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BCR_AK

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Reply with quote  #1 
Hi All,

Thought I'd post a few pictures ( / short essay [tongue]) to show my account of fitting the bonnet to my Avon. Sorry if this is probably not exciting news to any of you experienced builders, but was well over a week of work for me! (mostly thinking time)


Background:

I went down the GSXR1000 Throttle Bodies / Microsquirt route on a Blacktop 2.0 Zetec - partly to save cost compared to the standard Jenvey TB setup, partly to learn something about fuel injection / engine mapping.

Without getting into the details, the build has been slow due to a couple of relocations, career change and general life etc. I had the bonnet and nose cone in storage for a while, which prevented me trial fitting it much earlier in the process. Inevitably once I came to trim and fit the bonnet and nose, I ran into issues!


Nose Cone Positioning

Started by fitting the nose cone. Cut-outs required for the control arms and get the position fore/aft correct. Then cut-outs required for the upper shock mount and timing belt case - this gets the vertical position correct to match the bonnet fitment. So really it was a case of fitting nose and bonnet together at all times and making sure the join between them was compatible. Used CAD (cardboard-aided-design) to assist getting the right shape for the cut-outs. (Pic shows pre-cut). All going ok so far, but clear that it would be a very iterative process...

[image]  More nose cone trimming needed to position vertically to match bonnet profile




Bonnet Positioning

Nose cone more or less done. Now need to bring the bonnet down to meet the chassis rail. Oh-oh... Bonnet fouls on the attachment tabs on my pipercross air filter.

Dilemma: cut the centre tab down on the air filter and find another method to fix it, or cut the bonnet to have this tab sticking out and cause a potential issue for IVA / generally a bit unsightly.

Decision: had to cut the bonnet out, because it was clear that if I cut away the centre tab of the pipercross filter, the aft tab would also foul. I couldn't afford to lose 2 out of 3 connection tabs. I'd have to live with the unsightliness of the tabs and for IVA will have to just cover in foam / tape.




[image] 
  Fouling on air filter tabs


[image] 
  Main cut out for air filter still not sufficient. Huge gap to make up between bonnet and body. 

[image] 
  Partially trimmed for tabs to stick out. Will have to cover for IVA.


Fuel rail fouling

With air filter tabs poking out, the bonnet still fouls on the fuel rail inlet. I manage to disassemble the fuel rail to rotate the inlet through about 60deg, which helped, but bonnet then fouled on another part of the fuel rail, which I had no chance of modifying. So this whole GSXR1000 intake arrangement (nice kit bought from DanST Engineering) is sitting ~30mm too high [eek].

[image]  
  Disassembled and rotated the fuel rail inlet around by 60deg (it was hex keyed)
[image]  Even without the air filter mounting plate, bonnet still fouling on fuel rail



[image]  ~30mm additional height clearance required


Height Drop Options


So, some more head scratching and I figured I could do these things in increasing order of ball-ache / cost:

  1. Shorten the red silicone hoses between the TBs and the inlet manifold. This gets me some drop in the vertical, but also moves the TBs closer to the engine and hopefully into the bulge on the bonnet, gaining even more clearance.
  2. Shorter engine mount rubbers. Currently using Rally Design 50mm bobbins.
  3. Modify metal engine mounts. Had these made up a long time ago with a 45deg diagonal and took quite a bit of designing. There is some scope to shorten, but not by much. Fabricating new ones with smaller section (square instead of round) and an angle closer to the horizontal could help reduce height.
  4. New intake manifold with inlet pipes nearer to horizontal (I think like the one supplied with the Jenvey kit). Sounds costly and difficult to source - last resort.


Interim Solution

So basically did each of the above in turn until the bonnet fit on top of the engine! Thankfully only needed to go as far as number 2. Shortened the hoses as far as I could. Managed to find new bobbins from AV Mounts, only 20mm thick, but rated up to 158kg each. After a quick google, I estimated the Zetec weighed max around 120kg (with OEM ancilliaries?) But split across two mounts and the gearbox mount, figured this 158kg rating would be plenty.

The mounts arrived - a lot smaller than the original Rally Design beasts, but just as stiff. 

[image] 
Pic before I cut back the red silicone hoses. They bought me a little bit of height but more importantly pulled the fuel rail inwards into the bonnet bulge

[image] 
  Old (50mm) vs new (20mm) bobbins. New ones look much less up to the job, but they seem just as stiff, and rated to 158kg each. I'll give them a go.

[image] 
Back out comes the engine crane. Glad I didn't sell it!



Gap Closure

Despite all this, still couldn't get all the gaps to close up nicely between bonnet and main body. The reinforced / double backed fibreglass bit just in front of the intake was seating it too high on top of the nose cone.

So took a few days to make the decision, but I eventually chopped the bonnet underneath the air filter. Probably the scariest fibreglass cut I've ever made!

[image]  Double backed bit of fibreglass is seating on the nose cone, causing the bonnet to be too high

[image] 
Time to chop it off! Scary cut, took days to convince myself to do it [rofl]
[image] 
Looks muuuch better without that asymmetric side bulge (Tiger designed it for Jenvey TBs I guess). I'll fill the gap under the filter with some painted or wrapped ali plate.


Final Solution

A bit more fettling and also epoxied some locator pins in the bonnet to fit into grommetted holes in the nose cone to provide more support where the big cut was made for the inlet.

Added IVA bonnet catches, and reasonably pleased with the result.

Still just one bit of the bonnet sticking out on the nearside near the nose cone. I'll either clamp this to the nosecone with another fastener, add a spacer behind the nosecone to offset it out to meet the bonnet shape, or just finish the bonnet edge with U-trim and accept it. 

Not perfect, but glad that ordeal is more or less over and now have the finish line in sight. And thus concludes my essay [rofl].

[image] 
Some thread cut off some partially-threaded bolts to give me a pin. Epoxied one into each side of the bonnet front flange.  


[image] 
Match drilled holes in the nose cone for the locator pins to fit into. Grommets just to relieve any contact stress or slight misalignment.

[image] 
IVA bonnet catches carefully fitted. Happy I've got the right spacing between latch and keeper to get a nice tension. Aft end of the bonnet also trimmed to fit the scuttle nicely.

[image] 
Aside from the air filter tabs sticking out, this is pretty much the only bit I'm not happy with. Might be best to unclamp the nose to offset it slightly outwards to meet the bonnet.

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Tiger Avon | 2.0 Blacktop Zetec | GSXR1000 TBs | Microsquirt v3
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BCR_AK

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Reply with quote  #2 
So, top tips for anyone else about to embark on this:

  • Trial fit your bonnet as early as possible after your engine is in!! Be prepared to redesign your mounts depending on your intake setup.
  • If you don't fancy this ordeal and cost isn't an option, then just buy the Jenvey TBs (with Omex ECU?) as Tiger planned it
  • An oscillating cutter is an incredible tool for cutting fibreglass. Don't mess around with a jigsaw - many ways it'll risk damaging the gel coat
  • Cardboard templates are your friend
  • Fettle small amounts at a time
  • Measure 20 times, cut once, and hopefully get it right [crazy]


I wonder whether any of you guys had a similar story fitting the bonnet/nose? Or is it all nice and simple if staying standard Tiger kit setup? All part of the joy of building one!

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Abe

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Reply with quote  #3 
Lovely job mate! Thatโ€™s looking great. Those epoxy pins are a good idea. ๐Ÿคฉ๐Ÿ‘Œ
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vji4058

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Reply with quote  #4 
Nose and bonnet fitting is the worst part on a Tiger build,  I have found it helpful to have the engine up and running to get some heat into the bonnet to get it to mould better.
Your pin idea is brill [thumb]
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Abe

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Reply with quote  #5 
I remounted the nose cone and bonnet clips and yes I can agree, a time consuming job!
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Abe

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Reply with quote  #6 
Quote:
Originally Posted by BCR_AK
So, top tips for anyone else about to embark on this:

  • Trial fit your bonnet as early as possible after your engine is in!! Be prepared to redesign your mounts depending on your intake setup.
  • If you don't fancy this ordeal and cost isn't an option, then just buy the Jenvey TBs (with Omex ECU?) as Tiger planned it
  • An oscillating cutter is an incredible tool for cutting fibreglass. Don't mess around with a jigsaw - many ways it'll risk damaging the gel coat
  • Cardboard templates are your friend
  • Fettle small amounts at a time
  • Measure 20 times, cut once, and hopefully get it right [crazy]


I wonder whether any of you guys had a similar story fitting the bonnet/nose? Or is it all nice and simple if staying standard Tiger kit setup? All part of the joy of building one!


Oscillating cutter - never owned one but looks perfect for fibreglass, less dust than a jigsaw too I bet - I think you may have found my wifeโ€™s next anniversary gift to me! Nice ๐Ÿ˜
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MarkCopsey

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Reply with quote  #7 
Well done on all the work.

I fitted a duratec years ago (was one of the first on here) and similar problems. I had to get smaller engine mounts and used a company called RoBush (https://www.robush.com/) they have a MASSIVE range to help out ๐Ÿ˜‰

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BCR_AK

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Reply with quote  #8 

Cheers chaps. Finish line is in sight (provided COVID doesn't put a spanner in my job situation)!


Quote:
Oscillating cutter - never owned one but looks perfect for fibreglass, less dust than a jigsaw too I bet - I think you may have found my wifeโ€™s next anniversary gift to me! Nice ๐Ÿ˜

Yep. Mine is a Parkside and pretty impressed with the quality of it. Cuts accurately, good control and is far less aggressive than anything else I've used on fibreglass.


Quote:
I had to get smaller engines and used a company called RoBush (https://www.robush.com/) they have a MASSIVE range to help out ๐Ÿ˜‰

Ah, cheers for the pointer, they may well come in handy in the future!


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Tiger Avon | 2.0 Blacktop Zetec | GSXR1000 TBs | Microsquirt v3
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