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MG TD TF 1500 - steering rack play

Hi,
Trying to fix a little play in the steering rack. The car is a pleasure to drive with an accurate steering. But when driving through bumpers too fast, there is a knock noise on the left side. The car is RHD and the play is on the left side only. The ball joint is not the culprit. The play is radial and between the steering bar and the housing. The diameter of the bar is compliant with the specification of the WSM but I can't mesure the bore housing. Hence probably worn.

Another hint is that on some positions, it is possible to rotate a little bit the rack bar. A few degrees, not more. It seems that the only thing that prevents rotating is the pinion. So probably a little wear also on the teeth on either side.

I could buy a new one but it's rather expensive. So my idea is to install a second plunger on the left side of the housing. A flat area is already existing probably for this purpose on other cars.

What do you think of it ? Has someone done it ?

Laurent.






LC Laurent31

Way out of my league but can you have the bore housing sleeved?
Christopher Couper

we have done this on quite a few cars belonging to members in our local MG Octagon car club.
I think one was intended to go there but bean counters probably denied.
I did my own over 20 years ago and have never had to adjust it. I did not bother to fit a spring and button, I just drilled and tapped the housing and used a brass bolt and locknut.
Ray TF 2884
Ray Lee

Ray's brass bolt and locknut is a magic idea
do that---
Just out of interest--I have a ZA/ZB Magnette rack in my Y Special and they have a plunger or something there already, There's no adjustment externally so I would guess some sort of spring loaded thingy--I've never pulled it out for a look but can if you want to know what's in there-


William Revit

I did something similar to TF2071 in the early stages of the rebuild. As Laurent suggests it seemed like an obvious solution. In fact I just found the discussion on the other forum under Steering rack play

The car has only recently been driven for the first time in 40 years but apart from feeling a little heavy (after so many years of power steering) it feels very precise on corners but I suspect I need to tweak the toe in (crudely set at around 2mm using the string and tape measure) as there is a hint of a slight tendency to wander on the straight. steering wheel play is around 3mm

Hope his helps

Chris.
C I Twidle

The steering should feel light, so also check your tyre pressures.
Dave H
Dave Hill

Christopher, ID is about 28.5 mm. Only 10mm more for the external diameter. The inserted bush should be at least 2 mm thick leaving only 3 mm thickness for casting : to weak in my opinion. And rupture would be very dangerous.
Definitely no.
Let's note that the nominal play indicated by the WSM is 0.4 mm at pinion housing. Not very accurate but I guess this is the damper that cancels this nominal play. So I will do the same technique for the other end.

Laurent.

LC Laurent31

the main problem is that the bearing surface is not fully circular. To reduce friction the rack has 3 flats machined on it which causes spot wear. The added damper takes this out and as I say, mine has lasted a long time, it will probably see me out :-}
Ray TF 2884
Ray Lee

Hi Ray,The flats are not to reduce friction. But to allow for oil and air movement inside the housing. This is the purpose of the patent N° 539083 (Alexander Issigonis). Written on the patent plate on the scuttle of our cars.
For sure I'm gonna add a second damper.

Laurent.


LC Laurent31

Laurent,
Thanks for that, makes perfect sense.
Ray
Ray Lee

The bar shows a blueish color at the middle. As it was slightly heaten. Is it possible that the lack of oil could lead to such a temperature ? That color is also visible at the back of the bar.
However, I can't see any wear on the teeth. Neither color nor wear on the pinion side.


Could it have been treated for herdening ?

Laurent.



LC Laurent31

Interestingly, the Morris Minor WSM has a procedure to add a secondary damper to the rack. This applies to early cars as later Minors had the secondary rack damper as stock. Damper cup and spring are still available from companies such as ESM in the UK.




John Quilter (TD8986)

And here is the job.
Laurent.


LC Laurent31

LC Laurent is that wear on the top of the tooth adjacent to the blued teeth on the right of the pic or some sort of reflection? Yet to delve into the mysteries of the TD steering. Cheers
Peter TD 5801
P Hehir

Reflection. There is no wear on all teeth.
Laurent.
LC Laurent31

This thread was discussed between 16/11/2019 and 01/12/2019

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.