TR4/4A tr4 steering - inner ball joints loose

[derickson]

After getting my tr4 running again, I immediately noticed excessive wander in the steering. Initially I suspected front suspension bushings, but upon inspection discovered about 0.050" play in each of the inner ball joints! It's supposed to be 0.002". Does anyone have insights to share about rebuilding these? Is it just as simple as shimming? Is this a common wear-out mode? I still plan to rebuild the suspension, but want to make sure I'm not overlooking something else.

 

[tdskip]

I would have thought that these are just replacement items -but after checking it doesn't look like Moss or Rimmer carry them...

 

[Banjo]

Replacement or rebuild would be the only safe options. It looks like moss carries all the parts to rebuild one, just not the whole thing as a unit.

 

[Alan_Myers]

Hi,

Those inner ball joints are pretty easily replaced, probably best done with the entire rack and pinion unit pulled out of the car. You might also check the bushing in the RH side of the rack tube, that the rack itself slides in. That often wears too, causing lateral play.

For the tie-rod job, you'll also need new tab-locking washers and a bunch of shims of different thicknesses. I think there is a spring in there, too, that might need replacement. The "plunger" or cup around the ball doesn't seem to wear, in my experience.

p.s. By the way, if there is wear elsewhere in it - and there might well be if the ball joints are that loose - it's sometimes more economical to just get a rebuilt R&P unit from one the vendors. TRF does rebuild exchanges, occasionally puts them on sale, but I haven't priced them lately.

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The replacement ball joints themselves are made with white nylon balls now, while the originals were metal. I don't know if there is a big difference.

 

[derickson]

Super. Thanks for the help!

 

[TR4nut]

If you don't like the price of the rebuilt units, you may also have a chance to pull good ones off a Spitfire donor car - the rack is different but I believe the inner ball joints are the same.

 

[derickson]

I finished the rebuild this weekend. Much better. Two concerns:
1. the 'packing pieces' (the 1.5" aluminum spacers) above the front springs are missing. I assume someone removed them to lower the front suspension. Is this common? Is it a problem?
2. The car has very little restoring force in a turn. That is, when I turn the wheel, there's very little tendency for the steering to return to center. What could cause this? Castor is responsible for this force, and the castor in TR4s is fixed by the upper wishbone offset (which I checked is correct).

 

[Alan_Myers]

Hi again,

Regarding your item #1: Only the first few years of TR4 used the spacers or "packing pieces", later TR4 didn't. According to Moss' catalog, the change occured with car #CT29985, after which the cars would be fitted with longer springs that don't require spacers.

The packing pieces (aluminum spacers) were often deliberately removed when the later, longer replacement springs were installed on earlier cars. This was quite common and is a factory approved change, as is noted in the TR4/4A service manual.

Going from memory here, if the springs measure just about 10 inches tall when out of the car, they are the "short" type that require the packing pieces. If the springs measure roughly 11", they are the "long" type and the aluminum spacers aren't needed. The front ride height ends up about the same with both these arrangements, and there is no noticible difference in handling.

There were also heavy duty "competition" springs offered, about 9" tall, that do use the spacers, but still lower the car about an 1". I think there are also some longer, aftermarket competition rated springs that don't use the spacers and still lower the car, but I'm not totally certain of this. (These are different from TRF's heavy duty springs that actually raise the ride height a little above normal.)

Finally, yes, some folks with the shorter stock springs that would normally use the spacers *did* remove the spacers to lower the car. The result is pretty extreme and low-sitting, since the spacer is 1-1/4" tall and the car is dropped even more than that due to the slight ratio in the suspension geometry.

When the car is all together, it can help to measure ground clearance, to try to determine what's installed.

While the car is sitting with all four tires on level ground and is normally weighted or laden (i.e.: all body parts installed, battery installed, oil in the engine, full gas tank & approx. 150 lbs in the driver's seat), you should measure about 6" from the ground to the underside of the frame rail right near the front suspension when the car has either type of normally rated springs (either long springs w/o spacer or short springs with spacer).

If you see about only 4" to 4.25" clerarance, it's likely the short "stock" grade springs were used, but with their spacers omitted (and that the tires might rub, suspension will most likely bottom out over a hard bump, and the spring might jump off it's perch with a hard rebound).

If you measure 4.5" to 5" the car most likley has competition grade springs installed, either type (short with spacer or longer w/o spacer).

If you find close to 7" clearance, most likely the TRF heavy duty springs are installed.

Regarding your #2 question: You are correct, the caster is one key thing that effects the self-centering effect of the steering. Very early TR4 (up to CT6500 approx.) had 0 degrees of caster. This early setup is essentially the same as TR3 and shares a lot of the same parts, although the TR4 was fitted with rack & pinion steering. After TR4 CT6500, the suspension was changed and has 3 degrees of caster.

I see your car is registered a '63, but that would be the year it sold and it wasn't uncommon for TR4 to actually have been built much earlier (for example, my October 1962-build TR4 is registered as a '64). So if your car has a commission number CT6500 or lower, it would have the early/TR3 suspension geometry. It is possible to change this to the later by swapping out pieces, but a lot of parts need to be acquired.

If your car is later than CT6500, you might have an alignment shop check the caster to see if it's 3 degrees. If not, there might be something bent, some parts incorrectly installed, or some parts from an earlier car (such as TR3/early TR4 vertical links) that have been installed in error.

Other things that can effect the self-centering effect of steering include the rack & pinion tension adjustment and brand new tires that haven't "settled in" yet. However, these have less dramatic effect than changing the caster.

If the alignment shop finds caster is off, but all pieces appear to be straight and correctly installed, I understand it's possible to fit a Jaguar Mk IV upper ball joint. This is much narrower than the TR4's upper ball joint and gives room for some shimming to be done, changing caster a bit. A final alternative is Revington TR's adjustable upper fulcrum brackets, which give both adjustment for camber and allow shimming for caster.

Hope this helps!

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[derickson]

Alan,
thanks so much- I really appreciate the thoroughness of your postings.
My car is in the CT12xxx range, so it would have had the spacers originally. Currently, with no one in the car, the distance from the bottom of the frame to the floor is 4". I'm tempted to install spacers.
I'll also have the alignment checked.
One more question- I'm also experiencing the soft brake pedal phenomenon, which reading some of your other postings is likely due to insufficiently tight wheel bearings. How do you recommend I correctly set the castle nut? The brakes only go soft after driving even brief distances (100 yds), but don't show the symptom if the car is not moving, so I'm doubting any leak or hydraulic problem.
Thanks again.

 

[Alan_Myers]

Hi again,

Yes, sounds like it should have the spacers and that someone removed them in the past to lower the car (a lot!). Has it also been lowered in the rear (usually done with spacers on top of the leaf springs and longer U-bolts)? I'd suggest pulling one spring and measuring it, to see if it's about 10" long. If so, it either should have a spacer or should be replaced with a spring that doesn't need a spacer. You might be able to find an aftermarket "competition" spring that both doesn't need the spacer and lowers the car somewhat, to around 4.5" to 5" approx. ground clearance.

As it is now, besides the extra low ground clearance (maybe too low, but that's your call) my main concern would be that the springs have little compression on them when the suspension is fully extended, and might jump off their seats over a bump. See if you can move the spring around a little, when the car is jacked up and the front suspension is sitting on the bottom stop. You might also see some tire rub inside the fender (depends on what wheels and tires you are using) and the suspension might bottom out pretty hard over bumps. If one is installed, a front anti-sway bar might help prevent either of these, too.

An alternative to new springs would be to add spacers. Right now there are some new opportunities with this. In the past we cut down the original alu spacers (i.e. "packing pieces") to fine-tune ride height. Now TRF sells spacers in different thicknesses, that can be used the same way. If I recall correctly they have 1/2", 3/4" and 1" thick spacers. The originals are 1-1/4" thick. Each 1/4" difference in height at the spring will actually change ride height by about 3/8" to 1/2".

Once you get the front spring setup the way you want it, you might need to fiddle with the rear ride height to help get it balanced. You might be surprised how much effect the relationship between front and rear ride height and spring ratings have on handling, if and when you push the car pretty hard through some corners! It effects how much grip the tires get, which effects cornering, braking and acceleration, not to mention over and understeer.

Regarding the brake situation....

Yes, it's quite possible the problem is too loose front wheel bearings, which allow the hub and brake rotor to move in and out a little, bumping the brake pistons back into the caliper farther than they should go (thus the pedal stroke is very long before you find any brake resistance).

I'd suggest you pull a hub off while you work on the suspension. Take a good look at the felt seal on the rear. If it's protruding any more than about 1/16" from the rear of the hub, it's likely too thick. As a test you can completely remove the seal, temporarily reinstall the hub and follow normal tightening procedure to remove nearly all play in the bearings. Then mark the threaded part of the axle somehow and/or very carefullly measure the amount of threaded axle protruding from the nut. Disassemble again, put the seal back and use that mark and/or measurement as a guide to retighten the nut to exactly the position it was when the axle end play was correct. If the seals are over-thick, the nut will probably be quite a ways past where you think the hub is tight enough, by feel.

The only problem with doing it this way, and the reason I'd rather just trim the seal down instead, is that it's easy to overtighten and that's bad for the bearings, too, same as the overly loose condition.

Some other things that effect pedal stroke and the front brake calpers include the one-way restrictor valve on top of the 5-way connector, which is located on the top of the frame rail, RH side of the engine compartment. This is where all the brake pipes come together on your car. The pipe coming down from the master cylinder to the 5-way connector should have the restrictor that keeps too much hydraulic fluid from being drawn back into the master cylinder when the pedal and MC piston return, after braking. The restrictor looks like a silver extension on the top port of the 5-way connector, about 2 inches long I would guess. It's hex shaped, maybe uses 1/2" or 9/16" wrench. It's not uncommon for those one-way restrictor valves to be removed by POs and left off. If missing, you'll get the same sort of symptoms. (This is not to be confused with the hydraulically operated brake light switch that's located on the 5-way's port that's down on the side, pointing toward the engine. This brake light switch is larger diameter and has wiring connections, of course.)

It sounds like you have checked master cylinder, slave cylinders, calipers and all brake pipe connections for any sign of leaks, which might also cause a similar symptom. One final thing would be if a master or slave cylinder had been honed slightly oversize, or the wrong size seal were used inside it, that might give similar brake problems. Should see leaking fluid in this case, however.

Hope this helps!

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[derickson]

reviving a long-dead post...
I've completed most of the repairs I was elbow-deep in earlier, including the full front suspension rebuild, and the brake problem. However, I still have the lack of self-centering steering problem, so I decided to investigate the rack and pinion. I could see visible play in the end of the pinion when loaded transversely, which made me suspect that the pinion bushings were worn. I disassembled the pinion (without removing the rack), and measured the pinion OD and bush ID and found the following:
pinion OD: varies from .558 to .560 (while rotating)
bush ID:varies from .563 to .565 (end to end)
The pinion shaft that rides in the bush appears slightly elliptical, and bush is certainly worn in one end. I haven't checked the smaller bush or pinion end, but I suspect it's not as bad (less load).
Question: if I just replace the bush, will that be good enough? I'm concerned about the out-of-round of the pinion. Where can I get another pinion? Moss says N/A.

 

[Alan_Myers]

Hi,

You might be able to have a local machine shop turn the pinion you've got to a slightly smaller diameter, to get it back into round, and then have them make up a bushing to fit. AFAIK, replacement pinions for early TR4 R&P have been unavailable for some time.

You mention a lack of self-centering. I don't think a little play in the pinion would cause it.

Have you had the alignment checked? You're car should have about 3 degrees fo caster, which is the primary factor effecting self-centering.

Incorrect toe-in can also effect self-centering. With modern tires there should probably be 0 to 1/16" negative toe.

Another likely cause is the type of tires in conjunciton with the amount of camber the car has. If it's a lot of positive camber, as original, that might make steering pretty squirrely with modern radial tires. The suspension was originally configured with bias ply tires in mind. Specific radial tires might be worse than others, probably mostly depending upon the tread pattern used at the outside edge, since positive camber emphasizes the car's weight on that edge. Ideally, some changes to reduce camber to around 0 or even slightly negative would be the best solution, but involves making some rather permanent modifications.

One common method is to shorten the upper a-arms, or to elongate the ball joint mounting holes to repostion it more inboard. But, it's best if at all possible to *not* change the length of either the upper or lower a-arms when making this change, because that can induce or exacerbate bump steer or some other bad steering habits.

That leaves the following options:

1. Swap to TR4A lower/inner a-arm mounts, to allow shimming it out, i.e. moving the pivot point outward.
2. Change or reposition the upper/inner a-arm pivot. Revington TR makes an adjustable version.
3. Heat up and bend the vertical links.
4. Shorten the cross tube in the engine compartment, from spring tower to spring tower, to pull the top of the towers closer together.

All these require some careful work to get it right. A combination of methods might be used, rather than just one, to arrive at the desired camber.

Camber of between zero and negative .5 or .75 degree is probably about as much as you might want in a tyical street car. Racers go to 1, 1.5 even 2 degrees negative or more. But, that's pretty radical and will wear the tires pretty unevenly. Also, the more negative camber there is, the heavier the steering will be at lower speeds.

Is there any chance something was reinstalled incorrectly? That's one more thing that might really effect the car's handling. It's easy to mis-position the upper/inner a-arm pivots or, I think, swap the tie-rod brackets from side to side.

Finally, do you have a sway bar installed? If so, has it been adjusted since adding spacers and raising the car's ride height?

Hope this helps!

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[KVH]

How do you measure the play in the inner ball joint?

 

[derickson]

I thought about turning down the existing pinion, but it turns out moss has one for $40, and the bushing for $2.
I had the front end aligned after I rebuilt it, and I believe it has the correct caster and toe-in, but I'll check the sheet with the numbers and get back to you. I know I got the upper A-arms on correctly, with the larger offset arm forward.
I do have a front (and rear) sway bar. What's the method for adjusting?

The inner ball joints should have basically no axial play in them but still move freely. They can be checked by hand with the front end off the ground, or removed and checked in a vice with a dial indicator.

 

[derickson]

I finished the rack & pinion rebuild this weekend- it made a huge difference. I now have self-centering steering, and much tighter feel. I replaced the pinion and upper bush, and adjusted the tension in the R&P.
Just for the record, here are the alignment numbers:
Camber Left .35 Right .55
Caster Left 1.7 Right 1.05
Toe 0.11" each side

I still think I don't have enough caster, but it's not adjustable, and without the spring packing piece in place (mine were removed to lower the front end), I wonder if the suspension geometry is slightly different.
I'm still curious about adjusting of the sway bars.