PDA

View Full Version : TR6 TR6 Diff questions



Gliderman8
09-27-2009, 05:46 PM
Having just completed the resto of my '73 TR6 I am starting to hear some "clunking" type noises from the rear of the car. Thinking it was the diff mounting points I crawled under to have a look and the mounts look fine.
Next, I put the rear on stands and put it in first and reverse. In both cases, the rear passenger wheel had the drive while the drivers rear wheel barely turned at all and when it did it was quite "choppy"
I was surprised that both wheels were not rotating when in first gear.
Is this normal? Will both wheels rotate in a higher gear?
If I need a new diff, is it better to rebuild the one I have or look to buy another one? Does anyone know what a fair price is to pay for a used diff?
I know that I have posed a lot of questions, but I thank you all in advance for taking the time to answer.

Tinster
09-27-2009, 06:26 PM
Elliot-

It was my experience I could not tell if the diif mount
was OK or cracked without dropping the diff and sticking
my face of close to the studs. Look at passenger side,
front mount.

Does it always make a noise or only on shifts?

d

trrdster2000
09-27-2009, 06:28 PM
Elliot, all is normal in the wheel turning department, unless you have a pos-track rear. Your clunk may very well be a universal joint as one wheel is hopping around with the axles hanging down. Check those first as rears are very high dollar items.

Wayne

mallard
09-27-2009, 06:42 PM
The TR6 stock differential is not a limited slip type so only one wheel will turn when you have it off the ground. The Quaiffe style differential is like a poitive traction type. That will turn the wheel with the least resistance. Mostly found on high performance cars.

The clunking sound you hear is most likley from the axle, or broken mounts. Check to make sure the splines have grease and are not binding Also check the U joints.

As for rebuilding, I would not buy a used one and expect it to be in good shape. Check with TRF or Mark at Macys Garage for prices. You can rebuild one yourself but you will spend some time and most likley take it apart many times before you get it right. You will also need the correct tools.

Not sure of the type of restoration you did, but if the car sat for some time the splines may have dried up a bit.

A rear shock may also be loose.

bgbassplyr
09-27-2009, 07:03 PM
The wheel with the least resistance in the u joints, bearings and brakes will rotate while the other remains stationary. Thats how a differential works. When a turn is made, the wheels rotate at different rates and the drive is focused on the slower moving wheel, ie, the inside wheel. When you make a hard turn and apply power, the inside wheel will spin because it is unloaded, and you loose drive because all the power is just spinning the wheel. That why locking differentials were invented. When one wheel exceeds the rate of spin to the other, an internal clutch mechanisim ties both axles together, bypassing the function of the differential.

You will notice that with the rear wheels off the ground, gearbox in neutral, when one wheel is rotated, the other wheel will turn in the opposite direction due to the way the spider gears work. Wish I could give a better explaination. Also wish I had a million $.

The clunk could be any of the following:

1. bad axel u joint, either inner or outer.
2. bad drive shaft u joint.
3. loose or broken diff mount, rubber or frame.
4. bad pinion bearing allowing slop between the pinion and ring gear.
5. worn ring and pinion due to use/age.

Use a lever/pry bar to really load the diff against the mounts to check for breaks/ damage. Shaking by hand will not reveal problems here.

Check all the u joints in the usual way.

If you set the e-brake, gearbox in nuetral, and rotate the driveshaft back and forth, you will be able to tell how much free play in the pinion/ring gear there is. I don't remember how much you should be able rotate the driveshaft bump to bump, but it seems reasonable that more than an eighth of a turn would be too much, and indicate trouble within. Rebuilding is best done by a professional. Buying used is a crap shoot, IMHO.

Hope this helps, and if I have any of it wrong, others are invited to correct me. No offense taken.

Oh, and be sure it is not a tail pipe or muffler hitting something.

Good luck, Jim

poolboy
09-27-2009, 07:06 PM
Yeah, I doubt that you will hear the noise from a cracked differential mount with the wheels off the ground. From my experience there has to be some resistance to the torque from the differential for the crack to make the click or clunk.
Under what conditions did you hear the noise ?

Gliderman8
09-27-2009, 07:06 PM
I did install new universals when I did the resto but who knows... I guess they could be bad.
As for the rear shock, I never even gave that a thought...
Wow, I like this forum... the more heads the better.
Thanks guys!

poolboy
09-27-2009, 07:20 PM
.................................................. .................................................. .................................................. .................................................. ......................................
Under what conditions did you hear the noise ?

TR3driver
09-27-2009, 08:19 PM
Just wanted to echo the comments above; you can't tell if the mounts are bad by looking, because the diff is in the way. Grab it, do your best to shake it loose from the car, you probably still can't tell. Only way to be sure is to drop the diff and do a visual.

Here's what I found in the 'rebuilt' diff I bought for my Stag:
https://i258.photobucket.com/albums/hh260/TR3driver/DSCF0044_reduce.jpg

Gliderman8
09-27-2009, 08:25 PM
Specifically, I hear a slight clunk unpon putting into first, so that is what made me think it was the diff mounts.
BUT, I also hear some noise that when the car in in motion with car in gear and foot both on/off of accelerator.

P.S. Dale et al-
You are right... I plan on dropping the diff to see what's going on with the mounts.

poolboy
09-27-2009, 08:50 PM
If it's not the actual metal brackets that have the "pin" that the rubber mounts fit on, it might be that the inner metal sleeve in the original type rear mounts have come loose from the rubber that surrounds it. It's kind of vulcanzed to the rubber and when it breaks free, it clinks around upon the differential mount pin.
Easy to check W/O dropping the differential. Just remove the 2 nuts that hold the plate to the differential and the center nut that holds the mount to the "pin". If you do one at a time the differential won't move.

Tinster
09-27-2009, 09:01 PM
Elliott: I live in kind of a remote place in terms of LBCs.

My 69 TR6 came with clunk when it was purchased. I knew
very little about auto mechanics but everything I read
pointed to a broken diff mount, passenger side front.

I rented some lift time and rented two professional mechanics
to drop the diff so I could inspect the pins/mounts. Broken
pin/mount had already been repaired. I had the diff put back
with a new TRF mounting kit.

In retrospec Big mistake putting it right back in.
Out, I could have checked:

1. bad axel u joint, either inner or outer.
2. bad drive shaft u joint.
3. dry splines in axles
4. pulled off the diff rear plate and listened for bad pinion
bearing allowing slop between the pinion and ring gear.
5. worn ring and pinion due to use/age.

But I didn't know at the time to do this. So the diff went
back in and I replaced all those components and still have my
clunk to this day. It's inside the diff.

I bought a spare diff and it has no clunck. Live and learn.
And yeah, the first thing I discovered was neither rear shock was attached to the car. But they don't clunk.

best of luck with your clunk/

dale(Tinster)

RJS
09-28-2009, 01:03 PM
Hey Guys,

After 8 years I finally addressed the clunking in the rear of my TR4A. It would clunk in 1st gear - especially after backing out of the garage. A visual led me to believe it was not the diff mounts. By getting under the car on jackstands and alternately holding/rotating the driveshaft and axel shafts, I was able to isolate the play as being inside the diff. I would say the rotational play was ~1/2".

So, I dropped the diff which was amazingly easy. Took all of 45 minutes by myself using a floor jack to lower it. Four bolts on the driveshaft, four on each axel shaft, four diff mount bolts and out it came. Now I could confirm it was not the diff mount. I then had the diff rebuilt by Quantum Mechanics. It leaked oil like mad but, fortunately the crown & pinion were in excellent shape b/c I always kept it topped up. So, all the play was b/t the spider gears as all the old brass and fiber washers/shims had long since disintegrated. So, I got three new bearing, three new oils seals and the spider gears re-shimed for a very reasonable cost. Plus, he tapped an oil drain hole in the bottom so I can now change my diff fluid every few years. One thing I will say, this is VERY specialized work which requires very special (hard to find) tools and the hand of an experience professional to set the tolerances just right.

While the diff was out I used it as an opportunity to pull the sliding axel shafts apart to inspect and relube with moly grease. I also stripped and repainted the diff mounts. Lastly I improved on the original rubber bushings in two ways: 1) I opted NOT to go with polyurethane bushings but used original rubber 2) the hole in the bushing was not snug around the diff mount pin so I used some pvc tubing from Home Depot and cut a length to "sleeve" it (slid it right up over the pin to remove the slack) 3) I welded a slight side wall to the rear two washers creating a little "cup" for the bushing to sit in (TR6 set-up is slightly different I think so this may not apply).

Got the diff back, had it installed in a little over an hour and very, very happy with the results.

Bob

BobbyD
09-28-2009, 02:04 PM
Unless your diff mount is seriously ugly flat out broken in two you'll have to drop the diff to try and see if it's cracked. After removing mine and hitting the mount with a wire wheel and sandpaper I was finally able to see where the cracks where......as you can see, it only takes a hairline crack to cause the dreaded clunk! Then I got mine boxed in and the clunk went away. (https://tr6.danielsonfamily.org/DiffMounts.htm)

https://tr6.danielsonfamily.org/60thBirthday/Differential/Images/BottomCrack.jpg

TR3driver
09-28-2009, 04:29 PM
One thing I will say, this is VERY specialized work which requires very special (hard to find) tools It's actually not that bad, IMO. The special factory tools definitely make the job easier and quicker; but it can be done with just relatively common tools (hydraulic press, bearing separator, dial indicator etc.) and persistence.

The case spreader is not essential, the carrier can be pried out and tapped back in without spreading the case.

https://i258.photobucket.com/albums/hh260/TR3driver/Stag%20diff/DSCF0066.jpg

Instead of using the pinion depth gauge, you can assemble the unit and check the tooth contact pattern. When it looks like this, you're good to go.

https://i258.photobucket.com/albums/hh260/TR3driver/Stag%20diff/DSCF0065.jpg

The only tools I had to fabricate were bars for various holding functions

https://i258.photobucket.com/albums/hh260/TR3driver/Stag%20diff/DSCF0002_crop.jpg
https://i258.photobucket.com/albums/hh260/TR3driver/Stag%20diff/DSCF0001.jpg
and a little mount for the dial indicator (to measure carrier end float)

https://i258.photobucket.com/albums/hh260/TR3driver/Stag%20diff/DSCF0051_CROP.jpg

DNK
09-28-2009, 05:35 PM
[quote=RJS]...The special factory tools definitely make the job easier and quicker; but it can be done with just relatively common tools (...

Randle- All I got is an old craftsman 4" vice ,a rust pair of channel locks and a broken flat blade screw driver.
Any chances I can do this?

TR3driver
09-28-2009, 05:59 PM
Randle- All I got is an old craftsman 4" vice ,a rust pair of channel locks and a broken flat blade screw driver.
Any chances I can do this?

tdskip
09-28-2009, 06:53 PM
Don - you bought a screw driver finally?

poolboy
09-28-2009, 08:36 PM
I bet Don found it on the road.

bgbassplyr
09-28-2009, 09:22 PM
[quote=RJS]...The special factory tools definitely make the job easier and quicker; but it can be done with just relatively common tools (...

Randle- All I got is an old craftsman 4" vice ,a rust pair of channel locks and a broken flat blade screw driver.
Any chances I can do this?

2 chances


slim and none.