11 replies to this topic

[chuee]

I am  wondering what are the worst, most severe, cases of suspension wear liable to cause premature wear on the rack bushing.
 

Sure, EVERYTHING counts, and combines,  but What worn  components are most likely  to lead to failure in short time?    

I'd appreciate your experience and knowledge here, in a discussion, in order to help appreciation of forces.

 

For example, worn wheel bearing on d/s - would that  be as likely to cause wear in short time as a tie bar bracket with elongated holes?  Perhaps not. What about ball joints, certain bushes, mounts,  damper pins,  and other sacrificial components?

 

Some Vehicle history here:

---------------------------------

The worn rack was an original,  factory fitted on a  mark IV vehicle,  with about 70,000 miles on clock. It was on the way out when I acquired the car about five years ago,  and has got increasingly  worse with regular driving over bumpy roads.
My p/s rack  bush has by now deteriorated too far, I have the  steering rack removed, awaiting the new one to arrive. . Otherwise the rack seems good, but yet to dismantle and examine further and  I wonder if the ball end of the arms have unduly suffered, which is why I ordered a replacement.

I expect the replacement will  have a similar  grey  'plastic' (duralite?) bush, which in spite of doubt raised in favour of brass bushing, may in fact be perfectly adequate.

Since taking the motor over,  I replaced 13" wheels with 12",  reverted to standard ride height,  and have gone through entire suspension to  restore working parts that were or could be worn - all the rubber,  ball joints and  pinions. Also engine mounts, tie bar and bracket which had elongated holes,  wheel bearings, tie rods.

I have strengthened the rear front subframe mounting area of the floor, because it had been fitted with solid mounts along with solid turret bushes, which I like.

As I gradually improved all such aspects of suspension I got better at determining which unwelcome sound/symptom was which.

 

 

 

 

 

 

 

 

Cheers JOhn



 

Edited by chuee, 16 June 2025 - 04:37 PM.

[Cooperman]

I remember the original felt bushes on early cars - really poor.

We used to remove the rack gaiter, remove the steering arm, prise back and flatten the flange holding in the felt bush. Then we would fit 3 of the plastic bushes with the short grub-screw replaced to hold the centre on in place, then knock the flange back up with a small punch. 

The steering rod was then refitted, the gaiter clipped back in place after a quantity of engine oil was added.

Steering was a bit stiff for a few miles, but soon loosened up and the 3 bushes lasted for a long time.

[Spider]

Every single bump in the road, first pushes the wheel back and then forward as you drive over them. While most of that is taken up by the suspension,a fair deal of it is transmitted to the steering rack. As well as this, so are acceleration and braking forces too. The factory in their wisdom, fit the racks to the middle toeboard rather than the subframe, this was to offer some 'give' ('cushioning') to the rack.

 

They were originally designed to work with EP90 weight Oil and that was what they left the factory with, however with recurring warranty claims from oil leaking from the rack, a decision was made to swap to grease in the mid 70's. While that got them through the warranty period, the racks don't last nearly as well and can seldom be refurbished.

 

Back on the 80's, I used to overhaul these on a commercial basis for around 10 years for many of our local Mini parts suppliers. What I found was those that had grease in them, the inner rack would wear badly on the gear teeth, on that back side of that where the Yoke would slide, the Pinion would be badly worn, the bearings would be shot, the Rod End balls worn and on some, even though they had a felt bush (we retained them until 1979), they would show signs on wear on the inner rack there too.

By comparison, those that had oil in them, would usually show light wear on the rack teeth, often the pinions showed no wear, the bearings were nearly always good to the point of being reusable, there would be some wear on the back of the rack from the yoke, though this could either be adjusted out or a few minutes with lapping paste would have it back to a serviceable condition, the rod ends would seldom show wear. The felt bush would always be squashed flat and in out local racks, they had bevel springs for the yoke, nearly always one of these would be smashed, otherwise, it wasn't often these could not be overhauled, it was more usual that they couldn't be if the boots had torn and the oil leaked out that they were unserviceable, in a similar way to those with grease. Even today, now many of these racks are some 45 years later, these oil filled racks can still be overhauled. There's a couple that I have seen that I did 'back in the day' that have done over 300,000 km and other than replacing the boots a few times in that period, they are still going well. I'll add here that the felt bash, as Cooperman mentioned, would give poor life, I seldom fitted these to the racks I did as they were a bad idea.

 

I also find that when filled with oil, the racks had a nicer feel.

 

The new racks I believe are assembled with grease.

 

One other thing here too, is that I mentioned the racks are fitted to the Toeboard. I have noticed that some of the new replacement Toeboards are of the slightly thinner gauge and not stress relieved after pressing to shape. Using these can give a very poor feel and they give excessive flex to the rack mounts.

[chuee]

Every single bump in the road, first pushes the wheel back and then forward as you drive over them. While most of that is taken up by the suspension,a fair deal of it is transmitted to the steering rack. As well as this, so are acceleration and braking forces too. The factory in their wisdom, fit the racks to the middle toeboard rather than the subframe, this was to offer some 'give' ('cushioning') to the rack...

@Spider: Great Information -  all that you wrote in reply covers the topic question  very well !  Grateful for that.

I remember the days of oil filled racks - about that time of the changeover; When I got into minis at end of seventies, I would get to hear such  'complaints' parrotted, because most  minis on the road with a few miles had oil filled racks.

Q> > Would you say that i should fill this new greased rack with oil? I.e. By simply adding gear oil to mix with the grease applied by factory?

Edited by chuee, Yesterday, 02:52 PM.

[Spider]

Glad that was of help.

 

Q> > Would you say that i should fill this new greased rack with oil? I.e. By simply adding gear oil to mix with the grease applied by factory?

 

I've not had one in my hands to see the make up of them and no doubt, there's a few different manufacturers of these, so I can't say with certainty, but given their poor life, if it were mine, most like I would strip the rack, clean and inspect, then on assembly, fill (200 ml) with EP90 Oil. Be aware though, I'd almost certainly say, putting oil in them would likely void their warranty.
 

[chuee]

Glad that was of help.

 

 

... but given their poor life, if it were mine, most like I would strip the rack, clean and inspect, then on assembly, fill (200 ml) with EP90 Oil.....

AH too late! It arrived and I fitted it this afternoon.  Well then, what about mixing the oil with the grease, by topping up with oil - what do you say to that? Good Idea? Bad?

Edited by chuee, Yesterday, 07:30 PM.

[chuee]

I fitted the new rack today.

Lowering a subframe, at its front and rear with engine in was a new thing for me, and so I took great care to observe movement when lowering my jacking system.

Essentially, I supported the body at the jacking points by lowering it onto  ramps topped with a layer of  wood to protect the sillls. It scared me until it was well in place. I thought about the weight.

Next, I supported the front of the front subframe with a beam accross the mounting lugs, and a qulaity hydraulic jack under that. It was solid, and wouldnt move away, inward or outward, at all.  Toward the rear of the front subframe, under the upper  steering arm, i raised scissor jacks, good and solid, no sinking with them, one each side.

SO, I managed without jacking and lowering under the sump - no undue forces on the engine mounts.
I found I had to lower at the front of the subframe as well as its rear in order to get it to drop sufficiently for clearance to replace the rack.

 

I eyed up the u-bolts comparing them with the old,  I could see one old one was definitely across its ends. Trying to fit it with the rack was impossible. I had to bend it in a vise by about two god millimeters to get it to fit, and the other ubolt about one millimeter.

I noticed the u bolts were longer than the original by 1/4 of an inch. I can't think why that should be, except  just to make it harder for me! I gained a little extra clearance to cope with that, so I was able to install the new ones.


I suppose the friction strips are there as a washer, to take up unevenness due to machine tolerances; Possibly also  to prevent rapid oxidation at that point, where the two dissimilar metals touch. A good idea overall. I puta touch of silicon grease on there too, because if that is what the strips are for....

Edited by chuee, Yesterday, 07:41 PM.

[chuee]

I am thinking that a bronze bush is a good idea on our racks. I can understand the difficulty expense of fitting one at factory. For myself, I am going to strip the old rack , and if Its in good enough state, install a bronze bush.

[chuee]

The counterpart to the topic question is this:
Q>> Given excessive wear of the p/.s bush, what effect will that have on promoting wear in the rack?

Judging by the knock produced upon acceleration, I imagine a large effect, and that a car shouldn't be driven in that state for that reason, in addition to feel/driveability - like  twitchiness in steering at high speed.

Edited by chuee, Yesterday, 07:40 PM.

[Spider]

AH too late! It arrived and I fitted it this afternoon. 

 

 

Too late ? It's only 'nuts and bolts' to get it back out again

 

 

I am thinking that a bronze bush is a good idea on our racks. I can understand the difficulty expense of fitting one at factory. For myself, I am going to strip the old rack , and if Its in good enough state, install a bronze bush.

 

 

The counterpart to the topic question is this:
Q>> Given excessive wear of the p/.s bush, what effect will that have on promoting wear in the rack?

Judging by the knock produced upon acceleration, I imagine a large effect, and that a car shouldn't be driven in that state for that reason, in addition to feel/driveability - like  twitchiness in steering at high speed.

 

It seems that the early racks that used the felt bush were done so as a way of avoiding precision alignment of the housing or the need to line bore a more solid bush after fitting to the body. These were all made by an external supply contractor to BMC / Leyland / Rover, originally it was Cam Gears and at some point, TRW were making them under license to Cam Gears. The felt needed to be kept wet with oil to keep it swollen and maintain it's size, it was an inexpensive means of providing a bearing that would also self align and was noise free.

They started fitting the plastic bush after a few years (though we only got them very late, after local rack production ceased). If you look at them, they don't contact the inner rack all the way around, but are on 3 small 'pads', and they way they fit up, under these 'pads' on the OD, they are unsupported, so there's quite a lot of room to move so to speak, exactly what we don't want in our steering ! But it does allow for alignment. In my very early days of trying to improve these racks, I did try a nylon bush, it made sense, but was an utter disaster. I found that rather than sliding, it tended to grip the rack, so it was impossible to have a nice smooth sliding action. Long story short, I tried Bronze and well, never looked back, though it's not a matter of turning up a bush, fitting and assembling. Being a 'harder' material, running clearance needs to be small (I give them 0.0007 to 0.001") or it will rattle horribly on every single bump (going back to my first lines here) and it has to be quite precision aligned with the 'business end' of the rack or it will lock up.

1 of the 2 racks I mentioned above that's done the longer miles is fitted to my wife's Moke. I first fitted that in 1985, shortly after we met (she only wanted me for my rack!), other than new boots and during an overhaul of the whole car about 15 years ago, I striped the rack to inspect, at which time the only other new part I fitted was the pinion seal, it was perfect, didn't even need adjusting. I'll add here that Mokes with their big and heavy wheels are very hard on Racks, add to that, where we take them (often hundreds of miles of corrugations), I think it's fair that these have been 'tested' and passed.

There's a great pal of mine in the UK, Peter Laidler who does racks with Bronze Bushes. He only does this as a hobby though, he's not a commercial operation. He's not on this forum, but you can find him on the MKI forum.
 

[chuee]

 

blah blah...

There's a great pal of mine in the UK, Peter Laidler who does racks with Bronze Bushes. He only does this as a hobby though, he's not a commercial operation. He's not on this forum, but you can find him on the MKI forum.
 

 

Cheers Spider Appreciated. I dont think I could fit a bronze bush myself, with only a small lathe, given the need for alignment.
I'll contact him once I've stripped the old one, and find out if he's willing, and where he is based.

Edited by chuee, Yesterday, 11:40 PM.

[timmy850]

I rebuilt one of our locally made Australian steering racks (AYA6001) last year using a bronze bush from Spider. So far it’s been really good and no problems