7 replies to this topic

[Ant]

Hi all,

I was trying to set up my ground clearance last night, and I think I've got a good range to work with, but I'm not quite sure what to aim for.  How high is your average speed bump?

Can someone out there with a 2B on the road, and preferablly one who drives over plenty of speed bumps without problems, tell me what ground clearance they have at the lowest point of the tube in front of the sump, and at rear just in front of the rear arches.   I guess we'll have to compare unlaiden heights because obviously the car will sink slightly when the driver gets in.

Ta muchly

Ant

[Richard Grove]

Ant,

With my original 1.6 engine (un-modified sump) I managed just over 2" of ground clearance at the sump. I managed almost 6 weeks of driving before the sump sprang a leak. With a nicely shortened sump fitted I have approx 5" of clearance and no problems with speed bumps.

I found that I had to adjust the ride height once the car had been driven a couple of hundred miles as everything settled down particularly at the back. Make sure you leave as much adjustment as you can at the back.

Richard

[2BBoulton]

I have just replaced the sump on my 2B due to the many speed bumps and poorly maintained roads in and around Swindon. I would advise anyone building a 2B to mod the sump first before installing the engine as getting the sump off was a real pain in the butt.

I had 1.5" of clearence before (from sump to ground) when I bought the car and now have just over 3" (80mm) of ground clearence at the front since modding it.  Its a bit lower at the back but at least that end of the car doesn't tend to leak when scraped.

After I had holed my sump I checked out the goverments guidlines for speed humps (in case I could claim for damages   ).  There is no real rule of where they can and can't be placed but they do state that humps in 30 zones must be no higher than 75mm unless its a table hump and then they have to have the right type of gradient leading up to them. In a 20 zone the humps can be 100mm but there is a certain restriction about using 100mm high ramps.

Before doing the mod I tended to find that only the front caught the hump and provided the ground on either side of the hump was level and the same height then the back was OK.

Bruce

[bloke]

forgive me if this issue becomes clear as you progres with your build but its foxing me at the mo

my car is on all four now and ground clearance is 10.5 ins!!!! (im not trying to model me 2b + on rhsc rager!!!!) to bottom of side pannels

have arrived at this height (nothing else fitted to chassis at the mo) to 1) make the rear wheels vertical - any lower and the tops slope in. and 2) front bones and coilovers just miss unladened

??? ??? ??? ??? ??? !

can anyone shed some light

[neil gale]

The ground clearance from the bottom of the stainless panels should be around 6-7 inches, with the engine in. You may need to adjust the coil over shocks to lower the ride height (have you fitted the engine- this will lower the clearance quite a lot??)

The clearance under the car for the bottom U shaped sump guard (the lowest bit of the spaceframe chassis) is typically 3-4 inches, but with a standard sump which sticks down up to 2 inches below this chassis bar, the clearance can be 1.5-2 inches which is why speed bumps etc are so much of a problem.

The rear wheels must slope inwards to give the correct ride height - spacers can be made to straighten them out later, but they do slop inwards a lot.
As for the front, try moving the location of the coilovers on the bottom wishbone - this can give the correct clearance when the ride height is right.

Neil.

[bloke]

cheers for your reply neil

the neg camber looks un natural but if its supposed to be there itll grow on me and i can stop worrying...

[cjbailey]

What happens about tyre wear?  Am I being dumb, or will it not screw the tyres completely?

[timswait]

Negative camber gives good cornering and turn in (when it's on the front) but poorer stabilty. As for whether it gives good or bad tyre wear is up to your driving style. Driving down straight road with -ve camber will wear the inside of your tyres (as in if you do motorway driving). If you corner vigourously (as in track days) then the tyre will roll on the rim and -ve camber will prevent the outside of the tyre wearing. I've left the rear settings alone (as it's a bother to adjust, the only real option is to put shims under the hub carriers, there was disscussion somewhere else on this board about that) and my handling is great. The insides of the tyres tend to wear slighly quicker, but not much so, and my driving is a fair mix of most conditions. For the front I got the toe angle set up by a garage and set the ride height equal myself. I adjusted the camber until it went in a straight line without pulling to one side to get it equal, and then adjusted it until it was to my taste. (It looks about the same as the back)  The front tyres wear almost completely evenly.
As for ride height, if it don't grind it ain't low enough!! Just make sure that it grinds on something substantial and not the sump, a shortened sump is really an essential. Mine tends to ground out most often on the rear subframe mounting bolts, so I just keep an eye on them and I'll replace tem if they seem to need it. They've survived 7000 miles so far. Don't use the front suspension washers for the rear subframe mountings, though. On mine those only lasted a few hundred miles before wearing through. If you use flat washers you'll get a couple of inches more clearance.