Tyre pressures, some guidance please.

[JB052]

I'm the temporary custodian of a 1992 Ford engined Caterham. Built from new by a sadly departed friend.

The back end of the car (DeDion) feels a little unstable and I'm trying to understand why.

Everything seems to be tight, although there is some drag on the near side wheel.

Looking at basics, can you ganyone me an indication as to what sort of pressures should the tyres (195/50/15 Good Year) be set at?

Cheers...John

[Orange Blackbird]

Anything from 16 to 22 psi will be ok on the road. Depends on how you drive, for sedate stuff the lower end, for spirited drives and track work around the high end.

As the car is quite old the bushes on the suspension may need replacing. How old are the tyres? If they are older than 7 years then these could do with replacing.

[JB052]

Thanks for the info,

Are front and rear tyres set at the same pressures?

Tyres are about 4 years old and I will look at the suspension bushes.

[AndySuperSport]

I'm running 13" wheels with 70 profile Yokohamas and I run 16-17psi.

Mine is feeling a little loose at the rear too so I'm also going to get the bushes checked out and replaced. It's 18 years old and I don't think any previous owners replaced them, let alone inspected them.

[Roadru77er]

185/60-13 Yokohama AO21 on a K-Series run at 18 PSI here.

[JB052]

Tried the tyres at 18psi (cold) instead of the previous 16psi this evening. Still feels to loose at the back, and a lot firmer ride considering only 2psi difference.

Fully agree that its worth getting the bushes replaced, although I would like to check them first so I can understand what is going on.

Something is also dragging on the rear near side as well, possibly the brake or it might be a wheel bearing as that particular wheel is getting quite hot. Although I would have thought a bearing would get looser rather than tighter.

Also wondered what impact the state of UK roads might have on the general feeling of security on such a light car.

[jackh707]

Hi, we have a similar aged, 1991 de dion ford engined caterham. When we first got it it was exactly as you describe. Mid corner bumps would unsettle the rear and it felt like it was shimmying. New A frame bushes made a big difference but there is a still a little of that sensation. we put this is due to crap old suspension tht desperately need replacing. Hopefully will get some nitrons in the near future when funds allow.

What have you got a zetec or crossflow?

[JB052]

Car I'm looking after is the 35th Anniversary Edition with a 1700 Kent Cross Flow prepared by John Noble Motor Sports (150 bhp@7200rpm).

Did you replace the 'A' frame bushes yourself?

[JB052]

Thought I would post an update in response to my original question. It turns out the De-dion tube has cracked in the centre which seems to be a not uncommon problem.

See the thread started by jackh707 for additional information.

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[JB052]

Just to be clear, this was the cause of what I believed to be incorrect tyre pressures.