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ar4me
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Re: When should a gearbox have an oil cooler ?

Post by ar4me »

kevin wrote:Jes , how many laps have you done ?
Kevin, I ran the 3.7 for one track day + lots of dyno with a stock 100k mile transaxle :shock: After that I basically took the car apart for some major changes - still apart as real work has not allowed me time to finish it :oops: The box originally built for the 3.7 years ago has run many, many races (with 75/90NS) with a 3.0 12v QV engine. John has been running his 3.7 for a couple of events with a stock transaxle as well. Neither of us have had any transaxle problems so far. I have a close ratio race transaxle with 5.5" light-weight custom AP clutch for the 3.7 - builder specifies redline 75/90NS.
Jes
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87 Milano 3.0 Motronic - budget race car - Roxanne
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Re: When should a gearbox have an oil cooler ?

Post by kevin »

Jes, explain 5.5'' is that a weight or diameter. Not sure of that symbol. i have aslo worked out that both boxes broke when I geared down to second on a tight bend and then during excelleration onto straight failure occured at about 4000rpm in second. All the rest of the races between these two pinion breaks I did not use second.(much faster circuits). Pinion could have chipped a tooth on gearing down(went in a bit to fast and locked up - cold track) and then all hell broke loose on acceleration. This is a deviation from when should a gearbox have a cooler but trying to work out breakages. Your lighter clutches have less rotating inertia maybe a link there, maybe not.
Also noted that all the tracks in the eighties the GTV's raced had no tight second gear corners. Race tracks have evolved with different ratios to braking/direction change ratios.(safety - boring)
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Re: When should a gearbox have an oil cooler ?

Post by ar4me »

Diameter of clutch in inches - much smaller and lighter than stock, including flywheel - clutch housing looks empty. Light weight clutch disk is good for syncros. Smaller diameter reduces inertia, and low weight is helpful in general. All well-known.
Jes
87 Milano Verde - daily driver - Juliet
87 Milano 3.0 Motronic - budget race car - Roxanne
87 Milano 3.7 24v - race car
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Re: When should a gearbox have an oil cooler ?

Post by Mats »

As a contrast I'm aiming for a 200mm clutch, single clutch disc and sprung centre. Difficult to find high capacity single plate clutches with small diameter and sprung centre. I want a sprung centre to ease the life of the gearbox, especially with my solid propshaft.
Alu pressure plate and custom flywheel will keep weight down though.
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Re: When should a gearbox have an oil cooler ?

Post by kevin »

Jes, post a link on your clutch please and which housing you are using. i think I am going to start again on all aspects to save my pinions. I still have not ruled out oil temp yet as I think damage was done on previous race. Oils still an issue and hopefully i find the correct one. MD, any more info yet ?
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ar4me
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Re: When should a gearbox have an oil cooler ?

Post by ar4me »

Kevin,
This is all custom work - there is no link to something bolt-on. I'm using an Alfetta clutch housing and the Alfetta clutch slave setup (that mounts off the clutch cover instead of off the "V6" bracket further back.)
Jes
87 Milano Verde - daily driver - Juliet
87 Milano 3.0 Motronic - budget race car - Roxanne
87 Milano 3.7 24v - race car
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Re: When should a gearbox have an oil cooler ?

Post by Zamani »

Jes,

Is your clutch disc sprung? I was off the phone with Richard discussing my 155 V6 cams and we're going to do a lightened clutch flywheel setup with a lightweight and (maybe) an unsprung clutch disc. I'm just a little worried of the shock the gearbox will take on shifts.
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Re: When should a gearbox have an oil cooler ?

Post by Micke »

viewtopic.php?f=9&t=2433&hilit=4.5+clutch

Since that the 4.5" clutch also has a flywheel thanks to KTErkkilä.
5.5" clutch is in the endurance 75TS and the 4,5 is coming into the GTV in some weeks.
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ar4me
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Re: When should a gearbox have an oil cooler ?

Post by ar4me »

Zamani wrote:Jes,
Is your clutch disc sprung?
Certainly unsprung! Less inertia for the syncros to deal with. On a street car I would use a sprung disk. Also on the 155 consider that you have no give (like couplings on the 75) between engine and clutch.
Jes
87 Milano Verde - daily driver - Juliet
87 Milano 3.0 Motronic - budget race car - Roxanne
87 Milano 3.7 24v - race car
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Re: When should a gearbox have an oil cooler ?

Post by Zamani »

Jes,

Sorry I wasn't clear. The clutch in discussion with Richard was for my Milano.

Also do you have the gearbox/engine alignment tool from Richard? Can I rent it from you when I put a new clutch in?
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MD
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Re: When should a gearbox have an oil cooler ?

Post by MD »

Agree with others like mats that you need a spring centre if you are running a "solid" propshaft but not absolutley necessary if you are still using at least one donut- street or otherwise, just dont push your luck or the clutch centre will usually rip out.

Kevin, I got an interim list of oils but I am waiting for an official spec from Alfa themselves in Italy to settle on the final tally. Got a direct phone number to call and discuss from their international cutomer service centre but it turned out to be a toll free number only usable in Italy so I am back to square one with them.

Don't want to create any confusion down the track so I'll hang back posting unti I am confident in the list. Also specifically waiting on info from Agip and Selenia oils. Sorting out the additives without a degree in oil chemistry is certainly a pain in the derriere.

See what I can do next week.

BTW, if ultimately you settle on an oil that is not available in SA but it is here, I am happy to ship you some to try if you like.
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Re: When should a gearbox have an oil cooler ?

Post by MD »

Kevin,
Finally got this oil list together. Still waiting for the Oz Alfa dealers to get back to me. If they do, I'll post anything that's not already here:-

Transmission Fluids for the Alfa 75 Twin Spark Transaxle

1. Australian Alfa Romeo Dealership recommendations.

(TBA if and when it arrives)

2. The 75 owner’s manual. SAE 75W-90 API GL-5
No distinction is made for an open or limited slip differential in the manual. Lubricants recommended :-
2
Agip Rotra SX SAE 75W-90 >now LSX 75W-90
Shell Spirax 80W-90HD > now Spirax A80W-90
IP Pontiax HDS 75W-90

3. Oil company recommendations

Penrite, Street- Transaxle 75W-90 GL-5 Semi synthetic
Racing- Sin Gear Oil 75W-90 GL-5/6 Full synthetic

Valvoline Street/Race Duragear 75W-90 GL-4 Semi synthetic

Shell Street Spirax A80W-90 GL-5 Mineral
Racing XGO 75W-90 GL4&5 Synthetic

Agip Street/race Rotra LSX 75W-90 GL4&5 Synthetic

Mobil Street/race Delvac synthetic gear oil 75W-90 Synthetic

Redline Street/race Light/ Superlight 75W90NS GL-5 Synthetic
Street Heavy Shockproof, Synthetic
Race Lightweight Shockproof, Synthetic
Race Superlight Shockproof. Synthetic


Please note that obviously this is not a complete list of lubricants that are available globally nor is it known to me whether the above list of oils is available around the globe and known by the same designation. Contact your own local oil company with the above oil details and they probably will have a cross reference to it which maybe available.

Compiled by MD
05.June.2009
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Re: When should a gearbox have an oil cooler ?

Post by MD »

Kevin,

One of the things I did do to arrive at this list is to phone the technical advisory sections of these oil companies. I had a particularly enlightening chat with the chemical engineer from Shell. After explaining every detail of our LSD fitted transaxles, he gave me his personal recommendation from the Shell range and it is the XGO 75W-90 synthetic even though the shell reference guides make no mention of it being specifically suitable for transaxles. Currently I am using Agip LSX 75-90 in the Brick and it seems good. However we are fitting a new box shortly and so I intend to experiment with the Shell product as I am having a bit of trouble sourcing the Agip brew at the moment.

Likewise dscussions with some of the local racing guys, they are using pretty much what is on the list without any problems. One of the most cost effective ones being the Valvoline line. The Redline lightweight and superlight are also used and thought well of abeit expensive.

So mate, I hope some of this helps you.
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Re: When should a gearbox have an oil cooler ?

Post by kevin »

Dam fine relpy there mate. Thanks. Im going Shell as well.
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Re: When should a gearbox have an oil cooler ?

Post by kevin »

Read if you want to see how to fu%^& a gearbox.
Md I have been using the Castrol LSX 90 which has been perfect fro my LS but my gearchainge was taking major strain ie grating so I experimented with my road car which also has an LS unit. The bootom line is the LSX 90 oil is to 'thick' and not designed for synchromesh gears(this is also quoted by Castrol and Shell here.) Both my race car and road car had new synchros and both dont chainge smoothly anymore.
So I had this BRIGHT idea before the race last weak to use another oil so I would have the best of both worlds . I was sold on an idea from our current drag racing champion to use a high friction ATF as this would be perfect for LS and for synchros.
So I chainged the oil and went to test . First result was the car could shift up down perfectly with absolutely no grating whatsoever and secondly I knew it was good for the clutch type LS as this is similiar set up in the automatic clutch boxes in the drag cars. I was also told it was great for bearings as all the forklift companies had switched to this brand.
Mats I know you are laughing at this stage.
Anyway I drive to the track with everything perfect until I do my second lap on the track when I start to hear a whine. Luckily my alternator belt came off so i had to pull into pits.
Cut long story short the whine got so loud I had to tow car as this did not put a load on the crown and pinion.
I have taken it all out and found the faces of both crown and pinion totally worn as if this car ran dry. All backlash setting are still perfect.
I had pinion anylised at lab and conclusion was the oil totally failed under LOADING.
MD I have made enquiries at Subaru as the the WRX sti has also and LS unit with its gearbox upfront and they have come back with a blend of two oils. Sounds dodgy to me but maybe you can ask in oz.
I have been given other gearbox oil sloutions which I will post.
Check out this crown
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