Technical Mk3 panda lowest wheel offset

[DaveMcT]

These numbers convinced me the 100HP is pushing the boundary in order to fit its wide wheels.

"Ordinary" Pandas use 5.0 J x 14 ET38 165 and 5.0 J x 13 ET41 155. the ET puts a lot of the rim inboard of the hub.

100HP has wider wheels 6.5 J x 15 ET30 195 or 5.5 J x 14 ET32 185. The 100HP cannot put too much rim inboard as it would hut suspension gearbox etc. They actually have steering lock stops to prevent impact on full lock. The low ET puts more of the wheel outboard of the steering geometry, risking when wobble especially at the critical 40mph where tyres and suspension resonate.

 

[A3jeroen]

Never had any wobble at 64 Km/h. So... True or urban myth? I remember Mercedes SEC's with even a negative ET on the back axle.
Steering lock stops are there because of the wider 6speed IIRC.

gr J

 

[koalar]

True or urban myth?

gr J

loads of modified cars accidentally introduce the death wobble. Normally 4x4 with stupidly wide tyres. This is different to out of round or balanced tyres

even manufactures are known to get it wrong

normally you need something to start it off. Something like running over pipe in the road and a bit of play in a suspension component

Once it starts you can't stop it until you stop the car

how the suspension designed, location of lower ball joint etc. effects how much wheel offset is ideal. Without a degree in car suspension just placing the wider tyres inside the arch may to may not have a negative effect

I recommend to always stay close to Fiat. The Fait suspension has had at least 50 years of RD on would hope its well sorted by now.

 

[DaveMcT]

Wheel wobbles only become a lock to lock tank slapper in extreme cases. Banded or reduced offset wheels just do a more noticeable wiggle at about 40mph. 100HP has the lock stops to prevent the inner wheel/tyre hitting the gearbox (or whatever). But they also have least offset (ET) of any Panda. It's the only way to get 195 tyres under the car. This puts the tyre contact patch further outboard than any Panda and makes them more likely to wobble. A few mm of ET can make a big difference.

All cars and motorbikes have a resonant front wheel wiggle at about 40mph. It's caused by interaction between tyres and steering castor (self-centring) and totally damped out by the steering mechanism. A full on wobble is caused by a serious mismatch and will be as dangerous as you'd expect it to be. However a more than normal "wiggle" will lead to steering joints wearing faster and the problem increasing as the parts wear.

On a bike you hardly notice it but get some wear in the steering bearings and it will show up quite strongly. Not enough to be dangerous but worrying all the same. Work bike steering cause the wheel to prefer to stay straight so any wiggle fest exaggerated as the bearings bounce over the worn centre position. Suzuki sports bikes in the 1980s were notorious. People fitted steering dampers but effect was minimal. Suzuki stiffened the frame and it got even worse. The solution was to use a less aggressive steering geometry and a more compliant frame.

Cars are far less critical as they have mush more complex steering but excessive wiggle will wear the steering joints. Manufacturers choose the best compromise between aesthetics and performance.

 

[Calecosse]

Thought I'd do a small update, still got the x1/9 wheels on, I'll take them off soon for a winter refurb. Put some kw coilovers on over the weekend, booked in next week for a proper set up and alignment but they ride really nice! They've given her a go-karty feel without being horrible and crashy. The fronts need bringing down a smidge to level it out then should be all good!

 

[The Pretender]

Thought I'd do a small update, still got the x1/9 wheels on, I'll take them off soon for a winter refurb. Put some kw coilovers on over the weekend, booked in next week for a proper set up and alignment but they ride really nice! They've given her a go-karty feel without being horrible and crashy. The fronts need bringing down a smidge to level it out then should be all good!

I really like that, does remember me of my own Baby Blue Panda 1.2 Actual.

 

[DaveMcT]

The other day, I discussed wheel alignments with my MoT mechanic. He said the manufacturers settings are a start. After that you should drive the car a mile or so and check tyre tread temperature. The scrubbed side will feel warmer. Adjust the toe in (or out) until they are similar warmth across the tread.

This is exactly how I used to do my old Mini 1000. It never scrubbed the tyres.

 

[fourbie]

This is exactly how I used to do my old Mini 1000. It never scrubbed the tyres.

I still have a gadget I used to use decades ago for checking and setting tracking and is now showing its age!

 

[koalar]

The other day, I discussed wheel alignments with my MoT mechanic. He said the manufacturers settings are a start. After that you should drive the car a mile or so and check tyre tread temperature. The scrubbed side will feel warmer. Adjust the toe in (or out) until they are similar warmth across the tread.

This is exactly how I used to do my old Mini 1000. It never scrubbed the tyres.

Not how I would do it

Fiat settings are safe and tested. It’s what I aim for in a road car

you could be adjusting the toe to correct a camber fault if you use tyre temperature as a setting guide

 

[DaveMcT]

I had to do it on the 100HP because "correct" tracking chewed the tyres. Careful adjustment of tracking using that method solved the problem and improved front grip. I've had the 1.2 tracking professionally set but not touched it since. We will see how the tyre wear goes.

 

[koalar]

I had to do it on the 100HP because I fitted new struts to my 100HP and ended up with a very low ride height at front. It passed the MoT with comment that springs were not tight in the struts. I ordered new 100HP springs from Shop 4 Parts that took months to arrive. They were hardly any longer and were hardly any tighter in the struts and ride height was still silly low. I solved it by making 10mm long spacers for the top bearings on a lathe. The ride height is now ok but I fear the real problem is the wrong struts are being sold as suitable for 100HP. Sadly, I did not measure the old struts before throwing away."correct" tracking chewed the tyres.I fitted new struts to my 100HP and ended up with a very low ride height at front. It passed the MoT with comment that springs were not tight in the struts. I ordered new 100HP springs from Shop 4 Parts that took months to arrive. They were hardly any longer and were hardly any tighter in the struts and ride height was still silly low. I solved it by making 10mm long spacers for the top bearings on a lathe. The ride height is now ok but I fear the real problem is the wrong struts are being sold as suitable for 100HP. Sadly, I did not measure the old struts before throwing away.

I would fix the cause.

 

[portland_bill]

Wheel offset is specified to place the centreline of the wheel over the centreline of the bearings. Steels have the disc nearer the centre of the wheel, whereas alloys tend to place the mounting further out, hence sometimes different ET on the same car.

Ideally, wider wheels should add width equally to both sides, to keep the centreline over the centre of the bearings, but suspension may prohibit this, as might clearance issues on full lock.

If the wheel is set further out, this creates a loading on the bearings, which will shorten their life. By how much will depend on the extra offset, and the capability of the bearings. You'll just have to keep an ear on them. Don't ignore rumblings, better to replace bearings than adding hubs and CV joints to the repair.

Wheel spacers were a 'thing' on original Minis. Regular bearing replacement became a 'thing' also.