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Simon Marks - North Oxfordshire AO

Fitted Longer Travel Suspension to my XI This Weekend - What a Transformation

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Simon Marks - North Oxfordshire AO

I have had a fruitful Easter weekend in my garage with my Westfield Eleven.  Apart from changing the brake fluid and fitting a "puller" fan to the radiator (and thereby losing the large, restrictive to air flow, laser cut front mounting of the factory supplied "pusher" fan), the main task was to fit longer Protech dampers and springs to match. 

I have read much about the benefits of doing this and have bought 400 series 1.9" o.d., single adjustable (which controls bump and rebound), bearing mounting top and bottom to suit 1.25" bracket width and 7/16" mounting bolt.  The fronts are 12.5" long, the rears 14" long.  Springs to suit Front 7" x 300 lb, Rear 9" x 150 lb. 

Westfield supply 11.5"/12" shock absorbers and 350/200lb springs - quite a difference. 

Fitting was straightforward - though the axle now sits lower in the chassis so a hole needs cutting below the diff housing to allow it to drop.  I decided that, rather than leave this hole fully open and allow (even) more road grit to find its way into the rear of the car, I would frame the opening and cut and fit a rubber sheet as a gasket).

After trial fitting the shock absorbers / springs, it was obvious that the lower trailing arm bolts would need their heads reduced to allow the axle bracket and bolts to drop down past the bottom chassis tube.  I used a laser disc in a 4.5" grinder and my powerfile to halve the depth of the bolt heads.

With everything fitted, I was able to set the ride height much higher than I was able to with the Westfield supplied suspension units.  I have (measured from the ground to the underside of the chassis at the axle line) OSF 5.75", NSF 6.00", OSR 7.5", NSR 6.75".  I have seen these settings recommended as a starting point with these longer Protech suspension units and the NS/OS stagger allows for some driver weight.  I will have the car corner weighted in due course.

After tidying up the garage and cleaning the car, It was time for the test drive.  I screwed the shock absorbers up to four clicks (of 13) all round and headed out of the drive.  It was immediately apparent that the car was softer than before but the real change was the lack of crashing out (as the previously fitted suspension frequently ran out of travel).  A quick run down a straight road past a couple of nearby quarries where the road surface is rippled (by clay subsoil movement), and rutted (due to the heavy lorries) was so much smoother with the car properly running true.  No grabbing from the rear as the wheels seemed to be in contact with the ground pretty well all the time.

I then stopped off at a friend's house for a while and I put an extra click into the rear dampers.  Continuing the run round, I could tell that the rear was a bit firmer, but still there was no crashing out and I drove all sorts of roads, from poor surface lanes to the A34 dual carriageway where a section of road that sends my Renault Clio V6 pitching front to rear (with its short wheelbase), was an easy cruise.  I even took a little air over a hump back bridge and, whilst there was a tiny rear end twitch to the right on take off, the car flew OK and landed without dramas. 

The increased ride height took away all speed bumps and rutted lanes worries - another result!

There's still plenty grip and, as I am using more revs now that the mileage on the engine nears 1,000, the Eleven is turning into a really enjoyable sportscar.  All in all, a most enjoyable 50 mile run. 

Once I have a roll hoop in place (beneath the rear clamshell) I will head for a track day at Abingdon Airfield, continue experimenting and take it closer to its limits.

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The axle in situ, showing the hole cut to allow the diff housing to sit down.  I also rerouted the handbrake cables over the axle, as they were getting in the way of the axles extended droop.

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Two pictures of the rubber "gasket" around the diff.  Framed with some 1.5mm thick alloy checker plate, I used roofing membrane as the sheet material.  Some of the off centre fixings are where I used existing holes for handbrake securing clips and the battery box.

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Front and rear Protechs

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The "stagger" can be seen (particularly) at the rear when the car is parked (without my ballasting the driver's side).

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"Before and After" shots of the car.  In the one outside my office, the car was wound as high as I could (on the drivers' side) with the Westfield supplied suspension units.

Simon

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zei220

Thanks for a good write up of the changes. I think I need to talk to Westfield about a change to my order.

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stephenh

Sounds like a result, Simon. When I spoke to someone at Protech they told me that they can modify my dampers to increase the length by 1" each by fitting longer 

top bits (not sure what they are called!) and if that isn't sufficient they can fit slightly longer rods to add another 1/2" if required. I'm just so annoyed that Westfield insisted on supplying the (Protech) dampers instead of letting me source them direct and knocking the price of the dampers off the kit price. That way I'd have ended up with the correct ones in the first place.

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BCF

Sorry to ask this rather stupid question, but can Protech shocks be fitted upside down? I was led to believe the seal wasn't sufficient for them to last in that orientation. Or are this a special unit for this application?

Car looks absolutely fantastic, I bet it sounds brilliant too.

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Simon Marks - North Oxfordshire AO

Hi,

When the Protechs were collected from their works, it was specifically said that the dampers could be mounted upside down - so I took advantage of that offer!

Thank you for the compliments, by the way.

Simon

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BCF

Great, good to hear that's all ok & thanks for clarifying. 

Look forward to seeing you out on track!

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