Chris's new build of an MX5 based car

[CTWV50]

Originally Posted by RichardH

did you come up with a solution for the sump yet? just fitted my engine and i dont like how low the sump is to make the engine clear

Hmmm, I thought the same and had a 3mm piece of steel bent to be used as a sump guard, it wasn't a great solution and would pickup stones from my drive and actually come into contact with a lot more stuff. So I took it off. I have actually only grounded my sump out in use on those really short carpark speed bumps, the ones you literally have to go over stupid slow, if I come across these I just carefully push the sump over them , I mainly just avoid them. The sump has never made contact with any road surface during use and some of the roads round here are pretty bad. Obviously you don't want to let a narrow hump in the road go under the middle of your car but then you are acutely aware of the road surface you are on purely due to the nature of the car.

I thought about shortening the sump but I'm not sure it's needed and the gained clearance is minimal due to the gearbox. What I did do though is fit an oil pressure gauge, warning light and buzzer just incase.

My car has a lowered floor too which means I have to be careful anyway as I'll damage the floor of the car even if a shortened sump clears. I think part of the reason it hasn't been a issue for me is because I spent a lot of time figuring out the front suspension setup so I could retain the full steering travel lock to lock of the the escort rack, a side affect of this was fitting 450lb springs at the front so my car doesn't tend to dive at the front under breaking. I've also fitted 300lb springs at the rear which is a little more than the norm.

HTH

Chris

[RichardH]

thanks for that, i havent bought coilovers yet so i guess that will be the next hing to watch. some of the race cars i deal with have a sump protector bar rather than a sump gaurd that is another idea, the bar is the same height as the sump just four inches further forward so that hits before the sump does, almost sacrificial if you like

[CTWV50]

This is the post about the front suspension all explained best I can.

Originally Posted by CTWV50

I’ve been asked by a couple of people about why I’ve gone for 13” shocks on the front so I thought I might as well give an explanation on my build thread.

I have been working on the issue of the steering contacting wishbones on full droop. I thought I had resolved this by welding in rack limiters as you can see previously in my build thread. This seemed a good solution to prevent the steering on full lock contacting the front of the wishbones but after driving the car in a space large enough to complete a full turning circle it quickly became apparent that the amount of limiting done to resolve the contact issue was too much. I had something like a 19 metre turning circle which I estimated my using google earth lol! I also couldn’t make left turns without going into the opposite lane of traffic, a bit like a bus. So something had to be done.

I know others have used 14” open shocks and rack limiters and have been happy with the results so I maybe just a one off due to my particular Saturn wishbones and the fact I was using Gaz 14” open shocks and not 13” with a 1” top hat. I don’t know, but my turning circle was unacceptable to me.

As I was so far down the line with build and pretty much committed to using MX5 uprights and saturn wishbones (which I actually can’t see how you could improve for clearance without bending) I decided the issue was droop and I needed to limit that droop. Although I didn’t need to change the shocks to limit droop it seemed daft to keep them and not use their full travel. So as a quick test I fitted the 12” rear dampers but they weren’t able to give a correct ride height without a lot of preload and were giving me next to no droop at all and very little actual suspension. So I bought a set of 13” dampers to see were they would put me.

The 13” dampers worked well I could achieve a good ride height without spring preload and also level wishbones, which I’d not been able to achieve with the 14” dampers and 400lb springs (without them being loose on full droop) I also had plenty of droop and active suspension but I was getting contact again at the very end of the steering lock at full droop. So the options were limit the steering lock again but only by a small amount this time or move the shock bracket on the wishbone to again limit droop a small amount and prevent contact.

Limiting the steering was the easy solution but because I’d gone to all this effort I decided I might as well go the whole way and see were I ended up so off came the wishbone brackets and after a lot of careful measuring and estimation of ride height and droop I got them both tacked back on in the right position. It took three attempts to get the 2nd bracket in the correct location to get matching ride height and no wishbone contact.

By moving the brackets outwards slightly I had changed the ride height the cars front frame bottom rail, it was only 85mm off the ground with no spring preload. I could of put preload into the spring but I thought this would be excessive so I ordered some 450lb springs, which seems like a lot but changing the angle of the shock had increased the leverage on the spring.

I fitted the springs last night and with only hand tightening preload the car sits at a static ride height of 105mm. The springs can still be turned by hand when unloaded from the cars weight and the shock length with the cars weight on them is around 12” in length giving 1” of shock droop. Droop at the wheel though is around 1.5-2". The ride is supple yet firm, obviously I haven’t used the car in the real world so I shall keep hold of the 400lb springs for the time being just incase the ride is too firm at the front.

If you can get away with rack limiting with the wishbones you're using and you're happy with it then that’s the solution. As I’ve said mine was just stupid so I had to do something.

[CTWV50]

Made it out to a local Charity Classic Car Show at the weekend with some friends. All sorts there so I didn't feel out of place, met a Robin Hood owner who has a Haynes chassis in the garage, he's planing a bike engined build so we should see him on here soon.

[norton]

Hi, Could I ask please how you managed to get your handbrake cables to clear the chassis at the caliper end?

I have these calipers.



The bracket holding the outer cable is shaped such that the cable has to turn a very tight turn to clear the chassis. and thats with the car sat at a normal ride height so the problem will get worse under compression.

I'm baffled!

[CTWV50]

You need to remove the bracket and bend it a little more in a vice, then shorten the bracket and redrill the mounting hole to bolt it to the calipers. Hope that makes sense. Oh and when you go for your IVA wind the spring collors up on the dampers to make sure they don't touch on the day, skovs, and stots thread have more details.

[norton]

Ah fantastic, thank you!

[CTWV50]

Not done much of late, had the car out a few times but have been distracted by the purchase of my holiday hire bike (cheap, comfy and fast) and the weather. Doing more miles on that than in the car, training for my first Audax event (long distance cycling).

I have been collecting parts for the 1.8 engine fitment. I currently have the new alloy 3 core rad and alloy header tank, need some waterless coolant, some plumbing bits, and a few other bits n bobs but probably going to be a winter project.

[norton]

I think pictures of engine and radiator porn are required...

[CTWV50]

Originally Posted by norton

I think pictures of engine and radiator porn are required...

LOL, Voyeur like tendencies will be satisfied in due course.