750MC January Autotest, 10/01/16

[Roy Kemp]

Hey all,

Just got back from the Autotest. Had a pretty good day. Well, better than the last one, anyway. Here's how it went down.

You may recall the last time I took it out we couldn't really play with it, as the cooling fan died and we had to watch the temperatures. Glad to report that, this time, the two Cheapanese eBay replacements did just great. Temps didn't go above a comparatively icy 95 degrees or so all day with the fans wired on permanently. One weak spot resolved.

However, now that we were able to give it a little welly, we started showing up weaknesses elsewhere. Early in the day (and it was a cold, wet, miserable twat of a day right enough) we just couldn't provoke the thing into oversteer for love nor money. Just kept pushing the front end away. Those watching also said we were tucking the front wheels really badly on full lock, i.e. pushing in the bottom of the wheel and only keeping a tiny amount of tyre on the ground as the camber angle went positive.

We measured the geometry and noted that the front were toeing in a lot, which probably wasn't helping. So we set it up roughly neutral and dumped a load of air out of the front tyres. 

For the next few tests this seemed to help and we could get the car to pirouette, although it was still understeering at and approaching full lock.We proposed knocking up some lock-stops to stop us getting to the steering angles that were giving issues, but couldn't find anything in the tool/spares box that would work. So, just live with it for now. We did, however, notice that we had decent (although old and perished) Michelins on the back and some generic ditchfinders (also old and perished) on the front. We swapped them round and put 18psi in the fronts and 50psi in the rears.

Much, much better. We were now able to actually chuck the thing around like we wanted to, although it's far from easy. Steering's now very heavy with the low front psi. And it's always pulled left slightly, but now it's really bad. Oh, and I think we must have a cracked or at least flexing chassis, as we've broken the windscreen at both bottom corners. As we didn't hit anything I guess we've got some twisting issues. And the rear axle (single leafs on spax dampers) is tramping really badly. 

Anyway, we pressed on and both got a finish. Pete was last and I was 2nd last out of 13 entries. However, my total time for the day was around 255 seconds, and 5th-10th places roughly spanned 225 - 240 seconds. Without the thing understeering like a container ship in the morning I'd probably have been more in the hunt. Still, not too bad considering it's only my second event in the car - I'd probably say there are more nasty habits to be dialled out of the driver than the car!

So, thoughts before the next one:

• Maybe knock up a polycarb screen
• Order new air filter
• See if I can find some wider and stickier rubber for the front
• Research anti-tramp bars
• Research lock-reducers vs adjustable bottom arms
• Find out why it's pulling left

Overall, happy with the days work. Improvements with both car and driver, but lots of time still to be found from both. Happy to hear anyone's thoughts on the tech front.

Away to chuck up a couple of vids - Pete doing some extra-curricular donuts and another one of the club lads jumping in for a wee shot...

Cheers

 

[Roy Kemp]

Not got brake bias adjustment John, might be worth looking into.

Just ordered adjustable bottom arms... 

[John Allen]

Roy. Are you running a brake bias valve. Also cheap and easy.

[Roy Kemp]

Yep it's got a vertical hydraulic in there. I'm still getting used to using one in a RWD car - still very much an uncoordinated blur of feet and swearing!

[Nick carlin]

Have you fitted on hydraulic handbrake?

[Adrian Southgate]

I have six 185/60/13 colway inters in my lockup all well used but during the summer would give you much more grip on the front at very little expense.

[Adrian Southgate]

Check the ARB mounts are secure on the front of the chassis and that the alignment is the best you can get it. Maybe worth spending a few quid and having it checked on a proper rig.