One day.... It will be a race car!

OZgreen69

Well-known member
Joined
Apr 24, 2016
Messages
220
Location
Perth Australia
Hello,

I would like to show you what I am doing at the moment.

Fan of historic car racing, I am building/assembling/modifying, a 69 convertible to do just that here in Australia.
The rules of the group that the car will be into, are quite restrictive to keep the spirit of club racing alive ( Yeah right !! )
For example, no alloy heads ,or original gear box only, interior trim and a passenger seat must be retained , original kind of suspension . Well, all done to slow you spending too much ( Yeah right !! )

So I have been collecting bits and pieces along the way like :
A 69 coupe who was going to be a race car in 2003 for historic racing as well, but instead to be pushed unfinished in a dark corner of a workshop and left there until last year when I bought it as a rolling chassis.
As the frame as been prepared in the Chevrolet Power Book fashion, I thought about reusing it for my race car.
The previous owner modified it using few Guldstrand parts.
Solid pucks for the rear cross member and adjustable toe system for the trailing arm and more....
 
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So talking about the frame.
The diff as been raised, or the chassis lowered onto the diff, choose the one you like, by removing the rubber mounts and using solid spacers instead.
Nice job until I tried to align the diff pinion in relation to the gear box :confused : and :cussing:
It was necessary to cut the cross member brackets on the frame to be able to pivot the nose of the diff to a more correct position . I had 3 deg Down to now 1 deg Up more in line with the gearbox tail at 1.20deg Down.
Anyway, a bit anxious with the pinion height , I put the body on the frame to see that I have no room for the drive shaft to clear the floor and for the stub axles to touch the rear compartments !!

Does someone else did this mod?
Any help, ideas, welcome.


I have some difficulties uploading pictures, does TT thread still up to date ?
 

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Looks like the tape measures (from your picture) 4 3/4. I measured mine at about 2 inches. Hard to measure with the drive shaft in. My diff is down 1.3 degrees at the pinion with 1/4 spacer and no modification to the crossmember mounts.
 
Thanks for the replies.

BBshark , do you mean that you haven't modify anything ?
And that the pinion angle of the diff is still quite as per factory, roughly 1 degree down and the gearbox looking down as well ?

I went to a reputable driveshaft specialist to talk about drive shaft angles and especially about the W configuration, who is working well at low angles but mainly used on machinery rather than car. Their concerns were about the revs , low on machinery but high on cars. I am still waiting on their computer simulation.

RTJ, well this is that I would like to avoid, starting to modify the body. I looked at period pictures of racing Vets. And you can see clearly that few bodies are higher up on their respective frames, the side holes are a good measure.

Or maybe I just need to have a drive shaft with a CV joint gearbox side ?? As seen on another forum. But the drive shaft guys were not too keen because of the movement of the slip joint and the movement of the CV.

Anyway, the drive shaft angle is the question. From the factory the angles were in a W . Diff down AND gearbox down and no apparent vibration. If I can replicate this I am saved.
 
I spent more time in the w/shop doing different angle combinations.
So following BB's description and reading between the lines of Redvet reply.

I lowered the pinion nose back to a near factory 1.25 Deg down and G/box at the same angle and with a D/shaft going up the diff at 0.5 Deg, this give me according to SPiCER calculator, an operating angle of 1.75Deg for both.
This will be a W configuration.
I need to dig a bit further to see if this is ok or not.
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Thanks RTJ for the links, but I am not allowed to do what they do, especially like P Klutt !!! Still nice to see and who knows in the future :goodevil: !!
 
The angle just needs to be the same on both ends. I measured the trans yoke angle and adjusted the pinion spacer to match.
 
You can see the spacer in this picture. The 1/4 rotates the pinion/diff down a little more than 3/4 degrees You can tell from looking at it that is pretty close to the frame bracket. My diff is down 1.4 degrees. The drive shaft is down (at the rear) .8 degrees and the engine is down (at the trans) 3 degrees. This gives me 177.8 degrees between the engine and driveshaft and the same between the driveshaft and diff.

I will almost certainly have to raise the tunnel at the transmission so I may look into raising the crossmember. Not sure which is more of a hassle.

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Yes gents ! It is pretty easy to adjust the angle with the diff in original location. But when you remove the bushings in the cross member it will be now sitting way higher, as the nose of the pinion in relation to the frame.

Then either to have a Z angles configuration you may have to cut/raise the body, because the pinion is 3 inch or more higher the front diff housing is touching the body but with enough room on top
Or a W configuration who brings the pinion not much higher than factory, and room for the housing. But not too sure about the angles at high revs.
It is still holidays season here, so quite slow to find answers from the pros!

Thanks again.
 
Raising the body isn't the way to go, in my opinion. If the trailing arm pivots are stock or not welded shut and you don't want to cut the tunnel, make several square spacers out of 1/4 in alum plate and insert between cross member and diff. Pretty easy, square plate with 4 holes.

I looked at you pic again and it looks like the sombreros were raised. I don't think solid pucks alone would raise the diff much more than 1/2 at most. At least that's what I thought when I made mine.
 
Yes,you are right RTJ. It is no lifted by a lot, it is just the case of aligning the diff to the box again . Original W angle configuration = plenty of room.
Going for a Z configuration = Just enough OR not, but needs a bit of grinding or more.

I swapped my "race body" with the body I bought and who is gutted inside: no floor and plenty of openings on the rear section, handy to have a look from the inside.

It shows that if I use an original diameter D/shaft Dia 2 inch, the hand brake protrusion in the tunnel is not a problem BUT if would like to use my bigger D/shaft 2.99 inch with the 1350 Ujoints , I need to cut to make room.

But again, I will check the coming week if can use the W configuration.
I will post more pictures, now that I know what to do :banghead:
 
RTJ, you got me worried with your measurements!

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This is on my original chassis, and I check on the modified one. Same same but with no rubber.
 
Should be right now. I set my angles opposite at 1.5 diff and box, Dshaft at 1/4 up. This with two 1350 and a diameter of 2.90 inches .
I should show you what I did with my fuel tank.
I wanted to baffle it, not wanting the fuel sloshing around.I could have a proper fuel cell, but pricey, and as I cannot move the fuel tank from its original location , I thought, why not to modify the original one by filling it with blocks of foam. And adding a deep sump for the electric fuel pump.
Pictures to follow.
 
I finally received the fuel sender and screws to finish the fuel tank. I closed the suction side using my TIG, cannot do it with solder!
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Cannot use a brand new clamp ring , the sender was still moving around, end up using the original one !thum_39345895c24c168a2.jpg

Closing the foam's opening.
thum_39345895c24d65190.jpg

followed by the modified filler neck, the split tube will hold the foam block and the little holes will be used to check the fuel quantity left in the tank more accurately than the fuel gauge.
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Next I'll install the bracket for the electric fuel and route the brake lines.
 
folded a cradle for the fuel pump an did the soft fuel lines and bent a rigid one to replace the original who goes to the motor.

thum_393458a1a3968c5c2.jpgthum_393458a1a39794dfa.jpg
 
I know I know, but to follow the rules, I can have a safety fuel cell. But I must keep the original fuel tank in the factory location, then fit the fuel cell underneath, safer? Yes and no. But I understand your view.
 
I know I know, but to follow the rules, I can have a safety fuel cell. But I must keep the original fuel tank in the factory location, then fit the fuel cell underneath, safer? Yes and no. But I understand your view.


so your telling me all those vintage racers down under have two fuel tanks?
 
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