How close can tyres be to exhaust?

[Setok]

As some might have noticed here I got new winter tyres today.

 

I have noticed a bit of a funny smell driving around today. Something that kind of comes and goes, but it does smell of something getting hot. At first I thought it might have been the temporary manifold patch DaveMorris was kind enough to apply to stop it blowing, but that wasn't blowing any more than usual. Then I wondered if it might be the oil getting a bit too thick with this below-0 weather. That's still an option, and I'm getting new oil in tomorrow, but I couldn't immediately smell anything fishy with the bonnet off. Then I considered if it might be something coming through the heater as with these temperatures I'm wimpy enough to have it on.

 

Anyway, I noticed the smell again when driving home so I thought perhaps it's the new tyres, as that's the only other new thing. I checked the rear and with my rear-exit exhaust the tyre is pretty close to the pipe. Maybe 5-10mm, tops. I never bothered looking how close the summer tyres were so I can't compare. The winter tyres do obviously have a thicker tread and the rims are not Caterham ones. How much space should I have there? Could it just be the little bits of rubber you get on new tyres touching the exhaust?

 

---

Kristoffer Lawson

[6speedmanual]

Hi again

 

Unless the whiskers from the moulding are actaully touching/melting onto exhaust pipe, or the hot gas is blowing directly onto the rubber (which it shouldn't be if you have rear exit), I just can't see enough heat transfer to get the rubber up to smelly-point. [especially with such low ambient temp].

 

The tyres are not rubbing or catching somewhere else, are they, eg under the wings or on a rear coilover? or... if exhaust is touching tyre only on a dynamic situation (bumps/cornering), there would be tell tale marks on the pipe.

 

Can you smell it when moving or standing in traffic?

 

P

 

6SpeedManual

*tongue*There's no such thing as too much BHP per Ton 😬

[alextangent]

The standard U bracket holding my rear exit exhaust touched the tyre on occasions; it melted a small track around the inside of the tyre. It only did this while driving; stationery, it looked fine. In fact, the tailpipe was very close to the chassis member. I changed the bracket for a stainless strap type that reduced the diameter by 3 or 4mm, and that's fixed the problem.

 

Plus, check your front flexi brake hoses; they can touch on near full lock too if they're badly set up. The steering rack with clams allows much more travel on full lock than cycle wings.

 

Alex McDonald

A loud 1700 SS

[Dee Pee]

Setok,

 

I had this problem with rear exit exhaust and it eventually badly damaged the tyre even after changing brackets etc. The safer alternative was a side exhaust was James Whiting and was an easy fit.

 

 

[DaveMorris]

Is the 'offset' on the new rims the same as that on the original ones?

 

X-flow(er) power now resting. Trying Vx for a change.

[Setok]

Oil change done but still that smell. I just can't figure out where it's coming from, but it does now narrow it down a bit. I should try driving around without the heater to see if I get it then.

 

I notice it when I've stopped at lights or whatever, but that might not really help as when moving air tends to flow around quite a bit.

 

By offset do you mean the position it sets the wheel in relation to the sideskin? Like how close it is. To be honest, I don't know as the wheel change was done by a tyre shop. I know that the original Ford rim they tried was bad. It was too close to the exhaust. This is now a Peugeot rim.

 

---

Kristoffer Lawson

[Scalper]

Is the 'offset' on the new rims the same as that on the original ones?

probably not

 

Caterham rims usually have a much lower offset than most tintop rims

I wouldn't be surprised to discover that with the rims he is running the tyres are much closer to the sideskin/exhaust than they were with the original Caterham rims

 

however I have no clue wether this could actually be the cause of that smell

 

Enrico

My Caterham Seven's photo gallery

[Setok]

Scalper, do you run with the same rims summer & winter in the Alps or have separate ones for the winter? Beginning to wonder if I should've just put the tyres on the K&N rims ... Then again that would mean another trip to the tyre shop in the spring etc.

 

---

Kristoffer Lawson

[Scalper]

Kristoffer,

on my previous seven I had an old battered set of alloys that came with the car (standard Caterham width/offset) which I used for the winter tyres as this gave me the chance to quickly change from summer to witner tyres and viceversa. As I used the hakkapeliittas only for fun blats in the snow and skitrips this was a big plus. Unofrtunately here in Italy, contrary to Finland, the roads are clear of any ice or snow most of the time ☹️

 

On my current seven I still don't know what to do

I've managed to get hold of an old set of narrow alloys from a Ford Fiesta. But I'm afraid that while the alloys do fit ok, the tyres might foul the cycle wing stay. Unfortunately I have no way of finding out unitl the tyres arrive and I try them on. If as I fear the tyres don't fit I'll either have to get some spacers made, or fit them to my 6" summer alloys

 

Enrico

My Caterham Seven's photo gallery

new Yellow Banana pics here