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MG Midget and Sprite Technical - WIll 14' wheels fit?

Afternoon all. I've been trying, unsuccessfully, to have a look through the archive to see if this has come up before.

As part of a extensive update to my car during it's rebuild I am looking at fitting sierra uprights to the front and making all new wishbones. This bit is all fairly straight forward, however knowing what brakes I can fit is not. Ideally the sierra stuff will fit under most widely available and classic looking 14" wheels whilst still being able to use the off the shelf brake parts.

However, will those 14 x 5.5J wheels fit the SWA car? I know that 13" wheels fit, so I'm guessing a 14" with a slightly lower profile should too.

IF not, what is required to make them fit? I won't have any leaf springs at the back for them to rub against as that's all going to a de-dion set up and I can alter the trailing links should it be required.
S Overy

I ran 14 inch wheels with 60 profile tyres without a problem,however higher profiles do need the rear arch leading edge and front wing front edge reducing from my experience.
steve cowling

A friend and I toyed with the idea of fitting Seirra uprights (and brakes?) as whole units

however with my luck I couldn't risk parts from a scrappy and engineer reports so went for a specialist conversion route that ballsed-up but that's another story

as I'm in Northampton I'd be interested to see the results when you've installed them if that's OK with you

cheers, Nigel
N Atkins

Hi,
I did a calculation of rims plus tyres, mine are 13 inch rim with 155/80 and I have no problem. The table below should give you an idea of what is possible.


Rim Width % Diam
13 155 60 0.5162
13 165 60 0.5282
13 175 60 0.5402
14 155 60 0.5416
13 155 70 0.5472
13 185 60 0.5522
14 165 60 0.5536
13 165 70 0.5612
13 145 80 0.5622
14 175 60 0.5656
14 155 70 0.5726
13 175 70 0.5752
14 185 60 0.5776
13 155 80 0.5782
14 165 70 0.5866
13 185 70 0.5892
13 165 80 0.5942
14 175 70 0.6006
14 155 80 0.6036
13 175 80 0.6102
14 185 70 0.6146
14 165 80 0.6196
14 175 80 0.6356
Mark Wilson

Kim at Magic midget sells 14" wheels
see http://www.magicmidget.co.uk/
they're £75 minilite look a likes and wil take 185/60.
I was put onto MM by the Forum as I'm after an LCB and an RC40.
Jeremy
Jeremy 3

Cheers all. I was pretty sure they would fit, but I was mainly unsure of what, if any, mods might be required. Looks like I might have to buy a set once I've got all the suspension in place and take it from there.

Is folding the SWA rear wing inner lip much of a job? That seems to be the suggested mod that's needed, and since I'm still doing the bodywork, if I can get details on what's needed I can do it now. Since I'm looking at a full FB front end, that can be cut back to suit.
S Overy

We have 14x5.5 as well. All we have had to do to the wheelarch is jack the rear of it out by about 5mm on the LH side (Midgets usually being a bit assymetrical here with more clearnce on the right than the left, the RH arch doesn't need the tweak).

You need to be careful doing this, too much of a tweak and ye get a permanent dimple which will need fairning and painting. Worth paying a good panelman to do the job, doesn't take long and cheaper than a repaint.

Not much point in rolling the rear arch lip as it aligns with the rest of the wing (on square arch the wing doglegs out before returning inwards for the lip) Having said that I seem to recall that on one of the cars we usefully trimmed off with a grinder a few mm which did protrude a little. It wasn't necessary to go as far as the spot welds.)
Paul Walbran

The whole car will need finishing and painting once I'm done so that's not really an issue. Since they all seem to have been built slightly differently, I guess I'll just have to wait and see quite what I need to cut out or move out of the way.

Good to know it's easily doable, and won't be too difficult to sort. I'd hate to go through all this work only to find the damn wheels don't fit!!

Nigel,

The uprights and brakes will be available for viewing once I'm done and happy with how it handles. I having a feeling that there might be a few folk who want to see how I'm going to do it, as I know many wouldn't mind ball joints and cheap brake upgrades. Since my car's not registered here yet, I can do pretty much what I want to it before I do as the DVLA have no idea what the car is at the moment. Hence doing all the changes at once. The de-dion set up looks quite easy to do, and the front should just be a case of making the wishbones really.
S Overy

Don't forget the steering arm position relative to the rack, especially the height else you'll have massive bump steer problems.

Where does the steering arm attach to your Sierra upright at the moment, above or below the wheel centreline?

Cheers

Spencer
S Deakin

Unfortunately, the sierra, as with everything else I can find with ball joints, has it's arm at the bottom. The only solutions I can come up with so far are to either move the rack lower to match it, and possible remove bump steer altogether, or to put a tall spacer on the steering arm and use a rose joint to attach the rack. Neither is perfect, but both have their issues.

There are after market uprights that get round this, but the cheapest so far are over £400 for a pair. And that's before you have any brake mountings, discs and odd hubs made with a suitable PCD. If I can't get the sierra ones to work as I want, then I may have to go down that route. But I'd like to avoid it as the sierra stuff is so widely available that if I can work out the kinks, others may be interested too.
S Overy

I was making sure you had the bump steer side covered as you mentioned in your first post that:

"This bit is all fairly straight forward"

As far as fitting the Sierra upright goes!

In my opinion this bit of such a modification is often underestimated / over looked.

If you fit a rose joint as a T.R.E. you will significantly reduce the amount of suspension travel available, which is a problem for a road car.

If you try to lower the rack then the track rod will hit the forward, lower wishbone clevis (if you keep it as per the std Midget one) well before you get full suspension droop. Also if you lower the rack this amount you effectively chop the front part of the chassis leg off which means you lose your FARB mounts.

If your car is a track car none of this a problem as you can tolerate less suspension travel.

I only mention this as I have been through all of this myself, if you haven't already comitted to making your wishbones just make sure about your steering connection first as this is the 'deal breaker' in my humble opinion

Cheers

Spencer
S Deakin

Spencer,

All those thoughts are why I haven't yet made anything for the front end!!

My car will be my only car, but I have a work's van so it would get driven in a spirited fashion at the weekends so I can suffer some things more than others. The lower wishbones mounts are being done away with as mine have been bent in what I assume was a past accident and the new ones will mount to both the towers and the side of the chassis rails, so they will be much smaller and slightly more inboard. And most importantly out of the way of the rack ends.

Moving the rack might not be too much trouble as my front chassis legs need replacing anyway, and I was thinking about replacing them with something different as I might have a full flip front and want something less prone to rust. Or I can keep the normal legs and alter the radiator mounts to allow the rack to sit on the legs and against the front cross member.

The main point that I haven't yet thought of a way round is using a rose joint. If I can lower the rack enough, then this won't be an issue. If I can't then I need to find a way of getting sufficient angle out of a joint.

It's good to have problems raised before I start diving in, as I can be prone to not thinking things all the way through before hand!
S Overy

Simon,

I spoke to Peter May in the past about his 'anti bump steer' spherical T.R.E. kit he offers and he explicitly doesn't recommended this kit for road use due to the subsequent reduction in suspension travel.

If you are remaking the inner suspension pick up points and the chassis legs then you are in a much better place to start, as you state this helps the track rod in droop by not hitting the clevis.

If you decide to use a spherical then make sure you reposition a bump stop to prevent the spherical from necking out during bump travel as they are not designed to take bending loads and the cheaper ones will break - has a negative effect on steering ;)

My MX5 upright has a few mounting holes (for dust sheilds etc...) which I plan to use to attach a steering arm (a bit like the caterham ones do) along with the original TRE mounting hole. This allows me to get the TRE in the right place and then I just need to recreate the required taper to allow a std TRE to be used - all simple enough to say...

I am still looking into the spherical option myself as it recently dawned on me we used to use them on WRC cars which had plenty of suspension travel! But I just can't find any photos or details to remind me of the specific parts. But I have looked at all of the usual supplier websites without success so far.

Have you got the uprights yet / done any suspension geometry plans?

Cheers

Spencer
S Deakin

I've got the uprights, but I've been concentrating on finishing the body work off before I move on to the suspension. The back end is fairly simple as I'm using the upgraded Caterham Watt's linkage for longitudinal location, and their lower A arm for the rest, so it's mainly a question of making suitable mounts.

As for the front, I was mainly thinking along the lines of keeping the lower bone very similar to the stock one, and then play around with the location of the upper inner pivots as the rest is pretty much fixed by needing to get it all under a normal arch. The upper bone will have rose joints for the inner pivots, so I can later static camber and castor if required later on.

As for the misalignment, McGill Motorsports do a +/- 26 degree joint, and that should be enough if it's roughly central at road height.

If I can't find a sensible approach to the upright issues, MX-5 ones could be used, I would just need to have hubs with a Ford PCD to match the rears, or just have a different pair of wheels on the front. I doubt anyone would notice an 8mm difference in PCD!! You do have a distinct advantage with the various holes in the upright. That may be enough to swing it should I find the sierra stuff too fiddly to accommodate. I'm also keeping half an eye on the possibility of a bolt on system should it prove worth while, so I don't want to have to chop too much stuff about.
S Overy

This thread was discussed between 05/06/2011 and 07/06/2011

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