bnewport Posted September 8, 2009 Share Posted September 8, 2009 Every now and then my 44 has a problem down shifting, makes a grinding noise. Any idea what besides operator error is causing it. It's infrequent, maybe once every two or three laps. I have trouble sometimes where it will not go into first UNLESS I put it in second first and then it enters first easily. Quote Link to comment Share on other sites More sharing options...
Legends21 Posted September 8, 2009 Share Posted September 8, 2009 Before I would condemn the synchos, I would ask what gear oil are you using in the transaxle? Quote Link to comment Share on other sites More sharing options...
bnewport Posted September 8, 2009 Author Share Posted September 8, 2009 What ever Tim put in it when I got the car. I reckon there is probably one seasons worth of usage on it at this point. I don't know what the service interval is on the transmission fluid. Is it once a season, every race, every couple of years? I have no idea. It's something I can check in terms of fluid level though, right? Quote Link to comment Share on other sites More sharing options...
Sterling Doc Posted September 9, 2009 Share Posted September 9, 2009 There are two 17mm Allen plugs in the driver's side of the the trans. The lower one drains out the fluid, and the upper one is the fill port. You fill the trans until the fluid is about level with the fill port - pretty simple. See what drains out of the trans. If it looks OK, try refilling it with some Swepco, or similar fluid. Quote Link to comment Share on other sites More sharing options...
JerryW Posted September 9, 2009 Share Posted September 9, 2009 DO NOT drain the tranny before removing the fill plug. They are notorious for having issues and you would not want to drain it before you know that you can refill it. Quote Link to comment Share on other sites More sharing options...
bnewport Posted September 10, 2009 Author Share Posted September 10, 2009 Which swepco, 201 or 210? Quote Link to comment Share on other sites More sharing options...
Legends21 Posted September 10, 2009 Share Posted September 10, 2009 I do not have firsthand experience with Swepco. It is my understanding it is very good transaxle oil. I have experienced shifting difficulties with GL/5 rated gear oil and I now use a GL/4 rated synthetic that seems to work fine ( Amsoil Synthetic Manual Transmission and Transaxle Gear Lube 75W-90 API GL-4 (MTG)http://www.amsoil.com/storefront/mtg.aspx) Which swepco, 201 or 210? Quote Link to comment Share on other sites More sharing options...
Tim Comeau Posted September 17, 2009 Share Posted September 17, 2009 Hey guys, Billy, the car was serviced with Liqui-Moly 75W-90 synthetic racing gear oil. It's very high quality. What are some more details regarding the shifting difficulty? Which gears? Upshifting? downshifting? How's the shifter lever and shifter rod? All linkages on top of the tranny still tight including the pivot bolt? Clutch still feel ok? Quote Link to comment Share on other sites More sharing options...
cbuzz Posted September 17, 2009 Share Posted September 17, 2009 A 2nd to 1st gear down shift should really only be done at very slow to stopped speeds. My trans started having down shifting problems mid way through the Championship race. I then realized that I was not doing a good job of matching revs for the downshift. Low oil levels could certainly play a part in shifting difficulties. I change my gear oil about every 4 race weekends. That may be alot to some but then I get to see if I am getting alot of debris on the magnet on the drain plug. if ther are any pieces large enough to feel like little rocks then you are starting to have some issues. Usually it is a very fine (almost like mud) debris on the magnet. Charlie Buzzetti Quote Link to comment Share on other sites More sharing options...
bnewport Posted September 27, 2009 Author Share Posted September 27, 2009 I switch tranny fluid today to Swepco 201. The stuff Tim put in looked good coming out. There were some very small, I mean dust particle sized, shavings in the fluid that came out but it's a very small amount. We replaced the fluid by lifting the left side of the car and then filling the tranny using a hand pump. Then we let the car down allowing any overfill to drain out. Raise car again and insert the fill plug. The drain plug didn't appear to have a magnet on it. Is the whole thing magnetized or is there a visible magnet on it. There are no material on the drain plug regardless. I talked with Tim about it and I reckon the 3->2 shift grinding was mechanical over rev related probably. Given it has new fluid now and there was no materiel in the removed fluid, I figure it's all good now. Quote Link to comment Share on other sites More sharing options...
sagoston Posted September 28, 2009 Share Posted September 28, 2009 The magnetic drain plug that came with my car was not magnetic so I bought one from a local Porsche shop. I haven't seen them online anywhere and I think this was a genuine Porsche part. These drain plugs seem to be made from some non magnetic alloy so you can see there is a magnet inserted into the center which is clearly a different material than the plug itself. Charlie, what gear oil do you use? Do you have an LSD? Quote Link to comment Share on other sites More sharing options...
cbuzz Posted September 28, 2009 Share Posted September 28, 2009 I quit using LSD a long time ago Steve Seriously, I use Swepco 201 and I have a Phantom Grip LSD. It was in the car when I bought it and seems to work OK. The only track where I think it does not work well is Infineon. It is called a Phantom Grip because you never know if it is working It was put in by the person who originally built this car. I have found them online for about $400 new. I am a firm beliver that too tight of an LSD and it will cost you some time in high speed corners due to friction of the clutches. This has been proven when we raced the Pro7's. We would loosen the LSD for WSIR and tighten for Buttonwillow. It was worth about a 1/2 second at each track. Quote Link to comment Share on other sites More sharing options...
944-Spec#94 Posted September 29, 2009 Share Posted September 29, 2009 I ran miller with an open diff. Sadly not due to some really thoughtful planning like Champion Charlie, but 'cause I am too po to gets me one. Quote Link to comment Share on other sites More sharing options...
bnewport Posted September 29, 2009 Author Share Posted September 29, 2009 Charlies comments are for a clutch diff though, right? Is a quaife any better? You can vary the lock rates and it looks like internet wisdom says 70-80 is best. Any comments? Quote Link to comment Share on other sites More sharing options...
Sterling Doc Posted September 29, 2009 Share Posted September 29, 2009 A Quaife is a torsion type diff. Great for the street, but not so good on the track. They do not help manage rear lockup under deceleration (act like an open dif then). Also, they can only multipy the torque of the side with the least traction. If you hop curbs, and the inner wheel get airborn at all, you lose all drive to the out side tire, too (X*0 is still 0). At a track like Gratten where there are lots of elevation changing, off camber corners, and even a jump, a clutch-type diff is really valuabe. At a flatter, more open & sweeping track like Miller, not so important (as Joe showed very impressively), though I believe it still makes the car easier to manage under trail-braking. Quote Link to comment Share on other sites More sharing options...
sagoston Posted September 29, 2009 Share Posted September 29, 2009 Great info from all. Charlie, wasn't sure which LSD you were using to make the pass three wide through the attitudes. Very open thinking As for LSDs (the kind found inside transaxles), I was lucky to find a car with a guard LSD already installed. The only dilemma I have is deciding on a gear oil which is for good for both the transaxle and the LSD. Paul Guard recommended using Lubrication Engineers 9919 which is next to impossible to find in low quantities (I'm still searching). I flushed the gear oil with Mobil1 80-90w just to have something clean. Is the Mobil1 good enough? Or should I change to the Swepco 201 or any other recommendations? Quote Link to comment Share on other sites More sharing options...
cbuzz Posted September 29, 2009 Share Posted September 29, 2009 No real plan Joe, it came with the car. I could not see any reason to replace it if it was good enough. Very impressive drive with an open diff. Just goes to show that an open diff can be a winner on the right type of track and a great driver. The lock up types of diffs (Gaurds) are very good under braking. But that is the last place you will need to make any time. Spend the money on professional instruction and lap days. That is where you will get the most bang for the buck. Quote Link to comment Share on other sites More sharing options...
944-Spec#94 Posted September 29, 2009 Share Posted September 29, 2009 ... At a flatter, more open & sweeping track like Miller, not so important (as Joe showed very impressively), though I believe it still makes the car easier to manage under trail-braking. I agree with this completely. I had zero traction issues with my open diff, but never really felt the braking impact. I never felt it, but I do believe it is there. I probably could have gone deeper in turn 1 with an clutch type LSD. Same the black rock hair pin and turn 6 as well. However as Charlie stated it may have impacted my car in other places. How much so is tough to estimate. Thanks Charlie, I have been dealing with an open diff for many many years now. At Miller is much less of an issue. At my local track PIR is something I need to adjust for else I get rear wheel spin. Plus we have realy hard trail braking corner that need to deal with. Even so if I get things right I can run in the lead pack. The trick is with an open diff to be more carefull with set-up and understand how to deal with the traction issues and braking issues. Then figure the best compomise. Like I said at Miller I never felt the diff slowed me down any, but I have no idea how much I might have been giving up underbraking. Quote Link to comment Share on other sites More sharing options...
bnewport Posted September 29, 2009 Author Share Posted September 29, 2009 A guard is still like a Q-LSD, right? It's basically a torsen also so Erics comments apply, right? Quote Link to comment Share on other sites More sharing options...
cbuzz Posted September 29, 2009 Share Posted September 29, 2009 My understanding of a Guards LSD is that it has the ability to have varying degrees of lockup under acceleration and braking. These have to be determined before installation. It uses shims to get specific percentages of lockup. So NO it is not like a Torsen. It is better. If you live in an area where you have small tight tracks then this would be the best choice. If you have large tracks with big sweeping turns then an open stock differential will work fine. Please correct me if I am wrong. Want to make sure I am not sending out the wrong info. Quote Link to comment Share on other sites More sharing options...
944-Spec#94 Posted September 29, 2009 Share Posted September 29, 2009 Charlie you are correct. The guard clutch type is the best diff you can get and you pay for it. Guard also sells a torsen style diff too. One other option is to weld the diff. This is legal in 944 spec. It is relatively cheap, but I really don't recommend it that creates an entirely new set of issues. Quote Link to comment Share on other sites More sharing options...
bnewport Posted September 29, 2009 Author Share Posted September 29, 2009 Im looking at somewhere like Road Atlanta. There are some tight low speed corners followed by long straightaways so you'd figure a guard LSD would be beneficial there, right? Road America probably not, maybe T14. Mid America for sure. Quote Link to comment Share on other sites More sharing options...
cbuzz Posted September 30, 2009 Share Posted September 30, 2009 To me what would matter the most is if the lowest speed corner is follwed by the longest straight. If it is like laguna seca where there is only one slow corner then I would choose a diff with lots of clutch slippage. Like the Phantom Grip or a worn stock LSD. None of this really matters unless you are competitve with the front pack. And as Joe P. has proven a quality driver will be able to overcome most of these issues with set up and driving style even with an open diff. Quote Link to comment Share on other sites More sharing options...
944-Spec#94 Posted September 30, 2009 Share Posted September 30, 2009 Charlie is correct in a sense, but it infact is more complicated. It is not feasible on paper to really know how much LSD you need. The reason is that gearing plays a role. Some corners you maybe in the heart of the power band for a certain gear. thus wheel spin is more likely. In others you are a softer spot and therefore putting less power down in general. Road America vs road Atlanta... Road Atlanta only has 1 tight turn. Road America only has one too. It comes down to road surface and line. Now that is for corner exit traction. In the braking zones it is much harder to know when you need it and when it helps. Reason is wheelspin is easy to detect vs brake zone instability. Quote Link to comment Share on other sites More sharing options...
Big Dog Posted September 30, 2009 Share Posted September 30, 2009 This makes my head hurt! Big Dog Quote Link to comment Share on other sites More sharing options...
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