Compession locks very easily

[timewarrior 3]

Hi guys, now that my M50 powered E30 is back on the road I'm finding that it compression locks very easily.

It's been suggested that it's a suspension issue, might be that the rear springs are too stiff? Also the brakes are different: RX7 front brake conversion but standard discs on the back - could that be contributing?

Has anyone had this issue before and found a way to stop it? Cheers!

[hybrid 1043]

Its a combination of no weight in the rear, suspension, potential tire issues. Also it helps to learn to heel/toe down shifts.

[kiwi535 538]

so rear wheel lock ups on downshifts?

[yng_750 247]

Agree. ^

Real simple either too little rear traction. Which coulc be over stiff or dynamic camber\ toe change.

This can be made worse by to much dive under brales from a soft front end.

Or too much resistance from the engine. More than likely from bad down shifting. Are you using the clutch to speed up the engine?.

If its suspension you have bigger handling issues afoot.

If its from bad down shifts you will be about to destroy your clutch etc anyway. So learn to heel toe.

[timewarrior 3]

It's not my driving style, the guy who was working on it struck the same problem. It does it really easily, think pickup truck on bald tyres and you'll get an idea what it's like.

Doesn't help that the tacho is dead but I would be very surprised if I was getting anywhere near the redline.

[timewarrior 3]

Also the tyres aren't in great nick but they did get through a warrant so they're not bald as such.

[hybrid 1043]

Hard to say as we cant really test the tires on the internet. But if they are rock hard and supplying 0 usable grip then it will work the same way with little weight over the tires. Also take a look at your LSD and maybe consider your diff ratio in the factors of the equation.

When mine is a little light in the tank say around 1/4 its quite tail happy. But it will only compression lock at the up most extremes. Im running 11.3:1 which is on the higher end for a car and mines fine.

[timewarrior 3]

Diff is open and ratio is 4.1. Thinking back I think it did the same in the wet on the old tyres that were new and wider (but a cheap Chinese make). I'll fill the tank and see what difference that makes. Otherwise I might be in the market for new coils if anyone has any...

[timewarrior 3]

Tyres are bridgestone potenza g3s 205x40 17 only about 2 mm tread left, don't know the age, they came on the rims second hand. I don't know what the pressure is in them, will check next time I get petrol. Rims are 7 in wide. The shocks are Koni Sports E30 shocks, the springs - I dont know, previous owner put them in so I don't know lowering. Corner weights won't be far off standard, has a half cage, interior removed, m50tub25 in the front, cf bonnet. I'll check what the alignment sheet says for camber and toe. Compression will be standard for that engine

[timewarrior 3]

Great, thanks for the advice, I thought that the cage would have offset the removal of interior, I'll look into it though. And I'm going to have to practice my heel toe! One more thing, Koni Yellows are what I have in my Golf and I've read that the shock is the right length to use standard springs or go up to 35mm lower but not more. When I got my E30 the rear springs weren't captive so I got spring spacers put in, could these spacers be screwing up the spring rate?

[timewarrior 3]

And the springs the previous owner put in are too short for use with that shock?