Category Archives: 1. bowtie6

bowtie6‘s New Frame Takes Shape

Whew!  This has been a long week.

Worked on bowtie6 a little today.  The rear suspension came apart and took the transmission tunnel apart also.  Let me talk about the tunnel:  when the V6 was grafted into the TR6, we made an all aluminium transmission tunnel cover.  It is secured on a special square tubing edging that was welded to the floorboards.  My main concern with the Ecotec was that the transmission tunnel cover would be too small.  Well, by taking the tunnel off today we were able to determine there will be enough room.  We had to make room to run the exhaust pipes on the V6 and since the Ecotec dumps on the passenger’s side, we will have enough clearance.

Then today’s good news:  My cousin Jim has made some extraordinary progress on the front suspension.  Here is a small gallery showing the new front section of the new made-from-scratch frame.  You can see the new front suspension towers and the new coilovers that are so trick!  With these guys in place, ride height will be adjustable and best of all:  no more spring compressors in order to take things apart.

If you look close enough, you can see the steering rack mounts  Yes, those are aftermarket rack mounts and they work quite nice.  Needless to say, the rack has been positioned in a very special location in order to prevent bump steer.  The rack is stock TR6 – they are nice enough.  The front suspension also shows factory rotors, however the calipers are uprated Wilwoods with four pucks each.  They have proven to provide very good stopping power.

Take a look:

bowtie6 Ready for Disassembly

DST starts today and we are ready for disassembly.  Should give me some extra time to work on bowtie6. Watching the last stage of Paris-Nice on Versus right now – they are riding in some crappy weather.  The attrition rate has been quite high…

Anyways, today I was able to get bowtie6 over to my cousin Jim Thompson’s shop.  We started further tear down in preparation of the body removal.  We were able to get the front suspension apart for the last time.  The SPAX adjustable shocks and Richard Good competition front springs came out and will be soon be up for sale.  The replacement coilovers have been purchased and they will be nice.  No more hassles with spring compressors and that alone is worth the price of the coilovers.

Don’t have pictures yet, but the new frame is coming along very nicely.  The front suspension towers are fully built and now that we have the “A” arms apart, the new attachment points will be made.  The steering rack will come out next and its location will be found so there is no bump-steer.

Here are some pictures right before we loaded what is left of bowtie6 onto a trailer….

bowtie6‘s V6 Engine

The engine formerly installed in bowtie6 was a 60 degree 3.4 litre V6 as originally fitted to 1994 GM F-bodies (Camaro/Firebird).  The engine was in its stock configuration to begin with, however during the 4 years I’ve had it installed I’ve done a number of “improvements”.

I’ll start by describing the unusual intake manifold.  The original manifold on the stock 3.4 V6 is very restrictive.  The throttle body and runners are very small.  My cousin Jim Thompson is a professional machinist and he can do wonders with a milling machine, lathe and a welder.  So we decided to do a little experiment…

First, we cut off the nose of the original stock intake manifold.  Then, the manifold was chucked on a Bridgeport milling machine and a few passes with a large endmill were made.  This exposed the intake runners and we were finally able to see just how small and restrictive they are.  So, the runners were further machined and cleaned up.

Basically what we ended up with was the bottom half of the stock intake manifold.  Pieces of aluminium sheet stock were cut and carefully tacked to the bottom half of the intake manifold.  Soon, a more even and much larger upper plenum was formed.  Seams were welded up and some trick work was done with a file to shape the edges and make it all look seamless.  I think the end result turned out really nice.

Then we replaced the small throttle body with one from the legendary LT1 V8.  The LT1 throttle uses twin buttlerflies and thus can keep up with the extra volume of the new intake.  Fortunately, the LT1 throttle body also uses the same type of throttle position sensor and idle air motor as the V6 does, so the ECM recognized all this without throwing codes.  The intake is also made in such a way that the MAP sensor still mounts to its original location and is connected to the intake via a small rubber hose.  Finally all vacuum lines are located in their factory locations.

The intake was then cleaned very carefully and several coats of high-temp silver paint were applied.  While tacky, I sprayed several coats of high-temp clear.  The end result functions as good as it looks.

So why go through all this trouble?

  • We wanted to experiment what would happen with a bigger intake and throttle body.
  • The engine needed the extra air volume.  This engine is running larger injectors, a hot cam, 1.6 roller rockers, headers and fully ported and polished heads.
  • Last but not least, because we can do it.

The end result is pretty impressive:  Throttle response is amazingly quick.  With the collection of engine modifications, the engine does not run out of breath as much as it used to.  Also, the engine revs in a much smoother way with a higher redline.  One could argue that some lower end performance was sacrificed for a much nicer middle and upper range.  Sure.  But when this engine pulls a 2200lb car (instead of 3500 as in the F-Body) that is a very acceptable trade off.

Frame Failure – Continued

In an earlier post, I described bowtie6‘s frame failure.  Today, I have some pictures of the “issue”.  First, a little background…

Rear suspension

Rear suspension closeup

Soon after bowtie6‘s initial dismantling the frame was carefully inspected.  Although the frame was in excellent shape the rear differential mounting pins showed typical TR6 wear and tear: two of the four differential mounting pins were cracked.

Since a bigger engine was to be installed, we reconfigured the rear suspension.  A completely redesigned mount was made to hold the Nissan R200 differential as well as the coilovers that would replace the lever action shocks and springs.

The pictures on the right show the rear suspension from the passenger’s side.  You can see the coilovers, rear disc brakes and the suspension mount holding the top coilover perch.

This brings us to the following photo gallery showing the frame damage.  The frame rail has suffered a serious, unrepairable stress crack.  I have inspected the driver’s side and there too, I can see a stress fracture although it is not as severe as the one on the passenger’s side.

I’m sure there will be plenty of critics analyzing the frame failure from these pictures and coming up with all kinds of root causes for the failure.  Quite frankly, the thing is what it is.  I got 15,000 from what I thought was a very good frame but this endevour has proven to be more than this frame could handle.  The extra power the engine gained from the cam and head work plus the stress of getting hammered by the control arms caused the frame to eventually expire.  Since the rear failed this extensively, I have reason to believe other parts of the frame have also suffered stress.

As soon as the frame comes out again to see the light of day, I plan to do a full autopsy by cutting it up and documenting stress points, failure points and basically show where the frame held up and where it did not.  I’ll have that in a future article which should be very interesting to read.

And now for a little reflecting…

These frames are now 35-40 years old.  These frames are also marginal at best.  Sure, with the anemic tractor engine on the stock TR6 the frame will probably last, but not by much.   However, if anyone is thinking of adding any real horsepower then really think what you are planning to do.  These frames can be reinforced to hell and back (done that), boxed-in (done that), have gussets added (done that) and have every weld reinforced (done that), and yet they will fail.  Quite frankly, I am very happy this thing gave up the ghost – now a new frame is being built to last and handle the new ECOTEC engine with no “issues”.

bowtie6 Starts to Come Apart (Again!)…

This feels like déjà vu!

In order to save from getting a busted gut when we get the broken frame out, the body has to be a little lighter…

So, the process of taking bowtie6 apart has begun.  The bonnet, doors and boot lid have all come off.  This time, it has been much slower than when I first took the car apart:  I’ve got a very expensive paint job to watch over!

Here is a quick preview of what the new front suspension will look like:  gone will be the days when a spring compressor is required to take the front “A” arms apart.

The new coilovers for bowtie6 were ordered and UPS brought them to my door this week.  They look just like the ones in the photo.  As you can see, the stock “A” arms are still there, and since the frame is custom made, a new mount has been built for the top of the coilover.  The bottom is attached to a new mounting plate that screws to the bottom of the lower “A” arms (much like the way the stock front shocks mount).

The coilovers are fully adjustable for rebound, can be rebuilt and the springs are interchangeable (of course).  This makes it very nice for fine-tuning travel.  The rear suspension will feature a similar setup, except that the coilovers will mount to the new axle.