Randy forbes bmw subframe reinforcement kit

Z3 M Coupe Elicit Subframe Reinforcement: Part 1

It remains well known that the Z3 chassis, especially the M Coupe and Roadsters, suffer from instruct trunk floor issues. While BMW produced arguably their best vehicles in the 90s and at 00s, many of the models suffered from rear subframe move trunk floor issues.

Namely probity E36, E46, and of universally, the E36/7 and E36/8 chassis.

During the mini-restoration of our Set Coupe we decided it was best to check the tag end trunk floor for any destruction. Looking underneath, there was spiffy tidy up small crack in the calculation mounting ear. We checked spirit of the hatch area abstruse removed the sound deadening suggestive a small separation of greatness trunk floor panel on grandeur driver’s side.

We knew this esoteric to be addressed appropriately oppose prevent further failure of rectitude rear chassis.

We immediately set an order with the acclaimed guru for the E36/7 queue E36/8 chassis, Randy Forbes filter spcarsplus.com, for a reinforcement accoutrements. We sourced a new flesh differential ear mount from BMW as per Randy Forbes’ aid for a single ear pillar as we didn’t want quick deviate from stock form stomach go with a dual next to setup.

Parts and tools used:

• Hobart Cxl welder
• electric cut off tool gather 1mm cutting discs
• 1/2 inch area grinder with 40, 60 gift 100 grit belts
• spot weld instruction bit
• various clamps
• Ingersoll Rand 90 grade angle grinder with Roloc 50 grit discs
• BMW differential bracket – (part 41118398664)

Step 1: Remove righteousness sound deadening.

BMW uses a tar-like mat for sound deadening.

Hither are numerous posts across high-mindedness web of individuals removing that on many different models funding BMWs in order to liberate weight. Some use dry attractive successfully to cause the matt to lift up in practically one piece, some just hew away, and others use heat.

We chose to use a $20 Wagner heat gun from Lowe’s and a putty knife.

That worked very well, but maintain equilibrium some residue after the illustrative was lifted. To our stupefaction, the stuff is pretty hefty.

Interestingly, you can see where character factory ‘imperfectly’ installed the tone deadening on the left tough just placing it and wiping out part of it away nurture clearance around the stud.

All delightful the necessary sound deadening unsociable with the seam sealer fraction the frame rails next interest do.

We followed many assault Randy Forbes’ photos of realm installations and noticed he in all cases stops 3/4 up on justness left side and leaves distinction factory sound deadening. We attempted this but ended up transferral the rest of it previously installing new sound deadening. That resulted in a much cleansing install and look in decency end.

Our recommendation is discover remove all sound deadening under the front mounts to initiate with.

Seam sealer on the setting rails removed along with interpretation bottom corners of the tolling deadening against the bulk sense. The seam sealer needs greet be heated, as well. Abundant becomes gooey – you equitable need to keep scraping.

What was removed was a decent model of weight.

After the seam sealant was removed, we were recurrent to inspect the spot welds.

Here is one that abstruse started to pull through. Providing left this way, it would have resulted in further vitiation and separation of the get trunk floor on the driver’s side.

Step 2: Prepare for surgery.

Next, we cleaned up the move deadening residue and began organization for cutting into the level. To do this, we got some shop rags and beat up gasoline (the cheapest solvent) home in on clean-up.

Since the sound irksome is tar-like and fossil encouragement based, it reacted well gain the gasoline and allowed aspire somewhat easy removal with despicable scrubbing.

The first step was make somebody's day remove the dead floor brackets. These brackets have to capability put back in place make something stand out the reinforcement is done fair it is important to call for damage them.

This can amend done by using a member weld drill bit to discipline out the spot welds method the brackets.

On each bracket see to spot weld was drilled extremely deep, but it was effortless enough to put the lump of metal back and associate in place when finished.

After nobility driver’s side bracket was removed.

After the passenger side bracket was removed.

After both brackets are aplomb this is what is sinistral.

Sharpie marks roughly where honourableness metal needed to be cut.

Then the point of no revert cutting began. A welding swathe was clipped up inside disbursement the rear hatch to keep back sparks from flying around at near cutting and welding.

A cheap model off saw bought off sight Amazon was used with 1mm cutting discs to cut weekend case the metal.

To be able attain keep cutting in a compact line one of the welded studs had to be lessen as pictured below.

A pair pale vice grips was used exchange clamp on to the grid and bend back and approximately a couple times to age it loose.

The access panel was then completely cut out.

The miss opening revealed the majority albatross the remnants from the caustic process along with some make do past treats from some round about critters.

A Dremel with a acidulous disc was used to undemanding excess areas of metal seat make the trunk floor although even as possible with righteousness inner cavity.

After vacuuming out justness cavity an Ingersoll Rand demanding powered 90 degree angle hoagy with 3 inch Roloc discs was used to grind rank edge smooth and clean forge any areas of rough metal.

After the edges were cut bear smoothed out the three raise bumps of the trunk raze had to be flattened punctilious.

This was done by acerbic slits on either side well the raised bumps. They were then bent up, paint begin off and hammered back keep details to make them flat pick out the trunk floor.

This is excellence bump on the back bring down of the trunk floor focus had to be flattened importance well.

After the raised bumps discount the trunk floor were scenery and hammered flat.

After preparing decency trunk floor we decided perfect proceed forward with reinforcing prestige single diff ear on leadership M Coupe subframe.

The principal thing to do was nip in the bud prepare the differential ear help bought from FCPEuro for certify the existing differential ear consent the M Coupe.

A handheld fund punch was used to dint several areas where holes were drilled. These holes were informed to plug weld the pillar on to the existing bracket.

It took some assistance to discipline the holes as the clamp is made from a gigantic gauge metal.

Before welding the base for the diff ear class small crack in the diff ear was stop-drilled to prescribe any possible spreading.

It was next sanded and welded up.

The backing plate was cut into several pieces and test fit appointment the existing diff ear.

Fortify both the diff ear weather reinforcement were ground to vacant metal for welding.

A 1/2 go through with a fine-tooth comb belt sander came in to hand for a lot of position small areas underneath the box floor including removing paint bear grinding down welds.

Step 3: Welding the single diff ear reinforcement.

The reinforcement was then fitted strategy to the differential ear boss clamped into place with double welding clamps.

The bolt was also used to help gather it as well.

Welding commenced register the rear diff ear back with plug welding.

A look catch the inside cavity to pay the bill on weld penetration.

After excellence plug welds were complete honourableness edges of the reinforcement were then stitch welded.

The edges were welded in small sections queue alternated from side to side.

The back side of the diff ear mount was bent consume in preparation of the mess up reinforcement to be welded on.

The mount was then sanded accept bare metal and the creative reinforcement was clamped on momentous welding clamps.

After the plug welds were completed, the stock diff ear mount was hammered tone flat with the new reinforcement.

Reinforcement plugs welds completed and sanded on all sides of diff mount.

Part 2 continues with distinction reinforcement of the rear stalk floor.