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locked diffs
JoelP - 9/4/05 at 10:01 PM

anyone driven a light car, on the road or track, with a solid back axle (ie no diff or a welded shut diff)?

how did it affect handling? im just pondering cos we add a lot of weight and expense using LSDs, it would be a lot simple to use a solid back axle like a go kart does.

any thoughts?


andy d (rizla) - 9/4/05 at 10:11 PM

i used to do banger racing and 1300 stock cars with welded diffs,you cant go slow round corners or you go straight on,and to go round a corner you have to deliberatly swing the rear out and floor it(great fun)but no good for the road


JonBowden - 9/4/05 at 10:17 PM

I used to race karts. They have a solid axle (no diff) chain driven from something like a bike engine.
I only ever drove as fast as I could. The handling was quite brutal (or else I was no good at it)


RogerM - 9/4/05 at 11:03 PM

It would be, how can I put it, lively.

I don't even like the idea of using an LSD in cars as light as the 7esq set, well not ones from production cars anyway. Those diffs (like XR ones) can not be set light enough to cope with something like a Locost so all that happens is instead of finding traction you just spin both wheels up!

I think an open diff is better suited, just make sure that you have enough suspension movement to keep the inside wheel loaded to some degree (it's not like our cars have much body roll is it!!) and all will be fine.

I have used a Quaife non-locking diffs to good effect in both 7's and Minis (just as light and when I have introduced them to Mr. Turbo about as powerful).

Solid axle, not for me thank you.


andy d (rizla) - 10/4/05 at 07:38 AM

finaly someone else with common sense,a lsd from a sierra is wrong,its just not set up for light cars,handy for doing donuts thats about all


Northy - 10/4/05 at 09:46 AM

I think I read somewhere that it would be fine at a fairly high speed, as tire slip would cope with the difference in whhel speed, but it would be a park in the carpark!


JoelP - 10/4/05 at 01:02 PM

ah well, thats that sorted then! i might try with an old diff anyway, just welded up - you gotta be sure!


Rorty - 11/4/05 at 03:54 AM

A hell of a lot of race series run locked axles of one kind or another (spools, Detroit Lockers etc) and it's often mandatory. Locked diffs are fine for medium to fast speed, but would be a PITA in a carpark. The only way of getting the car to behave properly at low speed is to burn rubber.
Most doorslammers run locked axles and drive to race meetings. Then there are the dozens of 'Saturday Night Specials' that emulate their racing counterparts and seem to survive OK on their daily runs to work, albeit with a certain attitude!
I've driven a locker on the streets plenty of times, but now, as I get older, I would probably not bother.


britishtrident - 11/4/05 at 07:29 AM

Archie Frazer-Nash built cars without a diff that have been the road for 80 years but personally I would not go that way --- I once drove a factory fresh E Type that had a plate LSD so tight that it was a real pain in the neck at parking speeds.

However a "soft" LSD wil improve the handling on slow bumpy corners.


NS Dev - 11/4/05 at 07:51 AM

I race offroad in my grasser (another trophy on Sunday, first race out this year!) with a locked diff and it is fine but would be tricky parking etc on tarmac.

The Global Lights run by Graham Hathaway use locked diffs with no bother


GaryM - 11/4/05 at 08:33 AM

Karts have a solid rear axle but they also have in excess of 12 degrees of castor (15+ in the wet)!!!

This amount of castor is necessary to lift the inside rear wheel when steering lock is applied, this permits a change of direction without the need to scrub/spin the rear tyres.

Karts driven at low speed (less then 10 mph) don't like turning at all.

On a loose surface (dirt, gravel, ice) where it is relatively easy to spin the wheels, the lack of diff is not a big problem but on tarmac I think it would be a nightmare.

Diffs rule!!


Kissy - 11/4/05 at 09:07 AM

...to add to Gary's comments, Karts also have near rigid chassis with no suspension to enable the caster to have most effect. On cold tyres a Kart goes straight ahead, even on full lock! I suppose you could always make some high-caster top/bottom arms, weld up the diff, and replace your springs/dampers with a solid stay! Now that would bve fun, and a weight save to boot!


clbarclay - 11/4/05 at 09:40 AM

When road rallying my farther had a locking diff (possibly a detroit) in a MGB, parking etc. was interseting it the diff decided to lock and they don't unlock as easily as they lock.


Weld diffs (all three) are used formula off road 4x4, a great sport from iceland.
http://www.icecool.is/cool/info.htm

Then again they do have big block v8's and nitours oxide to held breakck traction for turning.