15" wheels; an alternative?

[Westfield 129]

Speed recalibration is easy if yiu have a good speedometer shop if you have a mechanical instrument. This is usually best done during the rebuild of the instrument, or when ordering a new instrument, as the cost of recalibration is then absorbed into the purchase or rebuild.

Here, we measure out 52'9" which is 1/100 of 1 mile. With this marked on the pavement, the speedo is disconnected so that the end of the cable is visible.

Paint the one side of the square drive cable white, so that the number of revolutions is easily counted. Roll the car down the measured course, and count the revolutions, to the nearest 1/8 turn.

From this number, the speedo technician can re calibrate your Smith's speedo with surprising accuracy.

I am sure that your speedo tech will have the correct distance for you to roll your car to obtain a revolution number that can be used to calibrate the instrument.

Or, you can get a speedo drive gearbox that allows the exchange of gear to get a correct calibration.

Electronic speedos are calibrated through the use of the dip switches in the back of the istrument.

Note that the recalibration has to occur with any change of rear end ratio as well.

I have recalibrated several Smiths mechanical speedos using the measured distance with excellent accuracy.

[Custardbadger]

I spent a couple of hours in the barn last night playing with the steering rack and body clearance. Good news - the rack had indeed been fitted with restrictors by Westfield for the IVA and having removed / altered them, I now have much improved steering articulation with bodywork clearance. Phew.

I removed the near side restrictor altogether (passenger side for a UK RHD car) and cut the offside restrict or down to 32mm. Without the offside restrictor removed, the rack would have allowed the tyres to contact the bodywork before full lock.

Pictures of the steering articulation achieved and the body clearance below. As I say, it's tight but workable.

[Custardbadger]

A few more

[Custardbadger]

Last ones

[Custardbadger]

I've got Protech shocks to fit this evening so I'll see whether lifting the car onto jacks creates any contact between tyres and the bodywork.

[Splat]

More very useful photos, David. And my goodness, it's a tight fit at the front, isn't it? I'd be very surprised if you (and I, too) didn't have to trim the ally sills back to the mudguard. Although, that'll be an easy enough job.

With my freshly-painted bonnet, and anticipating work needed to the headlamp bowls and sills, I've just ordered a cheap bodywork trestle (eBay, £21) rather than my usual method of laying the clips inverted on blankets on the lawn! The plastic bowls certainly neaten the headlamp installation but obviously need modding. Add my LED lights with their heat-sinks and their need for cooling air and I'm probably better-off with the open-backed, integral fibreglass bowls of the old bonnet moulding.

(As an aside, I read a little snippet a while back that claimed that it was as a result of the lopsided fronts coming out of the old mould (see my thread on my recent bodywork mods) that Westfield were prompted to made new moulds. It seems that it's this new mould that dispenses with the integral fibreglass bowl in favour of the nylon part.)

[Simon Marks]

Hi, David,

Seeing your reduced spacer reminds me that I had nylon spacer tubes (6mm thick) machined up to replace the thin steel tubes that Westfield supplied. I wasn't keen on a steel blade being bashed into the end of the rack housing every time the stop came into play. I told Mark Walker at the factory that I had done this and he has since advised at least one person that this is the way to go!

As my car is currently on 13" wheels, I must get my rack apart and remove / reduce spacers to get more steering lock. I was going to be marshalling at a rally this weekend but they are over-subscribed so I find myself with a (rare) free Saturday so this could be the perfect opportunity.

Reading this thread, and also lacking ground clearance, I am thinking of going to 14" rims myself. My car is on bolt on wheels so I can still get 14" alloys quite cheaply to suit. I'll probably stop there and avoid the close clearance issues that you guys are talking about.

Simon

[Westfield 129]

Set the ride height with the spring collars, with the driver's weight in the car. You will find that you have plengy of clearance when it is properly set up regardless of tire size. The reality is that the difference between the 15" wheels with 4.50 tires and a 165/13 is less than half an inch in ride height, everything being equal.
If your car is too low, resetting the ride heigh at the springs will give a greatly improved ride and handling.

Try a front ride height of 5"~5.5", measured under the frame at the front axle centerline, on each side of the frame, with 7" in the rear under the frame at the axle centerline, left and right side. Have someone do the measurement for you as you sit inthe car. (You might also check the front tracking or toe at the same time, as the alignment has to be done with the drier's weight in the seat.

If you are setting the ride height without weight in the car, set the passenger side up 1/4" high and the driver's side 1/2" high. This should get the car to the correct ride height with a 180 lb driver and the wedge (diagonal weight) within 1~2%.

Installing the longer early dimension dampers (see the recommended Protech measurements) makes this setting easy, and you get maximum ride improvement.

The pictures show a typical clearance with a 155 tire when the wheels are at full droop. BTW, a 165/13 can have the same problem at full droop. It can be tricky to remove a front tire when the car is jacked up with 13, 14., or 15" wheels.

[Splat]

So, two steps forward........ and then two steps back........

More photographs coming up. I've been helped and advised via email by Craig (Ellis) at MWS and many of these photographs will be useful to him in his continued efforts for me. Rather than clutter up his inbox with several emails, each with several attachments, I'll email him a link to this thread.

Hi, Craig! Click or tap on any photograph to have it open up full size.

And, before I start, I'm going to invent two new words and teach you all to suck eggs! The two new words are hopefully going to help us avoid confusion. When I talk about hubs (and I'm going to talk about hubs a lot!) I could be referring to either one of two different things on our cars. Firstly, there is the centre of the wheel itself. This Wheel Hub I shall henceforth refer to as the Whub. Then there is the part attached to the suspension, into which the bearings fit. For a car with wire wheels this part is splined. I shall refer to this Splined Hub, with it's bearings, as a Shub. OK?

As for sucking eggs, I doubt that anybody reading this doesn't already know that there are two generic types of wheel that we fit to our cars. They are referred to as either "disc" or "wire". The word "disc" has nothing to do with the type of brake fitted. A disc wheel is a solid metal wheel; it may be pressed steel with a hubcap or an alloy wheel like a Minilite. It bolts to the car using wheel nuts. In the case of the MG Midget, each wheel is attached using four studs and nuts. A wire wheel is hopefully self-explanatory. Ditto the splined hub (Shub!) that it's fitted to.

So........

Two Michelin XZX 145SR15 tyres were delivered to me on Thursday. I was visiting friends in High Wycombe this weekend, so I dropped into MWS in Slough on my way there. Craig fitted my tyres to two of his "trial fitting" wheels; the 48-spoke, 4 inch-wide rim that was OEM for the MG TF and MGA (the XW450) and the 72-spoke, 5 inch-wide rim (XW459) and I was able to test fit them to the car this afternoon.

Firstly, the fit. Almost no issues whatsoever! There is LOADS of room between the front tyre and the back of my headlights. Remember, I have the old bonnet moulding with it's short, integral headlamp bowls, with LED bulbs, heat sinks and drivers fitted. (If that's news to anybody, there's a separate thread on it!) Great (so far)!

All good to the front of the front wheel. Not so perfect to the rear of the front wheel. With the car up on axle stands and the front suspension at full droop, clearance between the tyre and the aluminium sill is at its most limiting. With any steering lock applied, the wheel impinges on the metalwork. The photo below shows the gap with the steering at neutral. This is the front/right wheel; with the wheels steered to the left, the back of the tyre moves to the right (outboard) and the gap INCREASES significantly. But with the front wheels steered to the right, the back of the tyre moves inboard and jams on the sill. It's the INBOARD front of the sill that'll need cutting back a little, but not by much; probably about half-an-inch off the forward edge of the sill from the chassis rail, outboard for about six inches. (This will not be a visible alteration!)

At the rear axle, clearance should be OK. I'll be fitting 165-section tyres which are slightly taller, having an overall diameter 30mm greater than the 145-section tyres that I've offered up. I may well have to reposition the fibreglass inner wheel arches, but that's the work of only a few minutes per side!

[Splat]

So why, "two steps back......."?

Well, the wheels don't actually fit! By which I mean that the Whubs are wrong for my Shubs! In the near future someone will be along to tell me that I need to fit MGA hubs and that to do so is easy. I'll explain why I can't do that, but I'll be advised to do so nonetheless.........

My 2006 car was originally built using a disc-wheeled donor car and fitted with the Westfield Minilite-alikes. To convert from disc-wheel hubs to wire-wheel hubs (Shubs) I had two options; "conversion" splined hubs, that bolt onto the cut-down studs of the existing disc-wheel hubs, or a full conversion to "proper" splined hubs.

I looked at the former and disliked the compromise, so I've converted to proper splined hubs. But the rear axle casing of a disc-wheeled car is an inch wider than that of a wire-wheeled car; so wire-wheel half-shafts are too short to fit into a disc-wheel axle casing. The only option is the hybrid shafts available from Peter May Engineering. They supply hardened half-shafts of the correct length for the wider, disc-wheel axle casing and come with the splined hubs permanently pressed onto them (as standard, the splined hubs of the rear axle are not permanently attached to the half-shafts). To fit MGA splined hubs at the rear would require a new, wire-wheel axle casing, restored and rebuilt with new, hardened half-shafts, with the required mounting modifications carried out by Westfield. Hundreds of pounds and weeks of work.

Likewise, at the front I've fitted proper, new MG Midget splined hubs. But I've also fitted the Peter May / Frontline Engineering 9" brake-rotor kit with MGB brake callipers. If I were to fit MGA splined hubs to the front of my car, I'd have to junk this kit and return to the inferior MG Midget brakes.

The Whubs of both of the 15" trial wheels are too deep. At the rear they do not have the back-side clearance to fit over the brake drum retaining nuts, so won't seat up against the brake drum. Therefore, none of the Shub's thread protrudes through the Whub for the spinner to engage on. (I didn't take a picture of this, but it's the same at the front, and that photo's coming up!)

At the front, the back of the Whub hits the brake calliper before the wheel is fully seated on the Shub. And again, none of the thread of the Shub protrudes through the Whub.

Here are both of the test wheels fitted to the front/right Shub. Note the back of the Whub is fully against the brake calliper. The third photograph shows a 13" Spridget wire wheel in place. It's fully seated on the Shub, the back of the Whub doesn't touch the brake calliper and the threads of the Shub protrude through the Whub, for the spinner to engage with.