Mx5 supercharged Dolomite

[nico]

Hi all

I am new here and have recently bought the supercharged mx5 engined dolomite built by Richard ("mx5 turbo Dolly" here I believe). I have done regular trackdays for several years and have had a few Mx5 track cars.
Here is my first one:

It had a standard 1.6 engine and was just fully stripped down. Great and bullet proof.
Then a 100% stock one that I used every day... and for the occasional autotest

My third one:


Cosworth powered
My current one:



1.8 VVT with Rotrex supercharger

And finally the Dolomite:



I just wanted to say a quick hello and ask a couple of questions.
Having been in the Mx5 world for a while I have a few sets of nice wheels sitting in my garage. They are PCD4x100. Has anyone looked into spacers to change the PCD? Any links?
What is the wheel/hub centre bore diameter on the Dolomite?
My car was built as a drift car but I will probably mostly use it on track. Is there anything adjustable in the dolomite suspension geometry? (apart from height with adjustable dampers)
Many thanks,

Nico

[Carledo]

Hi and welcome to the forum! I saw your car at RRG last year and hope you can bring it to Shelsey for RRG this year (31st August)
I think there are some hubs available (though not cheap) to convert to Ford PCD. I wish I knew of some 4x100s as I have rucks of nice Vauxhall wheels in that fitting! Spacers are not really an option on a car which DOESN'T have huge arch extensions like yours so you're probably on your own with that!
Regarding suspension mods, you've got a bit of adjustment in the front camber by de-shimming the top wishbone mounts and that's about it apart from the ride height control you already mentioned. With a live rear axle there's obviuosly zilch you can do with that.

Steve

[eightiesflamer]

Hey up nico
I have ford 4x108 hubs on my Toledo running 15inch ford pattern rims and custom made rear drive flanges that me and a friend made happen.
Check out sprintspeed on the web.

[nico]

Great thanks!

[Toledo Man]

Steve's right. You would need to change the hubs to change the PCD. One alternative would be to fit MGF wheels as they're the same PCD as the Dolly.

Welcome to the forum.

[Mad Mart]

Sprintspeed sell Ford PCD conversions...

http://www.sprintspeed.co.uk/pages/prod ... tub-axles/

[gmsclassics]

There are more extreme adjustments you can make to a race / track car. Not only removing the shims at the top of the wishbone mount but also where that bolts through the lower part of the subframe you can user spacers to force the lower end out. Also spacers between the lower ball joint and the vertical link. You need longer bolts and loctite in both cases! If you do this you need an adjustable drag strut (the link at 45 degrees forward). That will allow reasonable camber and caster to be set. A thicker sway bar helps as does zero toe, even slightly out.

Don't drop the rear height by much over one inch (measured from axle to body) or you run the risk of raising the roll centre to a point that destabilises the back end and it can snap away from you. Using lower profile tyres is fine, that doesn't affect the roll centre. You can overcome this by raising the body mounts of those 45 degree links to inside the car, just above the rear floor. However you end up with holes into the car which also need to be dealt with (rupture the fuel tank in a crash and you've got fuel in the cabin). Standard or no sway bar on the rear.

If you have a standard rear axle, don't forget you can change rear axle ratios using early triumph 2000 crown wheel and pinion which were made in 3.77 and 4.1 ratios. They can be hard to find. With arches you could perhaps modify another wider axle to fit. Maybe one with the pcd for your wheels - a big job though.

Good luck!

Geoff

[trackerjack]

Great stuff I love cross pollination and mixing various fans.
I have just built a Lotus 7 type special with an HSK turbo'd 1600 MX5 lump installed and it really shifts.
Busy with IVA at the moment and ready for its final check to clear it for road use.

Wife has an MX5 too and to think a few years ago I looked on them as I did Spitfires years ago...............as a girls car

That Cossie must have been a beast

[nico]

Thanks. Lots of good info.
I have got a couple of things to sort to MOT it. I'll then take it to get the geo checked. Then do a first trackday before doing any further modification. I might like it the way it is!

The front suspension and rear axle apparently come from a track prepared sprint. It's fully polybushed, has AVO shocks and a triumph 2000 diff (welded). I also have a spare standard axle and a TR7 axle (I believe).
At the front it's got a Sierra caliper conversion. I don't know what the discs are. I don't know if it has shims removed or spacers anywhere...
Someting I find very strange with the Sierra caliper conversion... it has copper pipes from the sliding caliper up to the bit attached to the top of the upright... surely that can't be right ?!?
(one of the things to fix for MOT is a dragging front brake...)

[Carledo]

Thanks. Lots of good info.

At the front it's got a Sierra caliper conversion. I don't know what the discs are. I don't know if it has shims removed or spacers anywhere...
Something I find very strange with the Sierra caliper conversion... it has copper pipes from the sliding caliper up to the bit attached to the top of the upright... surely that can't be right ?!?

This sounds like a "trackerjack" brake conversion, beloved of all speed freaks on here, including me!
This copper-pipe-into-sliding-caliper idea is the original design, I found it so offensive that I have had some special flexis made to get round the problem, see my thread in the dolomite related section of the this forum entitled "flexis for trackerjack conversion"
I still have one set of the first batch available and some slightly modded ones on order which will end the need to mod and move the bracket on the lower end of the main flexi. They are £29 a pair including uk postage. PM me for more details.

Steve

[trackerjack]

Alright alright my first few offered the copper pipe and my own car ran for 14 years with no problems with it like this because if you think about it it only moves the amount a padwears in thickness, however it is not a good solution really.

You can of course use two standard hoses, the first a standard UNF hose to the bracket and fit a female UNF to female Metric adaptor and use a standard Ford hose to the caliper.

There are many ways to skin a cat.

[Carledo]

Alright alright my first few offered the copper pipe and my own car ran for 14 years with no problems with it like this because if you think about it it only moves the amount a padwears in thickness, however it is not a good solution really.

You can of course use two standard hoses, the first a standard UNF hose to the bracket and fit a female UNF to female Metric adaptor and use a standard Ford hose to the caliper.

There are many ways to skin a cat.

Sorry Jon, I wasn't trying to be rude! TBH my major concern with the copper pipe is not movement in service, which as you say is minimal and takes place over considerable time, but all the stress put on the pipe when removing the caliper to change pads (or did you disconnect the pipe and have to bleed it all out afterwards, you must have changed a few sets in 14 years!)
In any case you must admit the flexi is a more elegant solution!

Steve

[trackerjack]

I agree totally with what you say and no dont tread on egg shells with me I know when I am wrong!
Yes pad changing is the problem and I removed the nut that holds the flexi bracket to ball joint but was being a cheap skate

[nico]

I've fixed all the little things... ready for MOT tomorrow morning.
I'll be at Castle Combe on the 28th for this: https://www.castlecombecircuit.co.uk/ev ... ventID=629
I've booked a couple of track sessions.

Anyone from here going?

[Dolly-Nut]

I've fixed all the little things... ready for MOT tomorrow morning.
I'll be at Castle Combe on the 28th for this: https://www.castlecombecircuit.co.uk/ev ... ventID=629
I've booked a couple of track sessions.

Anyone from here going?

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