GTD40 Restoration

Just checked my AN fitting. It is 3" tall and is 90 degree bend. Any speed shop that sells braided fuel lines should have a catalogue of most AN fittings. Mine is a 10 AN. They sell the fittings for valve covers that bolt on to the valve cover. Believe there is a baffle included with it. How tall is your filter??

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Bill
 
Hi Bill,
The valve cover hole is indeed 1,25".
The rubber grommet has a 1 inch inner diameter.
Not quite deep due to the inside screen of the valve cover.
The height which I have left for the breather or adapter is around 1" with a fairly large diameter, so estimate 1,5" when I keep close to the center of the hole.
Wish I had 3 inches, the normal pushon breathers would fit ;-)
Will post some more pictures soon.
 

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Sounds like you need to raise your tray. That is the simplest and least time consuming alternative you have. Does the breather on the left side of the engine hit the tray?? If not then get the push on cap and put it on the right side. You don't need two breathers for that engine. I don't on mine. You will find the "710" variety at any Parts store. I had to trim a little for mine to fit the opening. You do know about the 710 caps don't you:idea:????

Bill
 
Hello Andy,

I was reading your log with big interest. I'm in a similar position with My GTD40 in upgrading it.

From which region are you?
 
Hi Curt,
Love your colour on the GTD40, painting it blue is on my wishlist.
I sent a PM

Small update on the car.
Noticed some play on the rear wheel hub, the previous builder used M12 bolts in the 1/2" holes so the holes now are more like 13,2 mm due to endplay made the holes bigger. Gonna correct this with new bushes of 15 mm outer diameter and 12 mm inner diameter. And drill the inner 12 mm diameter to 1/2"=12,7mm.

The new rodends are in and costwise I went for the QA1's. They are much tighter fit and no endplay, feels like better quality so time now to setup the rear suspension and install 4 new CV joints aswell.

Interior is also done. Gonna post some pictures later on. The finish line is in sight and todo list is getting shorter. Still some hurdles, perhaps all the master cylinders needs to be replaced since I keep bleeding the lines, no bubles but also no firm pedal.
 
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Big milestone...today made the Maiden flight of the restored GTD40...small drive around the block :2thumbsup:
First impression, fun to drive, lots of turning heads :cool2:

Some small (hopefully small) issues to be adressed:
1. Braking can be improved. brakepads are glazed due to its age ? adjust front/rear balance bar setting can be the cause or leak master ? tbd.
2. Shifting 1 to 2 is not working smooth...looks like I was able to get in 2 only after double clutching and fiddling. The 4th gear is also difficult to engage...pedal feels firm. Perhaps tweak on the shifter mechanism in the back?
3. Front Ride height dropped from 130 to 90mm after the test drive...the car seams to be settled quite a lot. Corrected the height immediately ...but noted a difference between left and right front spring compression. Needed to screw the ring on the right spring about 60 mm and only 30 mm on the left. Big difference of spring compression on the front feels not correct. I know my garage floor is not level but 30 mm difference in spring compression feels too much. The rears springs ring are only handtight since already too high ride height (140mm). Looks like I need longer springs in the back ?

tips always welcome.
 
Congratulations for your first drive.....

- For the shifting I also struggled to get it smooth. If you have a shifter gate you could loosen it a bit. Run through all the gears and refit it again on that position. In this way I managed to get the last miss alignment right.
 
Curt,
Thanks.
Found that the shiftermechanism is not able to hold its location.
The design is such only the ends of the small bolts is trying to lock the position on the bar. Need to find another solution for this setup.
Any ideas always welcome, perhaps I gonna tig weld it for the time being.
 

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After lot of attempts, at idle, able to select all gears but during driving looks like the setting changes, leaving only the 1 and 3 gear...could it be wrong oil is used or is there a geometric change causing this ?
 
Hi Andy,
Are you running the original GTD shift mechanism, as they have a poor reputation for quality and lack of shift precision. You need to ensure that you have no free-play in any of the cable ends, as this will result in lost movement<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com<img src=" /><o:p></o:p>
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Andy,

as I said to you by PM, throw those ball linkages over the nearest hedge and use proper rod ends. A well set up cable linkage will work flawlessly.
 
Thanks guys for the advice. Gonna source the rod ends for sure.
Just checked the play and found the biggest endplay is in the big bolt holding down the triangle lever to the square block. The trick is too tighten it such that it will not bind the triangle but give no play in the setup...this is a thin line...and it looks to untighten itself after some usage. Will need some lock-tide I guess. Don't like this kind of solutions.
On the long term, I gonna redesign this bit (fun challenge by putting it in 3D to analyze the movements).
It starts with the shifter and its rotational hinge, funny and in one way clever design but the rotational movement there must be transferred to the rear and if on the rear, the geometry is off, the rotation movement will not translate properly in the lineair motion on the shaft going into the gearbox. Noticed that the small rod holding the triangle at the rear is influencing the amount of angle of the shifter which can be used. The way it was setup was that the shifter could only use half of its rotation. Corrected this. Now the shifter can move also to the right half of its operation. This gives much more control on the rotational movement and by this much more lineair translation on the shaft going into the gearbox.
At least with the engine not running, I am able to select all gears without any issue. Need another test run soon to see how it works on the road. At least I started to understand the idea of the designer :laugh:
And this forum also helps to see other ideas being used. Some ideas split the rotational and linear translation operated by one cable. Makes it much easier to understand what it does and by this, easier to adjust. But it would mean to redesign also the shifter mechanism. I feel a challenge upcoming.

I prefer this clamping from a Lotus Esprit.
Lotus_Esprit_gear_translator.jpg

Need to find out whether the diameter of the shaft is the same as on the UN1. Perhaps this part is a better starting point.
 
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Shifting is now sorted and did some test driving.
Went well besides need to replace the starter because when the engine is hot, the starter pulls too much amperage when trying to crank again. After it is cooled, it starts again so the new starter is on order. RAC407.
I noticed how close the ratios are together between the gears.
There is no ID on the renault transmission. Is it possible that the diff gear ratio is only 1 ? :laugh:
 
Did some calculations on the gear ratio, looks like the normal UN1 ratio and diff ratio of 3.89 is in transmission.
And at 2000 rpm, the speed in 5th gear is only 72 km/h (noticed on the road and calculated) but at 5000 rpm it is 180 km/h according calculations.
This looks bit too slow, what is the secret or what am I missing since it should go above 200 km/h.
Have the standard gtd tyres 265/50R15.
 
A 3.89 diff ratio means you probably have a gearbox coming from a Renault 25 or a Renault 30...
On these cars (except the R25 V6), the 5th gear ratio is 0.82. These will give you a slower end speed at a given RPM, than the most used UN1-13 (Renault 21 Turbo) with a 3.44 diff, (and sometimes an aftermarket 0.76 5th gear fitted...)

Overall in 5th Gear :

Renault 25/30 : 0.82 x 3.89 = 3.1898
Renault 21 Turbo : 0.82 x 3.44 = 2.8208

Huge difference...


Never made an accurate checking, but with my car (UN1-13, standard 0.82 5th ratio) at 3000RPM I'm around 135km/h, and at 5000 around 220-225km/h (but at that speed, I prefer keep my eyes on the track than on the speedo, at the other end of the dashboard !). Avon 275/55 R15 on rear...
 
Interesting discussion on the final drive ratio of the Renault transmission. I have a Renault un1-13 with 3.44 diff. I have recently installed a 3.89 final drive to keep my engine more on the "boil", as my engine's torque and power curve is higher up in the rev band. This experiment is purely for the purpose of track days. I know 3.44 diff is better for street use. I am am told I will experience a 13% effective increase in torque in each gear. However I will have to change gears more often. I have not driven the car with the new final drive yet.
 
Had a drive, one year ago at the wheel of a GTD fitted with a R30 "shorter" gearbox, same engine than mine more or less (347 stroker)... You could feel the difference, the car was more kicking on backcountry roads :thumbsup:, but a pity having that engine rev so high on the highway at legal speed (has been thirsty too...:tongue2:, poor gas mileage to say the least !)
 

Howard Jones

Supporter
In Andy's picture you will see that with the camera angle straight above, the mechanism is straight down or exactly 90 degrees in relation to the cables.

I have found that this, straight up and down orientation, is very important to get good function.

If you can source a Lotus translator like Andy's it will all work a lot better. The guys in England can help you with this.
 
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