exhaust and lowering.......

exhaust and lowering.......

Author
Discussion

beastieboy

Original Poster:

65 posts

248 months

Saturday 26th June 2004
quotequote all
i am thinking of getting a new spangly exhaust for the beast and getting some hi-lo's to get rid of the dragster stance. however i was talking to some one who said that if i lower the back end i'll have scrapage problems with a centre exit exhaust ! anyone had any problems with this ?
plus is there any point using hi-lo's with standard rover shocks ?
thanks

alextgreen

15,402 posts

249 months

Saturday 26th June 2004
quotequote all
What you need:

New rubber cones (particularluy front)

Shortened dampers

Hilos

New poly bushes all round.

Do it properly or don't do it at all mate, other than improving looks you'll have an undrivable car.

May as well give yourself a degree of neg camber on the front too. Lastly, find some who can measure camber, castor and toe AND tell you how to get it right once measured.

Might sound a bit harsh compared to a quick lowering job, but the results you'll see from this will knock your socks off, combined with sticky rubber you'll have a Mini that grips like a limpet and will outhandle any go kart.

Cooperman1

116 posts

250 months

Saturday 26th June 2004
quotequote all
I have never seen the point of lowering a road-going Mini - in fact it can help if you raise it up a little bit.
Reasons for saying this are, first of all, the Mini has very little suspension travel available to begin with, so on any sort of twisty & slightly bumpy road, which is where a Mini is most fun, you need more, not less suspension travel to keep the wheels on the road and prevent bottoming out. If the suspension is down on the bump-stops it won't steer or handle properly.
Secondly, the sump is so low already, and so vulnerable that it needs good ground clearance to avoid it hitting the ground and cracking (if it cracks you are into BIG money!).
I'm sorry if I'm repeating myself here, but the way to make a Mini handle are:

1. Fit 10" dia x 4.5" or 5" wide wheels (no wider) with decent rubber, like Yoko or Falken 165/70x10.
2. Set about 1.5 deg neg camber on the front by changing the lower arms.
3. Maybe raise the front slightly until the car sits nice and level. This improves the available suspension travel.
4. Set up the REAR suspension to give 1/8" toe-in and zero to 0.5 deg neg camber (this is probably the MOST important thing in making a Mini really handle well).
5. Use SPAX or AVO adjustable dampers, but don't set them too hard - let the suspension do its work properly.
6. Set the tyre pressures to about 32 psi all round.

My Cooper 'S' rally car will, I believe, out handle about 99% of Minis and it is about 0.5" higher all round, but the suspension settings are all spot-on, and I keep them this way. Lowered cars are really only good on smooth race tracks and b****y useless on overall road driving (ask Dodgy Dave about all this).
If you are fitting a centre exhaust and want some advice about fitting it with an lcb and making sure it never falls off, just let me know and, if you think it's of general interest, then I'll post an article on here.

I hope this all helps a bit.

beastieboy

Original Poster:

65 posts

248 months

Thursday 1st July 2004
quotequote all
thanks for the advice chaps. i've decided against the lowering thing and have also decided to get a bigger bore, stainless side exit instead of fannying about with a centre exit.
i would love to fit my min with 10" wheels but as it's on 13"s at the mo (its a sportspack) i've heard its a time consuming, if not to mention costly job.
once again, thanks.
no doubt i'll be asking more questions soon.

Neil8p

175 posts

254 months

Thursday 1st July 2004
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We've got a sportpack and to optimise the suspension we fitted adjustable tie bars and rear camber/track plates.

We experimented with the settings until we've got something that handles very well, doesn't bump and tramline, has no appreciable tyre wear and into the bargain gives good fuel economy.

We fitted hi-lo's just to help even up the ride height, but it's not lowered. We also fitted spax shocks as we found the koni's were too soft and not easy to adjust.

Neil

Cooperman

4,428 posts

257 months

Friday 2nd July 2004
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Neil, I've never liked Konis either. I used some years ago and it's stupid that you have to take them off to adjust them. It's so easy with SPAX.
I think Konis are stiffer on rebound than on bump which may be fine for some cars, but not for a road Mini.
Of course, I've heard some people complain about SPAX, but I recently changed a set on my red car which had done 22 rallies with no problems, including a lot of forest gravel mileage, and I would still be happy to put them on a road car - I just changed them as a reliability thing.
I really do detest lowered Minis on the road. They are fine on a smooth track, but they always seen to handle badly on ordinary road surfaces. They look very odd, as well.

haynes

370 posts

249 months

Friday 2nd July 2004
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What is 'standard' height? From floor to the lip on the sill, mine is 21.5cm front and 24cm at the back, this is with 10" wheels. Any lower, say 23cm at the back and the wheels will rub on the arch at full suspension travel and the exhaust scrapes over speed humps etc.

Cooperman

4,428 posts

257 months

Friday 2nd July 2004
quotequote all
I dunno.
Mine is just set to give a nice level sill and sufficient ground clearance witht he big sump guard on to clear the bumps so far as is practical and to handle nicely.
It has always been the case that handling is much more important in a rally car than absolute roadholding on dry smooth tarmac. If you drove my car you would know what I mean. When the guy from Mini Mag drove it last year he seemed surprised at how friendly it is to drive quickly. He said that it seemed soft, so I demonstrated its performance on a bumpy road when the suspension had to work to keep the wheels on the ground. That's the real test of any Mini other than a track-only car.
The original workshop manual has the correc theights in, but I don't have a copy here at the office. I can look it up if you want.

Peter

haynes

370 posts

249 months

Friday 2nd July 2004
quotequote all
Peter, until recently i was certainly under the common misapprehension that low and hard suspension is 'best'. I had very bad understeer despite 1.5°neg camber and i kidded myself it was somehow down to the power of the 1380, but when i fitted a 998 whilst the engine was rebuilt, and still had huge understeer i realised that something must be wrong with the suspension. Softening the front spax was the answer. Commonly quoted in the mini press is that you should set front spax about half way and rear at 2 or 3 clicks, i found the opposite to be the case unless youre using coilovers on the back. Stiffening the suspension reduces body roll which reduces weight transfer and that reduces grip, because you then have less weight pressing down on the inside wheel. So i can understand why someone might think your car feels soft yet handles well.

Mr2Mike

20,143 posts

262 months

Sunday 4th July 2004
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haynes said:
Stiffening the suspension reduces body roll which reduces weight transfer and that reduces grip, because you then have less weight pressing down on the inside wheel. So i can understand why someone might think your car feels soft yet handles well.


Stiffer suspension does not reduce weight transfer to any great extent, unless the center of the gravity is much higher than the roll center. Having very stiff dampers effectively stops the suspension doing it's job of keeping the tyre in contact with the ground. On an infinitey smooth surface, very hard dampers wouldn't cause understeer, but then again sprung suspension wouldn't be needed at all.

Neil8p

175 posts

254 months

Monday 5th July 2004
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Haynes, I'm surprised at your findings as I found having the rear stiffer than the front did nothing for the handling and made the car twitchy when I'm on the brakes.

I found that having the front a couple of clicks stiffer than the back, but keeping the whole setup quite soft seemed to work best for me.

I thought that wheel geometry had the biggest effect on under/over steer (can anyone confirm? ) A while ago I fitted neg camber arms, adjustable tie bars and rear track/camber plates to my old 998 racing green. I took measurements and thought I adjusted everything back to the same place ready for final adjustment.

I'd obviously got something wrong as the car oversteered on certain bends and roundabouts Good fun once I'd got the hang of it, but the tyres didn't last very long.

Got it all setup and bought some new tyres and it was a different car

edit for spelling

>> Edited by Neil8p on Monday 5th July 09:18

Cooperman

4,428 posts

257 months

Monday 5th July 2004
quotequote all
It seems to be a bit of everything, Neil.
The rear camber and track seems critical and I always start there with the 1/8" toe-in and zero to 0.5 deg neg camber.
On the front I like 2.75 deg to 3 deg caster and zero to 'a bit' neg camber. Front tracking I usually set to absolutely straight ahead i.e. no toe-out.
Tyres and pressures are a big factor and I find that with a 165/70 x 10 if I run at about 34 psi all round it's about right for most surfaces.
With new SPAX I set 3 clicks on the front and two on the back. I agree with MrMike regarding suspension settings and their effect on handling. However, with a stiffer rear damper the initial reaction at turn-in will be to improve the turn-in, but this will settle into whatever the other settings will give once the body roll achieves it's setting for the 'G' being applied.
The single most detrimental factor for overall Mini handling and 'friendly driving feel' is, in my humble opinion, the lowering of the suspension and its consequent reduction in available suspension travel. The message is 'don't do it'.

Neil8p

175 posts

254 months

Monday 5th July 2004
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Cheers Peter, interesting comment about tyre pressures as well.