The Triumph Dolomite Club - Discussion Forum

I've just got my Sprint back after the steering rack was replaced for the MOT. And the pull to the right I've been complaining about for a couple of years has gone. At least it seems to have: the steering is a bit more damped than before, and I was wondering if uping the damping might mask the problem, but never got round to it before the rack failed the MOT.

I have to admit, that leaves me even further at a loss to understand what the heck is going on with the pull - and how come the garage managed to measure the left wheelbase as 8-10 mm longer than the right, if it's OK now.

Anybody got any good theories?

Graham

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The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.

Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).

My theory is your steering rack was fooked.
Just a theory mind, if I'd been able to remove the rack, check it, replace if necessary and set up the tracking I would be able to prove it.
As it is, my theory is worth bugger all, like all theories. Theories need proofs.

My theory is this.
I have known draglink nuts to come loose until the nut gets to the split pin.
Could be the steady bars on the back axle having the washers set wrong.
I have had a partial seize of an original brake caliper (most likely culprit).
Collapsing flexable brake pipe.
These are just some of the possible causes.
Check everything but if its gone its a result.

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track action maniac.

The lunatic is out................heres Jonny!

It turns out that it is the slightly greater damping on the new rack that's masking the pull. If driven on a flat surface and left to its own devices for a minute or two, it slowly turns right, as before. But that extra bit of damping turns what was a really annoying problem into something that's barely noticeable.

All the front and rear suspension have been gone through a couple of times, before and when the suspension was polybushed. And the brakes are all fine. So presumably then, it's still 8 to 10 mm longer on the left side. Fortunately I've found someone who can jig the car before it goes for paint, which will show if it's backend or fore. I'm still betting on the subframe or front suspension somewhere.

I'm just amazed how much difference a small amount of damping makes to this problem. That change may explain why the problem seemed to make a sudden occurrence then. If the rack, or something else in the steering system, was damping the steering, and that got affected by dropping and replacing the subframe, it might have only unmasked the problem.

Graham

_________________
The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.

Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).

Well the newness is obviously wearing off the replacement rack, and the pull to the right is starting to be an annoyance again. It's not strong, but just feeling that the natural null point in the steering is off to one side is a problem to me. Maybe someone with a different set of compulsions and obsessions wouldn't find it so; but it's a constant niggle to me.

So it's off to be jigged ASAP.

Graham

_________________
The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.

Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).

Run two parallel fishing nylon lines either side of the car at wheel centre height and measure in to the hubs and equalise, now measure front and back at the wheel rim to find any anomolies.
I used this technique on the special I built and it handles like dream. (the Egyptians used it on their chariots )
No prizes for guessing I do not trust garages to do what they are asked to.

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track action maniac.

The lunatic is out................heres Jonny!

Well Dave measured the difference between the front and rear wheel centres left and right while it was on the tracking machine, so it should have been straight at the time. Also I hadn't told him that I'd calculated the difference as 8 mm from the radius of curvature it normally follows, just asked him to measure. So when he measured it as 10 mm, I though that's near enough a match. And the guy with the jig asked if the subframe might have been moved just from the measurements he had made (though I'm not sure what or where), without having had any of the story. So I'm fairly happy the car really is misaligned somewhere – it's just not obvious where.

So spending less than a couple of hundred to have it jigged up, when I'm having both rear wheel arches plated, both rear doors replaced, some serious repair work at the front of the left front wing and lower valance, and a full exterior respray, isn't an issue.

BTW, I think that the Egyptians only used two wheel chariots. I remember a Horizon or Time watch from the 80's about building a copy of a Chaldean four wheel chariot (a cart really) from 3000 BCE, when they only had Onagers to pull them. But I don't think anyone used four wheelers much after that, not even the Iceni.

Graham

_________________
The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.

Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).

String really is the way forward! I understand a certain F1 team regularly pop into a local fishing shop to buy fluorescent line
I used something similar on my spitfire to centre line it. A bit of faff, took me about 90 mins all in.
And made a camber/castor gauge buy copying this (literally, enlarged pic and used the scale!)
https://www.merlinmotorsport.co.uk/p/ad ... uge-adaccg

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Clive Senior
Brighton

Graham, just going back to basics here but have you tried swapping the left wheel for the right? Sometimes a tyre can cause a pull and if it moves to the other side when swapped you get a free answer.

Tony

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Membership 2014047

Yes, that was fairly high up the list with checking the tire pressures and the callipers, and well above swapping the suspension springs left to right.

_________________
The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.

Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).

How about a partially siezed ball joint?

I realise this is clutching at straws but something is to blame.

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track action maniac.

The lunatic is out................heres Jonny!

My Sprint used to pull to the left, and kerb parking was the suspect.

The hub bearing kit was replaced and problem solved.

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NRW 581W Sprint


On the motorway no one can hear me sing!
Construed as a public service, self preservation in reality.

It could be either of these, or possibly any of a number of other things. It did have both upper and lower ball joints in the last year or so, before the pull started. But they were gRimmer ones, and they're out of guarantee. Hub bearings are supposed to have been looked at, but nothing was found and nothing replaced.

I'm still swayed by Dave's measurement of 10 mm difference in the wheelbases: admittedly that's as much because it closely matched the theoretical value (8 mm) I'd calculated from the radius of curvature as anything else. So, for less than £200, it's off to Ormskirk to go on the jig and be measured.

Graham

_________________
The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.

Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).

I had a pulling to the right problem too - it turns out one of the bearings in the hub had seized at some point and had worn a deep groove into the stub axle...

All good suggestions, but I don't see how they explain the difference in the lengths of the left and right wheelbases, or the correspondence between the measured and calculated values.

Graham

_________________
The 16v Slant 4 engine is more fun than the 3.5 V8, because you mostly drive it on the upslope of the torque curve.

Factory 1977 TR7 Sprint FHC VVC 697S (Now all of, but still needs putting together)
B&Y 73 Dolomite Sprint UVB 274M (kids!)
1970 Maroon 13/60 Herald Convertable (wife's fun car).