2 replies to this topic

[wg83]

I'm fitting new pivot pins for the upper suspension arms. To remind you what the setup is: The unthreaded part of the rear end of the pin goes through the thinner thrust washer and the clearance hole in the subframe and is held in place by a spring washer and nut. The unthreaded part of the front end goes through the thicker thrust washer, which sits in the clearance hole (or perhaps an interference fit hole) in the subframe and is held in place by the retaining plate, which is held by two 1/4" bolts, and a spring washer and nut then goes on outside of the retaining plate.

 

My old pin fits very snugly in the holes in the old thrust washers and in the hole in the subframe. (All of the old bits, including subframe hole, are in good condition and have not become over-sized with rust). This means the old pin barely moves at all, which is what I would expect.

 

The new pins have a looser fit in the thrust washers, such that they can move a bit at the front end. Is this bad? Even when the spring washers and nuts are done up fully, I'm sure they won't overcome the forces on the upper arm and and hold that pin from moving - surely the pin will be continuously moving in the hole? I'm concerned that it will cause the pin, or the front thrust washer hole to wear, or for the spring washers to rub on the retaining plate face and wear it, causing the front nut to become loose.

 

The thicker washer itself fits perfectly in the large hole in the subframe, which is good.

 

At first I thought the parts I bought had been made wrongly, but I got some from another supplier and they were also a looser fit than my old ones.

I've taken some measurements and found that the pins are consistent in their diameters to within 0.04mm: they are an average of 12.58mm. The problem seems to be with the washers: the originals have a 12.74mm hole but the new washers have 13.00mm and 13.05mm holes, meaning that whereas the old pins could move in their front washer by about 0.15mm, the new ones can move by over 0.4mm. The hole in the subframe is about 12.7, which is consistent with the holes in the old washers, and means the pin barely moves at that point.

 

What do you think?

[Spider]

The plain ends of the shaft should be 0.497" to 0.499" dia (12.62 to 12.67 mm) and the holes in the Thrust Washers were 0.500" to 0.509" in dia. (12.70 to 12.93 mm).

You'll find that once assembled and the suspension loaded, the ends of the pins will settle in one position and stay there.

[DeadSquare]

I'd worry if the "Big thick washer didn't fit perfectly in the large hole in the subframe", but the holes being 13mm, not 12.5mm is annoying rather than critical.  Think of it as better to be too large than too small, although the engineer in me says "Why can't they use the correct size drill ?"

 

We have to be grateful.  It is the price that we pay for somebody making non standard parts for us.

 

As Spider says, it'll be OK.  if you lower the car on to a block under the bottom swivel joint and then nip the 1/2" nuts up tight, you can't do any more.

 

 

P.S.  Are the original washers in sufficiently good condition to be reused ?