Wandering Front End

Post by **PSL184** » Thu Dec 18, 2008 8:16 am

I took Jenny on another mileage accumulation run yesterday to build up some miles on the new engine. As I approach 70mph I start to get a slight vibration which I think is tyre related, but, also the front end starts to wander about a bit. Not huge amounts resulting in lane changes but enough to require small steering inputs to correct it. I've checked obvious things like steering rack, damper mountings, tie rod bushes etc and nothing appears to be loose, so just wondering where you guys think I might need to concentrate on pls?

Post by **IslipMinor** » Thu Dec 18, 2008 9:34 am

Tyre condition and pressures, damper operation, steering centralisation and then tracking.

Vibration can be damper related, are the front dampers working well?

The steering wheel needs to be centred by turning the wheels to full lock one way, then count the turns and part turns to the opposite full lock and turn the wheel back to exactly half the total. The wheel should be in the 'straight ahead' position, if not take it off and set it correctly. Then drive the car and see it it drives straight ahead too! (This is not necessarily the same as just setting the steering wheel to match the current straight ahead driving).

If the steering needs to adjusted to make it drive straight ahead when the steering wheel is centred, you will need to make unequal adjustments to the track rod ends to achieve this. Adjust each track rod by exactly the same amount, in opposite directions, to centre the steering and then get the tracking checked as normal.

If the steering wheel is correctly positioned, then check the tracking and if it needs adjustment, make sure that it is made equally on both track rod ends.

It may all seem a bit tedious, but once done, it will not need doing again, other than maybe a minor tweak to the tracking occasionally.

Post by **rayofleamington** » Thu Dec 18, 2008 9:45 am

tracking is likely to give 'wandering' at main road speeds.
Usually more noticeable when roads are wet as the front follows one wheel then another.
In the dry it tends to bias to the better tyre, and can leave one tyre more scrubbed than the other (or just scrub both tyres)

Post by **bmcecosse** » Thu Dec 18, 2008 7:31 pm

Could be looseness at the rear axle - causing rear wheel steering. Possibly rack mounting clamp U bolts are loose - this is common on Minis, so I suppose it could apply to Minor. But I would say tracking is the most likely cause.

Post by **PSL184** » Thu Dec 18, 2008 8:34 pm

OK thanks all - back axle has only just been off and I'm sure I tightened it all up properly

but I wil double check and as tracking appears to be the consensed opinion I will check that too - when it stops raining

Post by **bmcecosse** » Thu Dec 18, 2008 10:25 pm

Well - since back axle 'has just been off' - and the problem has only just appeared - that could indicate something not right there!

Post by **PSL184** » Thu Dec 18, 2008 10:29 pm

Nah - I never got it upto 70mph on the old engine

Post by **bmcecosse** » Thu Dec 18, 2008 11:00 pm

Not even down-hill ?

Post by **PSL184** » Thu Dec 18, 2008 11:08 pm

No, I never trusted the old engine to last at anything above moderate speeds... I think I most I dared go to before was about 65 (downhill) but now it pulls so easily upto 70 (and wants to go more) so I have no idea if the problem has been there for ages or only just appeared....

Post by **PSL184** » Fri Dec 19, 2008 2:01 pm

I'm starting to think it could be tyre pressure related as I've tried different pressures and it does make a difference... I'm running 185 70 14 (on alloys) - What pressures should they be run at do we think?

Post by **Kevin** » Fri Dec 19, 2008 2:06 pm

I find 28 all round works well on my 165's

Post by **bmcecosse** » Fri Dec 19, 2008 8:43 pm

Just keep pumping them up till it feels right. Modern cars seem to run about 35 psi on all wheels.

Post by **IslipMinor** » Fri Dec 19, 2008 11:55 pm

I run 185/70x13 and have them at 26 all round, unless fully loaded with luggage then 26F 28R. On track days up to 30F 28R, but this is just a little harsh on the road. With 14" rims, you might need 1-2 lb less?

Stability is a complete non-issue, it just runs straight, unless told to do otherwise, so unless you do find it is tyre pressures, I think you will be back to looking at suspension settings, such as tracking.

Have you made any changes to the front suspension in any way? Dampers, lowering etc.?

Post by **PSL184** » Sat Dec 20, 2008 12:20 am

Hi Richard, no suspension is totally standard. The only differences so far are the bigger wheels and tyres and a 1275 engine. I checked the rack as per your instructions above and it's very close to being central. Everything else is tightened up. I havent taken anything apart to check for condition of bushes but they look OK visually. I want to get the issues sorted before I do any more mods so as not to mask any problems, ie, when I fit front ARB. With the tyres at 30 psi it doesn't wander as much but the ride is very harsh... Also, just out of interest, the car tracks straight when you let go of the steering on a flat raod so I assume the tracking to be OK...?

Post by **IslipMinor** » Sat Dec 20, 2008 8:15 am

What width are your 14" wheels?

The 'tracking' is the amount of 'toe-in' or 'toe-out' that the front wheels have - a Minor like most, if not all rear?, wheel drive cars has toe-in. If this is not set correctly, it can have quite a significant effect on how the car handles. Any of the tyre fitting centres can check/adjust it. Checking is usually free.

Which way does the steering wheel point slightly when you drive exactly straight ahead? Knowing this will identify which way to adjust the tracking, if it needs it. Do not do any adjustment, unless you need to reset the tracking!

For example:

Steering wheel points slightly to the left, and the tracking has too much 'toe-in'. adjust the LH (nearside) trackrod only

Steering wheel points slightly to the right, and the tracking has too much 'toe-in'. adjust the RH (offside) trackrod only

Steering wheel points slightly to the left, and the tracking has too little 'toe-in', or has 'toe-out'. adjust the RH (offside) trackrod only

Steering wheel points slightly to the right, and the tracking has too little 'toe-in', or has 'toe-out'. adjust the LH (nearside) trackrod only

So long as the tracking error is small, this will help to correct the small steering wheel misalignment while it corrects the tracking at the same time.

Post by **alainmoran** » Sat Dec 20, 2008 11:04 am

This info is too good to be lost in a forum, I hope you dont mind islipminor, but I've decided to start keeping a record of these useful bits here: http://www.adaptavist.com/display/~amoran/Minor+bits

Post by **PSL184** » Sat Dec 20, 2008 11:18 am

I'm not sure about the width without going out in the rain to measure but I'm guessing at 5.5". I think I'll take the car to get the tracking aligned properly next week. My wheel is ever-so-slightly to the left so I'll take the info provided to my local tyre place who are very enthusiastic about classic cars and get them to set it all properly. As I am intending to fit an ARB over Christmas I'll order some new tie bar bushes aswell to be on the safe side.... Thanks for the help.

Post by **jonathon** » Sat Dec 20, 2008 12:05 pm

Whilst you are down at your 'garage' get them to do a full geo check on the front end, but only after you have fitted the ARB and new tie bar bushes. Did you say that the eyebolt pins,bushes eyebolts and top trunnion bushes are okay as any wear/play in these will cause 'unusual' handling.

Post by **PSL184** » Sat Dec 20, 2008 12:15 pm

All the bushes "look" OK Jonathon but I have not stripped anything down to inspect - merely pulled/pushed etc.... The bushes could all be way past their best as I don't have any history prior to me owning the car. A full rebuild is planned (time and money allowing) so they will all be renewed eventually... I should pop over sometime and spend some money with you - I'm almost ready to get the radius arm kit for the rear end - I just want to finish at the front end first

Post by **jonathon** » Sat Dec 20, 2008 12:32 pm

I'd delay the 'radius arm 'kit for the mo and concentrate on the front bushes pins etc, they are pretty cheap to renew and will give you an accurate point from which you can dial in the front end geometry. I would not bother doing any measuring untill these are replaced as required, otherwise you will just need to repeat the whole process again.