9 replies to this topic

[Deathrow]

I'm going through the process of replacing Elliot's ball joints for the second time as while I had the front subframe off I noticed that both hubs were suffering from quite a lot of sticktion which seemed to suggest the ball joints were too tight.
 
The last time I did these GraemeC was kind enough to show me the ropes and what the joint should feel like. Unfortunately I'm experiencing the same issue I did last time and I can't seem to get it sorted.
 
I'm finding that once torqued up and shimmed how I feel is correctly, the joint has areas where it is loose (it'll fall under it's own weight and you can wiggle it with a finger tip) but then other areas in the travel are already quite snug, they'll move with ample pressure but if I were to remove .001 of shim to take up the loose area then the snug area will become too tight.

I've taken a few videos of what the issue is to help, please excuse my narration and the garage floor, it's not that messy I promise.
 



What am I doing wrong?

Am I expecting something more than I can actually achieve with this?

How do others set theirs?

[sonikk4]

Did you lap them in Adam??

[Deathrow]

I did yeah. Assembled joint with fine grinding paste, rotated it by hand for about 20 minutes through all the range of motion. I didn't want to lap too much of it off.

[Spider]

That's just the 'quality' of the ball joints.

 

These need more lapping. Last set I was given to fit that needed lapping took me around 2 hours per joint before I felt they were 'acceptable', so yes, an all day affair.

 

If they need lapping, I won't fit them.

 

The OEM ones TRW made for BMC / Leyland were ground finished and were ready to fit out of the box, no lapping.

[sonikk4]

I did yeah. Assembled joint with fine grinding paste, rotated it by hand for about 20 minutes through all the range of motion. I didn't want to lap too much of it off.

 

To be honest i will replace the ones on Paddy as i did not fully lap them in. Could have done better. We need a supplier of ones we dont need to lap in.

[Deathrow]

That's just the 'quality' of the ball joints.

 

These need more lapping. Last set I was given to fit that needed lapping took me around 2 hours per joint before I felt they were 'acceptable', so yes, an all day affair.

 

If they need lapping, I won't fit them.

 

The OEM ones TRW made for BMC / Leyland were ground finished and were ready to fit out of the box, no lapping.

 

I'm guessing those are no longer available? The previous set that I did were pretty much exactly the same in behaviour and they were 'genuine' Unipart items.

Is it safe to keep lapping them in until they fit? 

 

 

I did yeah. Assembled joint with fine grinding paste, rotated it by hand for about 20 minutes through all the range of motion. I didn't want to lap too much of it off.

 

To be honest i will replace the ones on Paddy as i did not fully lap them in. Could have done better. We need a supplier of ones we dont need to lap in.

 

 

When you say fully lap them in, do you mean you ran out of material safe to remove or you just stopped before they were perfect?

I don't want to remove too much from them and make them a liability but they're not much use at the moment.

[Spider]

 

That's just the 'quality' of the ball joints.

 

These need more lapping. Last set I was given to fit that needed lapping took me around 2 hours per joint before I felt they were 'acceptable', so yes, an all day affair.

 

If they need lapping, I won't fit them.

 

The OEM ones TRW made for BMC / Leyland were ground finished and were ready to fit out of the box, no lapping.

 

I'm guessing those are no longer available? The previous set that I did were pretty much exactly the same in behaviour and they were 'genuine' Unipart items.

Is it safe to keep lapping them in until they fit? 

 

 

I haven't seen the TRW ones for a while, though I did pick up one set a little while ago NOS at a jumble meet. I know you've already got a set there, but the Delphi ones seem to be the go these days.

 

Yes, you can keep lapping them until they are right, but to go a little further on this, if you do manage to lap in to the softer material then they were never fit for purpose in the first place. Lapping, even for a couple of hours will only take off about a thousands, maybe as much as half as much again. The case hardening needs to be at least 0.010" or deeper. If it doesn't go deep enough, then it's like laying a sheet of 1 mm glass on a mattress then walking on it, it will break apart in 'sheets', but if say that glass was 10 mm thick, you could almost jump on it.

[sonikk4]

 

That's just the 'quality' of the ball joints.

 

These need more lapping. Last set I was given to fit that needed lapping took me around 2 hours per joint before I felt they were 'acceptable', so yes, an all day affair.

 

If they need lapping, I won't fit them.

 

The OEM ones TRW made for BMC / Leyland were ground finished and were ready to fit out of the box, no lapping.

 

I'm guessing those are no longer available? The previous set that I did were pretty much exactly the same in behaviour and they were 'genuine' Unipart items.

Is it safe to keep lapping them in until they fit? 

 

 

I did yeah. Assembled joint with fine grinding paste, rotated it by hand for about 20 minutes through all the range of motion. I didn't want to lap too much of it off.

 

To be honest i will replace the ones on Paddy as i did not fully lap them in. Could have done better. We need a supplier of ones we dont need to lap in.

 

 

When you say fully lap them in, do you mean you ran out of material safe to remove or you just stopped before they were perfect?

I don't want to remove too much from them and make them a liability but they're not much use at the moment.

 

 

I was caught between a rock and a hard place at the time Adam. I will say this they did last for two years with no issues and flew through each MOT. They were not perfectly lapped in. They did bind in a couple of places even with countless shimming etc. Now its full resto time i will be more pedantic with them.

[Deathrow]

I had the idea this morning to use a DTI to see how the upper surface of the swivel pin orbits in relation to the lower surface. I thought you guys might be interested to see this:

 

 

With that information, I decided to try lapping just the top face, I applied a small dab of grease to the lower seat and grinding paste to just the top surface and gave that a good go for around 20 minutes. I repeated the DTI measurement afterwards and found that Id made around half a thou difference. I shimmed up the joint again to see where I was at with the operation of the joint:

 

I think this is drastically improved here, while I've still got that small area that has a tiny bit of wiggle, the other areas are no longer tight, they can be moved around with a single thumb and light pressure. I tried taking .001 out and found the joint locked up so this is the happy spot. I used the DTI as best as I could to measure the end float in the bit that has play:

 

 

Apologies for the video quality. But it does show that in that area that does have play, there is about .002 of end float which is within the .003 the service manual outlines.

Does this seem ok? Ot should I have one last round of lapping tomorrow to see if I can improve it further?

[tiger99]

If it is only getting the shimming correct, the lapping is inappropriate and may even have a negative effect as the ball (or half balls of different radii) may end up non-spherical. The quick and easy way is to set the shimming up as close as you can get. If it is slightly too tight, take the small ball seat out and lap it's BACK on a carpenter's oil stone to fractionally reduce its thickness. If it is too slack, stone the flat face of the ball nut to allow it to go fractionally tighter.

People who adjusted the fit of bearings etc by techniques like that (and bearing scraping, and much more) many years ago we first known as FITTERS,a term that has now been downgraded to apply to someone who only changes spark plugs or brake pads. At one time it was an extremely skilled job. A few fitting techniques, such as the one I described, are easily learned at home. Bearing scraping, perhaps not...


Getting them right can be extremely satisfying. Have fun!