Heavy jumping bouncing

[Jimmy_GTT]

Drew my car yesterday in 2nd gear @30 kmph. Then pushed a wot and @4500-5000rpm probably the front wheels spun and a very heavy jumping/bouncing occurred. Even the instrument cluster jumped out from its place. (I know the 2 screws are missing. ) The road was new, smooth, dry.
I had such an issue earlier. That time I was not able to make a good start from 0 because such a heavy bouncing occurred. But changing my front suspension has helped a lot.
Now I have 4 yellow Konis, standard phase 1 spring, standard height (front and rear). The Konis were set to a medium setting. 13" wheels Yokohama A048.
So I think the slip is okay. It is already cold for the Yokos. But this heavy bouncing scares me. What could it be?

[Mr_Phill]

Hi
Sounds like what the americans call 'wheel hop'.
If you know for sure your shocks are good, then start looking at your suspension bushes.
You may want to poly bush all your joints, or at the very least replace the rubbers with new.
Even a small amount of slop will add up and cause enough movement that the tyre will grip then lose traction quickly, building up, and repeating, which leads to the hopping.
With that maybe look at fitting firmer springs up front. This will also help resist too much flex when launching hard, keeping the tyre planted.

[Jimmy_GTT]

Thanks Phill!

I was thinking about the firmer springs. But it is hard to find anything for the Phase I.

I'll check the bushes. What shall I look for?
Do you mean the ones in the trailing arms? Or the stabilizer bar's as well?
Do you have a source for the poly bush?

[Alex]

I'd be checking everything is tight and secure on the new suspension you fitted, making sure you haven't missed anything out etc. Maybe look at the engine/gearbox mounts for damage.

[Jimmy_GTT]

Thanks Alex!

I'll take a look on those as well.
Any description about the checking method?
Have to admit that the car is about 180Hp. So not extremely tuned but stronger than a standard.

[Jimmy_GTT]

Engine mounts seem to be OK. At least at a first glance.

But there could be some suspension issue :


Does it mean that the spring is not high enough for the shock?
I'd say a minimal movement could be ok, but it is much more on the left than on the right. And that knocking sound couldn't be nornal anyway.
I'll remove it tomorrow.
Any advice is very welcome.
Thanks

[Mr_Phill]

As above check anything and everything on the front end. any rubber bushes that are older than say 10 years, replace. Polybushing will tighten it all up and should last a while.
Only way id suggest checking fro excess movement is to jack the car up and use a pry bar to move joints, the suspension is unloaded like this.
Then drive it up on ramps to load the suspension and use the pry bar again to check for excess movement.
Similar tests for the MOT.

Sounds like quite a beast you have there!
The yoko's will be very grippy, which is highlighting any weakness in the suspension.
Any movement which allows the wheel to lift off the road surface will cause a loss of grip momentarily.
When the spring pushes back down, the tyre grips, loads the suspension, wanting to push back up, that little bit of movement will allow it up a fraction, it loses grip, spring pushes back down, etc etc Can be very damaging to the car.

Check rubber bushes on ALL the suspension. Any rubber, check it and replace as necessary.
Or
Polybush everything. Should cure it in one hit.
Or
Set shocks to the firmest setting. May help reduce it, but it wont cure a worn bush.
Or
Firmer Springs. As you say, parts can be difficult to get.

[Mr_Phill]

ok, just seen your video, are the top mounts meant to move that much?

[Ian S]

My car had it when the front Spax shocks were worn and not damping enough.

I already had harder slightly lower springs that I'd had made for me.

Fitted the Konis, and it stopped. They were probably set on hardest to somewhat match the harder springs.

I've forgotten the exact sequence of events now, but at some point I also fitted the
harder red polyurethane wishbone inner bushes,
new strut top rubber bushes,
yellow polyurethane anti roll bar bushes,
new bottom ball joints and
new track rod ends.

Also,
new steering rack to steering column standard rubber lined universal joint,
new steering column bushes.

Then I found the later rack and column had no rubber UJ but a steel one, and change both the rack and lower column to the later parts.

[Ian S]

Also, with my Fiat Cinquecento, I had front left 'wheel bounce' when moving off in the wet and again it was worn shocks with the rods just going up and down in oil. Not damping.

New shocks have more or less stopped it, there is still a bit sometimes in the dry as the tyre bounces on it's pneumatics, but not near as much as it was.

[Jimmy_GTT]

ok, just seen your video, are the top mounts meant to move that much?

I don't think so. Anyway the movement is about the half on the right side. And no knocking noise there.

[Jimmy_GTT]

Do you guys recommend the CGB yellow polies?
They have a complete set for about 70.

[Mr_Phill]

i really dont think it should be moving like that.
It would only make any movement worse surely, since the whole suspension and wheel assembly can move up and down separately from the car?
Personally id look at that first.

[Jimmy_GTT]

Tomorrow I'll take out the suspension and disassamble the shocks and springs.
Currently I do not understand what could be wrong.
It looks like the spring is not strong enough to have a preload.

[francob80]

I'd say you are missing a component at the top of strut or the struts aren't tightened to the chassis well enough. Which suspension is it ? I can send some shots of how mine are put together.

[Ian S]

Also, just seen your video.

Yeah, same as previous post, you have something loose, squashed, broken, cross threaded or missing up there.

There should be no clonking.

The spring should remain in both it's top and bottom seats when jacked off the ground.

The top rubbers can be squashed enough for some up and down movement, there would also a lot of sideways movement.

Google just found these. Never heard of that company but the mounts look like what we've been wanting and not really available all these years. Probably will cause added Noise, Harshness, Vibration,and it's not clear how that top moves around, if it's a rose joint, or if it's the bearing that allows the rotation, or if more parts are required, but you can adjust your camber angle and some caster angle: http://www.compbrake.com/product/ren...ly-guaranteed/

And these, never heard of that company either: http://www.ebay.co.uk/itm/Renault-5-...-/372062241320

New old stock? rubber from CGB: https://www.ebay.co.uk/itm/RENAULT-5...N/160684405640

[Jimmy_GTT]

I'd say you are missing a component at the top of strut or the struts aren't tightened to the chassis well enough. Which suspension is it ? I can send some shots of how mine are put together.

Phase 1 suspension. Yellow Konis, oem springs.
I'm very curious about what will I find in this afternoon. I have disassembled and reassembled many suspensions in the last 20 years and haven't had such an issue.
Could it be that I've mixed up some Phase I and Phase II parts? Or I have left out something?

[Jimmy_GTT]

Also, just seen your video.

Yeah, same as previous post, you have something loose, squashed, broken, cross threaded or missing up there.

There should be no clonking.

The spring should remain in both it's top and bottom seats when jacked off the ground.

The top rubbers can be squashed enough for some up and down movement, there would also a lot of sideways movement.

Google just found these. Never heard of that company but the mounts look like what we've been wanting and not really available all these years. Probably will cause added Noise, Harshness, Vibration,and it's not clear how that top moves around, if it's a rose joint, or if it's the bearing that allows the rotation, or if more parts are required, but you can adjust your camber angle and some caster angle: http://www.compbrake.com/product/ren...ly-guaranteed/

And these, never heard of that company either: http://www.ebay.co.uk/itm/Renault-5-...-/372062241320

New old stock? rubber from CGB: https://www.ebay.co.uk/itm/RENAULT-5...N/160684405640

There should be definitely something at the top of the strut. I've shown the video to a colleague in the morning and he pointed out that the spring is moving with the shock. It is not compressed at all.

Which donut would you prefer? The oem or the poly?

[Ian S]

Which donut would you prefer? The oem or the poly?

I'm not sure. I probably would have fitted the poly if they'd been available when I did mine. These new ones might be harder, or softer, weaker or stronger! I would need more info that I have now to make that decision.

[Jimmy_GTT]

So after some hours of work here is the 'solution'.
The left top hat on the strut moves much more than on the right. Could be an old donut I think.
And what was the knocking sound? A too long screw which could hit the upper spring plate.
Funy is that I have 4 identical screws.

[Jimmy_GTT]

Could it be anything else than the donut?

[francob80]

Just replace ALL the components, it isn't that much money to fully refresh. I run the polyurethane donuts and they have been good for a few years now.

I also have the Compbrake adjustable top mounts if you did fancy top mounts with more adjustment. I haven't fitted them yet but the quality is very good and I know a few who have been using them and rate them highly. Admittedly they are used on track/competing cars more than road.

[Matt Cole]

Francob80 which poly donuts are you using? I got some new ones recently but they are a smaller diameter which means they move about in the top plate cup.

[Ian S]

Jimmy, do you have phase two springs? Or shortened springs?

Normally, to get the top hat on, means using spring compressors to pull down the springs so the thread at the top of the rod can reach through the hole.

That slack there suggests the spring are not compressed but are at their full extension.

Do you have the bearing assembly in there? I can't quite see it in the shade in those photos.

[Ian S]

I have the Compbrake adjustable top mounts

How do they fit onto the original bearing and donut?

[Jimmy_GTT]

Jimmy, do you have phase two springs? Or shortened springs?

Normally, to get the top hat on, means using spring compressors to pull down the springs so the thread at the top of the rod can reach through the hole.

That slack there suggests the spring are not compressed but are at their full extension.

Do you have the bearing assembly in there? I can't quite see it in the shade in those photos.

No. They are phase 1 springs, oem, not broken. (About 33-34cm uncompressed)
I had to use spring compressor (quite a lot) to fit the top spring plate, bearing, top hat, donut, strut top assembly.
The top spring plate cannot be moved at all. It is only this strut top that moves.
But the strut top only sits on the donut and fixed by the nut in the middle. And I think if the donut is small or worn it can move like this.

As I've checked GT Turbo Spares site I have to correct the name of the parts. So it is the strut top (which is fixed to the body) which moves (as you can see in the video) not the top hat (which sits on the bearing).

[Jimmy_GTT]

A picture about the assembly:

[Ian S]

So what's holding down the upper spring seat and preventing it from pressing the seat up onto the bearing and upper parts?

Is the shock absorber rod so long that it's more then the spring, but then you wouldn'd have needed spring compressors.

Normally the spring would simply press everything up against the nut at the top, and pull the rod all the way out to it's limit.

[Jimmy_GTT]

So what's holding down the upper spring seat and preventing it from pressing the seat up onto the bearing and upper parts?

Is the shock absorber rod so long that it's more then the spring, but then you wouldn'd have needed spring compressors.

Normally the spring would simply press everything up against the nut at the top, and pull the rod all the way out to it's limit.

As I remember I always had this space on one side of the bearing and the top hat whit all the phase 1 suspensions I have. (I'm not sure about the phase 2s.)
As the last thread of the spring only pushes one side of the top spring plate and not the complete plate.

[Jimmy_GTT]

I've changed the donut and now the srut top fits tight
The old donut was much smaller than the one I've installed.

But I still have doubts if it would fix the wheel hop alone.
Could you please tell me how I can check if the wishbone bushes are ok or not?
The engine mounts seem to be OK.

[Ian S]

I don't really know. I changed the ones on the 5 for harder poly bushed as people at the time said they had and it was better.

With my Fiat, which it was up on the lift at the garage with the wheels off, I just tried to move each wishbone around by hand and see if it moved at the bushes in any wrong or excessive way, they didn't. So I used a large screwdriver or medium pry bar and gently levered around the bushes to see if that moved anything. Seemed OK.

[Jimmy_GTT]

First of all Merry Christmas to everybody!!

Yesterday it was sunny, 10C so I went for a ride after changing the donuts.
Car is much-much better than before. Sometimes no wheel hop, sometimes a minor and I feel it from the right wheel where the non oem bushes are.
I hope that Mike will answer soon and I can change all those bushes.
I'll post back after changing them.

[Matt Cole]

First of all Merry Christmas to everybody!!

Yesterday it was sunny, 10C so I went for a ride after changing the donuts.
Car is much-much better than before. Sometimes no wheel hop, sometimes a minor and I feel it from the right wheel where the non oem bushes are.
I hope that Mike will answer soon and I can change all those bushes.
I'll post back after changing them.

Merry Christmas Jimmy.

Good news on the suspension, I guess replacing them all is the right thing to do and should make a big difference.

[Jimmy_GTT]

Anyone knows about Mike?
I'm waiting for his answer since mid of December.

[Matt Cole]

Anyone knows about Mike?
I'm waiting for his answer since mid of December.

GT Turbo Spares??

I'm not sure. He does pop on here now and again so hopefully he reads this. Try email and phone Jimmy. If no luck, we could try and get a message to him.

[Jimmy_GTT]

Thanks. I'll wait some days.
I have no chance to replace them in the next days as they won't arrive.
But till spring I have time.

I had luck to buy 3 original ones from e-bay yesterday. (but only 3 )
They will have a good place on the shelf.