As some of you know we have a full service race fab and repair shop here at Vorshlag. In this thread I will show the rear chassis reinforcement and custom differential mounting we did on a customers Z3. This same work can be done to a BMW e30 chassis, which shares the same rear subframe and differential mounting issues.
Tony J's 1999 BMW MZ3 Coupe
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-qML9Tnj/0/M/photo-M.jpg)
This car has the same single ear diff mount that rips it self out of the trunk floor on many Z3 and E30 models. Tony's Z3M has an Active Autowerks supercharged S52, so it sees more torque than most! With cracked trunk floor (see above) it was in dire need of some Vorshlag surgery and upgrades.
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-PJX2sNH/0/S/DSC7539-S.jpg)
We started by a thorough detailing of the car on Monday. We always do this, as it shows everything clean up front and then we can wrap/cover any body and interior areas we need to work near without grinding dirt into those surfaces. Once it was spotless outside, inside and under the hood, on our guys put the car up on the lift to make some measurements and verify parts we needed to order. We have another car having an entire trunk floor replaced that got worked on Tuesday, but late that afternoon our guys got back to the Z3M and removed the rear interior panels/carpets, covered the inside rear windows with paper and made a plastic barrier to the interior, then covered the body areas with towels, then covered all of that with welding blankets (during welding - not shown).
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-68b3J3M/0/S/DSC7550-S.jpg)
The tar paper insulation in the trunk area we are repairing had to be removed and then we weighed it all(1.2 lbs). These "uncovered" areas were cleaned up in preparation for surgery.
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-JVTDJRR/0/S/DSC7546-S.jpg)
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-P8nt2LV/0/S/DSC7558-S.jpg)
Measurements were taken with the stock diff housing in place, then measured from the stock single-ear mount cover back to where the E36 dual ear mount Rogue Engineering cover would be. The placement of the new cross beam was marked on the chassis, the diff center section was removed and the and the cut lines were begun. The car has been up and down on the lift a dozen times by now.
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-74t7GCX/0/S/DSC7560-S.jpg)
Then out came the cutting tools - a variety of air & electric, metal and carbide cutting blades were used to slice out the 3" wide channel where the 3x3" x 11 gauge square steel tube will go.
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-wcF3mTf/0/S/DSC7561-S.jpg)
That's where we left it today - all still on schedule, even with the new maintenance items added. Should be wrapped up Friday night. We have all of the steel tubing now, more welding gas for the TIG and MIG welders will be here in the morning, and then its time to burn metal. I picked up some fresh seam sealer, proper metal etching primer, and managed to find a pretty darn close color match for some spot work (top side of trunk area - which will all still BE under the rear interior carpet).
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-txXJD2F/0/S/DSC7568-S.jpg)
More soon,
Tony J's 1999 BMW MZ3 Coupe
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-qML9Tnj/0/M/photo-M.jpg)
This car has the same single ear diff mount that rips it self out of the trunk floor on many Z3 and E30 models. Tony's Z3M has an Active Autowerks supercharged S52, so it sees more torque than most! With cracked trunk floor (see above) it was in dire need of some Vorshlag surgery and upgrades.
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-dcwt8VL/0/S/DSC7537-S.jpg)
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-PJX2sNH/0/S/DSC7539-S.jpg)
We started by a thorough detailing of the car on Monday. We always do this, as it shows everything clean up front and then we can wrap/cover any body and interior areas we need to work near without grinding dirt into those surfaces. Once it was spotless outside, inside and under the hood, on our guys put the car up on the lift to make some measurements and verify parts we needed to order. We have another car having an entire trunk floor replaced that got worked on Tuesday, but late that afternoon our guys got back to the Z3M and removed the rear interior panels/carpets, covered the inside rear windows with paper and made a plastic barrier to the interior, then covered the body areas with towels, then covered all of that with welding blankets (during welding - not shown).
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-4PBTSfF/0/S/DSC7548-S.jpg)
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-68b3J3M/0/S/DSC7550-S.jpg)
The tar paper insulation in the trunk area we are repairing had to be removed and then we weighed it all(1.2 lbs). These "uncovered" areas were cleaned up in preparation for surgery.
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-Vdz7Lcg/0/S/DSC7545-S.jpg)
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-JVTDJRR/0/S/DSC7546-S.jpg)
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-XpLgJQt/0/S/DSC7556-S.jpg)
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-P8nt2LV/0/S/DSC7558-S.jpg)
Measurements were taken with the stock diff housing in place, then measured from the stock single-ear mount cover back to where the E36 dual ear mount Rogue Engineering cover would be. The placement of the new cross beam was marked on the chassis, the diff center section was removed and the and the cut lines were begun. The car has been up and down on the lift a dozen times by now.
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-3g97Cvm/0/S/DSC7559-S.jpg)
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-74t7GCX/0/S/DSC7560-S.jpg)
Then out came the cutting tools - a variety of air & electric, metal and carbide cutting blades were used to slice out the 3" wide channel where the 3x3" x 11 gauge square steel tube will go.
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-8LT58jd/0/S/DSC7565-S.jpg)
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-wcF3mTf/0/S/DSC7561-S.jpg)
That's where we left it today - all still on schedule, even with the new maintenance items added. Should be wrapped up Friday night. We have all of the steel tubing now, more welding gas for the TIG and MIG welders will be here in the morning, and then its time to burn metal. I picked up some fresh seam sealer, proper metal etching primer, and managed to find a pretty darn close color match for some spot work (top side of trunk area - which will all still BE under the rear interior carpet).
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-Ftktjhv/0/S/DSC7567-S.jpg)
![](http://vorshlag.smugmug.com/Service/Chassis-Fab/i-txXJD2F/0/S/DSC7568-S.jpg)
More soon,
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