T350c on Bumpy Roads
Discussion
My T350c runs smoothly nearly all the time. But on minor roads with undulations, I bottom out the rear wheels at speed. I think this is the tyres fouling the wheelarches not the shockers bottoming.
This is an impediment to PH'er level of progress!!
Any thoughts or advice gratefully received.
This is an impediment to PH'er level of progress!!
Any thoughts or advice gratefully received.
I had similar issues recently, seemingly exacerbated by Goodyear F1 tyres over similar-sized Toyos.
I was offered an inner-arch modification and/or a slight increase in the ride height front and rear.
I opted for the latter which has helped.
From what I understand, there is a design issue with the rear suspension. As the wheel moves upwards it gains additional mechanical advantage against the shock / spring which means less force is required to compress it.
I guess you can tune out the worst of it with a combination of spring rate, ride height and tyre shoulder sizes but without modifying the mounting points on the suspension or the inner wheel arches, it's difficult to completely eliminate.
I was offered an inner-arch modification and/or a slight increase in the ride height front and rear.
I opted for the latter which has helped.
From what I understand, there is a design issue with the rear suspension. As the wheel moves upwards it gains additional mechanical advantage against the shock / spring which means less force is required to compress it.
I guess you can tune out the worst of it with a combination of spring rate, ride height and tyre shoulder sizes but without modifying the mounting points on the suspension or the inner wheel arches, it's difficult to completely eliminate.
Targarama said:
What suspension are you running? Standard? If so the factory suspension is very softy sprung and is much easier to bottom out/rub. Nitrons or similar come with much stiffer springs and make the ride much more controlled.
AFAIK the suspension is standard. The car is a Red Rose lightweight variant, so I don't know if that makes a difference. Handles well most of the time, but the front is light at high speeds.If I went for Nitrons, what is the approximate cost?
Thanks for the replies so far.
NailedOn said:
AFAIK the suspension is standard. The car is a Red Rose lightweight variant, so I don't know if that makes a difference. Handles well most of the time, but the front is light at high speeds.
If I went for Nitrons, what is the approximate cost?
Thanks for the replies so far.
Nitrons will cost around £1200-£1400 fitted and properly set up (which is important). I found they change the character of the car completely - before it was a lot softer (though much sharper and more 'on it' than my old wandering Chimaera), now it is still comfortable but much more 'hardcore', even with the adjusters at 8 from soft all round. I might try a bit softer to see what it feels like.If I went for Nitrons, what is the approximate cost?
Thanks for the replies so far.
Also, Str8Six's bump steer mod helps a lot on fast, cambered rural roads. Jason actually adjusted the kit as it was causing too much sensitivity on the motorway, now completely solved.
My t350 has just gone in to STR8SIX for Nitrons + eibach and also a full ACT cat back system.
Will let you know how the suspension fairs - never had a problem with rubbing until I changed to new F1 asymetrics the other day (standard sizes) and I'm sure I felt the rears catch on the arches after a big bump on a country lane. I'm not an expert driver by any means so am interested to see how the change affects the handling etc as it will be purely subjective for me I'm sure!
Will let you know how the suspension fairs - never had a problem with rubbing until I changed to new F1 asymetrics the other day (standard sizes) and I'm sure I felt the rears catch on the arches after a big bump on a country lane. I'm not an expert driver by any means so am interested to see how the change affects the handling etc as it will be purely subjective for me I'm sure!
willtvr said:
Standard rear tyre size?
I have these tyres fitted (this is what the car came with.)>> Rear: Toyo 235/40
>> Front: Goodyear Eagle 225/35
To try and be a bit more specific about the handling, there are two separate characteristics.
At moderate speeds (50-60 mph) on twisty lanes with a good flat surface the handling is fine.
Equally, on motorways at c.70 mph the car is very smooth.
But I get instability at the front above 90 mph on any surface, as in the steering is light and maybe understeering.
I also find that I am bottoming out on bumpy roads at anything above 40 or 50 mph. This is not so much caused by potholes, but the natural contours of the road. I live in the Dales so we have plenty of bumps! Basically I can get around these lanes quicker in my "not very hot at all" hatchback because it rides better than the T350.
(I am aware that you get "air separation" at around 93 mph, so what I am experiencing at speed may be related to that.)
What do you think is the matter? This is my second T350 and I also had a Tam, and recall neither problem with the other two TVRs.
NailedOn said:
I have these tyres fitted (this is what the car came with.)
>> Rear: Toyo 235/40
>> Front: Goodyear Eagle 225/35
To try and be a bit more specific about the handling, there are two separate characteristics.
At moderate speeds (50-60 mph) on twisty lanes with a good flat surface the handling is fine.
Equally, on motorways at c.70 mph the car is very smooth.
But I get instability at the front above 90 mph on any surface, as in the steering is light and maybe understeering.
I also find that I am bottoming out on bumpy roads at anything above 40 or 50 mph. This is not so much caused by potholes, but the natural contours of the road. I live in the Dales so we have plenty of bumps! Basically I can get around these lanes quicker in my "not very hot at all" hatchback because it rides better than the T350.
(I am aware that you get "air separation" at around 93 mph, so what I am experiencing at speed may be related to that.)
What do you think is the matter? This is my second T350 and I also had a Tam, and recall neither problem with the other two TVRs.
Sounds like you need to get the suspension checked and at the very least aligned correctly by someone who knows what they're doing with T-cars.>> Rear: Toyo 235/40
>> Front: Goodyear Eagle 225/35
To try and be a bit more specific about the handling, there are two separate characteristics.
At moderate speeds (50-60 mph) on twisty lanes with a good flat surface the handling is fine.
Equally, on motorways at c.70 mph the car is very smooth.
But I get instability at the front above 90 mph on any surface, as in the steering is light and maybe understeering.
I also find that I am bottoming out on bumpy roads at anything above 40 or 50 mph. This is not so much caused by potholes, but the natural contours of the road. I live in the Dales so we have plenty of bumps! Basically I can get around these lanes quicker in my "not very hot at all" hatchback because it rides better than the T350.
(I am aware that you get "air separation" at around 93 mph, so what I am experiencing at speed may be related to that.)
What do you think is the matter? This is my second T350 and I also had a Tam, and recall neither problem with the other two TVRs.
How low is your car compared to other T350s? When my suspension was replaced (and settled) it looked like the car was on stilts to me, but after comparing with all the other T350s at Chatsworth mine was about right after replacement, it was too low before - maybe due to softer springs or just the spring platforms needing adjusting higher. You could do this if you don't want to spend a lot of money and your shocks are OK.
Would agree with Targarama on this one. I've reverted to standard tyre sizes (same as yours) and have had to have the ride height raised to avoid fouling rear wheel arches when 2 up and touring. I'm on Eibach springs with Gas Gold Pros set quite hard. Handling and ride is acceptable laden or otherwise.
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