Can't solve my 1500HL problem

[xvivalve]

If it is only on acceleration, might it just be 'pinking', to the extreme?

[grahamwatson]

I thought the phase looked ok, bearing in mind clockwise view one side and anti the other ?

Tony

Nah. It's 90 degrees out if the car wasn't moved. You need to compare the front yokes of both UJ's i.e. the yoke closer to the gearbox on the front UJ, and the yoke further from the diff on the rear UJ. They need to be the same orientation. Bear in mind that in pic 5 the lug at 8 o'clock is part of the yoke closer to the diff.

And I have read that these phasing vibrations can be worse on acceleration or on over-run depending upon bush wear elsewhere. And, counter-intuitively, can be worse with newer bushes.

[tony g]

I disagree , the part bolted to the the gearbox and part bolted to the diff are the ones to look at, and they look in phase.
I would be tempted to unbolt the prop though to check the u/j's move nicely with no notchyness (sp) or play even though the joints look new

Tony

[steve5]

No real help to you, but, at the last mot the tester mentioned that the centre bearing mount had collapsed. As it passed the mot needing no work I got it replaced. I did not know I had a problem before, and it made no difference after. So that may suggest that even if yours was faulty it would not cause your problem. Maybe.

[grahamwatson]

I disagree , the part bolted to the the gearbox and part bolted to the diff are the ones to look at, and they look in phase.
I would be tempted to unbolt the prop though to check the u/j's move nicely with no notchyness (sp) or play even though the joints look new

Tony

Does the 1500HL have a third central propshaft joint? Is it UJ or CV?

[Jon Tilson]

Yes all non Sprints have a hardy spicer type joint around the centre bearing area.

Jonners

[Jon Tilson]

How bouncy is the rear gearbox mount on the cross member? There are a few different types of this mount around and they are often
mis-sold to dolly owners with detrimental results on refinement. They are meant for SD1's and TR7's IIRC.

The dolly one is supposed to be (from memory) tolerant of vertical movement and not so much of rotational and is "voided" in the rubber bush
part accordingly.

Give your box a shake when down the pit. If you cant move it much, that could be the issue.

Jonners

[grahamwatson]

Yes all non Sprints have a hardy spicer type joint around the centre bearing area.

Jonners

Not sure what you mean by a hardy spicer type joint. They seem to make all sorts. I think a key point may be whether or not it is a constant velocity type. CV joints obviously are, but standard UJ's are not. Rubber/laminate discs are not, but do not flex so much so do not produce as much rotational velocity variance as a UJ can.

In Alan's third pic, is that not a standard UJ I see peeping out from behind the central bearing?

I suggest to Alan that, whilst we continue this technical discussion, he shifts his propshaft by 90 degrees to see if it makes a difference! It may add to our understanding of this issue. Or it may not.

[Jon Tilson]

No non sprints were fitted with CV's as OE.
Hardy spicer is a common parlance for the cruciform type of joint as fitted in 3 places on a dolly non sprint prop shaft.

Jonners

[grahamwatson]

Thanks Jonners.

So with 3 standard/hardy spicer type/cruciform UJ's, Alan's propshaft is out of phase.

But if it was a Sprint, with a CV type central joint, in would be in phase, as Tony suggested?

[tinweevil]

New engine mountings

Keep your eyes open for some correct ones. There are two shore ratings for this design of mount for 1500 & 1850. Non intuitively the 1500 takes the harder and most of what is sold these days is close to 1850 hardness.

100% polybushed throughout

Please, not the subframe?

[alangraham]

100% polybushed throughout

Please, not the subframe?
[/quote]

Yes, subframe too; the lot.
Alan

[Jon Tilson]

I would suspect that has a lot to do with it then.
I'd be looking at going back to rubber for the rear axle tie bars to axle end. These are quite "Squashy" as OE and do a lot of driveline insulating.
You also dont want poly on the rear suspension radius arms where they join to the body either.

On the prop shaft the ends should probably be in phase and the centre not. TBH Ive only ever changed the axle end one so its never been an issue for me.

Poly bushed subframes dont cause any refinement issues on my Sprint and TR7 engined 1850.

Jonners

[Karlos]

Does the vibration only happen when accelerating ?
Does it do it if you dip the clutch?
Does it do it on overrun whilst slowing?
Are the compression pressures similar on all cylinders? (thinking here is a cylinder not working well at slow engine speed ie valve burnt/leaking)

Tony

Yes, only when accelerating.
Dipping the clutch will stop it.
Doesn't do it on the overrun whilst slowing
Compression pressures currently unknown.
Alan

If the UJ's in the prop were out of phase, then dipping the clutch should not stop it. Also if it was out of phase, the droning/whining/vibration would increase in line with road speed and not be affected by gear changes.

I am punting for the general increased droning from using poly bushes or maybe a fouling exhaust. As the engine is loaded when the car accelerates it will twist from its idle position and maybe clearance is fine if viewed when stationary but under load the exhaust may just foul on the car somewhere.

Dipping the clutch unloads the engine/gearbox so it 'relaxes' back to the position it occupies when idling.

[Carledo]

I agree with Karlos, an out of phase prop can cause noises and vibration but I think in this case it's a red herring. A lot of Sprint owners have had problems recently with replacement gearbox mounts that are far too hard, inducing driveline vibes and noise/harshness. I'd be looking closely at this AND the new engine mounts as well as checking the exhaust for load fouling as suggested.

Steve