Problem mating steering rack pinion to UJ. Help please!

[bazking69]

Tanoon all

Car is a November 1999 E46 BMW 323Ci

We are having an issue fitting the rack onto the lower UJ at the moment.

Basically, we cannot get the rack to slip far enough onto the original lower UJ so that the bolt holes match up with the indent in the pinion where the bolts sit in to hold it together.

It almost seems that the pinion diameter on the new rack is too big, as it comes up about 1cm short of where it needs to sat down the pinion on the rack. It seems alot tighter on the new rack and will only go so far before it won't budge any further onto the pinion, even with a gentle bit of persuation from a copper headed hammer.

We have even removed the UJ from the car and tried to fit the two together off the car, and still no joy, yet the UJ goes straight on the old rack with the merest of knocks to sit it in place...

The rack is from ACS and is a refurbed rack. It all seems OK, and indeed a quick call to a very helpful guy who refurbs the racks at said company has confirmed that there is only one rack for the whole of the E46 range(externally, the only difference is the internal ratio for lock to lock) as I thought, and they sell about 20 of them a week with no issues.

So I am at a total loss as to why this rack won't slip far enough into the lower UJ? I have measured every part of the pinion on the rack with a digital vernier caliper at it is near enough the same as the old rack, allowing for the most nominal of manufacturing differences which frankly shouldn't make an issue. I have also counted the splines and there are the same number, with no offset ones to denote where it should be mated.

Obviously I don't want to force it with a beating and risk damaging either the splines on either the pinion or inside the UJ, or damaging the interals of the rack itself, but I have run out of ideas of where to go from here, as we have been struggling for hours with no joy. I have also thought about trying to prize the UJ neck open a tad but again am reluctant as it is aluminium not steel.

The only thing I can possibly think of is corrosion on the splines inside the UJ, as it did take a bit of persuation to remove it, so I have left it in the cleaning tank for the weekend (head part, not the rubber in the UJ submerged!) which a view to carefully scraping out the splines on Monday and trying that, but surely the UJ wouldn't go onto the old rack unless you put in back on exactly the same way if corrosion was an issue?

Any ideas appreciated. The car is stuck on the ramp at work at the moment and I'd appreciate it back ASAP!

[Tripe Bypass]

I did some engineering work on a E46 steering rack remanufacturing project some years back for the OEM supplier. Unless there was dual suppliers (i.e. somebody not TRW) then the only significant differences between older and newer racks were valve curve performance and the c-factor (the amount of rack travel per revolution of pinion). For the purposes of supply of exchange racks to BMW, all types were "lumped together" under one part number. I'd open the coupling up a tad, just don't go mad.

[bazking69]

Exactly what I thought. The only differences seem to be the ratio, as this new rack is a quicker rack and is 3.0 turns lock to lock compared to the old one that is 3.5. The guy who refurbs the racks says that they do this to keep it simple and use the lower ratio to make sure that the rack will fit models with big wheels to prevent the tyre from clipping the arch on lock.

I also believe all the lower UJs are the same across the range, so it must be down to corrosion why the old UJ won't go onto the pinion on the new rack

Parts cleaner and wire brush here I come!

Thanks

[Tripe Bypass]

The refurb man is incorrect in this instance. The travel of the rack stayed the same but the ratio of the rack quickened. Less turns lock-to-lock doesn't always mean the rack travels less. It doesn't matter now because I see on the BMW forum that you've managed to fit the UJ to the pinion end. Hope everything OK.