T350 bump steer options
Discussion
I know this has been discussed a lot in the past but the solutions seemed to involve either using a Sagaris steering arm (no longer available) or fabricating your own (which I'd prefer to avoid). I believe the steering arm mod drops the track rod by about 15mm, and then using a different track rod can get you another 5mm or so, so the track rod pivot point is around 20mm lower in total.
That seems a lot! Is this right, and if so are there any other ways of achieving this?
That seems a lot! Is this right, and if so are there any other ways of achieving this?
Thanks for your replies.
Basically the car does not feel planted in a straight line at speed, even on a motorway. I haven't been over 70 mph and frankly wouldn't want to go much faster even on a track. Overtaking a car on a B road with any uneven surface does not feel pleasant at all. Grip the steering wheel and try and keep it in a straight line.
I am open to suggestions on how to fix this, but it sounds like bump steer to me. There have been quite a few threads on here discussing the front geometry and they all point to either raising the rack, which is limited to a few mm on a T350, or dropping the steering arm pivot point.
I am sure companies like str8six would not have been offering this mod if it was not necessary. Having said that, I find it strange that it needs sorting at all. Lotus got it right 50 years ago.
M4tti, what changes did you have made to your car?
Thanks for the heads up on the re manufactured sag arms. I'll look into it.
I am sure the car would benefit from a full geo set up, but it makes more sense to me to have it done after correcting the bump steer, if that is required. So that is the question: Is there a known problem here?
Basically the car does not feel planted in a straight line at speed, even on a motorway. I haven't been over 70 mph and frankly wouldn't want to go much faster even on a track. Overtaking a car on a B road with any uneven surface does not feel pleasant at all. Grip the steering wheel and try and keep it in a straight line.
I am open to suggestions on how to fix this, but it sounds like bump steer to me. There have been quite a few threads on here discussing the front geometry and they all point to either raising the rack, which is limited to a few mm on a T350, or dropping the steering arm pivot point.
I am sure companies like str8six would not have been offering this mod if it was not necessary. Having said that, I find it strange that it needs sorting at all. Lotus got it right 50 years ago.
M4tti, what changes did you have made to your car?
Thanks for the heads up on the re manufactured sag arms. I'll look into it.
I am sure the car would benefit from a full geo set up, but it makes more sense to me to have it done after correcting the bump steer, if that is required. So that is the question: Is there a known problem here?
It seems we have two camps. One says there is a fundamental, known problem with the design, the other camp says the design is fine, it just needs setting up carefully. There is obviously a lot of experience and expertise here, I have no way of telling which is right.
What does seem clear though is that I should get the car set up as best as possible as it is, and then see how it feels before making any design changes. The car has Nitron Racing Reds, no sign of leakage but they are a few years old. May be worth a refurb.
The front tyres are 225/35/18 87 XL Michelin Pilot Super Sport, the rears are 235/40/18 95 XL Eagle F1. The rear tyres need changing as they are old and developing cracks on the inner wall.
Maybe I should start another thread about tyres, that seems the place to start.
What does seem clear though is that I should get the car set up as best as possible as it is, and then see how it feels before making any design changes. The car has Nitron Racing Reds, no sign of leakage but they are a few years old. May be worth a refurb.
The front tyres are 225/35/18 87 XL Michelin Pilot Super Sport, the rears are 235/40/18 95 XL Eagle F1. The rear tyres need changing as they are old and developing cracks on the inner wall.
Maybe I should start another thread about tyres, that seems the place to start.
I'm sure you are right, getting the tyres right is the first step. As the fronts are Pilot Super Sport and pretty new I need to get something compatible on the back. I'm leaning towards Pilot 4s on the standard profile 235/40/18, as they come from the same stable and are supposed to be almost as good as the PSS.
Other option would be some more Super Sports on a slightly different profile, 245/35/18, but they are quite a lot more expensive and might foul the bodywork.
I've asked Michelin to comment, will report back.
Other option would be some more Super Sports on a slightly different profile, 245/35/18, but they are quite a lot more expensive and might foul the bodywork.
I've asked Michelin to comment, will report back.
That is interesting. I believe the T350 was originally launched with 225/50/16 on front and back. I have seen a T350 owners manual that gives that tyre size. That profile gives a rolling diameter of 631mm, The RD for 225/35/18 tyres is 615mm. If no suspension components had been changed that would alter the scrub radius. Your new tyres at 225/40/18 have a RD of 637mm, very close to the original figure. This would bring the scrub radius back to being very close to the design figure.
Gassing Station | Tamora, T350 & Sagaris | Top of Page | What's New | My Stuff