31 31 ... Instructions on Handling the BMW Spring Tensioner
31 31 ... Instructions on handling the BMW spring tensionerAfter installation:
^ Carry out wheel alignment check if a spring strut with support bearing has been installed without centering pin.
^ If necessary, carry out adjustment of steering angle sensor.
The following description refers exclusively to the spring tensioner currently sold by BMW.
Older spring tensioners may only be used in the model series mentioned in the relevant repair instructions if there are no corresponding spring holders for the current spring tensioners.
Follow the manufacturer's operating instructions.
The spring tensioner may only be used in conjunction with the relevant BMW repair instruction (latest edition).
Warning:
^ Prior to use, always check the special tools for functional reliability.
^ Do not use special tools which are damaged.
^ Do not make any modifications to the special tools.
^ These special tools are intended solely for the purpose of tightening and relieving cylindrical and tapered suspension springs.
^ Keep special tools dry and free from grease.
^ Never use impact screwdrivers.
The corresponding spring strut must always be removed completely beforehand.
The following special tools must be used:
Basic tool 31 3 341
Depending on the model, appropriate spring holders (1) and protective inserts (2) from special tool kits 31 3 350, 31 3 380 and 31 3 360 (refer to repair instruction of relevant model)
Basic handling:
Clamp basic tool 31 3 341 at strip (1) in vice.
The protective inserts protect the sensitive springs against damage. Therefore always use the spring holders with the appropriate protective inserts.
On some vehicle model series (e.g. E60), there is the risk of the spring turning during removal/installation together with the protective insert out of the spring holder. This poses a danger to life! In this case, the protective insert must not be fitted with the spring holders.
Reference is clearly made to this in the corresponding repair instruction.
Spring holders must each be inserted from chamfer (1) into the basic tool.
Depending on the model, feed the corresponding spring holders (here 31 3 352 and 31 3 354) and if necessary together with the protective inserts (here 31 3 367 and 31 3 354) into the fixtures (2) of basic tool 31 3 341 (1) and lock in place.
The correct spring holders for the corresponding models are specified in the repair instruction.
Locking pins of fixture (2) must be felt and heard to snap into place.
Before inserting spring tensioner, clean spring to remove coarse contamination.
Never tighten or untighten special tools with an impact screwdriver.
Lay upper turn of coil spring into corresponding spring holder.
Turn spring tensioner and position spring strut so that the last turn is flush with the corresponding spring holder, feed spring into spring holder and gently tighten spring tensioner.
Model-specific tensioning specifications are given in the relevant repair instruction.
Important: In some case, a special spring holder (here 31 3 381) may also be used. Reference is made to this in the corresponding repair instruction.
Warning:
Check correct seating of spring in spring tensioner again
When tensioned, the spring coils must rest completely in the spring retainer recess.
Compress coil spring until stress on piston rod is relieved.
Warning:
Do not compress spring to full extent.
There should always be a minimum gap (A) between the spring turns. Gap may be "O" if both these spring turns do not rest on each other all round.
^ Release nut only when tension is relieved on piston rod.
Screw connection of support bearing to piston rod must not be released with impact screwdriver!
^ Depending on the model, release nut with corresponding special tool (here 31 2 210) (refer to repair instruction), gripping the piston rod in the process:
- Vehicles without EDC: internal hexagon
- Vehicles with EDC: external hexagon