Kiwi scratchbuilt

flatchat(Chris)

Supporter
Hey boys --this is what we use , Corvette C4 /5 wheel hub --just bolt on and go ( the CV drive spindle is extra)
Kevin , those bearings are good ,but fitting them is a PITA ---they're pressed into something and retained by a large circlip
 

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Hi guys , the fronts on the Skyline,300Zs etc are double tapper rollers, This is what I am using in my front uprights.
Cheers Leonmac.
 

Russ Noble

GT40s Supporter
Lifetime Supporter
Hey boys --this is what we use , Corvette C4 /5 wheel hub --just bolt on and go ( the CV drive spindle is extra)
Kevin , those bearings are good ,but fitting them is a PITA ---they're pressed into something and retained by a large circlip

Just had a quick look on a Corvette forum and it would appear that there are longevity issues too with the C4/5 stuff when used in anger. And you have to replace the complete unit which is not cheap. Hmmm....

Besides the bearing issue on all four wheels there were a couple of other areas that needed attention in the back. The trans which is only supported by the adaptor plate was found to be moving up and down as the plate flexed due to torque reaction from the driveshafts. Not something I had expected with 12mm 7075 aluminium tooling plate!

I also found a crack in the rear chassis crossmember, this was caused by chassis flex as that area was essentially untriangulated. The original plan was to fit a plate under the chassis at the rear to stabilise it, but the bellhousing was going to get in the way so I temporarily threw it in the too hard basket!

So the logical step was to tie the trans into the rear of the chassis which is well structured to resist the vertical trans movement and also to tie the suspension pick up points into the bottom of the trans to stop sideways chassis deflection. I have done this on both sides, and at the rear we now have a 'birdcage' GT40! Tubes everywhere! I also put a couple of flanged gussets on the rear crossmember to spread the loads. These have a hole in them, not so much for lightening but as an attachment point for the shackle and chains used to secure the car on the trailer. Killed two birds with one stone. Actually, I did the gussets the night before the 13 Dec race meeting as I spotted the crack during my pre meeting preparation. Welded it up and fabricated and welded in the gusset to spread the loads in the tube junction.

Anyway, car is now back together with all the essential work done and suspension reset. I have reduced the camber to 0.5° all round and reduced rear caster to zero. I'm hoping this will lead to a further improvement in lap times. We seem to be going in the right direction. We will be using a digital thermometer to measure the tyre temps this weekend and will further refine the settings based on the readings.

Pics.
#1 is the original chassis configuration
#2 shows the gussets added to the rear crossmember
#3 shows additional right hand support
#4 and #5 show it's starting to get quite busy round the back now
#6 is how it all looks from the back with suspension and ride height set.
 

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Russ,
Lots of bracing. If you still have problems you can always cut out the rear main cross member do a bit of welding and put in a beefier version done in plate. I've seen quite a few versions even in my car.
Dave
 
Russ, you have a very nice looking rear end of the car...

Following on from KevinB's post about Commodore rear bearings, Harrop offers a possible wear solution for this kind of set-up with its bespoke billet bearing hubs - at a price:

99-ADRV8013-00
 
Russ, wont you need something along these lines to fix the flex issue, even when you disengage the clutch it must try to bend the adapter plate slightly.
 
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flatchat(Chris)

Supporter
Spot on Jac -- the trouble with Ford motors --ther'se no support for the bell housing below the crank centre line -- the natural torque of the trans is to try and lift the motor --or fold the adapter plate under the engine.

So,- the trans needs to be supported and the adapter plate braced --the motor needs to be mounted fairly solidly as well.

Our solution for eg. :-
 

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Spot on Jac -- the trouble with Ford motors --ther'se no support for the bell housing below the crank centre line -- the natural torque of the trans is to try and lift the motor --or fold the adapter plate under the engine.

So,- the trans needs to be supported and the adapter plate braced --the motor needs to be mounted fairly solidly as well.

Our solution for eg. :-

Chris old buddy, I feel the real problem is the super expensive Porsche bolts that Porsche feel so guilty about that they only fit four of them to the bell housing, the same problem would occur when you try to adapt one of those other highly regarded [ by the few:thumbsdown: ] motors from the other camp as well, if they were only capable of some long term power output.
Mind you, if the only trans being fitted to these replicas were ZF & T44 & mounted in similar fashion to the originals we wouldnt be discussing this as they were mounted on the two top lugs of the R&P cover & the lugs on the bottom of the bell housing along with the engine mount pads... 6 points in total.
 

Russ Noble

GT40s Supporter
Lifetime Supporter
Exactly right guys, but there is no room to run the stays forward to the engine mount bosses and also that doesn't cure the chassis flex situation.

Now, since the motor is solid mounted, it is much easier to kill the two birds with one stone and tie the trans into the chassis, as I have done, and this will stiffen everything up. QED
 
the same problem would occur when you try to adapt one of those other highly regarded [ by the few:thumbsdown: ] motors from the other camp as well, if they were only capable of some long term power output[/QUOTE]

Geeezzz Jac, for an old one eyed bugger, you seem to see things very clearly, Most of the time:laugh:

Cheers leonmac
 
Hi Russ, Good to see you are getting the bugs out 1x1, just curious, the flexing and other little bugs you are having. Are they a product of your very light construction or are other 40s prone to similar teething. I know you built your car with weight a major concideration as it was always going to be a race car so when you build Lims chassis will it be heavier constuction being aimed at more road work??

On another note, I'm back at work and have put in my flight bookings for coming home in Feb and have booked to fly into CHCH on Friday the 12th and out on Monday the 15th to New Plymouth so I can come to Timaru for the SFOS weekend as I'm missing out on the McLaren meetings in Auckland at the end of Jan. I will be staying with a mate who lives in Kiapio and we will both come to the Levels for the weekend. If you could send me your contact details we could catch up.

Cheers Leonmac
 
the same problem would occur when you try to adapt one of those other highly regarded [ by the few:thumbsdown: ] motors from the other camp as well, if they were only capable of some long term power output

Geeezzz Jac, for an old one eyed bugger, you seem to see things very clearly, Most of the time:laugh:

Cheers leonmac[/QUOTE]

Thats a very astute observation for a a North Islander, must be your Southern Heritage kicking in....;)
 

Russ Noble

GT40s Supporter
Lifetime Supporter
Hi Russ, Good to see you are getting the bugs out 1x1, just curious, the flexing and other little bugs you are having. Are they a product of your very light construction or are other 40s prone to similar teething. I know you built your car with weight a major concideration as it was always going to be a race car so when you build Lims chassis will it be heavier constuction being aimed at more road work??

Yeah, get rid of one bug and find another......... This time totally unexpected, the motor is pumping out it's water.......Nevertheless, in a too brief qualifying session punctuated by a couple of spins due to water on the right rear tyre, and one other caused by just getting it wrong, I managed to improve my times compared to the last meeting by 1¼ seconds to 1:35.7. I'm DNS for the rest of the meeting now, got to get the water problem fixed first. The car's starting to look a bit secondhand too.... Race patina! Will put more details on the Race Track thread later.

The chassis flexing is now cured by the addition of the braces that I have fitted, more an execution problem than design or lightness, I was going to fit some bracing but hadn't got round to it! However I am sure if it had been built out of 2" RHS and ¼" plate I would have had no problems! The upright problem was due to being built too light, but a nights work fixed that.

Lims chassis is more substantial but will still be reasonably light.

Be good to see you at Levels. My shoe phone which you can get me on before the racing (it sits unattended in the truck glove box once the racing has started) is 021 075 2199, Work is 384 9023, Home 960 7442

Had a long talk to Carey Taylor today, an excellent peddler in his own right and top race mechanic. He was involved in the McLaren CanAm project and actually test drove the car just a few minutes before Bruce took over and suffered his fatal accident. Amongst other things, we talked about wheel bearings, and yes, they ran a similar setup to mine. Also spinner direction, he's trying to refresh his memory on that one. I'm hoping to get more details from him later......
 
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Yeah, get rid of one bug and find another......... This time totally unexpected, the motor is pumping out it's water.......Nevertheless, in a too brief qualifying session punctuated by a couple of spins due to water on the right rear tyre, and one other caused by just getting it wrong, I managed to improve my times compared to the last meeting by 1¼ seconds to 1:35.7. I'm DNS for the rest of the meeting now, got to get the water problem fixed first.

Russ, water issue might be head gasket or buildup of air trapped in the system that maybe a couple of air bleeds up front will fix.

35s are not at all shabby at Ruapuna - good work - sorry your weekend was cut short.

Cheers, Andrew Robertson, Wellington NZ
 

Russ Noble

GT40s Supporter
Lifetime Supporter
Andrew,

Bleed system is fine, probably a head gasket. But why?

After a few checks, a stripdown in the next day or so should reveal all.
 

Russ Noble

GT40s Supporter
Lifetime Supporter
Looks great Russ. Well done! Best get those headlight covers on if you're to reach max top end... :)

Done!

Lim finished those the night before the most recent race weekend. Looked good, unfortunately the extra 2mph must have been my undoing...... RHS spot cover and LHS headlight cover now need to be redone. Not to mention some fibreglass......

Some good news from the weekend though. I thought my best time was a 35.7 which I had found a bit disappointing after a months solid work on the car. That time was from official qualifying on the Saturday. I have just had the opportunity to check my transponder for Friday times and see I did a 33.4 in the free practice. That was the level I was aiming for last weekend, so all good. Progress continues.....
 

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Andrew,

Bleed system is fine, probably a head gasket. But why?

Hi Russ,

some wild-arsed guesses assuming that it's not det due to fuel or ignition:

1. the period during which you were chasing the miss - breakdown situations are a bit tough on gear - could have started then

2. deck surfaces or headgasket quality

3. clamp or stud yeild issues

4. spark scatter at certain RPM due to valve train harmonics etc, especially if still running mechanical advance in distributor rather than electronic advance and locked dizzy.

5. water pump issue - speed/cavitation, flow etc.

...i've run out of steam. Good luck with the diagnosis, and good work on doing 33s.

Cheers, Andrew
 
Geeezzz Russ, are you sure your not a V8 Supercar or an ex Escort Sport class driver, you seem to be knocking that lovely peice of machinery around a bit :cry: anyway, How are you getting on with the water issue?? I hope its not serious as I'm realy looking forward to seeing it in action at the Levels in Feb. My tickets are booked and I arrive in CH at 3:15 on the 12th so will go to timaru on the Saturday morning. I have those numbers in my book so will give you bell on Friday evening, will you be in CH or already in Timaru??. Good luck with the motor and I'll catch ya soon.

Cheers Leonmac.
 

Russ Noble

GT40s Supporter
Lifetime Supporter
Thanks Andrew, it's a head gasket problem. Everything else checks out good. Probably a legacy from some months ago when I threw a waterpump belt and it got pretty hot. Also going to change from MLS to composite.

Leon, the damage is only cosmetic and easily fixed. It's a race car, shit happens.....

Got a couple of sets of head gaskets coming down from Auckland but won't be able to test till Fri week. Should be OK.

At present the plan for Timaru is to go down Friday. Look forward to seeing you.
 
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