Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Extra ground clearance on a Mazda boxed +4

My NB +4 has 185/70/15 tyres and has never grounded on anything.

By any chance Kieth are you lucky enough on your narrow car to have the 4/4 Mazda box variant? Without the +4's soppy gear stick extender and rear mounting monstrosity?

Something for Dave....

Craig's Mazda box

Montegue, I have the 65 profile tyres and have just over 100mm everywhere with the Ford box. and the cross member with the bash plate fitted is the lowest point.

It really makes it hard to believe when you hear the vid's of Morgan talking about their latest design achievements when half a dozen years ago they were happy with the likes of that mount. Must have been designed and fitted by the vertically challenged as I'm sure you'd get sick of banning your head on it when the car was on a lift!

My 2012 Plus 4 Sport was fitted from new with 205/65r15 and it has the best ground clearance and most compliant ride I have ever experienced in a later trad. (Probably just tempted fate with that last comment). It is the most flat cornering trad I have ever owned.

Well I have to agree with you about the ride John on 65 profile tyres. My original tyres, yokohama were 60 profile and although looking new were 10 years old! They still gripped well and garaged hadn't been effected by the dreaded UV light. However I wanted that extra little bit of ground clearance and if they gave me more tyre compliance and a better ride so much the better. Being in the VW polo tyre size you could also get top premium tyre's for about half the price too. I took the gamble and fitted five new Bridgestone turanza 195 65 R 15 options for somewhere ITRO £335.00. To say I was delighted would be an understatement. I noticed no difference to the drive or grip but the comfort factor is light years better than the originals and I have achieved about 10mm extra clearance under the car. Doesn't sound a lot does it, but described as 12% sounds huge! and in fact seems to work rather well!

I was surprised at the ride difference that the 205/65 gave over my 205/60 tyres on my Roadster. I'm not sure what difference there is in the engine weights I assume the Roadster engine was heavier, which may affect the ride compliance at the front compared to the Plus 4. The rear ride felt much better.

Wow, that's way better Roger!

Sorry for the dumb question, but can you explain why the 4/4 Mazda box variant doesn't need the stupid big box rear gearbox mount I have on my Plus 4?

Or perhaps the better question would be..... 'what forced Morgan to fit the giant gearbox mount to the Plus 4 when they transitioned to the Mazda box?"

Also, do you have any images of the +4's soppy gear stick extender?



Hi Keith, I dod look at 195/70s which in terms of ground clearance would actually be ideal, however, the issue is this is a size only seen on small vans so the tyres are typically XL rated, and come with hard as hell long life rubber so not the best for grip.

I also looked at the Dunlop tyres you get on a Suzuki Jimney, these are 195/80 so would take Monty up by a whopping 70mm!! The tread is not really off-road looking on these tyres and the Jimney only weighs 1060 KG, so they should have a fairly Morgan friendly sidewall. But 70mm is a lot, with Monty lowered by 40mm and with a 22mm wheel arch gap the tops of the rear 195/80 tyres would be sat under the wheel arch lips, and I do want some gap there if only for for aesthetics.



Funily enough, I've been looking at this solution John.

Monty is currently sat on 185/65r15 tyres, going up to 195/65r15 gives me another 10mm of ground clearance which would be useful, but fitting a set of 205/65r15 would lift Monty by 26mm, and I believe 26mm would totally put any concerns over limited ground clearance to bed once and for all! I'd be running 104mm of ground clearance at the stupid gearbox mount, and 124mm if I can slim it down by 20mm as planned.

My concern with fitting 205/65r15 is my wheel arch gap goes from 22mm down to just 4mm, that's fine if the tyres fit under the wheel arches as there's plenty of depth to them, but looking at it on Monty I'm fearful the addiional 20mm of tyre width in total, and more specifically the estra 10mm at the wheel arch lip, will cause rubbing under suspension compression? I appreciate the Supersport runs 205/65r15 tyres without issue and has the same wings as Monty, but I suspect Morgan solved any potential rubbing issue by using a different offset on the Minilites compared with Monty's 6" wide wire wheels?

TBH on 185/65 I already have 90mm of ground clearance at Monty's now shaved crossmember and his 'Lip & Tuck' bell housing, so on 195/65s I'll be at 100mm which is fine at these more forward points, and given Monty's approach and departure angles are pretty good. The issue is definitely that stupid rear gearbox mount, not only is it the lowest point on Monty by a good 12mm, it's also right in the middle of the car, this means it enjoys zero lift benefit from eirther the front or rear axle as the car goes over speed humps.

To place that great lump of a gearbox mount right at the point of 'breakover' was very poor engineering from Morgan! If Monty or any other vehicle for that matter drives over a breakover angle larger than it is capable of, the vehicle will contact the apex point of the angle. It's very central position means Morgan's great lump of a gearbox mount is right at the apex of Monty's breakover angle, so while cutting off Monty's gearbox lip and inverting the arc of the central crossmember made a massive improvement, I actually now believe the greatest improvement is still to be found by slimming down the gearbox mount.

Every milimeter I can increase Monty's ground clearance at his pont of 'breakover', is the same as removing many more milimeters in areas under the car that are closer to the axles. If I look at Monty's breakover angle (otherwise known as rampover angle), it's quite clear the apex of the two lines fall precicely at the point Morgan fitted their giant rear gearbox mount (see 'M' below)



I definitely think its days are numbered

I don't know for sure Dave but will hazard a guess.

Maybe that rear mount is there because the Duratec lump is mounted further forward than the 4/4's Sigma? And hence the need for the shift extender on the Duratec. The 4/4 also has the clutch slave cylinder configured internally as it looks too close to the bulkhead to mount externally, unlike the Duratec. I'm also guessing but the 4/4 rear mounting arrangement will be more standard and similar to the MT75 box.
So not too optimistic that Keith will have one.

No room for the slave cyclinder

Craig's box again...

My car. Ignore the arrow!

Cheers Rog, that makes sense, thanks.

I'm still confident the 'Big Box' Plus 4 mount can be improved upon.

If I can shave even 20mm off its depth and then fit a set of 195/65 tyres Monty's ground clearance will be 88mm at the critical rampover point, and if I could squeeze a set of 205/65s under Monty's arches this increases to 103mm, I'll start by slipping a cheap old part worn 205/65 on Monty's spare wheel, then trial fitting it front and rear to see if I suffer any rub?

Watch this space

Monty my gearbox doesn't seem any different, why not try 185/70 Avon CR6ZZ expensive but available in soft compound.