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Go Back   Madabout Kitcars Forum > Mad Build Area > Marlin 5exi builds

Marlin 5exi builds Calling all you sexi builders....sorry 5exi builders, show us your progress.

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  #21  
Old 8th January 2008, 21:01
Ric H Ric H is offline
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Good description John, and spot on in describing my car's behaviour. The problem becomes more apparent at speed. In, ahem, high speed trials on a 3 lane deserted, ahem "closed track" I found the car really very stable under power up to a speed when my nerve ran out. However, as soon as I eased off it was a different matter - the rear snaked to such an extent I needed half of each lane either side to keep it under control. A little unnerving, I'll say.

I'll be very interested to see how you get on with the new rear, John. I've been a bit preoccupied recently and haven't got around to getting mine ordered. In the meantime I've been wondering what I might be able to achieve by playing with the rear toe. I've wondered if it's the toe swinging out under deceleration (it is pretty flexy afterall) that initiates the snaking, and so am thinking of trying some significant toe-in at the rear. Not sure what other effects that will have but hey, it's all experience gained!

Richard
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  #22  
Old 8th January 2008, 22:19
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Quote:
Originally Posted by Ric H View Post
... am thinking of trying some significant toe-in at the rear. Not sure what other effects that will have but hey, it's all experience gained!
What is your toe-in setting at the moment?

I'm running 0 deg, 20 minutes.
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  #23  
Old 8th January 2008, 22:40
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Running parallel at the rear at the minute (within the accuracy of careful string measurements!). I was thinking of toeing in 1-2mm, which a quick calc says is about what you've got? Maybe I should try more... though it's so easy to change that I might just play around for a bit.
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  #24  
Old 8th January 2008, 22:48
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Hopefully I'll find some time to get my car through the SVA retest (haven't got a plan at the moment - might need to buy some time off ), by which time Marlin will hopefully have fired up production again, and I'll get my phase 2 rear suspension.

When I fit that, I'll set my rear toe the same as it is currently, and report my findings. I've got a dunlop optical gauge.

To be honest, although playing with the toe will be provide some intrigue, I don't think it'll come close enough to solving what Marlin have already admitted is an inherent flaw in the early rear suspension design.

For the record, I've got what must be phase 1.5 rear suspension, in that the upright is a reinforced item. Mark M pointed it out to me when I collected my kit, that I had Type-R specific rear uprights, strengthened to take higher loads.

I don't know what speed you "lost your nerve" at, but I had an "oooh I don't like that" experience, similar to what you described.

I can fully understand why at Llandow over the course of a lap, I was faster in my dagenham dustbin, than you were in the 5exi - one is constantly changing from loud to slow pedal, and in that situation the 5EXI with the floppy rear-end does not inspire confidence, whereas in a docile FWD car I could drive on the limit with no bother at all.

I know my comments are all based upon a lowly 140 miles of driving my 5exi, and some people may discredit my comments on that basis.
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  #25  
Old 8th January 2008, 23:30
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Just a quick comment on SVA, I would try to get a retest sorted as soon as and ask for the same examiner that way the car will still be fresh in his mind. In my case I got my retest within a week and the same examiner - he only checked the things on the fail sheet had been rectified.
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  #26  
Old 8th January 2008, 23:41
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I'd love to get the car back soon, but my work pressures won't allow it. There are only 2 examiners at the Taunton SVA centre, and my car's examiner did seem genuinely intrigued by the car (never seen one before), so as long as I get it back within the next month (which I hope to do), I'd like to think there will be no problems.

The tester did say he'd only check the faults he spotted at the time of the test... which didn't include the cracked windscreen!

Thanks for the heads up.
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  #27  
Old 9th January 2008, 06:55
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4 wheel alighment is hopefully one thing I will be doing soon. Friend has a 4 wheel alighnment kit using the string method. Only by eye and toe in gauge at present as I need a flat floor!

Going to be doing the same settings as big Rich.

145mm ride height.
Front. -3/4 degree camber. 1/4 - 1/2mm Toe out.
Rear -1/2 degree camber. 2 mm Toe in.
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  #28  
Old 9th January 2008, 07:18
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Quote:
Originally Posted by kenmorton View Post
Just a quick comment on SVA, I would try to get a retest sorted as soon as and ask for the same examiner that way the car will still be fresh in his mind. In my case I got my retest within a week and the same examiner - he only checked the things on the fail sheet had been rectified.
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Originally Posted by alackofspeed View Post
I'd love to get the car back soon, but my work pressures won't allow it. There are only 2 examiners at the Taunton SVA centre, and my car's examiner did seem genuinely intrigued by the car (never seen one before), so as long as I get it back within the next month (which I hope to do), I'd like to think there will be no problems.

The tester did say he'd only check the faults he spotted at the time of the test... which didn't include the cracked windscreen!

Thanks for the heads up.
Same for me in Southampton, retest by the same guy but I left it a few weeks just to be sure I had enough time to sort everything. I left booking the retest until I was happy with the car. Got an appointment only a week or so later. He only checked items that failed first time which too about 15mins.

BTW I'm surprise they let you take pictures during the test, they nearly took my camera off me when I wanted to!
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  #29  
Old 9th January 2008, 12:33
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I dunno if I simply wasn't spotted taking pictures, or if the chap didn't really care.

My concern is my windscreen is cracked, but as it wasn't spotted first time around will it fail the retest if spotted....? No point messing about - I'll just call and find out.

Fitting a new screen is a [insert expletive of choice...] compared to the failure points!
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  #30  
Old 9th January 2008, 18:36
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Would have thought the SVA wouldn't have cared less about the windscreen being cracked. From what I can see in the SVA manual they are more concerned that its of the correct standard e.g. how it operates if cracked rather than if its cracked thats more an MOT issue. However best to check especially as some SVA inspectors seem to be a law unto themselves.

Guess my SVA centre will be Norwich when I get to that stage... Doubt they will have seen a 5exi before either.
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  #31  
Old 9th January 2008, 19:22
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[QUOTE=
Guess my SVA centre will be Norwich when I get to that stage... Doubt they will have seen a 5exi before either.[/QUOTE]

Do they have cars in Norwich?
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  #32  
Old 9th January 2008, 22:47
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Quote:
Originally Posted by limpabit View Post
4 wheel alighment is hopefully one thing I will be doing soon. Friend has a 4 wheel alighnment kit using the string method. Only by eye and toe in gauge at present as I need a flat floor!

Going to be doing the same settings as big Rich.

145mm ride height.
Front. -3/4 camber. 1/4 - 1/2 Toe out.
Rear -1/2 camber. 2 mm Toe in.

What are your camber (front and rear), and front toe units? Also, when you're measuring the X mm toe, from what edges of the wheel? I ask, as if you're measuring from a rim edge, then different diameter wheels will yeild a different toe value.

I'm using 15" wheels, and my angles are presently:

Front: 0 deg 40' camber, 0 deg 10' toe out
Rear: 1 deg 40' camber, 0 deg 20' toe in

It's interesting that Rich ran more front camber than the rear - that's not usually the case with RWD cars in my experience.
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  #33  
Old 10th January 2008, 05:42
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Quote:
Originally Posted by alackofspeed View Post
What are your camber (front and rear), and front toe units? Also, when you're measuring the X mm toe, from what edges of the wheel? I ask, as if you're measuring from a rim edge, then different diameter wheels will yeild a different toe value.

I'm using 15" wheels, and my angles are presently:

Front: 0 deg 40' camber, 0 deg 10' toe out
Rear: 1 deg 40' camber, 0 deg 20' toe in

It's interesting that Rich ran more front camber than the rear - that's not usually the car with RWD cards in my experience.
I think it's a bit of sucking and seeing. I'm using 15" wheels as well. May have different handing due to Rich having a much lighter engine?? Does this matter???

Rich may have said 1/2 -3/4 at the front. So It is my that has mistaken the readings from Rich. I'll set the fronts at 3/4 and rears at 1 degree and see how the car feels.

Waiting for a clear dry day to get the car down to mates workshop to get the equipment on it to line up correctly. Well when I say correctly. To the figures above. Which may or may not be correct for my car.
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  #34  
Old 10th January 2008, 20:56
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Hi Guys,

Changed my settings a bit since I posted . Currently running:-

Front - toe out by approx 0.5mm. 1/4 deg neg camber.

Rear - toe in by approx 1mm each side, 1/2 deg neg camber


These seem to be OK...front toe out slightly helps any wandering on the road. Front camber setting is with no pass / driver...when 2 up this figure is a fair bit nmore (not measured it) but visualy as the suspension is lower, the camber alters accordingly.

As for the rear.....yes I too have experienced the "whoooooo...what was that" moment. Tends to be on throttle back / coasting at speeds over 80 (on track of course). Initially this did seem worse with less toe in at the rear...running 1mm each side helped the feel and I'm contemplating going upto about 1.5mm each side to see if this helps further. That said, I still need to fiddle with the track control arms front and rear to get the bumpsteer sorted.

Rich
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  #35  
Old 11th January 2008, 11:38
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ah cock - earliest retest is 28th Jan!
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  #36  
Old 11th January 2008, 14:39
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Quote:
Originally Posted by bigrich View Post
That said, I still need to fiddle with the track control arms front and rear to get the bumpsteer sorted.
What rear end do you have Rich? Is it the same as what is in the pictures when you were building it??

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ah cock
I really must see what the definition is in my book of technical words & phrases
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  #37  
Old 11th January 2008, 15:57
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Jon,

Phase 1 back end as in my build pics. Planned to use spacers and longer securing bolts on the inner chassis end of the track control arm to build up / build down the pivot point and hence reduce b/steer.

Rich
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  #38  
Old 15th January 2008, 21:53
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Quote:
Originally Posted by alackofspeed View Post
Craig, while I remember - the Elise seats are fine, but the part of the car they mount to, needs to be welded in place, and really obviously substantial. You must also use the OEM seat frame mounts, and not cut and shut them. I don't know how you've done yours, so thought I'd give you a heads up.

John, mine are not welded as they are not welded in the elise/exige, but did you mean the actual car frame?? I think you added extra tubes? I managed to get mine on the actual chassis!

My seat subframes are cut and shut but think they will be fine as they look oem, the bottom of the seat was originally lower than the subframe

Craig
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  #39  
Old 15th January 2008, 22:11
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Yes, I have longitudinal box section welded to the chassis, fitted with captive nuts.

I suspect if they look OEM, then you won't get any issue - I told my inspector I'd fitted my seats as Lotus intended, and he took my word for it (it is a true statement though).

I just thought I'd give you a heads up, so that you can avoid failing on a simple aspect of the build.

If the seat bolts through the chassis, make sure the bolts don't act to compress the box section when being tightened.
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