 9" axles so that crosses over in my mind. So I'm asking myself do I want to spend $500 when you include bearings and wheel studs to make it perfectly in spec? If you look at pictures of the Moser and Dutchman axles you will see a significant difference in finish when compared to the Quick Performance axles. But does that mean the machining that counts is better? I'm at a strong maybe on that one given my recent experiences. I did at $60 have to buy non stock spacer brackets for my Wilwood rear brakes because the 2.50 axle to flange offset was really 2.570 on the QP axles. It all adds up!

 

Are axle bearing widths the same on old/new axles?

Are bearing pockets same depth?

Are axles same length?…edit missed 1/2”

Just thinking of where differences may stack up possibly.

 

What do the retaining plates look like?

Is there an offset for the bearing?

 

The bone is for a stock differential and allows room for the spider gear shaft that the True Trac doesn't have. That much space is not needed with the True Trac as the thickness of the center divider is not much more that the thickness of a washer. IIRC, there are only about 1 1/4" of splines on one side in the True Trac and 1" or so of splines on the other, close to the center washers.

Moser is well aware of this and add additional length to their axles when a True Trac is installed.

 

The bone is for a stock differential and allows room for the spider gear shaft that the True Trac doesn't have. That much space is not needed with the True Trac as the thickness of the center divider is not much more that the thickness of a washer. IIRC, there are only about 1 1/4" of splines per side in the True Trac. One side has splines that need to be interlocked for proper function. Moser is well aware of this and add additional length to their axles when a True Trac is installed.

I did some measuring this evening and the center divider on a True Trac is 1/4" so I could easily add a 3/8-1/2" to both axles. If I order too long I can always cut them shorter.

I'm picky and I'm ok with that.

 

Here is a 31 spline axle that did not have enough length of splines in the True Trac:

It wasn't found until the True Trac broke:

This axle had better depth:

Needless to say, these stock type axles had seen plenty of trips down the dragstrip.

The center washers I mentioned are shown below:

Location of the washers:

 

This side of the true track is splined the continuous length of the gear . . .

The other side is only partially splined:

 

Glad that you measured it out as I was trying to refresh my memory from over 10 years ago . . .

Good Luck!

 

I called Moser engineering today and the standard axle they sell for a 65-66 is 5/16" longer the my current axles but noted the 1" of engagement I have now is "acceptable". Don't know what to do, new quality axles will be about $600 when all is said and done with new bearings, studs and such. You would think I would learn that going cheap on important parts always ends up costing me much more in the end.