29 replies to this topic

[Cooperman]

Cooperman... You are my hero, you know so much... I want your brain please.

No you don't. if you had you would have my age (shhh, I'm 73 going on 21!).

After 53 years with Minis and a qualified aerospace engineer (well retired) I've made all the mistakes in respect of steering, over damped suspension, over-cammed engines, bad brakes, lousy road-holding, poor handling, etc. I've worked out what was wrong, corrected it and that is the sum of my knowledge. If someone on here does something wrong and feels embarrassed they should not be, as I'm sure I've already done it, got the T-shirt and the skinned knuckles.

Never feel that you might look silly by asking a question about anything. We 'Mini-Docs' are all here to help and advise. We are true Mini enthusiasts and want to keep 'the ultimate classic car' running and running well. My own main interest is in keeping the Mini to the forefront in historic rallying.

I know I get criticised when I go on about not lowering the cars, not fitting wheel arch extensions, etc.,but that is because performance and efficiency are more important than perceived styling. I do believe that the immortal Alec Issigonis felt that way as well. He hated styling trends, which is why the Mini is so superbly functional.

The Minis I love the best are the original 850 and the rally 1275 'S', but then I guess I'm biased.

[Ripple]

After nuclear war, the only things left will be cockroaches and 850 lumps... I know I couldn't kill one!

Back on topic...

I've had 10's, 12's and 13x7's and in my opinion, 10s are certainly the best to look at on the car, 13s give you a whole new aggressive look but I never managed to get the balance between stance and performance. 12s give the best of both... Larger discs, still keep a thick tyre, better on motorways. I've just switched from the standard 5.5" up to a 6" superlite with a bigger offset. Still on sorn at the mo so time will tell

[Cooperman]

A short while ago I had to drive a 1997 MPI with 145 section tyres. I had expected it to lack dry road holding, but I was pleasantly surprised at how good it actually was. It had new KYB dampers which suited it as a standard height road car. It handled very well indeed as well.

But then it rained and it felt very sure-footed and the handling was superb, even when I drove it quickly. Braking was very confidence-inspiring in the wet.

Tyres were new 145/70 x 12 Falkens and I thought they were super. Steering was precise and it felt like a 'real Cooper'. The front sub-frame was a solid-mounted one.

Indeed a lovely car to drive.

[Cooper1]

A short while ago I had to drive a 1997 MPI with 145 section tyres. I had expected it to lack dry road holding, but I was pleasantly surprised at how good it actually was. It had new KYB dampers which suited it as a standard height road car. It handled very well indeed as well.

But then it rained and it felt very sure-footed and the handling was superb, even when I drove it quickly. Braking was very confidence-inspiring in the wet.

Tyres were new 145/70 x 12 Falkens and I thought they were super. Steering was precise and it felt like a 'real Cooper'. The front sub-frame was a solid-mounted one.

Indeed a lovely car to drive.

someone thick stepping in hi what do you mean by solid mounted subframe iv never heard that term?

[Cooper1]

 

Cooperman... You are my hero, you know so much... I want your brain please.

No you don't. if you had you would have my age (shhh, I'm 73 going on 21!).

After 53 years with Minis and a qualified aerospace engineer (well retired) I've made all the mistakes in respect of steering, over damped suspension, over-cammed engines, bad brakes, lousy road-holding, poor handling, etc. I've worked out what was wrong, corrected it and that is the sum of my knowledge. If someone on here does something wrong and feels embarrassed they should not be, as I'm sure I've already done it, got the T-shirt and the skinned knuckles.

Never feel that you might look silly by asking a question about anything. We 'Mini-Docs' are all here to help and advise. We are true Mini enthusiasts and want to keep 'the ultimate classic car' running and running well. My own main interest is in keeping the Mini to the forefront in historic rallying.

I know I get criticised when I go on about not lowering the cars, not fitting wheel arch extensions, etc.,but that is because performance and efficiency are more important than perceived styling. I do believe that the immortal Alec Issigonis felt that way as well. He hated styling trends, which is why the Mini is so superbly functional.

The Minis I love the best are the original 850 and the rally 1275 'S', but then I guess I'm biased.

 

what group arch would you line up on a 1275 cooper if it was on 12s? on 145/70 x 12 i was going to stick with the 8.4" discs but just change to vented discs with braided lines but surely a camber kit can improve the handling no?

[Haynes]

Do you have any pics to show us of your 91 Cooper?  These are getting rarer, i think you should keep it original with 12" rover minilites and standard arches.  I have a heavily modified 91 cooper, now with 6x10s and grp 2s but i noticed last night someone down the road from me has a very original one and i was quite envious.

 

If youve not dirven an 850 on 3.5 x 10s with 145 tyres, youd be surprised how lovely they are to drive, comfortable ride, easy on the steering etc.

[madaboutcherry]

10s or 12s, but not 13s. Ruin the feel of a mini. Who would think an inch would make so much difference?
[/that,s what my wife saysquote]

[Cooper1]

Do you have any pics to show us of your 91 Cooper?  These are getting rarer, i think you should keep it original with 12" rover minilites and standard arches.  I have a heavily modified 91 cooper, now with 6x10s and grp 2s but i noticed last night someone down the road from me has a very original one and i was quite envious.

 

If youve not dirven an 850 on 3.5 x 10s with 145 tyres, youd be surprised how lovely they are to drive, comfortable ride, easy on the steering etc.

http://www.theminifo...y-first-cooper/

 

its soooo tempting to put it back to original but there are so many tempting mods out there 

[Cooperman]

With 4.5" x 12" wheels and 145 tyres there is no need for any wheel arch extensions. The offsets and hub positions are the same as the original Mk.1 Cooper 'S' which didn't have arch extensions.

You don't need vented discs. They are very expensive for no gain on a road car. Just use good quality good condition solid discs and decent brake pads. Mintex 1144 are ideal.

A camber kit which accurately sets the suspension to the right settings can improve both handling and road-holding, but it must be done correctly. The rear suspension is the critical thing to set and is more important than the front. Set zero to -0.5 degs negative camber and 1 mm to 2 mm toe-in on the rears at standard ride height all round. 

[Jayme 1275]

 

Cooperman... You are my hero, you know so much... I want your brain please.

No you don't. if you had you would have my age (shhh, I'm 73 going on 21!).

After 53 years with Minis and a qualified aerospace engineer (well retired) I've made all the mistakes in respect of steering, over damped suspension, over-cammed engines, bad brakes, lousy road-holding, poor handling, etc. I've worked out what was wrong, corrected it and that is the sum of my knowledge. If someone on here does something wrong and feels embarrassed they should not be, as I'm sure I've already done it, got the T-shirt and the skinned knuckles.

Never feel that you might look silly by asking a question about anything. We 'Mini-Docs' are all here to help and advise. We are true Mini enthusiasts and want to keep 'the ultimate classic car' running and running well. My own main interest is in keeping the Mini to the forefront in historic rallying.

I know I get criticised when I go on about not lowering the cars, not fitting wheel arch extensions, etc.,but that is because performance and efficiency are more important than perceived styling. I do believe that the immortal Alec Issigonis felt that way as well. He hated styling trends, which is why the Mini is so superbly functional.

The Minis I love the best are the original 850 and the rally 1275 'S', but then I guess I'm biased.

 

 

I Must say i thoroughly enjoy reading your technical advice.

 

my car handled really well on the old 12" wheels, i put on some 13x7 ultralights and over the years swapped my suspension for adjustable stuff, IMO this has changed the car more noticeably than the wheels, when tracked right the car will handle very well, but thats compered to my daily driver. I currently have a set of 13" force racing wheels which are very light, coupled with a539's and protech shocks im very pleased with how my car handles

[Cooperman]

The other thing not mentioned about 10, 12 & 13 wheels is the difference in un-sprung weight.

When I lift one of my 4.5" x 10" Minilite wheels with a tyre on it feels very light. I lifted a 13" with a 175 width tyre and it was much heavier. The un-sprung weight does have a big influence on road-holding and a heavier wheel/tyre combination needs a softer damper setting and more suspension travel to best keep it in contact with the road. Which is a further reason for raising the suspension if using 13" wheels and ultra low profile tyres. Again, not an issue with racing cars on totally smooth surfaces.

If you have never driven quickly on a race track you have no idea just how smooth it is and how fast a corner can be taken with wide sticky slick tyres on a lowered car. But it is totally different on the public roads and a race spec car on road wheels & tyres is always horrible to drive, even slowly.

[Tomm]

I was thinking about this last night, general question here, I have no idea of its relevance to this subject.

The original design built with the 145 on 10" at 3.5, would offset not bear a relevance here?

In my head, when I have thought about it, I think it would?

[Cooperman]

I was thinking about this last night, general question here, I have no idea of its relevance to this subject.

The original design built with the 145 on 10" at 3.5, would offset not bear a relevance here?

In my head, when I have thought about it, I think it would?

 

The original steering was designed for 3.5" wheels and has never been changed in terms of geometry.

So, as stated above wider wheels and/or wheels with a different datum offset alter the scrub radius which 'screws-up' the steering.

Rear my earlier post above.

[Tomm]

I was thinking about this last night, general question here, I have no idea of its relevance to this subject.

The original design built with the 145 on 10" at 3.5, would offset not bear a relevance here?

In my head, when I have thought about it, I think it would?

 
The original steering was designed for 3.5" wheels and has never been changed in terms of geometry.
So, as stated above wider wheels and/or wheels with a different datum offset alter the scrub radius which 'screws-up' the steering.
Rear my earlier post above.

Thanks for that cooper man, I do find your posts extremely interesting.

What, out of interest was the original offset, having read through your previous posts I can not seem to see the exact figure?

Thanks

[Cooperman]

The drum braked cars and 997/998 Cooper had a different offset from the Cooper 'S' & other 1275 disc-braked cars.

I'm not sure what the actual offsets were.