1972 Range Rover bolts

I can't tell you the sizes of all of them (they, the sizes, are not all in the parts book), but the parts are all the same up to 1985 - despite the parts book showing a separate drawing for early rear radius arms, springs and bump stops.

Richard

I've got a '75, but can't tell you what size those bolts/nuts are because I chucked them out years ago. Replaced them with proper length ones that don't have the mountings wearing on the thread. This was responsible for most of the rattles. Could never understand why they didn't make the mountings so that everything sat on the shank area. I had to use a few spacer washers, but it was well worth it.

PhilD

On or around Sun, 29 Oct 2006 12:48:59 GMT, "Rich" enlightened us thusly:

later radius arm bolts are 16mm.

Early ones MIGHT be 5/8" UNF - I've seen 5/8" UNF used, but they didn't fit as well as the 16mm ones.

Undoing a nut will tell you, if the thread looks quite fine, about 1mm pitch, it's UNF and if it looks more coarse it'll be metric.

Ah so it looks like I have UNF then as the threads are quite fine, would they be metric fine pitch ?? I presume I could just use metric high tensile bolts of the correct length instead as per the post above and ensure the bushes sit on the shank of the bolts rather than the threads, is this a better option or do I use the correct original spec bolts ??

Rich

OP's bolts will be 5/8" for the radius arm and the axle end of the rear arm. The panhard rod bolts will be 9/16", I think.

The difference between 5/8":M16, and 9/16":M14 will not matter as far as the bracketry is concerned as it's probably worn anyway. There is, I think an issue with the bolt size and the bushes e.g M16 bolt won't go through the early bush. Get the bushes first and find suitable bolts afterwards.

It mattereth not whether it's UNF or UNC provided the bolt and nut threads match. LR used UNF for what it's worth.

Phil's comment about not taking the side load on the threads is valid. If you can arrange the grip length/spacers to avoid it it's worth while.

I think the idea was that the side load was carried by friction with the plate onto the bush centre tube and nut. Certainly the pressure endways on the bush centre should be enough to prevent any movement. But despite this I agree that having the threads through the hole at one end is poor engineering. JD

That's certainly the theory and it's the only way that the rubber in the bush does any serious work. The most important thing in dealing with these and similar bushes is to maximise the contact area between the bush's centre tube and the bracketry. It's only about 3mm wide at best. If you want to spend time making any improvements in this area the best thing is to reclaim the holes in the bracketry and ensure that the bush centre tube has something flat and solid to bear against. Then keep the bolts tight.

Ok I like the idea of spacing to get the shank through the otherside of the axle brackets ect, but moving on a bit, what are the opinions on blue polybushes, yes I know this has been done to death but obviously they are easier to fit and replace in the "field" do they really tighten up the looseness in a slack Range Rover does stay tight, and what is the life expectancy for normal on road with a bit of playing at weekends is it as much as the original metalastic bushes?

Rich

On or around Sun, 29 Oct 2006 18:15:52 GMT, "Rich" enlightened us thusly:

If you buy replacement genuine ones they're apt to be metric. I've seen UNF ones, on a 110, but I've no idea if they were original.

can you measure the thread pitch?

Yes I can measure the pitch on the ones I have but cant on the ones I don't have.... I will let you know when I find the thread pitch gauge.

Rich

This is becoming overly complicated. Did you see my earlier note?

The thread form is irrelevant if you are changing bolts and nuts. Just make sure that the bolt fits through the bore of your bush.

Ok so will standard metric 1mm pitch High Tensile bolts and nylocks of the correct size do if they go thorough the bush tubes and using heavy washers to get the shank through the otherside of the mounting hole ?

Rich

The pitch is not an important issue. Don't waste your time trying to replicate the 5/8"-18 tpi (that's about a 1.4mm pitch) of your original UNF bolts in a metric form. Either repeat the 5/8" that you've got in either UNF (18 tpi) or UNC (11 tpi) or go for the commonest metric.

The most readily available M16 bolts will be the 2mm pitch. There are

1.5mm and 1mm pitch versions but expect to struggle to get them (especially without paying a premium). LR used the 2mm pitch.

Bolts should be at least grade 8.8 if metric.

Be careful about selecting the nylocs - most of those around are like cheese. To get the most out of your bolt you want a class 8 or higher nut to match your 8.8 bolt. If you've gone for 10.9 bolts there are class 10 nuts.

Blimey, can you get metric bolts of those diameters with 1mm pitch threads, you'll have to go easy on the tightening torque or you'll squash the bushes.

Martin

You actually loose so much torque in underhead and thread friction that it won't make much difference!

"Dougal" wrote >

The frictional area is still the same but the fine thread pitch will effectively gear it down so you will overtighten it if you're not careful.

"loose" I think you mean lose, it won't come loose either with a finer thread.

Martin

On or around Mon, 30 Oct 2006 18:30:46 +0000, Dougal enlightened us thusly:

It's irrelevant if you're changing the bushes - if you have bushes with accurate 5/8" holes, the 16mm bolts won't go through them.

If you're changing bushes as well, then it's easy, get bushes, get bolts that fit.

Right now I know where I stand, I think, so the only other thing to do is to decide whether to fit Polybushes or original, the fact of pressing in and out the original spec bushes does not enter the equation but I have never used polybushes and might consider giving them a try to draw my own opinions, I have heard good and bad about the poly type bushes and have searched Google very confusing many swear by them and others hate them !!!!!! :-(((( Don't know what to do !!!

Rich

I'll admit to a spelling mistake! Lose was intended. (Too close to bedtime.)

The effect of the fine pitch is well understood. In reality bolts of that pitch are not going to be readily available and it is also too 'delicate' for this kind of environment.