MG MGB Technical Rebuilding steering rack BBS discussion at MG-Cars.net

MG MGB Technical - Rebuilding steering rack

Hi George It's a little bit difficult diagnosing without seeing/feeling but we'll have a go First off , with the car sitting on the ground, if you lightly wiggle the steering wheel left right left right, does it have much movement , does it feel nice and connected or is there a loose spot in the middle --just wriggling it with one finger how far does the rim travel- If you do have excessive free movement in the wheel you need someone to move it L/R while you check to see if it's in the column--worn U joint-- in the rack itself--or rack mountings broken off the cross member Also in the attached pic. from left to right we have tie rod inner ball joint rack housing Are you saying the tie rod moves in and out in the inner ball housing, or is it that the whole rack shaft is loose and moving freely in/out in the housing, the housing itself is bolted down and doesn't move unless the mountings have cracked off the crossmember which can happen but reasonably rare If the boot is still in place you'd probably need to hold the ball housing through the boot so you can determine where the movement is or release the boot and slide it along the tie rod out of the way to see what's happening willy

William Revit

While we're on steering racks, and with your permission, George: this is off the '73 BGT (see recent Telescoping Steering Column post) - am I right in thinking it's a non-original but good quality addition?(by my PO) - it looks very much like one advertised by B Hive in the UK; but where the balljoint housing locates into either end of the rack tube at full turn, there is just metal-on-metal - I would have expected some sort of bushing to be there. Does anyone have the same rack and wish to comment? I am emailing B Hive separately in case they can help. Thanks again, John.

J P Hall

I may have misunderstood. The drivers end of the rack shaft is positioned by the pinion and its damper, and the passenger side by a bush 17H8664 in the rack tube which was originally felt or plastic but now seems to be phosphor bronze or similar. The ball joint housings just move back and fore inside the gaiters, and maybe the very end of the tube on full lock, but I wouldn't expect them to be touching the tube. Current racks seem to have an adjuster screw and locknut in the cover that was previously over the shims, to set the damper. There's been several complaints about the quality of these racks, including the components under the cover being fitted in the wrong order which allows the drivers end of the rack and track-rod to move about all over the place

paulh4

Thanks Paul. Comparing the original balljoint casing (see Willy's excellent photo earlier) with my aftermarket version, it is widely written that the original design enabled either (1) complete separation of the rack from the tie rod, by unscrewing the balljoint housing from the rack; or (2) adjustment of the tension of the balljoint, per John Twist 's video. The closeup of my aftermarket version below gives me the tiniest bit of hope that it might also be screwed together - see the little ridge where the rack and balljoint housing join, the width of a fingernail, in the photo. My understanding is that separation of rack from balljoint is the only way to remove the rack, examine the bushes, replace and reassemble. Has anyone tried (successfully or not!) to unscrew the Argentinian-made version? I don't have the gear at home to safely (nervously) attempt this, but have an engineer who can have a go for me on Monday. Thanks always. John.

J P Hall

The original certainly did allow for complete removal and adjustment of the pressure at the ball joint to control articulation, I've done both in the past. The threads were very fine and horribly easy to cross. The crucial aspect for doing those, that doesn't seem to be part of this ball-joint, is the threaded sleeve that locks into recesses in the ball-joint housing and the rack shaft to prevent the housing rotating relative to the shaft, as in the attached. Without a similar visible locking method I would suspect that it has been locked in some other way that won't allow non-destructive unlocking. The worst part of that would be if the rack was fitted to the tube before the ball joint housings were fitted, making it impossible to remove the rack shaft from the tube. But out of interest why do you need to disassemble the ball-joints?

paulh4

That's one reason why I've actually been keen to salvage my current aftermarket rack - in spite of the problem I've found internally - because even with apparently no centreing of the rack inside the tube, and no effective bushing at either end (but see below!), the bloody thing has been working well in terms of free and easy steering - albeit with a loud clunk on initial takeup of the wheel. SO - today I decided to remove the circlip inside the free end of the rack tube, and see what the moving part was, lurking behind the circlip. It is best described as TWO washers or shims, the innermost one smaller than the outer; absolutely no evidence of other bushing material - just two shims which I guess were originally a tight fit against the inner wall, but which by now are floating loosely! The inner rack wall appears to be slightly conical, hence the smaller innermost shim. But as far as I can see, these shims achieve nothing, nada, nix - their internal diameters are about 28.5mm and 30.5mm respectively, while the shaft (round section) is only 25mm. I can't understand why these shims were put in, unless I'm missing something. Thought others might be interested in this mysterious bit of engineering, especially if anyone has an "Argentina" rack on their car. I'm certainly going to follow up the possibility of inserting some properly functioning bushing at each end of the rack tube. John.

J P Hall

OK - doing my best, here are some measurements, Willy: The outside wall of the end section of the tube (some 87.5mm) tapers from 46.75mm down to 43.8mm, so we might assume that the inner wall of that section of tube reduces by the same amount. The visible part of the inner wall, immediately inboard of the circlip, measures pretty close to 35mm, so the most inward part of the taper is probably about 32mm - BUT the smaller washer only sits about 13-15mm down the tube; the outer (larger) washer is thus 13-15mm nearer the circlip, and the circlip sits in its groove. Follow?? A photo is attached, but it's b##### hard to get a good shot. I don't know whether this helps you to wrap your head around it, Willy! What a shame no suppliers seem to want to make a steering rack that we can open up and repair. Just sayin'. John. PS In the photo, what you can see right down the tube, is the smaller washer, poked down as far as it will go.

J P Hall

Slightly better lighting - the first internal "step" is part of the housing, 20mm down the tube; this is where the larger shim and the circlip go. What looks like a second "step" is in fact the smaller of the 2 washers/shims, sitting in place 20mm further down the tube. So it looks like a bush to interference fit from the lower washer up to the top washer, secured by the circlip. Measurements as near as I can get for the bush would be: o/d 35mm, maybe tapering to 32mm. i/d 25mm. Width 20mm. I could also put a second bush in the outer section of tubing, but it would need to be secured somehow. John.

J P Hall

Drew a roughy up for you--something like this would work

William Revit

Quick update for Willy and anyone interested: as luck would have it, my new (aftermarket/reproduction) rack arrived from MGOC on the very day I was in Townsville showing the "old" one to a steering/cv joint specialist. The specialist reckoned it would be a few hours work to strip, create and fit a bush at the free end, and reassemble - at $160 an hour plus at least $200 for materials. It was a short conversation, as he was not interested in helping me by just making a bush and letting me worry about prepping, fitting and reassembly. So my mechanic son looked at my early thinking, plus Willy's drawing - while at the same time examining the bush arrangement in the brand new item supplied very promptly by MGOC. Conclusion: the new rack has a white neoprene(?) bush at the free end in almost exactly the position I had first considered (ie the outermost section of the rack housing), BUT held in place by a grub-screw. I think this type is mentioned in Paul Hunt's Steering section. We can try to fabricate a slightly tapered bush in HDPE, with a split in it, to slip over the shaft and push down inside rack housing - held in place by the original retainer and circlip; OR we can make a simpler bush, akin to the new MGOC example, not tapered, and add a rollpin or grub screw to help retain it. Theoretically, we could do both. The first photo just shows the look of the new rack, with the rhs boot pulled back to reveal the "sealed for life" balljoint housing. The second photo is a closer look at the balljoint housing and the grubscrew. Again, the new replacement rack does not appear to allow separation of inner balljoint for withdrawal of the rack - so not helping maintenance or repair. I plan to buy some black HDPE stock and get a mate to practise making bushes. Cost - a few beers. Will report more soon. Yours, John.

J P Hall

This thread was discussed between 06/11/2020 and 06/12/2020

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