Well, she is finally back on the road. As usual there are a couple of loose ends to finish up but at least I’m driving it.
Now on to the good stuff. Initial impression of the rear subframe forward attach point reinforcements is that the car feels like the engine is directly connected to the wheels. This car has never felt like this as long as I’ve owned it. It’s a massive improvement. I have not had a change to do a hard launch yet but I did a rolling second gear burnout by punching it in second with the traction control turned off. It was smooth and straight. The RE71Rs didn’t have a chance at holding that.
More to come, I’ll put the GoPro under the back of the car to compare before and after subframe movement....
Where do I place my order? Hope you or someone comes up with a kit for the rest of us.
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I made templates.
I’ve been scared to do a hard launch, just incase are the rear subframe attach work didn’t fix the hop, but......... she is tight. Those poor RE71Rs got lit up a bunch of times from a launch first at 2000 rpm, then 3000 rpm and then close to 4500 rpm just to be brutal. Nice smooth black stripes and only a slight remenisant feeling of hop as it was bouncing off the rev limiter (not hop). Yay, I finally won that battle. Screw you hop!
1989 535i - sold
1999 M3 Tiag/Dove - sold
1998 M3 Turbo Arctic/black - current
2004 Built motor TiAg/Black - Sold
2008 E61 19T Turbo-Wagon - current
2011 E82 135i - S85 Swap - current
1998 M3 Cosmos S54 swapped Sedan - current
1998 Turbo: PTE6870 | 1.15 ar | Hp Cover, Custom Divided T4 bottom-mount, 3.5" SS exhaust, Dual Turbosmart Compgates, Turbosmart Raceport BOV, 3.5" Treadstone Intercooler, 3.5" Vibrant resonator and muffler, Arp 2k Headstuds | Arp 2k Main studs | 87mm Je pistons | Eagle rods | 9.2:1 static compression, Ces 87mm cutring, Custom solid rear subframe bushings, Akg 85d diff bushings, 4 clutch 3.15 diff, , Poly engine mounts, UUC trans mounts W/ enforcers, 22RPD OBD2 Stock ECU id1700 E85 tune, 22RPD Big power Transmission swap w/ GS6-53
I think the popped spot welds are more common than people think. People just aren’t looking for them. Another local guy was ribbing me about the crack and spot welds so I looked in his car and pointed out the popped spot welds in his car. His is a 328 that he uses for HPDE and is NA.
The two holes in the black piece bolt through the angle side of the subframe attach box section to stop it from flexing up and down at the narrow section where the driveshaft passes through. Mine flexed so bad that I had a five inch long crack there. It still flexed like crazy even after welding up the crack and the popped spot welds and all the additional spot welds I added.
The only two down sides from this mod so far are the additional weight (sorry Jaker) and I get a bit more driveline noise because there is a 1/4” thick strip of rubber sandwiched between the brace and the forward part of the subframe. The back seat kills most of the noise though.
Last edited by chikinhed; 05-19-2019 at 01:32 PM.
When does production start for the reinforcement kit?
I will personally inspect your car for cracks if you’d like
I was just reading an article in muscle mustangs & fast fords on subframe braces. Basically from subframe to a suspension mounting point to the rocker on on each side. Have not looked to see whether this could be done on our cars. Goal was to reduce wheel hop. Mustang subframe was observed moving 1/2 inch up and down under extreme stress.
Last edited by pbonsalb; 07-16-2018 at 11:38 PM.
The diff cover project will continue. I’m almost at the end of my ‘busy’ season so I can start playing with it again. The next step is make a mounting spot for the VSS. It will be a bunch of cutting and welding and drilling.
That’s good to hear that stiffening up the attach points also works for other chassis out there. The car did well on the track, no strange behaviours.
Ah yes, I remember being asked that very same question about fourteen (>14) years ago!
And just like chikenhed, it all came about as a desire to fix my own cars, and then other enthusiasts wanting to do the same thing. Barely a year later, I had to quit my day job, so the reinforcement business holds a lot of promise!
Good job!
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