Car unsettled over bumps
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Not many rules really, this board being aimed at technical issues, it shouldn't fall foul (hopefully) of some of the more personal issues that can affect forums.
Rule 1 - Is that you need to think very carefully before posting anything technical or asking anything technical relating to the security system of the car - See 'Security Issues' sticky for more info.
Rule 2 - We (MGF Register) do not support copyright infringement and therefore references to CD ROM, PDF versions or paper copies of the workshop manual (for instance) should not be posted on the forum. We don't want to get into trouble and we'd rather sell you a genuine hard copy through our Regalia shop anyway!
Because advice is honestly and freely given in this technical section, much of it will be amateur experienced based, so any information is given in good faith and is not guaranteed as correct.
Car unsettled over bumps
My car gets unsettled over bumps, particularly if I cross the centre line or move between lanes.
Car is a 97, the right Yokohama Advans on the front, previous owner fitted Rotalla's to the rear just before I bought the car:(I had the tracking checked recently and had it set to the compromise values suggested in the table at the bottom here: http://mgf.ultimatemg.com/group2/suspen ... acking.htm It's only done 43k miles, it is entirely possible it's never had new bushes.
My thinking would be the next thing to look at would be the rear lower arm bushes, thoughts please?
On the subject of bushes there are clearly lots of vendors out there. On other cars I have previous good experience with PolyBush and PowerFlex. I'm keen to not make the ride any firmer. On my Sprite I used PolyBush blue and was very pleased with the results but they don't do a blue version of the F bushes. I'd value opinions on the best bushes for a good ride.
Many thanks in anticipation
Car is a 97, the right Yokohama Advans on the front, previous owner fitted Rotalla's to the rear just before I bought the car:(I had the tracking checked recently and had it set to the compromise values suggested in the table at the bottom here: http://mgf.ultimatemg.com/group2/suspen ... acking.htm It's only done 43k miles, it is entirely possible it's never had new bushes.
My thinking would be the next thing to look at would be the rear lower arm bushes, thoughts please?
On the subject of bushes there are clearly lots of vendors out there. On other cars I have previous good experience with PolyBush and PowerFlex. I'm keen to not make the ride any firmer. On my Sprite I used PolyBush blue and was very pleased with the results but they don't do a blue version of the F bushes. I'd value opinions on the best bushes for a good ride.
Many thanks in anticipation
- Reckless Rat
- Posts: 1889
- Joined: Tue Apr 01, 2008 9:01 am
- MGF Register Region: Europe
- Model of Car: 97 1.8mpi in BRG
- Location: South of France - in the Gard.
Re: Car unsettled over bumps
Has the car had the hydragas spheres re-gassed? Is the ride height correct at 368mm (front) or has it been fitted with lowering pins?
I personally wouldn't run either make of tyre you mention. Toyo T1Rs are the dogs.
I personally wouldn't run either make of tyre you mention. Toyo T1Rs are the dogs.
- RobboMC
- Posts: 1059
- Joined: Wed May 09, 2012 1:36 am
- MGF Register Region: Eastern Australia
- Model of Car: 1999 Mpi
Re: Car unsettled over bumps
I think the conventional view is that these cars should have the same brand and pattern of tyre on the front and rear.
My son has Yokohama Advan 701's on his Toyota MR2 which has the same front/rear combo as the F, and he drives away from the pack on the club runs.
So my concern is that your car has different grip levels front and rear if the tread wear rating of the tyres is a lot different;
so you could be chasing an issue that's not in the bushes.
By all means replace the lower arm bushes, I have done front and rear on my car in last 12 months to keep it running straight.
Start with the easy things first.
My son has Yokohama Advan 701's on his Toyota MR2 which has the same front/rear combo as the F, and he drives away from the pack on the club runs.
So my concern is that your car has different grip levels front and rear if the tread wear rating of the tyres is a lot different;
so you could be chasing an issue that's not in the bushes.
By all means replace the lower arm bushes, I have done front and rear on my car in last 12 months to keep it running straight.
Start with the easy things first.
- Rob Bell
- Committee Member
- Posts: 14425
- Joined: Tue Oct 02, 2007 2:36 pm
- MGF Register Region: South East
- Model of Car: MGF 1.8i + MGF Shed!
Re: Car unsettled over bumps
I'm with Rob - have a thought about changing the rear tyres (or replacing all four at the same time): squirrely handing often results from mismatched front/ rear tyres on mid-engined cars.
Re: Car unsettled over bumps
Thanks for your thoughts folks. Ride height is OK and I'm not aware of any modifications and the previous owners weren't those sort of people. I do recognise the mismatched tyres issue and the Rotalla's wouldn't have been my choice however I'm a little surprised that this effect would manifest at at lower speeds. It's not like I'm driving on the edge at a track day.
Changing tyres is much easier than fiddling round with bushes though so I suspect that's what I'll do.
Changing tyres is much easier than fiddling round with bushes though so I suspect that's what I'll do.
- Steve55
- Posts: 54
- Joined: Wed Dec 15, 2021 7:12 pm
- MGF Register Region: East Midlands
- Model of Car: MGTF 135 Sunstorm
- Location: E Mids
Re: Car unsettled over bumps
Have you tried jacking up each corner and seeing if there’s any play in the geometry/ bushes/bearings MOT style - hold wheel at 3 & 9 o clock then 12 & 6 o block and move back and forward checking for movement.
- Rob Bell
- Committee Member
- Posts: 14425
- Joined: Tue Oct 02, 2007 2:36 pm
- MGF Register Region: South East
- Model of Car: MGF 1.8i + MGF Shed!
Re: Car unsettled over bumps
Odd handling can appear very quickly and even at low speeds with mismatched tyres. It is certainly worth replacing all four.
Steve, I agree - worn rear wheel bearings can also cause untoward handling - and MGF/TF bearings don't seem to make noise when they fail (no idea why not!)
Steve, I agree - worn rear wheel bearings can also cause untoward handling - and MGF/TF bearings don't seem to make noise when they fail (no idea why not!)
- Steve55
- Posts: 54
- Joined: Wed Dec 15, 2021 7:12 pm
- MGF Register Region: East Midlands
- Model of Car: MGTF 135 Sunstorm
- Location: E Mids
Re: Car unsettled over bumps
Just replaced all the upper ball joints, front and back and it’s made a positive difference to the handling of my TF.
Re: Car unsettled over bumps
Thanks folks, I have had a wheel waggle but I might go round again a bit more brutally.
Just done my tax return and I've got a couple of hundred coming back so I might spend that on two Yokohama for the rear to match the six month old ones at the front.
Just done my tax return and I've got a couple of hundred coming back so I might spend that on two Yokohama for the rear to match the six month old ones at the front.
Re: Car unsettled over bumps
OK, splashed out on a couple of Yokohamas to match the front, and based on a ten minute test drive the car's poise is much better. I have an Autosolo at the weekend so that will be the acid test.
Thanks for your contributions to the thread.
Jeremy
Thanks for your contributions to the thread.
Jeremy
Re: Car unsettled over bumps
Acid test passed, car handled beautifully on dreadful West Sussex roads and the billiard smooth Goodwood circuit. I just want slightly better turn in now.