Suspension & Drive Line.


We had debated for considerable time on what suspension changes we wanted to make. Our consensus was that 5” of lift was required however how do we achieve such. I was dead against a body lift and also wanted to enjoy as much suspension articulation as possible. By leaving the spring mounts in place and getting longer springs [ie more turns] we could get the extra height, maintain a comfortable suspension and get more potential suspension movement / articulation. After reviewing the commercially available springs and also investigating purpose built springs we decided to go with the Rovertym Engineering RR4- 5 springs. These are new springs that have just been bought on the market. Whilst still a little experimental in set up it was felt that with the shortened rear of the Discovery that similar springs all around would work in lieu of going for the Rovertym RR1-5 springs in the rear. The RR4-5 springs are a linear rated 250 lb/in spring whereas the RR1-5 is a progressive 330 – 360 lb/in spring. After some live testing we will see if this set up works best.  


The above pictures are direct from the Rovertym Website.

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Click on the above 2 thumbnails to see and enlarge picture of the Springs and new shocks fitted to the rear of the Discovery.

The Rovertym description of these springs is as follows:

“The new RTE springs offer variable or constant rates. Precision process by domestic MFG. which incorporates military processing and strict quality control standards resulting in exact and consistent dimensions and heat treat processes. All springs have been shot peened for a clean smooth finish quality. Scragged to insure repeat performance and consistency.”

As most suspension specialists would agree, including Rovertym , Roto-Flex coupling driveshafts do not like suspension lifts. Luckily our Discovery already had the conversion done to remove the Roto-Flex to the more traditional 4 bolt differential / drive shaft interface configuration. With current marketplace suspension lifts available, your Roto-flex drive shaft may have to be replaced with a standard u-joint shaft.  

The front springs were fitted on Saturday 14th and look great. Unfortunately we do not yet have the front Bar and winch attached so once the car was taken off the jack and stands the front end did not drop very much. Hopefully once the new front bar and winch are installed the front end will drop a little and level off. Since the springs are such are large lift they are not that easy to install. Luckily we had access to an industrial spring compressor which allowed them to be fitted relatively easily. With out such access the front radios arms would have needed to be disconnected at the chassis to allow enough front end droop for fitment. 

At present this extra height has stretched the front brake lines to their full extent. I have some Range Rover extended brake lines which I was going to reuse except that the fittings are different. I have therefore purchased some new 25" extended steel braded brake lines from Rovertym and will fit then upon receipt. I have used their brake lines before and found them to be very good. The ABS will be removed from the vehicle so these lines will not be an issue.

The Rear springs will be fitted this coming weekend. Hopefully I will be able to update photos early ext week.

Shocks / Dampers

Like springs we investigated a large number of shock options. In the past I have been a big proponent of Koni shocks for off road use. In the USA they do not seem to have any following whatsoever. Given their lack of general availability we discounted them. I have also used Ranchos on my 1988 Range Rover for the past 18 months. Whilst a reasonable cheap option we felt that they just would not have the capacity to stand up to the punishment that competition work would place them under.

Many members of the Solihull Society of which I am a member have run Foxx Shocks in the past. From their experiences these were also discounted. Most previous owners seemed to be moving to Bilstein.

Ok it took about 2 months of back and forth discussion and investigation before choosing to go with Bilstein. We chose their 7100 series for 2 reasons. (a) They are an excellent off road shock that is re-buildable and user friendly with many variations; & (b) They were semi reasonable in price. We would have liked the 9100 series but could not justify the price [especially to my wife who is being patient with this project as it is].

That was out of the way but what length and set up option should we choose. In the end we chose the AK7112SB06 version of the 7100 shock. This means the 7100 series, short body, external reservoir, 12” stroke, 360/80 valving option. Using the short body version minimized any issues we had to contend with for space for the shocks. With a compressed length of 16.03” and extended length of  28.06” compared to the standard length shock stats of 19.61" and 31.34" respectively. 


Specifications taken from the Bilstein site are:

Bilstein 7100 Series Technical Specifications  

bulletSelf-Adjusting Deflecting DiscValving 
bullet2" Diameter Shock Body
bulletHigh-Flow Piston Reduces Harshness
bulletChoice of Valvings Schrader Valve Shocks with Dividing Piston
bullet 8", 10", 12", & 14" Travel 

Body:  2" Seamless Extruded Tube Conventional or Threaded Body
Rod:  14mm Centerless Ground, Case Hardened, Chromed and Super Polished
Seal:  Aluminum 1 Piece/Rod Guide
Piston:  46mm Bilstein Racing Piston
Valving:  "Self Adjusting" Deflective Disc Independent Rebound & Compression
Oil:  Bilstein Fade Resistant High Temperature Racing Oil
Reservoir:  2" Seamless Tube
Hose:  Aero quip -6 High Pressure Hose
Rod Ends:  1/2" Teflon Uniball w/ Eye Ring
Finish: Electroless Nickel
Coilover Hardware:  2 1/2" (2 1/4" upon request)

As with the springs after field testing we will see if the valving choice is correct. If not we will be able to change the valving.

Front shocks were fitted on Saturday 14th and look great. As the shocks are eye to eye as opposed to the standard Discovery pin to pin configuration we had to adjust both top and bottom fitment. To handle the top we used 2 Discovery II shock towers which are set up for eye styled shocks. A large hole was cut out of the shock towers to allow the Bilstein external reservoir to be fed through and leave space for the hose from the external reservoir to the main shock body. This set up worked extremely well. We have not yet determined the final reservoir placement but will do so when updating the engine bay set up.  To hold the bottom mount we fabricated a spring retainer similar to that used on the rear springs and then welded 11/2" upright supports which were drilled to hold the shock eyelet. This was a simple fabrication and seems to work quite effectively.

The rear shocks have been fitted and are shown in the picture below, yes that's me fitting them. I do some work and not just take pictures and write about others work. Click to enlarge. The pictures shown above under springs also show how the new shocks fit in the rear.

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As the shocks are much longer than standard we have had to refit new shock mounts top and bottom. You can probably see the bronze coloured upper shock mounts in the picture above and also in the pictures under the spring section. RoverTracks  produce a version very similar to these however the ones shown on the vehicle are from Rockware. The only reason we [read I] reused the Rockware ones instead of using a set from RoverTracks was that I had them from a previous vehicle and there seemed no good reason to simply discard then and go through the effort of getting a set from Keith. Keith makes a great kit at RoverTracks and if I were buying more I would get them from him. I did however fabricate a new rear lower shock mount to hold the eyelet in lieu of the standard Land Rover Pin set up. The rear bottom shock holder is shown in the right hand picture above at the bottom. The upper bar in this picture is one of the new rear top spring retainers fabricated to ensure that we did not pop out our rear springs, a possibility with these new long travel shocks.

We also installed 25" steel braded brake lines from Rovertym to handle the extra rear suspension drop. These are significantly longer and more durable than standard Land Rover brake lines.


Trailing Arms

We are building custom trailing arms based on the RoverTrack heavy duty trailing arms. Ours are longer and use a front Heim joint in lieu of the standard round rubber bushing. The Trailing arm can be seen below after painting. I will provide a comparison picture shortly showing the standard Rover Product to the extreme duty arm fabricated for this project.

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You can see the new engine on the stand in the background of this picture.

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As the rear bushing is larger than standard a purpose built bushing has been made. This is basically a cut down Jeep component that was turned down on a lathe, a simple process. It was then inserted with a metal sleeve as per the first picture above, the second giving a closer view once the bushing ad sleeve have been inserted. The third picture above shows the Heim joint. These joints are normally used on front end loaders so provide more than sufficient strength of this application. To provide additional lubrication a grease nipple has been fitted to allow periodic lubrication.

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A new mounting bracket is also needed for this arm. The first picture above shows the raw unpainted joint after fabrication. The angular section is to provide some additional protection to the Heim joint form front impacts [which I hope there will never be]. The second picture shows the new joint welded to the frame. You can also see the standard bushing joint to the left of the new joint. Note the new position further forward than standard and the raised position to provide addition protection and reduce clearance issues that the standard position must contend with. The third picture has the new joining bolt pushed through giving some idea of how the new joint should look. Once the trailing arm is attached the bolt will actually come from the inside out with the nilock nut on the bracket side.

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The standard Discovery trailing arm is approximately 31 inches long. Our new extreme duty arm is actually 41 inches long. the differences in length can be seen in the pictures above. Whilst the pictures are not as good as i would have liked, if you look closely enough you will notice a considerable difference in arm diameter from standard to new. Both the overall diameter and metal thickness have been increased significantly.

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The above picture shows one of the new trailing arms actually in place. You can note that the bolt holding the arm to the chassis goes form outside to the inside. This is to provide a little more protection for the bolt and threads than if installed the other way around.

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The above two pictures give a slightly better orientation of the new trialing arms.

Caster Correction

We have been debating about how to attack this problem. Our two options are either to re-drill the swivel ball housings or to install a modified Radius arm such as that produced by QT Services. The biggest concern we have with the Radius arm option is the Pinion angle change. See further comments under Drive shaft section below on how we approached this.

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The above is the 6 degree correction radius arms from QT Services out of the UK. I actually picked these up from Adrian Strata of who is the US importer for QT Services products. We have installed these using standard Land Rover Bushings. We had hoped to use softer bushings but every company we contacted about them seemed to have no customer service ethic whatsoever with email requests for information being completely ignored. 

The Radius arms went in with great ease. They have almost completely eliminated any drive wander or wobble and are working out as an excellent addition to the suspension set up. The picture below shows one in place.

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Other Bits and pieces:

Drive Shafts.

We are currently using Great Basin Rover Heavy Duty Drive shafts both front and rear. Given the height increase and the proposed use of the QT Services adjusted Radius Arms we need to account for the increased pinion angles on the differentials. To help with this we have moved from a 20 degree flange yoke to a 30 degree flange yoke. The actual part is a Spicer 2-2-459 Drive Shaft Flange Yoke. The pictures below show the standard 20 degree item [in green] against the 30 degree flange [silver]. The last picture shows one of the flanges yoke installed. 

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Bump Stops.

To provide additional support and protect the shocks we have install Energy Suspension  Bump stops. In particular we installed their item number 9.9104G Bump stops which are designed with a large reinforced metal plate welded to a mounting plate and molded-in. They are 4 1/2" tall and 2 1/2" wide. They do not bolt straight onto the Land Rover set up so we cut off the mounting bolt and welded them to the original Land Rover mounting plate.

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