pulling to the left......... and then pulling to the right!

[evonaut]

Since collecting my fully restored hydro car, it seems to have developed a steering / suspension annoyance. Or at least its got considerably worse.

The effect is pronounced travelling at speed, about 70 ish, although it is detectable at slower speeds.

The car is stable and straight whilst driving at constant speed and throttle, but as soon as you lift of the gas it lunges quite violently to the left, and this is then countered when you reapply the gas, lunging to the right.

The tracking also gradually went out but i had this reset and it has not cured the problem. The steering / suspension garage that looked at the tracking suggested that the bushes could need shimming and trimming? does this sound likely? we looked at the car whilst it was on a ramp and all the steering and suspension arms etc are tight - no lose or wobbling bits?

The vast majority of original steering and suspension components were used in the re build. Obviously bushes and other consumables were replaced.

Does anyone have a view on the above? wouldn't mind knowing if it sounds feasible prior to having a garage spend a day buggering around.

Many thanks

Evonaut

[gs.davies]

Bottom arm bushes perhaps. I had similar symptoms on an Escort when the track control arm bushes were shot to bits.

[Dr S]

Loose tie bar bush on mine was very similar. It had just crushed down and deformed leaving some free play...

[swifty]

How about re tightening the steering rack U bolts . If there's plenty of paint around them and the mounting panel it can have that effect once the car had been driven for a few miles . At the other end of the car , has the toe in/ out and camber been set . I know positive camber on the front wheels makes them drive terrible . ... Ken

[Spider]

I'd say one or both the Steering Arms are loose. The bolts for these often stretch and while they feel tight with a spanner, they are not tight on the Arm, only in the Thread. New bolts are sometimes the answer.

It could be the steering rack itself, but usually by the time they get to the point like you have described, they also get very noisy.

When the tracking has been done, it was set for Toe OUT and not Toe in wasn't it? Though this usually make them weave ever so slightly all the time.

[Nevsmini]

Sounds like a worn diff pin

[abri]

I have the same symptoms on a '63 Morris 850. I'm pretty sure it is due to a worn steering rack. If you jack it up and try to wiggle the wheels at 3 and 9 o' clock there is significant play.

[cheleker]

Certainly start with the easier-to-fix steering issues, but Nevsmini's lead to differential problems could be right.

[evonaut]

thank you all for your very useful comments

the steering rack, diff pin and all bushes etc are new so wear is unlikely to be the problem

also, when the car is on the ramp, there is no play in any of the steering or suspension components!

i have spoken to the garage who carried out the rebuild and he has identified the possible problem as the differential shims. the 'evidence' was reported on another forum and it does describe exactly what i am experiencing.

gonna have a word with the engine / gearbox builder to gauge his opinion......

[Spider]

'Shimming' or pre-loading of the diff carrier bearing causing 'torque steer' is a misnomer. It just can't happen and yes, I've read that in many books. It makes no difference what so ever if the shims added to one side or the other as the pre-load to the bearings will be the same, it also will make no difference (to the steering) if it's under or over pre-loaded.

I will also add that because some of the parts are new, keep an open mind, they may not be right.

[LarryLebel]

I would say get a different engine builder who knows how to shim the diff.

[wantafaster1]

Have you checked the rear of the car at all?
And, you haven't got 165 tyres on a 4.5 inch rim by any chance?

[evonaut]

I would say get a different engine builder who knows how to shim the diff.

the engine builder is very experienced and highly regarded, and builds a lot of race engines so i'm sure he would know what is required......... will wait to see what he says?

Have you checked the rear of the car at all?
And, you haven't got 165 tyres on a 4.5 inch rim by any chance?

Apparently the rear of the car was tested and shimmed to suit, to ensure all was true.

I wondered about tyres too, as yes, they are 165s, although the rims are 5" not 4.5........

might be worth testing on a set of 4.5" rims with 145s on

[ianh1968]

Has anyone asked if the swivel joints are too tight?

I had exactly the same problems when I put new swivels on a car once and
thought that although they were a bit tight, that they "bed in" once the car was
driven.

It was horrible...

Ian

[evonaut]

Has anyone asked if the swivel joints are too tight?

I had exactly the same problems when I put new swivels on a car once and
thought that although they were a bit tight, that they "bed in" once the car was
driven.

It was horrible...

Ian

Hi Ian

and............

.........did they bed in?

or did you loosen them off?

[spoon.450]

I have had these symptoms on my dry car and it seems all down to corner weights. A bit more difficult to determine on a hydro car.

[ianh1968]

It was horrible...

Hi Ian
and............
.........did they bed in?
or did you loosen them off?

No they didn't, and yes I did...

I thought that it was @%$*ing dangerous, so I sorted it straight away!


Ian

[mini63]

'Shimming' or pre-loading of the diff carrier bearing causing 'torque steer' is a misnomer. It just can't happen and yes, I've read that in many books. It makes no difference what so ever if the shims added to one side or the other as the pre-load to the bearings will be the same, it also will make no difference (to the steering) if it's under or over pre-loaded.

I will also add that because some of the parts are new, keep an open mind, they may not be right.

my thoughts exactly.....the shims only serve to preload the carrier bearings like any normal differential.

[nick@dunsdale]

'Shimming' or pre-loading of the diff carrier bearing causing 'torque steer' is a misnomer. It just can't happen and yes, I've read that in many books. It makes no difference what so ever if the shims added to one side or the other as the pre-load to the bearings will be the same, it also will make no difference (to the steering) if it's under or over pre-loaded.

I will also add that because some of the parts are new, keep an open mind, they may not be right.

my thoughts exactly.....the shims only serve to preload the carrier bearings like any normal differential.

I agree on the diff theory's i think it is something slack or tight

As mentioned above top and bottom ball joints are worth a look knock off both track rods end and compare the resistance by swiveling hubs lock to lock

Have all the subrame mounting bolts been checked for tightness, in particular the tower bolts and floor bolts, the front ones wont make much difference

i would say check the rack for any tight spots but if the problem results from the straight ahead position unlikely to be the tight spot in the rack

what happens if you decelerate and brake does it still dive about

[ianh1968]

my thoughts exactly.....
the shims only serve to preload the carrier bearings like any normal differential.

My view is that as they are mostly just plain old-fashioned ball bearing type affairs,
that the shims are only there to take up the slack, ie the difference between the width
between the outside edges of the bearings and the available width between the side
flange covers.

The manuals state +0.001" - Really? When you factor in "goo" and varying tightnesses
of the bolts, a tolerance this close would seem to be almost academic... I think that
basically they are implying that you should just take out all the slack, not that the bearings
really need to be "pre-loaded".

I guess if there was loads of slack, the whole assembly might move about by a few thou,
but I doubt that this would cause violent steering changes.

Another possibility: Unequal length steering arms...
Have the front wheels been "toed" with the rack in exactly the centre?
If the rack was not central when the tracking was done, there will bee differing amounts
of thread engagement in the track-rod arms which will make them effectively different
lengths. This produces a different angle of the rods from left to right, and consequently,
different geometry.

There has been talk on here about this before, most of it way way above my head...

I did all my swivels recently and changed some wheel bearings and then found that
the clunking noise that I had been hearing was the "nut-less" lower arm pin shuffling
backwards and forwards.


Ian