if the back end of a saph 2wd is almost solid and doesnt squat much on a launch will that put less strain on the diff compared to squating on its arse ? i only ask as i didnt start breaking diffs until i changed my rear springs for a bit softer as it was uncontrollable at high speed on back roads. car definiteley squats abit now when trying to launch.

 

Suppose so... more squat, more weight transfer, more grip, so less wheelspin = more stress on diff

 

squat is bad for grip on a sierra as it pushes the geometry out giving as much contact patch as a BMW tyre.

but what porkie says about grip=stress sounds right

 

The fix is to STOP LAUNCHING . It won't matter how stiff your springs are. 500bhp + standard diff + launch = broken planet gears everytime. The longevity between different diffs is purely down to how much these SECOND HAND items had been abused before you got hold of them .

 

Weld the planet gears then they won't break.

 

i didnt launch the car before i got the new springs from you mate. i was gonna put shocks as hard as theyl go and try it but i dont think il bother then cant be arsed to change the diff again

 

Tramping is a big killer of diffs, so make sure you dont get any tramping because of how you launch it.

 

EFA!!!

 

IMO the squat is more important to help grip on a launch as it induces weight transfer..

Weight transfer and half a tyre will give more grip than a full tyre and no weight transfer.

Obviously full tyre + weight transfer is best of all.

 

Also... on a launch.. a narrower tyre can also give more grip to an extent as when the weight transfers in can force the tyre further into the ground giving it more bite with the road

 

If anyone is worth listening to about launching cossies, its this man!

 

TiB - I would have thought it would be the opposite as the greater the contact area with wider tyres BUT from your results i'll take your word on it lol.

What sort of spring stiffness would you guess is a compromise between handling and launching.

 

i put it down to new tyres why my grip was much better but now youve said that could well be the little bit of squat. car didnt squat at all with old springs and always lost traction in 2nd in the dry.

 

Tyre width versus 60ft time is an inverse bell curve, there is an optimum size for any given application.

 

chip any links for info on this to read up on, I got lost at 'inverse bell curve' lol.

I've purchased some 8x17 alloys with R888's to help with traction but not sure what spring rates I have as they came with the KW V3's.

scooby slayer - are you still getting wheel spin in 2nd or has that stopped since the new tyres and softer rears?

 

Here is a highly detailed research paper ive just written on the subject:






sorry mate, dont really know of anything on the net, my google skillz are pretty weak, lol

 

edited my mate still signed in

 

chip thats perfectly clear now lol

 

mark4

nowhere near as much wheelspin now. broken diffs instead

 

There is a time when you give up and fit a stronger diff, for me that was after doing seven standard ones in 18 months . I then fitted a Quaife ATB (no planet gears) and never had any problems (the diff is still going strong in the re-shelled car ).

 

so do adjustable rear beams reduce squat or do they just help the rear wheels stay inline rather then getting forced out?

 

They promote more rear end grip by ensuring the entire contact patch stays in touch with the road as the suspension squats. Obviously this will mean MORE strain on the diff and more blown planet gears .

 

still can not make up my mind whether to get one of this rear beams why to sapps squat alot harder then a 3 door?is it purely down to having the boot hanging further out?

 

Softer springs as standard...

 

Ummm, yeah, I'm still not quite there yet !! Done my fair few diff's tho & if the planets break I jus weld em up till the CWP then lets go !! So technically I can blow the same diff up twice without it costing anything !!

jb

P.s. Anyone got any broken diff's they dont want ?? Go to a good home & I'll do it proud ??

 

but even with uprated suspension they squat harder etc?

 

With same suspension (including settings), same wheels, same tyres and same power, they will squat as good as identically. However, you can't expect to compare different specs (or as I am fond of saying) - "apples and oranges" .

 

apples and oranges

fair enough mr rainbird!

 

Would this have been planet gears exploding? I.e. Can I save this one too!

 

And if it helps my car runs silly bad negative camber, VERY low and squats VERY badly and mine has done 3 diffs and its only around 380bhp. Not sure if thats a direct corralation or just shagged diffs!
Only one went on a launch too