Series 3 Parabolic Problems

I'm up to rolling chassis stage in my SWB S3 restoration.

I have got GME parabolics mounted front and rear. Standard Rover diff at front. ENV diff at rear. Standard 2.25 engine and box.

When I bought it, the car had been a farm wagon for about 20 years and had been severely abused. Lots of stuff did not fit or had been bodged. The propshafts were identical - both were fronts. But strangely enough, they did fit! It was on standard springs.

Trouble now is, the front prop is too short, by about 30 mm. And the rear is too long, by about 10 mm.

Now I know the rear shaft that I have is actually a front shaft, so it is no surprise that it does not fit. I have ordered a rear shaft and so that end of things should sort itself out. Question is - why does the front shaft not fit right? I mean - it is miles out.

My thoughts on what's wrong:
1) Extra ride height from the GME springs is to blame.
2) Are the axles in the correct position relative to the gearbox (ie front to back) - Both axles appear to be a bit forward of their respective bump stops. They would hit them on full bump, but not squarely. I have measured the overall wheelbase and it is spot on for 88". So it may be that the axles are both a bit far forward. Which would point to the springs.

I am running new, standard SWB shackles all around. The springs appear to be symmetrical, ie it would have made no difference if one pair were reversed front to back, the mounting for the axle is in the middle. All the springs are the same way around, ie the writing on all four is the same way up, viewed from above.

Anyone got any experience with probshaft problems associated with GME springs? I could get a front shaft fabricated, or put a spacer in, but I don't want to bodge a workaround if I am missing something fundamental.

Cheers
Andrew

Could be just the fact yours is just a rolling chassis without the weight of engine, gearbox, body ect.
This is a question that comes up quite often when folks are doing a total rebuild no matter what type/make of springs.
New springs of any type take a bit of time to settle in their every day position even on complete trucks. Prop will close up as the weight comes on and they settle. Don't overthink this.

As tottot said and you probably can't fit the shocks either, when i did my ground up rebuild i couldn't fit the shocks till all the weight was on the springs, GME paras and std shocks then

Hi guys. Thanks for your input.

Bit more detail:

Engine and gearbox/transfer case are in. Shocks are on. Battery is in. Bulkhead is on. Fuel tanks and exhaust are on.

So there’s a bit of mass there.

I guess at the risk of overthinking it, the most disturbing thing I can see is that the front axle really doesn’t line up with its bump stops, and the difference is roughly the amount that the prop is short by.

It’s late now here, but I will get a couple of photos posted tomorrow to illustrate the point.

I don’t think it is just the lack of sag in the springs. Sure, that is not helpful, but it does seem as though something else is out of kilter.

Photos may assist a diagnosis!

Cheers
Andrew

Here are a couple of photos of the situation.

I am pretty certain that the front springs are symmetrical. It is 440 mm from the centre of the front spring hanger bolt to the middle of the axle, and 440 mm from the middle of the axle to the rear spring hanger bolt.



If it looks like the axle is forward of the bump stop in this shot, that's because it is, by about 35 mm. Is this normal? I know that the distance will tend to decrease as the axle rises up, but only by about 15 mm or so. It doesn't matter what the axle does, it will never hit the bump stop square in the middle.

Here's a view from directly above the centre of the axle:


This shows that the axle is well forward of the bump stop.

The final picture shows the missing propshaft - with a tape measure inserted as a cunning replacement.



I guess it does not really matter which way I stare at this - if I leave the setup as it is, I am going to need a longer propshaft than standard. Any advice on a factory option? I see that the Defender flanges are the same as Series ones, but I am not sure what lengths are available. Early Range Rover might also be an option. A bit more Googling required.

If anyone can shed any light on this for me I'd be very much obliged. It seems to me that there is only one way to assemble the parts I have, and this is it. What I need to know now is what my options are to make it all work! The engine and box are possibly a short distance rearward from optimum. There is a little bit of offset in the slotted mounts under the gearbox, but the difference probably amounts to maybe 5 or 6 mm, certainly not the 35 mm I need to correct this debacle.

Any wisdom will be appreciated.

Oh and if anyone is interested, this is the Heystee Defender disc brake setup, on a Series 3.

Cheers
Andrew

I was going to say that loading the vehicle to get the suspension to move so that the old prop shaft can be made to fit, isn't really a solution. When you drive and the suspension needs to move as intended, it's going to rip something out of the gearbox and/or diff.

I'd really look at why the axle is out of position. The springs may well be symmetrical, but are you sure they are the right ones? Someone else on here had fitted a rear spring to the front previously, as I recall. They are different lengths.

TheMegaMan said:

I'd really look at why the axle is out of position. The springs may well be symmetrical, but are you sure they are the right ones? Someone else on here had fitted a rear spring to the front previously, as I recall. They are different lengths.

Click to expand...

Scratch that - I think I'm talking bo11ox. I've just been out to look at mine, and the rear springs are waaaaay longer, (over a metre long), so I don't think you could have mixed them up. Which baffles me as I'm sure someone said they had, a while ago. I'll have a look and see if I can find the thread.

FYI, my axle is also slightly in front of the bump stop centre line, but maybe not by 35mm. I'll try and get out to check it properly at some point, but it'll probably be a couple of days before I get a chance.

This is the thread: https://www.landyzone.co.uk/land-rover/rear-axle-alignment-problem.366965/

It was actually the rear axle that was the problem, not the front. Almost certainly irrelevant to your problem, but does show simple mistakes can be made...

Megaman - I had a minor panic when I read your first post and rushed down to the workshop to measure the springs front and rear....!

I have had another good look at the front setup. It all looks fine. The shackles are more or less vertical with the current loading (missing the front wings and the bonnet, but that's about all at the front). The axle is right in the middle of the spring, on the little locator bolt. Reversing the springs would not make any difference that I can see.

In order for the axle to be in the "correct" place (nobody has confirmed yet if their axles actually line up with their bump stops, but let's assume that they do/should) it would need to slide back along the spring by about 35 mm, OR the spring would need to move back by the same amount. The spring position is obviously governed by the position of the front spring hanger, so unless my chassis has been modified, that should also be correct.

Unfortunately I threw my old front springs away when I took them off. They were rusted solid and had a couple of broken leaves, so I picked I wouldn't be using them again. So I cannot measure them to compare.

I have a mate down here with an 88", so I will get under his truck with a tape measure in the next few days and confirm where my setup is different from his.

Meanwhile - I will make a few enquiries about longer props.....

Cheers
Andrew

Kiwi Landie said:

Megaman - I had a minor panic when I read your first post and rushed down to the workshop to measure the springs front and rear....!

Click to expand...

Yeah, sorry about that. I should have looked at mine before posting!

Wondering whether the simple answer to this is:

1) Remove front axle/spring assembly.
2) Separate axle from springs.
3) Remove U bolts and take off the bottom spring plate.
4) Redrill the locator hole about 30 mm back.
5) Weld up the old hole.
6) Reassemble.

This will have the effect of moving the axle back to almost in line with the bump stops, thus neatly solving both that issue and the short propshaft issue as well.

Sound like a reasonable idea?

I did measure a mate's 88" and his front axle is forward of the bump stops, but not by as much as mine. He is on standard springs.

Where you shackle bolts all tightened before the engine and gearbox where fitted?
If so loosen them and add some weight to front bumper and see how much the axle moves back under load , a few mates strategically placed may do it.

Yep - I will try that before I dismantle everything. Might gain a few mm.
My basement workshop has a concrete roof so a couple of jacks on top of the dumb irons may have to do instead of the fat mates!
Thanks

Have you standard engine, gearbox/transbox fitted?
I have a 1979 3 for restoration and the front propshaft is 615 mm no matter how I jiggle the gearbox (no engine in at present).
Springs, old set are 440 centre of hanger bolt to centre of 'leaf bolt'.
Have a set of GB Parabolics and both fronts are 445 and 450 over same measurements!
And Bump Stops, they will always sit behind the axle 'seat' because the axle is going to move backwards when under pressure, how far back is thing.....

Stop, what ever you do DO NOT drill the springs. This will weaken them at a section that moves and welding will destroy the temper.

You are with out doubt over thinking this.

As David says above, " They will always sit behind the axle seat because the axle is going to move backwards under pressure."
Also as they settle parabolics will flatten out some.
If you are not happy with the parabolics then get a set of standard springs and be happy.

Kiwi Landie said:

Wondering whether the simple answer to this is:

1) Remove front axle/spring assembly.
2) Separate axle from springs.
3) Remove U bolts and take off the bottom spring plate.
4) Redrill the locator hole about 30 mm back.
5) Weld up the old hole.
6) Reassemble.

This will have the effect of moving the axle back to almost in line with the bump stops, thus neatly solving both that issue and the short propshaft issue as well.

Click to expand...

What this will achieve is to move the plate so the U-bolt fixing holes are in the 'correct' position, but when you place the axle on the spring, the locating dowel will still be in exactly the same position, so the axle will also still be in the same place - just that the fixing holes will now be in the wrong place. It's the dowel that's incorrectly placed, surely?

Just a thought - I assume there is only one hole in the bottom of the axle that the dowel can locate in? There isn't another hole further forwards that you should be using instead, which would move the axle further back?

I'm still worried by the comments that it might be the vertical position of the axle/shackles that's causing the problem. as I said previoiusly: "I was going to say that loading the vehicle to get the suspension to move so that the old prop shaft can be made to fit, isn't really a solution. When you drive and the suspension needs to move as intended, it's going to rip something out of the gearbox and/or diff."

The suspension is going to move when you drive it. The prop shaft needs to be able to cope with the suspension in any position, or something is going to break sooner or later.

Put an over long prop on and it will bottom out when suspension reaches full movement when hitting a big bump, if lucky you would probably rip engine and or gearbox rubber mount apart.

Are the axles located on the protrusion on the springs correctly.....GME springs are good.....something is very wrong.

Hi All

Tottot is correct - I have given this a lot of thought - but necessarily so in my view. Things are clearly amiss at present. I cranked up a decent push down on the front of the chassis last night and can confirm that no amount of loading is going to correct the mismatch such that the standard prop will fit without it being stretched out to the max.

David - I have a standard 2.25 engine and box.

Nick - Yes the locator dowel sits nicely in the middle of the U bolt plate hole on both sides.

By my measurements and by comparison with a set of standard springs, the dowel in the centre of the GME springs is too far forward by about 20-25 mm. The springs I have are symmetrical so cannot be mounted 'wrong way around'. My proposed solution was to simply redrill the hole in the bottom spring plate (the one the U bolts go through). This having the effect of sliding the axle backwards along the spring, so it is in more or less the correct position. I agree that drilling the springs themselves is not a good idea at all.

I agree that having the axle a little forward of the bumpstops is not a bad thing when the vehicle is static and lightly loaded - the axle will tend to move back a touch as the springs flatten out under load. However, by measurement, even if the spring is flattened right out, the locating dowel (and hence the axle in its current setup) is still well forward of the bumpstop position. This (in my mind anyhow) has to be incorrect. After all, 35 mm is half the length of the bumpstop. I could see 10 or even 15 mm offset being beneficial, but not the amount I have.

I also agree that having a propshaft that is not in (roughly) the middle of its slip length when the vehicle is static will eventually end in disaster. Hit a bump and you will push hard on the transfer case, go over a hole and the prop will fall apart.

So - the question is - is the dowel position in my springs incorrect? I have measured the chassis against another truck and the key dimensions are identical so I don't believe my chassis has been modified.

If the dowel is wrong, is there fundamentally a problem with redrilling the U bolt plate to slide the axle backwards a bit?

I have asked Paddocks for their opinion on the springs. Not heard anything yet and am not overly hopeful of inspiration from this quarter. I may be wrong though.

I'm reluctant to chase down a longer prop if my suggested modification will work.

Thanks all for your input thus far.