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Installing Quaife LSD

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darrellwalker Darrell Walker
Vancouver, Washington, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
Hi Jeff,

Thanks for the info, some answers.

For backlash, I was comparing to similar sized American diffs. Triumph doesn't give a spec for backlash measured off of the crown wheel, they have you measure side to side clearance of the carrier, and shim to give a clearance there. I was just recording it for cross-checking when I reassemble.

I've already removed the pinion, my fabricated wrench worked great. I did have to drive the pinion out, the outer bearing was tight on the pinion. Is that expected? I also had to use a puller on the collapsable spacer, should that be expected as well? It also appeared that the spacer wasn't fully seated on the pinion shaft.

The GM spacer kit that Richard mentioned looks like it will work, the spacer fits nicely on the pinion.

I didn't get a picture of the pattern on the pinion gear, and it is now too smeared since I removed it.

I did not check runout on the crownwheel, but am planning to do so when I install the Quaife. I used a block of wood wedged between the crown wheel and diff case to put load on the gears when I did the pattern.

-Darrell



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA



Edited 1 time(s). Last edit at 2017-03-10 06:28 PM by darrellwalker.

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tirebiter Jeff Garber
Dighton, MA, USA   USA
Ok so I studied/read the explanation of how to setup the differential crownwheel-to-pinion-gear backlash. It actually does state in paragraph 59 page 156 of the factory service manual, 0,004"-0.006" backlash. The 0.006" you measured is certainly in the ball park . Strange that it is not included in the list of data or specifications ...

The tool you made sounds like it will do the job. Good work ! If the handle breaks off, I'm sure you'll try to weld it again.

As I understand the small Mig welders, they make a hotter arc when the feed is faster. Sacrificing some wire to heat up the weld parent metal, can push a smaller welder to do larger welds.

The Factory service manual does also say to drift off the outer pinion bearing and also the crush collar. Just as you described it happened.

darrellwalker Darrell Walker
Vancouver, Washington, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
Hi Jeff,

In reply to # 1440874 by tirebiter Ok so I studied/read the explanation of how to setup the differential crownwheel-to-pinion-gear backlash. It actually does state in paragraph 59 page 156 of the factory service manual, 0,004"-0.006" backlash. The 0.006" you measured is certainly in the ball park . Strange that it is not included in the list of data or specifications ...

Yes, but as I read the manual, their backlash measurement is the lateral distance between the crown wheel and pinion, not how much the crown wheel can rotate.

Anyway, I was going off of a recommendation to look at Ford 7.5 specs, which give backlash as 0.011-0.016”. But checking GM and Toyota 7.5 diffs, they are 0.006-0.010”, so much more like the TR spec.



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA

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tirebiter Jeff Garber
Dighton, MA, USA   USA
Darrell,

I see what you're saying about how the text describes the backlash. The arithmetic does show it as 0.005" along the axis of the carrier bearings. Makes me wonder why they use the term "backlash" if it is not actually backlash but some calculated phantom clearance, instead. It's not the first time a misprint shows up, if it's a misprint.

I guess by setting it up as a "phantom clearance" of 0.005" as described in the text, you can then measure the backlash afterwards. Since the gear teeth are not on 45 degrees, I assume the backlash will be noticeably less than half the "phantom clearance". That could be problematic.

I wish you luck. I also wish I could see a photo of the tool you welded to get an idea of how much clearance it had underneath the flange. Also wondering what you used to cut it with, in the first place. Must not have been a quick or easy job. Kudos to you for getting it the tool to happen.

darrellwalker Darrell Walker
Vancouver, Washington, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
In reply to # 1441434 by tirebiter I also wish I could see a photo of the tool you welded to get an idea of how much clearance it had underneath the flange. Also wondering what you used to cut it with, in the first place. Must not have been a quick or easy job. Kudos to you for getting it the tool to happen.

Hi Jeff,

Here are some more shots of the "tool". I'll try to remember to take one with it in action when I reinstall, to show the clearance. But it is just about right, the flange will go almost all the way on. The plate ls 3/16" x 2, a little more than a foot long (just something I had around). If I was doing it again, I would probably get a 3" wide piece, and drill a hole in the center. Then I could have welded all the way around the wrench piece. But this seems to be strong enough so far. I used a sawzall to cut the end off of the wrench, then a belt sander to smooth out the stub. I bolted a 3' piece of c-channel to extend the handle.

-Darrell



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA


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tirebiter Jeff Garber
Dighton, MA, USA   USA
Looks pretty serious ! Thanks for posting it.

By the way .. anybody ever tell you your shop floor is too clean ?

darrellwalker Darrell Walker
Vancouver, Washington, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
In reply to # 1441456 by tirebiter By the way .. anybody ever tell you your shop floor is too clean ?

Certainly not my wife!



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA

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darrellwalker Darrell Walker
Vancouver, Washington, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
Here is a picture of the "tool" in action. The flange isn't fully seated, but probably 90% of the spline is engaged.

I got the pinion reinstalled. I ended up reusing the old crush collar, as the GM spacer was too short. It took quite a bit of bashing to expand it 10 thou. I sanded down the inside of the old outer bearing, because I wanted to make sure I expanded the collar enough. That worked well, I could easily determine that I had just a small bit to slop when the bearing bottomed on the collar.

Before I installed the pinion, I checked the runout of the Quaife. Book says 0.003" max, I have well under 0.001" (right around 0.0005"winking smiley.

It is very nerve-wracking turning the big nut a tiny bit, checking the preload, rinse, repeat...

Also, 13-20 inch-pounds it a lot more than I would have imagined!



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA



Edited 1 time(s). Last edit at 2017-03-14 03:37 PM by darrellwalker.


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ROAR Mihael Rogers
Arroyo Grande, USA   USA
I've had good luck with just getting the patterns into the middle toward the bottom where the teeth are the thickest.

BTW: what kind of a rear end are these and what other cars are they used in, I want to go to a taller ratio, I have no problem starting in 2nd. and am spinning too many RPMS for freeway speeds with my TR-8.

I have Gordon Churchill's old car which was a member.

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darrellwalker Darrell Walker
Vancouver, Washington, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
All buttoned up and ready to go back in!



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA


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darrellwalker Darrell Walker
Vancouver, Washington, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
In reply to # 1441921 by ROAR BTW: what kind of a rear end are these and what other cars are they used in, I want to go to a taller ratio, I have no problem starting in 2nd. and am spinning too many RPMS for freeway speeds with my TR-8.

Hi Mihael,

I believe the crown wheel and pinion are unique to the TR7/TR8 and the Rover SD1. From what I've read, the available ratios are:

3.9:1 - early TR7
3.45:1 - late TR7
3.08:1 - TR8
2.84:1 - one of the Rover models

I'm sure Todd can chime in with many more details. I think the 2.84:1 is very rare, at least in the US.

What ratio do you have now?

-Darrell



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA

tirebiter Jeff Garber
Dighton, MA, USA   USA
Darrell, did you end up measuring the rotational backlash of the ring gear with the clerance set to 0.005" as described in the Factory Service manual ? Did you check the contact pattern after reassembly ? Questions .. .questions ...

Apparently 90% of the splines was plenty enough to get the required torque to achieve the proper pre-load. Did you by chance re-check preload after the seal was in place ?

Looks really good by the way. I'm sure you are dying to find out how well it works on that uphill-turning-into-traffic intersection that prompted you to delve into this project.

Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, Oregon, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1442099 by darrellwalker All buttoned up and ready to go back in!

Obsessively clean, painted the correct satin black, with brake lines properly capped, I might add. I am betting there are no dirty ashtrays in your car, either... smoking smiley

Can't wait to hear how it performs.

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

darrellwalker Darrell Walker
Vancouver, Washington, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
In reply to # 1442469 by tirebiter Darrell, did you end up measuring the rotational backlash of the ring gear with the clerance set to 0.005" as described in the Factory Service manual ? Did you check the contact pattern after reassembly ? Questions .. .questions ...

Apparently 90% of the splines was plenty enough to get the required torque to achieve the proper pre-load. Did you by chance re-check preload after the seal was in place ?

Looks really good by the way. I'm sure you are dying to find out how well it works on that uphill-turning-into-traffic intersection that prompted you to delve into this project.

I never could get a reliable measurement on the side-to-side method in the ROM, so I gave up on that. I put it together with the same shims, and got the same backlash as before I started taking it apart. I did check the contact pattern after assembly, and it was similar to the pre-disassembly pattern. So I'm pretty confident that the two gears are in the same relative positions.

I did not check the preload after putting in the seal. I didn't put the front cover on until I had installed the diff carrier, but I don't think the seal would have really made any difference.

I got my brake backplates back from the power coater, but now I'm waiting on a new rear axle bearing. The new, one-piece bearing came apart when I tried to drive it onto the axle shaft with a piece of pipe. I'll get them pressed on instead.



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA

tirebiter Jeff Garber
Dighton, MA, USA   USA
I hear ya about the confusion quotient of altering the backlash shims from stock. Apparently it worked for this long and apparently the Quafie carrier is made to the same dimensions as the stock carrier is.

I just hope any added traction doesn't tax the gear teeth too much more than before this modification.

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