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For the last couple of days I have been looking for some wheels for my car.

The 108 pcd and offsets are a pain in the a**e

So have came up with an idea.............!!!

I am thinking of re-drilling the hubs to take a more common size like say 114mm pcd, this is really popular with the jap cars, i have found these rims that are 8 x19 and 10 x 19 for the rear.

wheel1.jpg

They come with an ET of 20

So the plan is to make a drilling rig out of 15 mm steel, with the centre to fit the spoigot excatly and then have 3 x 14mm holes at the 108 pcd at 72deg 216deg and 288deg (to clamp the rig to the disc/hub) Then drill 5 x 3mm holes at 32deg 104deg 176deg 248deg and 320deg on the 114 pcd.

This would then leave me with 5 pilot holes in the disc/hub that are excatly half way between the original holes. Then drill and tap the pilot holes (in the hub only) to M14 for the wheel bolts and drill the disc with a clearance hole for the wheel bolts.

This would then in allow me to re-fit the original if I ever wanted to.

So would this work ?????????????

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They need to be be exact, even 1/4mm out and the car will feel awful to drive, I'd suggest getting a machine shop to do it, and simply have a spacer/ converter made to fill the distance between the original offset and the wheel offset. Enough specialists do them, or any machine shop could do them.

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I work in a engineering college and can make these within 0.01 mm , do the wheel bolts not simply clamp the wheel to the hub and the really important job of keeping the wheel central being done by the spigot. Lokking on the fact file the corrct et should be 19mm for the front and 17mm for the rear so dont know if the 1mm and 3mm would make that much differnce to the offset ??

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Thats how I look at it,

The bolts clamp the wheel, the spiggot takes the strain (indeed how it should be)

I'm making rear spacers at the moment - bolt through ones with longer wheel bolts - I've turned the new spiggoit to a very tight tollerance so it holds the wheel as well as it can.

If you have the tools (dividing head or similar) at your place then I dont see why it should be a problem.

The major issue I can see is the hub is you are RIGHT on the edge of the hub itself with a 114 pcd - the front hub diameter is only 134mm. The rear hub diameter is again only 130mm, your threads will be 130/2 - 114/2 = 8mm - M14/2 = 1mm left around the edge. (S4 cars)

If you need any dimensions of the hubs lemme know but at least you found out before taking the car apart :respect:

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Get BOLT PATTERN ADAPTERS made. Much easier and reversible.

Here are a couple of vendors:

http://adaptitusa.com/

http://www.wheeladapter.com/wheel_adapters.php

Luke Colorado, Super Spy.   -  Lotus Owner No Longer

1987 Zender Widebody 560SEC | 1994 Lotus Esprit S4 | 2013 Honda Fit EV (#269)

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keep in mind the spacers made by the above people can only be made so thin before they wont be able to work....

cobraesprit, if you do this, PLEASE keep us posted! if 19x8 with that offset works in the front on the earlier stephens cars with the adapter method, i may scrap my idea of getting custom (i.e. expensive) 3 piece forged wheels made for my car...

shade

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Get BOLT PATTERN ADAPTERS made. Much easier and reversible.

Here are a couple of vendors:

http://adaptitusa.com/

http://www.wheeladapter.com/wheel_adapters.php

Probably the best option in my eyes, as said at least they are reversable, also you could just ajust the offset of the wheel i.e making it more + offset to get slighty wider adaptors in there for strengh!

Just my two pence, by the way wheel mania are a good company and sell pretty decent alloys have bought of them in the past and they are fairly clued up.

Regards danny

A

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Thats how I look at it,

The bolts clamp the wheel, the spiggot takes the strain (indeed how it should be)

I'm making rear spacers at the moment - bolt through ones with longer wheel bolts - I've turned the new spiggoit to a very tight tollerance so it holds the wheel as well as it can.

If you have the tools (dividing head or similar) at your place then I dont see why it should be a problem.

The major issue I can see is the hub is you are RIGHT on the edge of the hub itself with a 114 pcd - the front hub diameter is only 134mm. The rear hub diameter is again only 130mm, your threads will be 130/2 - 114/2 = 8mm - M14/2 = 1mm left around the edge. (S4 cars)

If you need any dimensions of the hubs lemme know but at least you found out before taking the car apart :lol:

Just trying to get my head around the hub sizes, if the pcd is 114mm this means that the centre of the m14 would be at 114, now half of the 14 would be 7 . Ok so add the 7 to the 114 would give 121mm which is 13mm inside on the front and 9mm on the rears...............think thats right.

And the standard mount holes would be untouched so would be able to fit either wheel.

If the drilling jig idea works then I would have no problem sending it to people on here with the drills and taps, we could pass it around to everyone who wants to have hubs that accept both standard and jap wheels :respect:

This is how the rig would look

hubdesign.gif

After the pilot holes are drilled the rig would then be removed and the hub drilled to M14.

Using this method all we need to do is ensure the offset (ET) is close to the for the width of rim from here.

http://www.espritfactfile.com/Parts.html#Road%20Wheels

Edited by cobraesprit
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You cannot halve the m14 value only becuase we're not working in diameters, we're working in radius'

As before in my calc - if the hub diameter is 134 and the pcd is 114 - you need to subtract the 2 and then divide by 2 = 134-114 / 2 = 10mm material around the 114mm pcd.

Now take the M14 and divide that by 2 = 7mm. The result is you have 3mm of bulk around the thread which imo is not enough for an M14 you could risk splitting the hub - you might get away with it on the front but the rear is an absolute no go - if I knew someone who had done this to their car I'd take their keys away.

If in doubt, try drawing it (I did it on CAD) and seeing the physical difference.

3618171406_cb800b1a83_b.jpg

See how close the holes are to the outer edge - only 4mm of material surrounds the bolt holes.

2202248694_acfb7044b6_o.jpg

This is also a scale drawing of the front hub from a brembo car - agan note how close they are.

Lucas is right, adapter is the only way to go unfortunatly.

Lots of people have looked into wheels for the Esprit and they are a royal pain in the arse because of the PCD.

My advice also is an adaper and allow at least 20mm thread on the bolts or you might find the wheels come off around a corner ! This means you have to tailor the offset accordingly to take into account the adapter.

I had many a headache over this myself.

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Correct - the original is a 108mm diameter ring, the 5 bolt holes' centres are equispaced around that ring.

I draw it on CAD by asking it to draw a circle with 5 sides at a diameter of 108mm.

Becasue I am such a nice chap (shut up those that know me...) I've done it on CAD for you.

The background are very accurate scale drawings of the front and rear hub, I've put on the proposed PCD to show you using a 5 sided circle at 114mm diameter with the bolt holes as well at 14mm diameter - you can see the issues if you look closely at the marked new bolt holes position.

3831428350_64d31e0d54.jpg

Front hub

3831428894_dfbd0b50de.jpg

Rear hub

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Thanks for that.

Ok then if i have to make adaptors if they were say 20mm thick would that mean that the ET fo the wheel would increase to 40 or would it reduce to zero. Also what material would you use as alloy is very very poor as far as tapping goes, or woud you use studs and nuts (would make wheel changes far easier)

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You could also have the lug holes in the rims offset drilled with steel inserts fitted. That would entail a centre shift of 3.15mm. May be easier, cheaper, satisfy registration and insurance bodies plus avoiding extra unsprung weight.

DanR

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The inserts usually are mushroom headed, countersunk into the alloy and an interference or serrated fit into the wheel. Yes concentric and fill the slightly larger hole resulting from the offset boring.

Oh and if you go this way make sure to have the wheel offset right since there will be no change.

Edited by DanR

DanR

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Have looked into the adaptor that are on offer and I am alarmed to see they have no spigot to locate the wheel

chris_mustang.jpg

5lug.jpg

This to me is really really bad.

If i do go down the adaptor route i would bore the inner to fit the spigot on the hub and then machine a new spigot on the outter side to properly locate the wheel

Thanks to everyones help so far :respect:

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I would definatly try and fit a spiggot - the issue is whether you can and again how much meat is around the spiggot.

I'll try and do a drawing of the spacers Iam making atm, but you'll need to know some key dimensions such as the disk hub thickness and so on - I've got all that info for the brembo / bendix cars which I'll publish later.

IMO I would try and use a large spacer as possible so you have as much thread as you can - I dont trust alloy either which is why mine are bolt through, however you could make steel threaded inserts for the alloy.

Either way look at the grade of alloy/ali you're using - not all metals are made the same.

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Thanks again

I think I would use bolt through and for the outside spiot there is no reson for not leaving the whole of the centre intact ( cover the nut for the bearing ) .The spigot could then be made to fit the wheel perfect and leave it proud for the clamping face by say 12-15mm.

Would it be possible to measure the amount of material left on the rear hubs ( from the outside of a stud to the outside of the hub.

The reason I ask is I am wondering if I could re-drill and tap the fronts, but do not want to have less material than Lotus have left on the rear

:respect:

Edited by cobraesprit
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See the previous posts - a 114mm would leave 1mm at the rear and 3mm front. I would suspect Lotus did something like this on purpose, re-drilling the holes in the hub is not a good idea, not only for that reason but also everytime you need to change your brakes you'll have to drill them as well !

I would imagine the fronts have more meat around the thread becuase of the steering and multi direction of that hub vs the rear - I believe it has more loading on that aspect, dont take that as gospel though.

Do it the easy way, you'll be a lot happier with it.

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Yes I understand. The wheels can come with a choice of offset 20 30 35 45

so am I correct if I make adaptors that bolt through that are 25mm thick then the wheel et would need to be 45 ( instead of the original 20 )

or do subtract it which would give a negative et of -5 ???????????

We have some 6061 to make them from .

Once again thanks with this Jonathan..............You will get a free beer off me !!!!!!!!!!!

Quick update, today I have removed the front brake disc from my MGZT-160 to do some measurements.

So here goes

1. The wheel bolts are M12x1.5mm and there are 5 of them.

2. The distance between the wheel stud holes and the outside of the hub is 5mm

3. The thickness of the the hub is 10mm

These measurements were taken with digital calipers.

When you consider that this car has an unladen weight of 1550 kg compared to 1300kg of the Esprit and that the MG has far more weight over the front axle due to being front wheel drive and the extra forces that are applied due to this.

So with is info I have decided to use the M12x1.5 bolts

This is the drawing I have done

001.jpg

You can see that the new holes are 4.5mm from the outside, I think that this is adequate.

So I have started to make the rig. the new holes are where it says drill to 10 mm, I will be making inserts to fit into these out of steel ( to help with wear) with a 3mm hole to act as the drill guide, these will be 40mm long to ensure the piolet holes are true. The other holes that say drill to 14 mm are for mounting the jig to the hub.

To ensure that the holes are at the precise 72deg I have used a bit of maths

c^2=a^2+b^2-2ab COS C

This means that at the 108pcd the holes are centered at 63.46mm to each other

002.jpg

As Jonathon rightly says this will not work for the rear hubs as there is not enough "meat" left between the new hole and the edge of the hub.

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'Meat' grrrrrrrrrr

Remember the Esprit has much more suspension dynamics than it's static weight on the axle/hub.

Cornering force, tyre difference and so on have to be taken into account - I really would speak to Lotus technical about this and ask their oppinion, incase you're doing something dangerous.

Keep in mind you can make this adapter much larger diameter than the orriginal hub if you like - it's not restricted by the disk when it sits on top of it, infact you could happily take it to ~ 148mm which is the outside diameter of the front disk hub, and what the wheel originally bolted onto - infact to support the wheel I wouldn't recomend anything less than that - that gives you much more meat to play with :doc:

Anyways, you've got the essence of it. Remember you need to get those 2 mating faces parallel (I used and engineers clock to get mine within 0.05mm max/min and I havent finshied yet....not sure if the lathe I have can do a tighter tollerance.

Front disk hub thickness is 7mm iirc from the EBC disks I have - this leaves approx 18.5mm of spiggot protruding out.

Keep in mind the minimum thickness for the new hub needs to be about 30-40mm in order to support a new spiggot you need to find a wheel with quite a large offset value (orignal ET + the thickness of the new hub adapter) - nice thing is the wheels can move out 10-15mm and still look ok but I think the offset of 45 is a minimum requirement.

Have a look at this.

http://www.1010tires.com/WheelOffsetCalculator.asp

Your original wheels (if this is an S4 car ?) are 23.3mm offset - you have a max new offset of 45mm - in order to maintain the same track you can only afford to put in a spacer of 45mm-23.3mm = 21.7mm

I think you can push the wheels out on the early car by at least 10mm so you're now upto 31.7mm adapter thickness.

You can see why so many companies leave the spiggot off !

Your only other option is to reduce the original spiggot on the lathe a bit and balance the two.

EDIT - here look :

3833912433_266dff332a_b.jpg

This is the S4 onwards hub, with an EBC disk (in essence the same spec as standard on a brembo brake car) and your new spacer/adapter fitted.

The spacer is 148mm diameter and 31mm tall giving you an idea of what it would look like - you'd need a bit of ali about 50mm thick to do this job (most of it will end up in the bin as swarf)

Please if you want to keep the pictures right click/save as becuase they do get deleted from time to time when I have a clear out

Edited by Jonathan

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Jonathan, I know ive pestered you to death about this in the past year or so but I need help with wheel fitment once again... I dont know if i will be going the custom forged route anymore because it is turning out to be way too expensive...

Im going to have to go with a spacer/adapter and fit some wheels that have a 5x114 bolt pattern on them...

anyways, the wheels im looking at now are 19x9.5 for the rear and 18x8 for the front, +38 offsets all around....

If i want them to sit in the proper V8 (18x10 +17, and 17x8.5 +19) stance, what size adapters would I have to get?

last time you helped me i was planning on doing a custom spacer that would have pushed out the wheels to the point of the sport 300 rims because i had the arches to go on my car... im keeping this simple for you this time though! :spell:

shade

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What wheels have you found with a ET38 ??

To calculate the position first thing we need do is convert the rim width to mm

8.5 x 25.4 = 215.9 ( old fronts )

8 x 25.4 = 203.2 ( new fronts)

So to make the wheel with the same offset sit to the same place to the arch you would have to add 1/2 differnce of the widths so that would give you 6.35 mm

With me so far, so you would add this to the original offset of 17 which gives 23.35

This means these wheels would stick out 14.5 mm than the original.

That is with no adaptor, if you added an adaptor that was say 25 mm then the wheel would stick out further to 39.5 mm

This is the whole reason that I want and am adapting my front hubs.

If you do the same maths on the ET20 wheels the wheel would sit -3.35 mm away from the arch, This is easy to over come by making a shim of 3.35 out of steel that will also increase the strengh of the hub as the shim can be larger in diameter than the hub and will help increase the strengh.

Over to you Jonathon.......................

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Jamie - a 27mm spacer on the rear will work - 25mm front. That runs true becuase both the wheels are 1/2" thinner and have the same offset - the originals are 2mm difference (17mm & 19mm)

http://www.1010tires.com/WheelOffsetCalculator.asp - that site will do what you want, the spacer is the Outer Position value.

If you run without arches I would be tempted to bring them in 2-3mm becuase they are a bit wide on a standard body, see my GT3.

Offset is the distance from the mating face of the wheel to the centre line, the greater the number the further it is away.

Keep in mind you can have + and - offset, it's rare to see wheels having a negative offset though.

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