TR4/4A tr4 rear end in a tr3a

[gwb]

hello fellow listers
i just purchased a tr3a and have rear end problems. right rear tire is outside wheelwell by about an inch and at times scraps the rear quarter panel. my mechanic says i have a tr4 rear end (that is wider) and we need to switch to correct tr3 rear end..could it just be frame is off center? how to tell a tr4 rear end from a tr3?
many thanks
billunc@gmail.com
bill browning
704-408-2711 cell
Charlotte

also, need some local advice about other correctness to this 1958 tr3a ...any triumph knowledgeable people locally , would like to pick your brain
thanks

 

[tdskip]

Welcome! We are glad you are here.

The Moss site lists different axle shafts for the TR3 vs 4's, so something is different.

https://mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=36462#36

I'm sure one of our "regulars" will be along soon to provide a more definitive answer.

Any spacers on the wheel/axles? What wheels and tires are you running?

Any pictures of the car to share?

 

[Andrew Mace]

The TR4 rear track is about 4" wider than the TR3. It's pretty obvious with the two axle assemblies side-by-side, there is around 2" greater distance between spring perch and brake backing plate on the TR4 axle.

 

[TR3driver]

Andy is right of course about the TR4 axle being wider. The spring perches and everything else is the same, so the TR4 axle will bolt right up, but it moves the hubs out. Maybe you can see the difference in these two diagrams, and compare to your car. The TR3/A axle has the bulge for the inner seal very close to the U-bolt (which is located by that bump visible on top of the axle.

The TR4 axle has rather more room there, although I think the difference is closer to 1.5" than 2"

However, that should not put the axle off center, meaning both rear tires should be in roughly the same position relative to the body. 1/4" difference is probably within factory tolerance, but 1" says to me that there is something else wrong; possibly some previous accident damage that wasn't repaired properly, or mis-matched wheels.

I drove several years with a TR4 axle under a TR3A. With stock disc wheels and 165 (as I recall) tires, the tires would rub the fenders lightly only on hard turns. It polished up the sidewalls, but never damaged the tires.

Some of us are more oblivious than others, I guess ... I never noticed the difference until after I had the axle installed.

 

[Andrew Mace]

also, need some local advice about other correctness to this 1958 tr3a ...any triumph knowledgeable people locally , would like to pick your brain
thanks

Sorry I missed this part before, Bill. You're right in the heart of Triumph Club of the Carolinas territory, and there are lots of good, knowledgeable folks in that club, some right in or very near Charlotte!

 

[Tr3aguy]

The track should be the same on the front wheels and the rear wheels. So in other words if you measure the center to center track on the front.....it should be the same for the rear......

 

[NickMorgan]

As has been said above a TR4 axle should leave the tyres in the same relative location on both sides of the car. Potentially the axle may not be located correctly. It is possible for it to be knocked back if the car has had a bit of a knock. I suppose it is possible that the axle is off-centre. You really need to do a whole load of measurements. Check that the wheels are both correct TR3, or at least matching. Same with the tyres.
The body shouldn't really be able to move on the chassis, unless it has been poorly rebuilt. Possibly the rear wing cold be misshapen.
Can you post some pictures of both sides for us to look at?

 

[gwb]

thanks everyone for your prompt replies
great information and we will get to the bottom of the mis alignment in the rear

glad to be on board this Triumph ship

cheers
bill browning
Charlotte

 

[gwb]

thanks for all your help
my complete recently restored tr3 was totaled tuesday august 10th by another driver

wish me luck
bb

 

[HerronScott]

Oh no Bill! Are you and any passengers OK?

What happened?

Scott

 

[gwb]

scott
every body is ok, driver is still in hospital, happy that he is ok and alive, sad about my triumph, my first triumph, and he didn't hit another car
it's a mess though

thanks for your concern
bill b