Dolly (suspension) disease

[slant4]

I've seen various threads and mag articles over the years about front suspension geometry problems - ie the tyres are frathering on inner edge and the front wheel camber looks out. Is there a definitive cause? Front wishbone bushes? TCA bush?

My 1500 FWD has started and my Sprint has always been a pain for it! Bot never been rebushed. I intend in doing both, but noticed the 1300 doesn't seem as prone!

[triumphdolomiteuk]

Usually a combination of wishbone bushes and tiebar bush - my Sprint munched its way through a pair of expensive tyres before I worked out what was causing it.

[tinweevil]

Blue has these symptoms and has had since the suspension was rebushed. I can't remember if it's always been like it. I've got a bunch of camber shims but havn't got around to experimenting with them yet. I'll be watching this thread closely.

Tinweevil

[slant4]

The odd thing is on the 1500 being fwd, that one wheel is ok, the other not, which causes a rather odd stering charatistic. I wondered if it was to do with the trust angle, and if the toe had been set wrong, but I'm not convinced as there is a fair positive camber on the nsf, which is not what you want on front suspension if you can help it! (I'll get on with the article I've promised to write about suspension agles and negative offset, etc) If you have rebushed and not had the geometry checked since, it ould be that the track is now out, as previously it would have been set up to worn bushes. I've got a slight therory, not proven yet, that the large void bush on the inner face of the tca will be off centre through age and forces. I'm also a little concerned about putting excessive castor on the wheel by winding up the tie bar too much. its been such a while aI can't remeber if there is a point or stop!

Value everyones imput on this one!

[Dollyboy]

my interpretation of what happens in basic terms is as follows:

standard on sprint (or the few that i've seen stripped to that level) is 2 camber shims between the top mount and subframe (not sure about other models).

people commonly fit lowered springs, or regardless, the springs get tired and compress with age anyway so the car sits lower.

as the wheel goes higher up into the arch (just front we're talking here) the camber decreases (becomes more negative), and while aiding grip as the car leans on cornering, even on generally straight roads (the majority of distance covered by the car) the suspension is running lower as when cornering, hence wearing inside of front tyres.

i've rebuit my front end using 3 camber shims each side, and will be on 1" lower springs with adjustable seats, and planned to drop her a bit more too.

im not sure what effect this will have on castor angle, but should be able to compensate when tracking is set up.

sprint should be slightly toe in i believe, have data somewhere... no idea what fwd should be, or if the subframe/geometry is much different to rwd dolly

all a bit trial and error really id say...

[george]

rule of thumb is fwd's should toe out and rwd should toe in

[Lewis]

Yea, my fronts used to wear really quickly on the inside edge.



Can't fathom why

Could be worth going and getting it tracked again at a garage? Always stopped it on my 1850, used to scrub the inside off the tyres in a few thousand miles

[slant4]

If the suspension bushes have been replaced, ther should be no need to change the shims. Absolutely right about the track on FWD vehicles and the pic shows the condition perfectly. Track will not show up a problem with caster or camber, etc. 4 wheel alignment will. The camber shown is adverse and is not the condition you would expect by lowering the suspension. All shortened springs do is allow the car to work on a different part of the suspension sweep. Even though this will alter the camber from normal, it wouldnt be to this extent.

A colleage of mine reckons it was a problem back in the 1970's and was to do with corrosion and sagging of the suspension turrets, but I doubt that. I know 1300's can suffer with that problem and push the wings up and out, but the spring turret moving to this extent on a Dolly type shell would be rather obvious! I think he is getting mixed up with stags, which I think did have a problem.

Lets get our heads together on this ! More theroies

[1300dolly]

You say the 1300 is not as prone but isn't the suspension arm different and also no anti roll bar, could this be why??

[Dollyboy]

The camber shown is adverse and is not the condition you would expect by lowering the suspension.

disagree, sorry, all abit subjective. on other cars possibly, but i've seen it too many times dollies for it to be coincidence. my 1500 from yrs gone by behaved exactly the same way and other lowered dollies i've seen generally have the same tendancy. I havent really gone into this in any fine detail but does anyone know if the top n bottom wishbones are in exact parallel with eachother? based on how common these symptoms are with lowered dollies i'd have a reasonable guess at 'no'.

if the bushes are shagged then the symptom is gona be caused by things floating about too much

in my technicoloured cartoon world, that is probably what I'd expect to see, based purely on experience if nothing else. theres probably a valid reason for it, but need a car handy for measurements. best way to check properly would be to remove the shocker, raise the thing up n down on a trolley jack n take measurements at various intervals, or seeing as the guts of my front end from orange are built up but not in car, I could have a look at this next week... interesting one...

[Jod Clark]

If you lower the car or if it lowers itself, get the tracking checked, you'll be surprised how far if will be out. Look at the angle of the track rods to see what will happen when the car is riding lower. Add this to the increased negative camber caused by the different lengths of the upper wishbone and lower tie bar and radius arm and a little lowering will need a lot of tweaking to put right. If you're going to lower the car and not adjust the base suspension setttings to suit, you'll never reap the benefits of lower ride height.

Jod

[slant4]

You are right as ever Jod! The number of cars I see at work where some boy racer has played with suspension, etc, and modern cars are worse. To comment on the previous comment, I can assure you the vehicle I'm talking about has a far advers camber.

Lowering a car affects its c of g, however the full benefits of negative offset, which is what you will find on a modern performance vehicle. However, it makes the steering heavy, hence only really come into play since the advent of as. All to explained in more depth soon.

As for the matter in question. Are we of the consensius bushes?

as a matter of interest, a sprint should have 3/4 of a degree poss camber +- 1 with 1/16 toe

fwd :1/16 toe out camber 1 degree

[slant4]

We are aware of big issues concerning 3 series, which bend the top strut mount when going down medium potholes!!! Most modern cars suffer with excessive castor due to going up and down kerbs!

What will they be like after 30 years!

[Jon Tilson]

tracking is out....
For the inner wishbone bush to be worn to the extent of causing tyre wear would be an instant MoT failure...
Have you ever looked at one? The rose joints I have seen dont wear that much even at 100k up. I think Ive only ever changed them once on all the dollies I own.
Its always the inner TRE that wears, causing toe out under drive.
Trouble is when its adjusted out, it soon wears again.
Reshim the inner TRE's

Jonners

[tinweevil]

Tracking is not the be all and end all.
I rebuilt Blue with all new standard bushes, new tyres and new shocks and it has shown this problem since despite being tracked as soon as it was on the road. I don't recall which parts I tightened on the ground and which were done in the air. Once the inner edges were going I had the tyres swapped front to back and had it tracked again. This set wore out on the inner edges too so I put different tyres on the front and had it tracked again. Guess what the new tyres are showing sign of? The only component I have not changed is the springs. I don't think they are lowered springs, it doesn't seem right given the cars history for it to have them. It appears to sit about a sensible height but the negative camber is very visible. It does sit lower than Orange so maybe....

I look forward to the article.