Tracking & Alignment - Spitfire

[Neil Clark]

This job is looming after the rebuild onto the new chassis.  I've done a string box on cars with solid rear axle but really not sure how to approach this on the Spitfire.  Everything has been taken off, adjusted and hung back on and the front suspension needed new bushes etc.  I've put back the shims I took off and set the steering rack /track rods to the same number of threads as on the old steering rack I took off but that's as far as I've got.  I also need to do a "safety" tightening, which was an annual kit car habit, but I'm not starting from a known basis point and in a  way the tracking needs to come first I suppose.  I can't see my local trusted tyre fitters / aligners having the knowledge.  If it isn't a one man job, anyone recommended in London / Surrey? 

[Clive]

The string box works perfectly on a spitfire. Finding the centre line is a faff though.

I had already set the front camber to 1 degree negative

I started by setting my front wheels to parallel (tape measure and 2x2ft lengths of steel sat on blocks against the tyres)

Set the string box up from that, and measured distances to the centre of the rear wheels. I had to adjust the string box a few times until I was happy.

I then set the F+R wheels with a tiny amount of toe in, then adjusted the front castor. 

All in took a couple of hours, and rechecking after a few hundred miles was much faster. 

The other alternative is to set it about right, and find somebody who uses the Hunter alignement equipment:

https://alignmycar.co.uk/

But some places are better than others..... and take the specs you want, plus some spare shims. I would also get some miles on teh car first to get everything settled.

[JohnD]

I find the string method unbelievably fiddly, so I have my own 'laser' system.

A handyman's laser level projects a vertical beam of light along the side of the car.   To ensure that this is parallel to the centre line, I've fitted two lengths of plastic tube with stops that engage with fixed parts of the car, so that they always go back in the same place.    Each is marked with permanent black marker an equal distance from the midline.

 

Then the laser level is positioned on an axle stand to project its beam and adjusted so that the beam strikes both distance marks.   This is 'fiddly' but once done there's no string sag, and you can't trip over the  light beam !

Then it is simple to measure the distance from  front and back wheel rims to the beam:

[Neil Clark]

I need to think about this.  My garage is so narrow it's a squeeze to get down the side.  

[Pete Lewis]

see also

 

[Neil Clark]

That's lots of helpful stuff and ideas Pete, thanks.

[Neil Clark]

I've had it tracked and have also fitted a reconditioned steering rack I was given that is far better than the old one that went through the accident.  However the car is still feeling loose and wanders around the straight ahead.  I've lowered the tyre pressures to 18psi front and 24 back and it is better but not right.  The TRE's are new.  The front camber looks visually wrong side to side - left looks to be positive camber, right side looks almost vertical.  When I had it tracked the camber measured 2.05 degrees positive on the left and 1.38 degrees on the right.  Any thoughts?

[Casper]

It's not only camber but caster you nee d to think about.

 

If you have the Club's CD of Couriers then see the series of articles " Suspect Suspensions Sussed" by Carl Heinlen in Couriers 158 (Aug 93), 159 (Sep 93) and 160 (Oct 93).

I did post a pdf onto the message board a while ago but can't find it.

C.

[Pete Lewis]

did they load the car to its static height  and use what specification was used 

Pete

[Neil Clark]

Hmm.  Lots to re-think.

[chrishawley]

15 hours ago, Neil Clark said:

feeling loose and wanders around the straight ahead

More Hmmmmm. Resolving this could be easy-peasy or longer than a bit of string. " Suspect Suspensions Sussed" is indeed a very useful grounding.

2.05 and 1.38 degrees positive (presumably static unladen condition) while not grossly incorrect are possibly off specification. With the proviso that static unladen mesaurements are only a rough guide to the true measurements that will be observed under the loaded condition, then normal would be 2.0 to 3.0 degrees positive each side. Given one shim is about 1 degree an extra pair of shims on the right could be tried.

As an aside, I recently found chapter and verse from Triumph about laden v. unladen measurements. The GT6/Vit WSM is specific that the suspension is designed, specified and set to the laden condition; and unladen measurements are only for checking when the geometry has previously been determined as correct.

Expanding on Casper, above, caster setting is more critical than camber: Incorrect camber setting carries an implication that caster may not be correct. Again see SSS.

Two further thoughts:

1) Front suspension geometry has to be considered along with the rear. Incorrect rear toe-in can have really nasty effects on handling not least 'sidestepping' on bumps.

2) On poor handling I've been caught out (repeatedly!) by simple mechanical factors such as steering column bushes too tight, mast pinch bolt insufficiently tight, lower steering coupling failed, looseness of components, and (many times!!) out of true wheels and 'the-use-by-date-was-somewhere-in-the-Jurassic-period' knackerd tyres.

Here's hoping you get an easy solution.

 

[Neil Clark]

Chris - to paraphrase "The Hitchikers Guide to the Galaxy" this may require a specialist greater than I!  I can do the unbolt, disassemble, re-assemble stuff as per Meccano but for closer tolerances and adjustments I am just a bit ham fisted.   After the last two years plus work the car is now too good in terms of chassis, body and paint and I want to feel confident using it on longer journeys.  I've got the names of a couple of specialists from entries elsewhere on the forum and from the club and I'm going to chat with them and then book it in.

[Pete Lewis]

do a search for one of these  its so simple and you get the answer in a minute 

costs have gone up a lot   used to be around £45  but no heading for £70

use it on your mates and get some moolight ££s  back 

Pete

[Neil Clark]

I'm feeling a bit daft after all the advice and do now wonder about the flexible coupling on the steering column where it joins the rack.  I see on the exploded parts diagrams that there are rubber bushes in the coupling.  I'll try to get someone to help me observe the relative movement when the steering is turned but I'm not sure how to translate that into the coupling being being in spec or out of spec.

[Clive]

1 hour ago, Neil Clark said:

I'm feeling a bit daft after all the advice and do now wonder about the flexible coupling on the steering column where it joins the rack.  I see on the exploded parts diagrams that there are rubber bushes in the coupling.  I'll try to get someone to help me observe the relative movement when the steering is turned but I'm not sure how to translate that into the coupling being being in spec or out of spec.

Any play in that coupling and it is knackered. Not easy to see, but get somebody to slowly move the wheel back and forth, and watch carefully. Also check teh pinch bolts are all good and tight, I have seen one where a bolt with a too-long unthreaded section was used, and it bottomed out before clamping adequately. Solved with a washer.

New ones fail in months, so don't bother. If you are lucky, you can take yours apart and spend £20 with Mr Witor and get a set of poly bushes to rebuild it. Or fit a quality solid UJ type, but again, I had a new one that was terrible out the packaging. 

 

[NonMember]

As clive says, rebuilding that coupling isn't hard and will usually result in a better one than you can currently buy. I wrote up my steering rebuild in my LJ some years back.

[Neil Clark]

Ah.  Clive do you mean a new universal joint type that was terrible?  I see Rimmers only list that joint type and call it "improved", Moss are back order and the Canley site is a bit vague with lots of FAM1718 but not much clarity as to why so many! 

I'll go and check mine.

[Clive]

1 minute ago, Neil Clark said:

Ah.  Clive do you mean a new universal joint type that was terrible?  I see Rimmers only list that joint type and call it "improved", Moss are back order and the Canley site is a bit vague with lots of FAM1718 but not much clarity as to why so many! 

I'll go and check mine.

Yes, a new UJ type was worse than the old one. Sadly I had it on teh shelf, in a sealed packet, for several years and can't remember the source. Witor sells a very good cast UJ, for a t2000 that works, but may require a little jiggling to fit without hitting anything. Mine worked on my spitfire. However, I am currently using a rebuilt stad type with poly bushes.

Some original type couplings are wired-tied, some repros have a "crimp" on the end of the thread, while my one was a repro with neither. When I reassembled, I used threadlock, then a nice dot punch on the end of the thread. It won't come undone easily....

[chrishawley]

3 hours ago, Neil Clark said:

In spec or out of spec

It can sometimes be more informative when assessing total free play in the steering to do it in reverse: In particular. Jack the front of the car so both wheels are just off the ground then tug the right hand wheel in and out by a gnats (that's a British Standard gnat, not a new-fangled metric gnat). Even a tiny movement of the road wheel should result in very marked rotation of the steering wheel. If there is any degree of lag at all then that's indicative of an unwanted situation.

With the bonnet up and a ruler (or similar pointer) taped to the steering wheel it becomes a one man job (observing the pointer through the windscreen).

As mentioned above, for a car that's 'all over the place' an essential check is the security of the pinch bolt between up and lower masts (right in the depths of the footwell so often has to be done by feel alone). This needs to be seriously tight - the WSM method is 'as tight as it will go before the allen key begings to bend'.

[Neil Clark]

And there is in fact loads of play.  It's a UJ type.  I clamped the column in mole grips and watched the joint.  The moles moved the same number of degrees as the steering wheel does before the joint took up the slack.  The bolts in the UJ are tight to the column and the rack so it is not slippage.  Given my mechanic-ing skill set I'll replace it with another UJ type.

But I'll also re-check the pinch bolt again Chris.  I had replaced that with a new one when re-assembling the car and did follow the WSM instruction on tightness but it won't hurt to do it again.

Thanks all.

[Mjit]

I've had one of the UJ types on my Spitfire for years and find the pintch bolts need a good tighten every couple of years or you get some slop, not in the joint itself just the connection (from memory usually rack/UJ side rather than steering column/UJ side).  Also found with the mole grips on lower steering column technique

[Pete Lewis]

something often overlooked with any UJ type coupling is  at straight a head the cruciform should be aligned to be +  not x     always --l--  not / or \

 

not so critical in a straight shaft but on  any angular shafts change  the joint can affect feed back if its not aligned straight  

pete

 

[Neil Clark]

Thank you

[Dick Twitchen]

4 hours ago, clive said:

Witor sells a very good cast UJ, for a t2000 that works, but may require a little jiggling to fit without hitting anything.

Thanks to Clive's tip on this a while back that is where I sourced one from and all well on my GT6.  Checking the bolts tightness once in place is easily done.

Dick

[Neil Clark]

So I got the UJ and fitted it. It says to use 25Nm torque to secure it but i can't see how I can ever get a torque wrench near!  I've made it as tight as I can.  Incidentally, the Allen screw in the steering column clamp has decided to jam so I can't finish the job - I'm soaking it in WD40 overnight but this is the replacement I got because original had also jammed!