P38A Bit of a wobble

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
G

Ginger Tom

Active Member
Posts
63
Location
Wisbechistan
Morning all,

Since owning the P38 it's had a wobble.

First though was the prop-shafts, checked and found that the front u/j's were out of line, sorted that and the wobble was subdued, still there but less so.

Checked the tyre, found scalloped, presumably from the imbalance of the prop-shaft. Thanks to a blow out when green laning it's now had four new boots and the wheels have been rebalanced so that negates it being the tyres.

Again changing the tyres has subdued the wobble further but it is still there.

The wobble is at its worst from 50-55mph stops between 56-60mph and then it's back but to a lesser extent.

Has anyone else had this, going through this atm, got any other ideas as to what it could be???

Cheers

Tom
 
As above the P38 is very susceptible to tyres, size and pressures.....especially when running 18" ...... the pressure need to be spot on and at times not what the book says and it is a case of trial and error till you get a reading that rides well.....then when you change tyres, you have to do the whole trial and error again!
 
I've found "wobble" on mine in the past and have always attributed it to poor balancing or a "missing" weight. Always started at c.55MPH and disappeared at around 65MPH.
There's stuff on You-Tube about P38 "Death-Wobble" as the Americans like to term it.
 
Front tyres 28 psi, rears 38 psi. Are the wheels still round after off-roading?

UJs are definitely where the suspicion would be. There was a big argument on here a while back about the "phasing" of the prop-shafts and I've got a feeling that Britpart were different to the GNK originals. I put a video up in a thread somewhere about testing the UJs. They're on Youtube.

Another thing to check would be the VCU, especially if you have scrubbing on the outside of the front tyres. Lifting a front wheel, transmission neutral, you should be able to tease the 32mm hub-nut to turn the wheel with about 70 nm of force. If it is taking 140 nm then it is probably worth swapping it for a refurbed one.

Then there's radius arm bushes, drag link, track-rod ends and swivel-hub joints.
 
Datatek said:
Common problem, what size wheels and make of tyres are you running?
Click to expand...

Saint.V8 said:
As above the P38 is very susceptible to tyres, size and pressures.....especially when running 18" ...... the pressure need to be spot on and at times not what the book says and it is a case of trial and error till you get a reading that rides well.....then when you change tyres, you have to do the whole trial and error again!
Click to expand...

DanClarke said:
I've found "wobble" on mine in the past and have always attributed it to poor balancing or a "missing" weight. Always started at c.55MPH and disappeared at around 65MPH.
There's stuff on You-Tube about P38 "Death-Wobble" as the Americans like to term it.
Click to expand...

Saint, Datatek and DanClarke

I'm running 255/55 19 Nankang's. Not sure on they tyre pressures and I would doubt there were any missing weights as the tyres were only fitted yesterday morning but as I said it has helped lessen the wobble and it doesn't happen between 56-60mph.

Grrrrrr said:
Front tyres 28 psi, rears 38 psi. Are the wheels still round after off-roading?

UJs are definitely where the suspicion would be. There was a big argument on here a while back about the "phasing" of the prop-shafts and I've got a feeling that Britpart were different to the GNK originals. I put a video up in a thread somewhere about testing the UJs. They're on Youtube.

Another thing to check would be the VCU, especially if you have scrubbing on the outside of the front tyres. Lifting a front wheel, transmission neutral, you should be able to tease the 32mm hub-nut to turn the wheel with about 70 nm of force. If it is taking 140 nm then it is probably worth swapping it for a refurbed one.

Then there's radius arm bushes, drag link, track-rod ends and swivel-hub joints.
Click to expand...

Grrrrrr,

Phasing on uj's is a problem, when I used to work on trucks you only had to be one spline out on the slider and it would cause a massive wobble. I don't suspect the VCU as the tyres that came off were very evenly worn which surprised me, was hoping that could point me in a direction.

tomcat59alan said:
Where do you feel the wobble?, keep it clean, if it's through the steering wheel, how's your steering damper?
Click to expand...

Tomcat59alan,

It's not through the steering, it's felt through my seat, kept it clean, if it was through the steering I would suspect the wheels being out of balance or a buckled wheel, though I've not checked all the wheels for roundness the one that took the impact to blow out had no dents or was out of round.

I will get the other half to shake the steering for me to check the ball joints and see if there is any play in those.

Not sure the missus is going to like me spending more money on, what is effectively, mine and my son's toy, I'm sure she will get over it by some time next year.

I will try the tyre pressures that have been suggested and repot back on my findings with the ball joints.

Thanks for the replies

Tom
 
wammers said:
If you are running L322 19s, tyres should be 255/50/19 have you got spigot rings fitted?
Click to expand...

Bollocks, I just copied the sizes which where on the side of the tyre, I have probably f@£#ed up there then. I believe they are RRS 19's, as per pic below and I don't know about the spigots, I can't remember seeing one when I took the wheel off to change it for the spare so they are either stuck in the wheels or non existent, I'd be inclined to go for the latter.

Hopefully that pic has worked.

I will try to check tonight when I get home from work.

Cheers

Tom
 
Ginger Tom said:
Bollocks, I just copied the sizes which where on the side of the tyre, I have probably f@£#ed up there then. I believe they are RRS 19's, as per pic below and I don't know about the spigots, I can't remember seeing one when I took the wheel off to change it for the spare so they are either stuck in the wheels or non existent, I'd be inclined to go for the latter.

Hopefully that pic has worked.

I will try to check tonight when I get home from work.

Cheers

Tom
Click to expand...

P38 wheels are located for rotation by the conical wheels nuts. L322 wheels are located rotation wise by the hub centre. L322 wheels have a larger bore than the P38 hub centre so you need to fit spigot rings in to make up the difference. Or the wheels will be up and down like a brides nighty. With 55 tyres your speedo will under read true speed. So don't sail close to the wind past cameras. https://www.ebay.co.uk/itm/4-METAL-...a:g:c1gAAOSwtxlb7rcy:rk:1:pf:1&frcectupt=true
 
My p38 came with 255/55/19 tyres on. Waiting for them to wear down then I'll put something a bit better on. As for the Speedo, it seems to be spot on, compared with gps on the sat nav
 
Also get the balancing checked by a different tyre fitter. I've had "low cost" Asian tyres on other vehicles in past that had balancing issues. The sticky weights used on most alloys could not fix it, so eventually my fitter used old fashioned clip weights on the rim edges which worked. Also, double check rears if the steering isn't wobbling but seat is.
 
Ginger Tom said:
Grrrrrr,

Phasing on uj's is a problem, when I used to work on trucks you only had to be one spline out on the slider and it would cause a massive wobble. I don't suspect the VCU as the tyres that came off were very evenly worn which surprised me, was hoping that could point me in a direction.
Tom
Click to expand...

Found the thread: https://www.landyzone.co.uk/land-rover/front-propshaft-phase-offset.230945/

Front propshaft has an offset of about 15 degrees on the originals. Britpart are in line. I remember staring at it with MrGorsky and we had 3 P38s on the drive at the time. Having looked under all of them the Britpart one went back in the box with a note saying "no thanks!".
 
wammers said:
P38 wheels are located for rotation by the conical wheels nuts. L322 wheels are located rotation wise by the hub centre. L322 wheels have a larger bore than the P38 hub centre so you need to fit spigot rings in to make up the difference. Or the wheels will be up and down like a brides nighty. With 55 tyres your speedo will under read true speed. So don't sail close to the wind past cameras. https://www.ebay.co.uk/itm/4-METAL-...a:g:c1gAAOSwtxlb7rcy:rk:1:pf:1&frcectupt=true
Click to expand...
Sorry Tony, but the LR alloy 16" or 18" wheels are not located by conical nuts, the mating surface is flat and the nut shank is not a particularly close fit in the wheel. The centre hole on the other hand is a very close fit on the hub stub.
There is a certainly a conical end on the nut but it mates with nothing unless you fit the steel spare sometimes provided.
 
The first thing I'd do is find an MOT station that has a good rep and put the vehicle in - they'll soon find any slop in the myriad of joints, bushes etc that compose the suspension/steering malarkey.
It's worth the money than trying to do it yourself on your back - wife talking to you through pursed lips in an unamused kind of way as you ask for assistance.:(
And of course as an added bonus, the tester will pick up on other possible rectification work required - or it might simply pass which means beer o'clock.:)
 
Ginger Tom said:
I'm running 255/55 19 Nankang's. Not sure on they tyre pressures
Click to expand...

i'm running 19's on mine. (with spigot rings of course)

drop the pressure 28psi Front and Rear. I have and get even wear across the faces on all 4.

nankangs ?

when I got my Cayenne there were budget tyres on it and the wheel vibrated like buggery. a set on new Uniroyal Rainsport 3 all round and you could build a house of cards inside at 90 now. I like the rainsport 3 so much that's what I put on the P38 all round as the Pirelli Scorpions only come in runflat now.
 
You must log in or register to reply here.

Similar threads

S
Death wobble experience
Replies
4
Views
1K
Brown
Brown
S
Bit of a challange (PART 2)
Replies
18
Views
906
brianp38dse
brianp38dse
spookytooth
modular wheel wobble
Replies
14
Views
2K
GrumpyGel
GrumpyGel
Martin H
P38A Bit of a handling problem.
Replies
15
Views
2K
Grrrrrr
Grrrrrr
C
Disco 1 death wobble
Replies
5
Views
1K
haigy
haigy
Back
Top