TR4/4A TR4A Replacement Axle Shafts

TR4A IRS Replacement Axle Shafts

Hi

I spent about 2 hours under the rear of my TR4A this afternoon trying to diagnose a clunk in the rear end. The clunk occurs when pulling away in first gear. I was able to rule out differential and differential mounting brackets (both were rebuilt about 4.5K miles ago). As best I can tell, without removing the axle shafts for close inspection, it is both u-joints in the axle shafts and worn sliding splines in the axle shafts. Soooo, I am at that decision point about the best course of action for repair. I prefer not to spend any more than necessary but, this car is a long term keeper and I want it to work at peak condition. My driving consists of easy-to-spirited weekend drives. My options appear to include in order of cost (low to high):

1. Stock replacement axle shafts for about $200 a pair
2. Improved modern type axle shafts with grease zerks from $260 to $320 a pair
3. Uprated axle shafts for higher HP for about $880 pair
4. CV Joint Axle/Hub Assembly for about $1,500 a pair
5. Heavy Duty U-Joint Axle/Hub Assembly for about $1,650 a pair (honestly I would go for the CV joint axles before these)

The first 3 do not include the cost of (4) new u-joints, etc. The last two, while much more expensive, due away with the problematic sliding splines and offers a significantly upgraded and stronger hub assembly. I figure the hub assemblies alone are worth $700 for the pair.

Any first hand knowledge or thoughts on the above options? I prefer to do a job once and do it right the first time. This is not something I want to revisit again for many thousands of miles.

Thanks

Bob

Hi Bob

Here in Oz, the Triumph Sports Owners Association had sufficient members who suffered stub axle failure to cause them to start a world wide search for solutions to the problem. These failures had consequences from frightening (all four corners of the car damaged by the Armco) to potentially life threatening (multiple roll-over). Wear or even failure of the sliding splines will cause clonks and lock up of the shaft but will not cause wheel loss. If you still have the original single circuit braking system, stub axle failure will cause the loss of the wheel and brake drum, causing extreme directional difficulty (note understatement) as well as total brake failure.

I believe that the problem is twofold. Firstly, the stub axle design was not great to start with. Secondly, the cars are now almost 50 years old. The springs on the 4As were too soft and as they have aged and sagged, the suspension bottoms more often. Once the bump rubber is compressed, the rest of the impact is taken by the stub axle. Sufficient impacts and they break. I initially went for the uprated shafts with Datsun sliding ball joints. However, these keep the old stub axles. After hearing of the problems experienced by others, I changed to the CV axles with modern bearings and much stronger stub axles. I figured that with the amount of money and blood that I had in the car, the last thing I wanted to have was a catastrophic axle failure. I also went to dual circuit brakes out of a TR6. The clincher was that when some of the rust was cut out of my car, the repair sections came from the wreck of a TR6 that had suffered - you guessed it - stub axle failure. So my vote is CVs first, the rest nowhere.

Re: TR4A IRS Replacement Axle Shafts

Hi Rocky

Thanks your reply. And, thanks for drawing my attention to the failures on the stub axle/hub assembly. I've done some more reading and see that rear hub failure on the IRS suspension is a known issue. When the car was restored 14 years ago, only the wheel bearings were replaced in the rear hubs. My driving is fairly tame but, at the very least, what ever I do about the axle shafts, I'm fairly certain I will upgrade the hub assembly. There seem to be a 1 or 2 options out there with significantly stronger units, not simply new or rebuilt.

I plan to pull the axle shafts and hubs today and give them a full inspection. Short of a full tear down of the hub, is there any way to inspect for a weak or failing stub axle? In the meantime, does anyone else have experience or thoughts on axle shaft or hub assembly failures or replacement options?

Bob

I put in new Goodparts hubs with the original axles and new u joints and Heli-coils in the trailing arms. I would have liked to change to his entire set up however $ ruled.

Richard

Due to $$, I am considering similar. New "improved modern type" axle shafts (~$290 pair) with new u-joints and Goodparts hub assemblies. While I am in there plan to do the heli-coils or keen-serts on the trailing arms.

If I drive about 1,000 miles a year of easy (occasionally spirited) weekend driving, will the "improved modern type" axle shafts serve me well? I would love the CV jointed units but, the cost is high and they may be WAAY more than I need given my driving habits.

Bob

Bob, you'll be better off than me. I used the old axles, replaced the Hardy-Spicer u-joints and added new Goodpart hubs at $349 ea. I sometimes get an annoying little clunk but not too worried about it.

Re: TR4A IRS Replacement Axle Shafts

I ordered CV axles from Richard at Goodparts. He gave lots of free advice. That was an excuse for me to strengthen the IRS bridges with some fabricated braces. There's a whole thread on that from 3 years or so back. The prior owner already upgraded the differential, so I was part way there. I started thinking about new U Joints, upgraded axles, etc., but the cost savings wasn't big enough in view of the incremental benefit of just going with the CVs. Been great since. Good luck.

Re my rear driveline clunk, I removed the full axle shafts yesterday and inspected. The hub assemblies look great with no play. The rest however...all four u-joints have some small level of play. Also, the splined axle shafts appear to have some minor play (I grabbed both ends with a set of channel lock pliers and could feel and hear an audible "clicking" when moving back and forth) - left side worse that right side.

Remarkable to me is each joint has barely any play at all (hard to see but, you can "feel" or hear the play) but I guess it all adds up to enough to cause driveline clunks.

So, I have a couple of questions
-I am no expert in u-joints but, one u-joint cup showed minor play inside the yoke. Is that only a failed u-joint or does that mean the yoke is bad?
-regarding the play in the splined axle shafts, is there any level of play which is "acceptable" or is there supposed to be no play whatsoever? If any play is allowed, I have read about keeping these joints thoroughly greased. If I add tons of grease inside, is that sufficient to compensate for the play? I'm just trying to understand the design of these items.

I will admit, I am really waffling on how to fix or what to replace. I like to remain with stock parts when they are maintained, in good shape and perform as expected. But, if the original factory design was flawed from the beginning, I have no problem upgrading to CV joint axles. It's just that I hate to throw money at a problem without good reason.

I guess where I am going with this is if I can get away with only replacing all four u-joints and loading the splined axles full of moly grease?? Will that work or am I in for new axle shafts to remedy this once and for all?

Bob

Hi All,

Just to circle back and close this thread, I can report great success on my new axle shaft slip joints. No doubt the Goodparts CV joints would have been the ultimate solution but, I believe they were over-kill for my car and the type of driving I do. Plus, I balked at the price, the need to remove the trailing arm and the need to install nylatron bushings in the trailing arms.

After much research and debate, I elected to go with the "improved modern type" axle shafts with grease zerks for $290 a pair. These were #675-550 from Moss, also commonly known as TKC853. I also installed 4 new u-joints from NAPA, PUJ 344 at $28 each (which is the same as the Precision brand manufactured by Federal Mogul).

This was a straight bolt-in swap, the only challenge was my learning curve on installing 4 u-joints with 16 bearing caps and 16 snap rings. It took me longer than I realized to get them properly seated and adjusted so they swiveled freely with no binding. If there ever is a next time, I may consider taking the axle shafts down to the local shop to have them press out the old u-joints and press in the new.

Any way, the results are fantastic. All clunking in the rear end is now gone. It was horrific before pulling away in 1st gear or when reversing. The rear suspension also "feels" firmer but, perhaps that's all in my head. I was also relieved that, after all this work, it wasn't still play in my differential (which was rebuild about 4,500 miles ago). That would have really bummed me out. So, far I have been on two 15 mile test drives and everything works great with no weird vibrations or noises. Whew!

Last, as respects service, I plan to grease the axle shaft every year via the grease zerk (I used Lucas Red N Tacky #2). And every other year pull the axle shafts out of the car completely (easy 30 minute job), disassemble, clean, fresh grease, reassemble and install. At the same time I can hit all four u-joints with a blast of grease.

Regards

Bob

Bob,

Have any pictures of the Moss part?

Scott

Scott

Sadly, no. I have to get better at that. I will admit, I ordered one axle shaft first so I could inspect it for overall quality. I figured if I didn't like it I could easily return it. Once satisfied, I ordered the second axle shaft with all new nuts and bolts to mount to the diff flange and the hub assembly to the trailing arm.

Photos next time for sure

Bob

Sounds great. I may keep that in mind. On my car, the U-joints all seemed problematic, and I wasn't good with the assembly of the U-joints, either, which is partly why I just opted for the CV axles. By the way, there's no need to remove the trailing arms to install CV axles. Those axles go in one of two ways. Either drop the differential and slide them in from the middle, or remove the trailing arms. I followed the first routine. Now if I could cure my pre-ignition, I'd be a happy dude.

KVH said:

Sounds great. I may keep that in mind. On my car, the U-joints all seemed problematic, and I wasn't good with the assembly of the U-joints, either, which is partly why I just opted for the CV axles. By the way, there's no need to remove the trailing arms to install CV axles. Those axles go in one of two ways. Either drop the differential and slide them in from the middle, or remove the trailing arms. I followed the first routine. Now if I could cure my pre-ignition, I'd be a happy dude.

Click to expand...

I did not have to drop the diff or remove the trailing arms to put the CV axles in. I disconnected the tube shocks at one end, dropped the trailing arms down and removed the springs. That made it easy to move the trailing arms down far enough to insert the new axles. Then I bolted the bearing carriers onto the trailing arm from the outside, feeding the stub axle through before you bolt up the six bolts on the trailing arm as standard . Put the springs back in, reconnect the shocks and then bolt the inner flange to the diff. Once you have the wheels back on, tighten the nut on the stub axle (100 ft/lb I think) and you are done. Now if you find a cure for pre-ignition, please let me know!

Wow, sounds right to me. But it looks like the frame would still be in the way if the diff were left in place. Come to think of it, I have a LSD Diff from Goodparts, off a Nissan, so maybe it gets more into the way. I'll have to look at that. Not sure. BTW. had a Peugeot 404. Among the greatest cars on earth in its day.