Plenty of carbon steels that would be suitable rather then stainless. You can have someone PMI your original part and do a micro hardness on it for a small charge. That will give you a good idea of the base material and and hardness/stress relieving done to it.
I was serious and if you could upgrade it with my current MSD box and make it whistle then lets make it happen.
I agree but the price difference betweek Stainless Stavax and 4140 is minor and the stainless looks better for those who like nice looking parts. I for one go for a part that looks too good to hide like an H-beam Manley rod or a Harland Sharp roller rocker. A sculpted stainless steel carrier hidden away in a gearbox is a pity but its makes me feel good .
Paul, I wouldn't worry so much about how pretty that stainless is - it will, after all, be hidden away. It will look just as beautiful as it disappears into the oil-filled casing, if that matters. Just make it from material as strong as possible, to get the weight down, please....pretty please. I was wondering if your Diff. source was someone like Guard (or if you contacted them http://www.guardtransmission.com/lsd_info.htm ). I've mentioned them previously, and they have told me that they can build one for us (those for the Porsches run $2-3K) if a good unit was provided for measurement, and would have a ramped LSD. Below is my stock Audi Diff. carrier (left) next to the Guards 944 unit(right), when we were test-fitting. A shame to hide it away, because it really was almost a work of art when you held it in your hands. Image Unavailable, Please Login
Every shop that was contacted about doing the gears said "no problem" until they saw the gear then they said "no way I cant do that". The pinion shaft is complicated unlike most conventional differentials and the crown gear offset was another issue. I also thought about weight savings and decided it wasnt worth the cost. To reduce the weight significantly it would need to be made of titainium and then what difference would it make to 0-60 times by having less rotational mass? In a race car yes, street car no. I want it to be unbreakable and the same dimensions as the original so the nay-sayers are kept at bay. I want it to be without question that the carrier we produce is reliable.
Paul This is the first time I am seeing such detailed pics of the diff-thanks. Please forgive me for my ignorance but what are you going to do differently on the piece that you are having made up? Its been said that the 512m has a bolted unit instead of a welded one-where would the bolts go to improve it? Wouldnt it be better to copy the upgraded unit as opposed to the original one?
I have more pics, ones that will show you how much of a pile of cow dung this carrier really is. Ill post them a little later today pointing out the issues. All the carriers have the bolt on end cap, its the opposite end that is the issue. The original unit for the boxer and TR right through the 512TR have one bolted cap and one welded cap. The 512M has only the bolted cap and did away with the welded part. Its tougher to make but stronger with the integral end rather than the welded end. You'll understand more when I post the pics. I dont need a new one, its simple, you just make the carrier in the more difficult and stronger fashion out of a solid chunk of high strength, high quality material.
Thanks for the info Paul-looking forward to seeing the detailed pics. This thread really allows people to see what is the real story behind this diff. Great timing on this BTW, I am a year away from getting the major done on the TR and would love to be able to update the diff. I assume the diff fits in the TR as well as the Boxer-correct?
Ok, here is the carrier with the bearings removed. I needed to take them off because I needed to magnaflux the end plate, the bearings need to be replaced and I needed access to copy the part. This carrier passes the magnaflux test but it was suggested that an x-ray is more reliable since the welds always get highlighted where they meet the metal, which can look like a crack or hide a crack. The welded on end-cap is actually made up of two parts, the center bearing support and then a filler ring that fills the gap between the center support and the outer shell. You can see two parallel welds around the perimeter of the shell then just near the support in the center. The reason for making the carrier with no ends to begin with is so they can broach the clutch pack slots through the carrier housing. After that, they weld the end cover on and voila! One cheap easy part to make that may or may not break. The 512M carrier is harder to make. You cant broach the slots, you need to EDM them which requires a specific tool to be made for the job. It complicates the job but I can still make them at a reasonable cost and they would be not only pretty but stronger than any other part in the transaxle. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
The carrier will be $4K cdn or $3300 USD with the dollar the way it is currently (it might be less because material prices are rough until next week). It would be made of high quality stainless steel (mild steel cost will reduce the price slightly because its priced by the pound) . Its labour intensive mostly because of the machining for the clutch pack setup inside combined with being a solid closed unit on one end. The carrier would be impossible to break and my internals will go right in. The carrier will be identical in dimension but superior in strength and bolt right in as well. Its a direct replacement part. I made several calls today to Algar, Ricambi, Trutlands and ferrari of ontario. They all say NLA on gears and carriers. Used gears from rutland are $1700USD, no carriers available including the M carrier, they used to sell rebuilt ones for $4600USD exchange ($1000 more without a core) but NLA now. Im sure there are some out there, cost is the issue. Ill be updating my carrier to the stainless one, its piece of mind for me plus I can sell my good used one to recover some of the cost.
Dear Ferraristi, Newman, Very impressive work. I was wondering, we've all heard that if you upgrade to the 512M diff, or in this case, yours, you just push the weakness down the food chain. As I understand it...the quill shaft? Please correct me if I'm wrong. What would be involved in finally making the TR gearbox sort of bullet proof. I have no problem with my diff but I would like to upgrade to yours when I have my next major done. What else you you replace besides the diff itself? The reason why I ask for the bullet proof gearbox is that I may want to upgrade the engine to a Norwoods turbo system in the future...just thought I would inquire. Thank you, Shamile Freeze....Miami Vice !
As I understand it the quill shaft is like a fuse. Blowing it does not really cause dmage or problems, the rear diff carrier creates a major mess.
Hello Spoke to the assitant of the gentleman who made the gears and he told me it is 8620 carburized and hardened. Greek to me but there you have it. Brent.
Thanks Shamile, Like Sean says the quill shaft acts like a fuse. If that shaft were to be upgraded for example, you then open yourself up to breaking something else inside the gearbox. If the shaft breaks, you replace it for around $1700 IIRC but you would also have to clean the metal debris out by dropping the pan etc.... if it shattered like ive seen them do. If you break a diff carrier its like a bull in a china shop and it buggers everything around it. If it happens on the highway the damage is great, if it happens pulling into your driveway then its not as bad but still costly. The carrier isnt supposed to break nor is it a fuse in the system, its more like a bomb IF it ever breaks. If you have an upgraded carrier, you now take that possibility out of the equation along with the other stuff it may have destroyed. It wont cause something else to break that wouldnt break anyway. I dont know how you would make the gearbox bullet proof, the pinion support wall in the box is bound to deflect under heavy load which changes the pinion/crown gear clearance and who knows what else. The gearbox isnt made to handle massive amounts of HP so how you apply the power is what will matter more than anything. You pound on it and it will break, its that simple whether a gear snaps in half and lands in the pan or the quill shaft breaks, who knows?
Turns out the cost of materials was less so now the carrier will only cost $3300 or $2700USD. If anyone is interested in a carrier I can have them make a few more at that time. Please remember that the original internal gears and clutches from the old carrier must be transfered to this updated carrier as it comes empty.
That is a sound choice of base material and surface treatment. The simple explanation is that this is a good quality medium carbon level chrome moly steel. After near finish machining it is heat treated to increase the strength of it by increasing the hardness. The carburizing increases the carbon content on the surface only- which results in a case hardening beyond what the base material is hardened to. Once carburized, a final finish grind gives the final shape and tolerance to the teeth. The case hardening gives better wear resistance to the gears themselves.
I'm coming to this thread a little late, but wonder what the cost of your improved carrier would be in moderate quantity - possibly a group buy of 10 or 20 units? If the unit price were substantially reduced I believe many of us would purchase a carrier to have available for installation at a future time.
Yes, $2700. is a fair price. However, if 10, 20, or more units are scheduled for a production run the cost per unit is substantially reduced. The supplier benefits from reduced unit materials and unit shop setup and tooling costs, and the supplier is then able to pass along some of this savings to the end user who benefits from a reduced unit part cost. Introducing a supply of a NLA critical part also benefits present and future TR owners and betters the marque. Economy of scale usually results in a win-win for all parties.
What you're suggesting wasnt overlooked by myself or Brent but thanks for the suggestions anyway. The number of units hasnt been decided on and that investment risk falls right on myself and Brent. Whatever savings we can make without sacrificing quality will be passed on to the buyer so stay tuned. Thanks Jay!
Would this be the kind of upgrade you could easily do when the unit is having it's 30K major? How much more time / expense do you think it would add to that service. I am due for my service shortly, and with an early 86TR, it may be worth the upgrade.
I agree with what you are thinking Adam. I will be in the same boat next year for a belt service. You know, while you are in there...
Thats the best time to do it and thats what im doing myself. For me its peace of mind knowing that particular failure will never happen rather than possibly happen. On the Boxer we have one more possible issue and thats the sodium filled exhaust valves breaking. I plan to address that too at the same time.
Having done it on my own car in my father's garage it is the best and the only time you can do it. I had my major, replaced my noisy gear box with one I purchased. Unfortunatly that gearbox also has problems (hence the start of this thread). So out comes the engine again. I thought hard about a way to get the gear box off the car without removing the engine again but it's impossible. I believe that 3 out of 4 motor mounts are directly attached to the gear box. Once the engine is out on the subframe, the exhaust , the air pump and clutch have to be removed, then the engine can be lifted off of the gear box. It's not what I would call easy and quick but you're working away from the car and their's lots of elbow room. As far as time...I never counted but I believe that garages quote around 15-20 hours on top of the major...but there are more qualified people than me could answer that. Thanks. Brent.
