Lotus Elan

Bump Gauges - VMEP

PostPost by: miked » Fri Mar 31, 2017 8:10 am

I have just sorted the bump steer on my Elan. I had done it in the past with a make shift rig. Then I saw this. I contacted them and Alex had a hub plate made to suit an Elan peg drive hub. I found that I needed a piece of pipe as a spacer to hold it down with the spinner. I happened to have a Ford Zetec water pump pulley so used this. The first plate was not quite right as the DTI tips were close to the pegs and also one of the 3 ears of the spinner. I did manage to get it working and just miss the pegs but needed DTI extensions. Then Alex redesigned it from 6 inch DTI centres to 8 inch centres. This clears both the pegs and the spinner ears. I am very pleased with it and the help given. The price is reasonable IMO. I also bought the platform which helps positions the rig that bit higher to allow more room underneath for your self and the jacks. See link to web site.

https://www.vmep-ltd.co.uk/chassissetupequipment

I had never used the 2 DTI method but got used to it quite quickly and set the DTI's mid way (under tension) at 5 at ride height. I found that through bump and droop this gave me the readings I needed to make the corrections. I have no connection but pleased with the customer service and help that Alex has given. We had courier damage which was sorted each time.

PS Top tip, to keep your jack under the shocker, make a clevis and bolt it to a large socket. This goes through the bottom shocker bolt and then sits in the jack cup and you get repeatable results without the jack slipping out.


Mike :D
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Mike

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PostPost by: Certified Lotus » Fri Mar 31, 2017 10:58 am

i have a couple of questions (please excuse my ignorance on this subject). I had thought the only way to correct bump steer was to shim the steering rack? Is that true and if so, how do you know which shims to use?

Do you need two of these measuring tools to do both sides at same time or can you do one side at a time?

Great recommendation of reasonably priced equipment and great customer service.
Glen
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PostPost by: miked » Fri Mar 31, 2017 6:29 pm

Hi,
You adjust by shims under the rack as you say. Also if our cars had rod ends on bolts instead of track rod ends they can be shimmed with washers and the adjustment made there. I have actually seen the same Triumph steering arms converted from taper to parallel on formula Fords to do just that.
Sorting out the shims is a trial and error process after taking readings. See article link. You need patience.

http://www.longacreracing.com/technical ... ?item=8162

You only need one gauge rig that you move from side to side. Important bits are suspension arms and bushes in good condition. Steering rack mounted central and track rods same distance each side of rack. Note that when you shim one side you alter the other side reading. You get a feel and can see when you are getting nearer (or have gone too far). I made a chart so I could compare each set of readings after each shimming. Also you can see when you go from Toe in to Toe out during the exercise. Generally Lotus racks seem to be low suffering a lot of toe in under bump. I don't profess to know much about it technically but wanted to ensure I cured some odd goings on under heavy braking on uneven surfaces. I actually had some rear problems too with toe out on driver side. Now cured.

Mike :)
Mike

Elan S4 Zetec
BSA B33
Suzuki Hustler T250
BMW rninet scrambler
Suzuki TC120 trailcat
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