Rocky Mountain Parabolic Springs Installation
This method is recommended for owners installing their own springs, working on one spring at a time. Those with more facilities may choose to do an axle at a time.
Please read through before starting.
- Loosen slightly the lug nuts of one wheel, but do not remove.
- Jack up your Land Rover’s chassis until the wheel is off the ground.
- Remove the wheel and place an axle stand under the chassis rail, then lower the truck onto the stand.
- Remove the shock absorber from the lower mounting plate.
- Remove the nuts holding the ‘U’ bolts to the axle and/or cut the ‘U’ bolts off.
- Place the jack under the axle to support it.
- Remove the lock nuts and bolts holding the spring eyes to the frame and shackles, then remove the old spring.
- Check condition of the chassis bushing, it should be firmly located in the frame. The shackle plates should have unworn round holes, the bolts should not show significant wear. Clamping plate under the spring should be flat and un-cracked. Check that the new ‘U’ bolts pass freely through the clamping plate holes; we use a full ½” dia. thread that may require slight enlarging of the 7/16” holes on some older trucks. The shock absorber mounting post should be round and parallel to the plate surface. Check shock absorber for resistance if they are to be reused. Check that upper axle buffer is in place and serviceable. NOTE* Warranty is void if axle buffers are not in place. Parabolic’s will lose arc if overextended. Any increase in ride height/shackle length must be accompanied by an equivalent downward adjustment to the axel buffer position. Ensure that the rear check straps are in place and serviceable. Clean and paint reusable parts.
- There can be traces of rubber residue in the spring bushing’s inner 9/16 tube, check the shackle bolt passes through and if not remove residue. The spring eye outer wrap may be tighter at one end than the other, for the front springs install the tightest wrap in the frame mounting horn. This can be important as variations in truck manufacture make some very constricted. If necessary the spring center pin can be loosened and one outer wrap tapped rearward to give a tighter front eye. The upper leaf has a slotted hole for this adjustment.
- Using the reverse procedure bolt the new spring into place on the chassis without fully tightening up. You may need to raise the axle slightly.
- Lower the axle onto the new spring making sure the spring center pin is located into the hole in the axle bracket.
- Install the new ‘U’ bolts and tighten enough to remove slack, do not torque.
- Remount the shock absorber, and wheel.
- At the rear, the check straps should be adjusted so that they stop the downward progress of the axle approximately ½” before the shock bottoms.
- Repeat procedure for other three springs, and with the Land Rover standing freely on its new springs rock the truck back and forth energetically to settle the mountings. Do not expect your truck to sit perfectly level, parabolic springs are more load sensitive than cart type springs which is what gives improved ride and articulation . There may be very slight differences between pairs of springs that you can use to tune your trucks side to side static position. You may wish to position some weight in the truck before doing this to simulate your most common loading of driver, fuel, etc.
- If possible find three adults to stand on the bumper while you tighten the frame and shackle bolts to 70ft./lbs. of torque. Torque shackle lock nuts to the same torque. Torque ‘U’ bolt nuts to 65ft./lbs., repeat for other end of truck. Important ‘U’ bolt torque must be rechecked after first week of use and rechecked periodically afterwards, especially in rough road conditions. Spring’s are not designed to flex across the center section and may fail if ‘U’ bolts become loose. Torque settings are for dry components,anti-corrosion products should not be applied until after tightening, overstressed ‘U’ bolts can lead to failure and damage to axle plate.
- Springs can be lubricated with any used oil to prevent squeaks and coated with Waxoil or a similar product to reduce cosmetic corrosion.
Rocky Mountain front spring pairs are supplied with three 78456UB-S plus one 78456UB-M for the inside right hand axle position, rear springs are supplied with four 78456UB-M.
Parabolic springs may raise the height of your truck slightly and will alter its suspension performance. Please drive carefully until you are familiar with these new handling characteristics.
As Series Land Rovers are not equipped with anti-sway bars, good quality shock absorbers are necessary to control the improved spring performance. Rocky Mountain has PRO COMP manufacture shock absorbers exclusively for us, to fit our springs. These are based on their 9000 series premium gas shocks, modified to our specification, and offer 2” extended travel.
For any installation questions or additional parts, please contact us.
Thank you for purchasing our product.
Service Bulletin; RMPJP010812