chassis bracing?
Discussion
is there anything i can buy to stiffen the chassis a bit ,sort of like strut braces or similar?
i know i keep going on about my cars 'feel'but it just doesnt seem right. i could do with one of you guys with longer ownership experience having a go.
the car came from a main dealer so surely must be generally right?
i going to get the geometry checked at the weekend but even so it wont make the car more 'tight' will it.
any ideas?
mike.
i know i keep going on about my cars 'feel'but it just doesnt seem right. i could do with one of you guys with longer ownership experience having a go.
the car came from a main dealer so surely must be generally right?
i going to get the geometry checked at the weekend but even so it wont make the car more 'tight' will it.
any ideas?
mike.
Agree, its always worth getting the geometry checked first. Also, in my experience the v8 will need its wheels balancing approx every 8-10k miles - something to do with the way it wears its tyres i think. After a balance its always much nicer to drive with less vibration.
Not heard of anyone fitting chassis braces to an esprit (other than johan's full roll cage
) but it might be worth checking that the bolts that secure the body to the chassis are all tight. These can loosen over time which makes the car feel a bit 'loose' over bumps etc.
cheers
Rob
Not heard of anyone fitting chassis braces to an esprit (other than johan's full roll cage
) but it might be worth checking that the bolts that secure the body to the chassis are all tight. These can loosen over time which makes the car feel a bit 'loose' over bumps etc. cheers
Rob
rob.e said:
Not heard of anyone fitting chassis braces to an esprit (other than johan's full roll cage
I seem to remember that the Sport 300 and X180 had chassis braces as stock (if you can call them stock)? Factory produced anyway.
I hear that JAE is developing somthing similar.
Mark - 88 Turbo
Hi,
In the parts manual, in the chassis area, there are listed two "Bracing tube, crossbeam to chassis" pieces . Part numbers shown as P691.3011.802CF and P691.3011.801CF. Also a "Crossbeam, engine bay stiffener" with part number P691.3011.013AR.
Remarks state: s1391 (USA) (Brembo brakes) This was apparently available for the Sport 300.
Don't know if this helps.
Rich
In the parts manual, in the chassis area, there are listed two "Bracing tube, crossbeam to chassis" pieces . Part numbers shown as P691.3011.802CF and P691.3011.801CF. Also a "Crossbeam, engine bay stiffener" with part number P691.3011.013AR.
Remarks state: s1391 (USA) (Brembo brakes) This was apparently available for the Sport 300.
Don't know if this helps.
Rich
flowers said:That's excellent information. The question is: what do they bolt to? Do the Sport300s have welded-on fittings? I've seen pics of the Sport300 engine bay but never the mounting ends of the braces.
Hi,
In the parts manual, in the chassis area, there are listed two "Bracing tube, crossbeam to chassis" pieces . Part numbers shown as P691.3011.802CF and P691.3011.801CF. Also a "Crossbeam, engine bay stiffener" with part number P691.3011.013AR.
More than once, I have considered handing the car to Mitch Piper in VA (custome cage guy extroardinaire) and saying "Here, do something with this" but common sense has prevailed.
Hi,
Unless using the car exclusively for Track use, I'd be very careful about messing with the chassis/suspension setup. It is simply too easy to screw it up.
Lotus is considered the Premier suspension specialist in the automotive world and has done work with GM, Aston, Ford and numerous others who do not then go and second guess them with additional tweaking.
The car has an inherent amount of flex and the suspension was designed in accord with this to create the whole unit. Arbitrarily mess with one part, and you may find adverse effects on others. You won't be eliminating the forces which cause the flex to occur, other areas of the car will have to deal with it. It is possible that the body will have to take more of the load resulting in one big Spider Crack a couple years down the Pike.
Also, realize that while you may be able to acquire bracing from the Sport series, or X-180R, these too were designed as whole units. Without the springs, shocks, bushings, tires, track and other ancillaries, not to mention these cars unique weight distributions, you won't necessarily be gaining any advantage, but could just as easily be gaining some disadvantages.
I'm not saying don't do it. I'm saying proceed very carefully, be sure that the evidence you gather is empirical and not anecdotal or 'what you want to hear'.
Start by making sure that your chassis isn't faulty, yielding more flex than it should. Then, contact Lotus directly for their thoughts, before spending copius amounts of dough and making semi-premanent changes.
Deciding that there is so much chassis flex that a correction is needed puts you in the minority of Esprit owners, and they're a pretty smart bunch as a whole. Could it be merely a matter of too high an expectation? Still, you may be on to something, just be very sure. Happy Motoring! ...Jim'85TE
Unless using the car exclusively for Track use, I'd be very careful about messing with the chassis/suspension setup. It is simply too easy to screw it up.
Lotus is considered the Premier suspension specialist in the automotive world and has done work with GM, Aston, Ford and numerous others who do not then go and second guess them with additional tweaking.
The car has an inherent amount of flex and the suspension was designed in accord with this to create the whole unit. Arbitrarily mess with one part, and you may find adverse effects on others. You won't be eliminating the forces which cause the flex to occur, other areas of the car will have to deal with it. It is possible that the body will have to take more of the load resulting in one big Spider Crack a couple years down the Pike.
Also, realize that while you may be able to acquire bracing from the Sport series, or X-180R, these too were designed as whole units. Without the springs, shocks, bushings, tires, track and other ancillaries, not to mention these cars unique weight distributions, you won't necessarily be gaining any advantage, but could just as easily be gaining some disadvantages.
I'm not saying don't do it. I'm saying proceed very carefully, be sure that the evidence you gather is empirical and not anecdotal or 'what you want to hear'.
Start by making sure that your chassis isn't faulty, yielding more flex than it should. Then, contact Lotus directly for their thoughts, before spending copius amounts of dough and making semi-premanent changes.
Deciding that there is so much chassis flex that a correction is needed puts you in the minority of Esprit owners, and they're a pretty smart bunch as a whole. Could it be merely a matter of too high an expectation? Still, you may be on to something, just be very sure. Happy Motoring! ...Jim'85TE
Some of my thoughts...
I understand that the weakest link in the chassis may be caused by flexing thru the shifter cut-out area in the backbone.
If you can visualize twisting chassis it would seem to me that either end is pretty stiff when compared to the torsional resistance of the backbone section, especially if the the cut-out area does not match the shear resistance of the top sheating of the box section. I understand that Lotus had, at one time, improved that area. Whether it was enough, who knows.
I cant imagine the body shell offers much resistance with all the openings it has. I think the shell contributes somewhat, but is likely pretty much just along for the ride.
I would think that a stiffer backbone would reduce body flex and hence the possibility of cracking/ squeeks etc. Stiffening the body shell itself would not be the route to go IMO.
From all accounts of discussions Ive had with chassis builders, the concensus has been to have a stiff chassis so that the suspension is doing the work. By having a flexy chassis, suspension tuning is made very difficult.
Even in karting the trend over the last 15 years has been to use very stiff chassis and tune using geometry, axle stiffness, tires, ride height and weight dist. I know there is little comparision in the designs, but it illustrates the concept of tuning using measurable values.
I believe that lotus have worked to make the best of what they had developed for the Esprit. Even the new cars are based fundamentally on the early 80's chassis design. Sure, Lotus are very good at what they do. But honestly, they have had only so much to work with in the design of the Esprit chassis. Imagine what Lotus could have done if they had built the Esprit backbone using carbon composite!
Even though this may not be for everyone, I personally would prefer a stiff chassis, tune-able suspension, and a stop watch at the track.
Jan
I understand that the weakest link in the chassis may be caused by flexing thru the shifter cut-out area in the backbone.
If you can visualize twisting chassis it would seem to me that either end is pretty stiff when compared to the torsional resistance of the backbone section, especially if the the cut-out area does not match the shear resistance of the top sheating of the box section. I understand that Lotus had, at one time, improved that area. Whether it was enough, who knows.
I cant imagine the body shell offers much resistance with all the openings it has. I think the shell contributes somewhat, but is likely pretty much just along for the ride.
I would think that a stiffer backbone would reduce body flex and hence the possibility of cracking/ squeeks etc. Stiffening the body shell itself would not be the route to go IMO.
From all accounts of discussions Ive had with chassis builders, the concensus has been to have a stiff chassis so that the suspension is doing the work. By having a flexy chassis, suspension tuning is made very difficult.
Even in karting the trend over the last 15 years has been to use very stiff chassis and tune using geometry, axle stiffness, tires, ride height and weight dist. I know there is little comparision in the designs, but it illustrates the concept of tuning using measurable values.
I believe that lotus have worked to make the best of what they had developed for the Esprit. Even the new cars are based fundamentally on the early 80's chassis design. Sure, Lotus are very good at what they do. But honestly, they have had only so much to work with in the design of the Esprit chassis. Imagine what Lotus could have done if they had built the Esprit backbone using carbon composite!
Even though this may not be for everyone, I personally would prefer a stiff chassis, tune-able suspension, and a stop watch at the track.
Jan
lotusguy said:
You won't be eliminating the forces which cause the flex to occur, other areas of the car will have to deal with it. It is possible that the body will have to take more of the load resulting in one big Spider Crack a couple years down the Pike.
I don't see how that could be the case. Increasing the stiffness of the chassis, specifically the torsional stiffness, would decrease your likelyhood of a crack. The same forces applied through the suspension would twist the chassis (hence the body) less. You're not eliminating the forces, just limiting their effects.
I really have no intention to actually do anything about it though, unless someone spoon-feeds me a solution. When I'm ready, I'll just get a 355. ducking
Jan, I think your right on all points. Lotus even updated the chassis in '95 (and again for the V8) but the US didn't get it.
EDIT: I found a reference to the gear shift hole Jan mentioned -
said:
Chassis
Increased torsional stiffness achieved by modifications to gearlever access hole, front crossmember and backbone, and addition of engine bay crossbrace Competition rollcage mounts added
Related to the S300. See here. Interesting to see the comprehensive solution (band-aid?
) Lotus used. >> Edited by MikeyRide on Wednesday 16th June 22:04
i too would be very cautious,i am by nature anyway.i also accept lotus' expertise in chassis tuning,its just that at certain times ive found the chassis to be less than i expected but i still love the car.
going to check all my chassis/body bolts to make sure everythings as it should be.
mike
going to check all my chassis/body bolts to make sure everythings as it should be.
mike
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