73speed Posted May 27, 2005 Share Posted May 27, 2005 hey everyone, my ls1 purchace went south so now I have to wait for a while to find a good deal again. Since I'll be waiting for a while, I was planning on working on other things that will get my car ready for some v8 power. I have thought about all the LSD options we have, but I wonder why nobody seems to have asked the question about using just the differential out of a c4 corvette. not a complete irs swap, just the diff and adapt the half shafts to use the rest of the datsun irs. people are swapping to lsd's and modifying the halfshaft, etc. anyway right? just a thought Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted May 27, 2005 Share Posted May 27, 2005 That's what I am doing in my RX7. Quote Link to comment Share on other sites More sharing options...
strotter Posted May 28, 2005 Share Posted May 28, 2005 Scottie, have you worked out any details yet? Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted May 28, 2005 Share Posted May 28, 2005 Sorry. Should have said "what was done". Been in the car for a while. The finished product is a stock RX7 suspension with a C4 diff and TII CVs. - The RX7 diff and rear cover was removed - The C4 rear cover was narrowed - The C4 diff stubs (u-joints) were modded to add with an adaptor to allow bolting up to stock TII CVs - Simple front mount was made See pics which include the narrowed cover, the diff in place with the stock diff stubs, the modded diff stubs, the finished product installed. Car retains the great ride and handling of the stock RX7 suspension and has already clicked off a 1.51 60' on DRs without really trying hard. With the 3.07 ratio, recorded 33mpg on a stint from Reynolds, GA where construction limited speed to an average of 60-65mph. HTH, Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted November 18, 2006 Administrators Share Posted November 18, 2006 Scottie, I’m considering installing a C-4 Dana-36 in my Z using CV’s Could you tell us more about what these TII CV’s are, came from, etc, and could you please go into a little more depth on what materials were used for the diff stub mod and who did that work? I have access to a Dana 36, 3.07 ratio from an ’85 C-4 that spent most of its life as a dedicated Autocross car and the clutch pack it that diff has recently been set up a bit tighter as well. I am SERIOUSLY considering this for my Super charged V-8 Z using CV’s. Thanks, Paul Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted November 18, 2006 Share Posted November 18, 2006 TII = 86-91 RX7 Turbo II The machinist decided what material to use to weld up the adaptor. The TII CVs are the opposite configuraation of the Z CVs. The TII diff has a stub and the CV has a 4-bolt flange that bolts to the diff stub and an integrated stub that goes into the hub. The Z has the integrated stub that goes into the diff and a 6-bolt flange that bolts to the stub axle that goes into the hub. That reads funny but sure you know what I mean. Quote Link to comment Share on other sites More sharing options...
stony Posted November 18, 2006 Share Posted November 18, 2006 hey everyone, my ls1 purchace went south so now I have to wait for a while to find a good deal again. Since I'll be waiting for a while, I was planning on working on other things that will get my car ready for some v8 power. I have thought about all the LSD options we have, but I wonder why nobody seems to have asked the question about using just the differential out of a c4 corvette. not a complete irs swap, just the diff and adapt the half shafts to use the rest of the datsun irs. people are swapping to lsd's and modifying the halfshaft, etc. anyway right? just a thought If you are considering any type if diff and axle upgrade dont for get the stubs. if you upgrade all the stuff the stubs will be the next very weak link.... ask me how i know Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted November 18, 2006 Administrators Share Posted November 18, 2006 If you are considering any type if diff and axle upgrade dont for get the stubs. if you upgrade all the stuff the stubs will be the next very weak link.... ask me how i know Stony, I’m assuming you are referring to the stubs in the strut housing. The ones you broke, were they the 240 or 280 stubs? Quote Link to comment Share on other sites More sharing options...
stony Posted November 18, 2006 Share Posted November 18, 2006 They were Z31 300ZX stubs. Had the struts machined to accept the correct bearings and used the CVs from a Z31 with custom chromoly axles. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 18, 2006 Share Posted November 18, 2006 Why do I seem to recall that the only LSD available for the D36 was the extra crappy Trak-Lok which had an extremely weak lockup, no torque sensing ability, and tended to chew up spider gears and clutch tabs really bad? Is there another LSD for this diff, cause I would definitely not go to all the hassle to put an 8.5" ring gear in with a crappy LSD? I guess the upside is you can get those taller gear ratios some of you turbo guys are looking for... Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted November 19, 2006 Administrators Share Posted November 19, 2006 I can't speak for the Dana 36... but I do have a bit of experience with the Dana 44, in a competitive C4. I would expect some design similarities. With the 44, total lock-up can be adjusted beyond neccessary, without gear/clutch failure. Some people, particularly with softer suspended Vettes, have experienced rapid clutch wear (when pre-loaded appropriately). Jon is pretty well right about torque sensing... there are no ramp angles to speak of due to the spider gears being 'pinned' to the center section. Side gear seperation comes only from the bevels in the gears. To make these work, they need to be pre-loaded accordingly. There are obvious tradeoffs for doing it this way. Keep in mind... some of the fastest autoX cars out there run this diff. P.S. The early Vipers (and maybe late?) ran a 44. Quaife's are availabe for the Viper's 44... it may be possible to slip one in a Vette's 44? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 19, 2006 Share Posted November 19, 2006 There are 2 D44 LSD's that I'm aware of. The Powr-Lok which is basically just like the Nissan LSD. Salisbury LSD, ramps, torque sensing, the whole 9 yards. Then there is the Trak Lok which is literally the crappiest clutch LSD you can buy, at least in my experience. I used to sell replacement LSDs all the time, and the parts were about as much as the whole thing, so we almost never tried to fix them. I seem to recall they usually ran about $140. The Trac Lok has belleville springs under the clutch stack, and that was the only thing providing pressure to the clutch stack. So you could shim it tighter, but the clutches were weak and that would be the next issue you'd run into. I seem to remember problems with the case too, like the cross pin shaft wallowing out the hole just like our R200 open diffs tend to do. It was the "trick question" diff when we were learning about LSDs, because it looked like an open carrier. Big holes on the sides to put the gears in. You could only tell it was LSD by looking at the ends and seeing the holes where the tabs for the clutches went. Dana makes their own version of a helical LSD called a TrueTrac. If they have one for the D36, it probably runs $300. I know they have it for the D30 and the D44, and the D30 version has an adjustable preload "block" that you can tighten to make the diff more aggressive as I recall (the hot ticket for Volvos). It's been 3 or 4 years, so things might have changed, or I might just remember wrong. Maybe people have figured out how to make them work without grenading. Maybe Dana has improved the design. All I know is I wouldn't put one in my car... Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 19, 2006 Share Posted November 19, 2006 A trick for you Ron if you do go down that road. I just remembered you have to make a clutch stack compressor out of a bolt and nut to put the gears back in the carrier too. Also, looked it up at ringpinion.com, and here's what I found: Trac-Lok (T/L) Built by Dana Spicer for use in Spicer rearends, AMC rearends, and 1998 & older 10.25" Ford rearends. The old design built up until about 1989 was weak. The 1990 and newer design is fairly strong and even rivals the Powr-Lok for impact durability, but the clutches do not provide as much lock-up force and tend to wear out in about 50,000 miles if used in the rear. Works better in the front of vehicles because it's not aggressive. The main selling points for this design are the fact that clutch chatter is almost non-existent, and it is very inexpensive. These two points make it a great unit for many applications and a very good value for the money. This unit makes a great front limited slip and works well for those who need a little extra traction but cannot tolerate clutch chatter. The Trac-Lok came factory installed in many models such as D28, D44, D60, AMC 20, AMC35, 10.25" Ford. The problem with this unit is that it is not very aggressive and power transfer is minimal. Also, 1988 and earlier units tend to break fairly easily. (1piece case, 2 pinion gears, and 2 tab clutches). (factory) Powr-Lok (P/L) This clutch type limited slip is the strongest and most aggressive limited slip differential available from Dana Spicer. It is a clutch type unit using floating cross shafts that ride up on ramps in the case. When power is applied, the shafts ride up the ramps and load the clutches for a positive engagement. A Powr-Lok will not lock up 100%, but it is a very durable unit that will hold up fairly well with tall tires. It can be rebuilt, and can be set up smooth or aggressive by changing the clutch design or stacking configuration. Powr-Loks are easily identified by their 2-piece case. They are a very strong unit due to the 4 spider gear design that provides twice as many teeth to carry the load as a 2 spider gear unit does. However, the case bolts can stretch or loosen after severe use over time. (4 pin, 4 tab clutches) (factory) Detroit Truetrac (TT) Based on the worm gear principal and works like clutch type positraction. Does not wear out, not recommended for tall tires over 33". Detroit Truetracs are similar in design to the Gleason Torsen®, only the Truetracs hold up well with reasonably tall tires. They use worm wheel gears that work on the same principle as a worm gear. When the unit is loaded, the worm wheels are forced away from each other and against the case. They develop locking torque by the light friction between the worm wheels and the case. This light friction is multiplied by the ratio of the worm wheel which depends on the size of the worm wheel relative to the size of the side gear. The manufacturer can change the amount of torque biasing or lockup by simply changing the diameter of the gears, or the pitch and spiral of the teeth. A larger difference in the size for the worm wheels and side gears (smaller worm wheels and larger side gears) will increase the lockup force. Increasing the pitch and spiral of the teeth will also increase the lockup forces. Like everything, there is a limit as to how much lockup force is reasonable. Making the unit too "aggressive" will cause tire scrub during everyday driving and will cause the unit to wear out too quickly. All of the feedback that I have received from customers indicates that the unit works very well for mud and snow, while going unnoticed during every day driving. When used in situations like rocky trails where one wheel gets off the ground, the unit will not lock up 100%. Light application of the brakes will help the differential engage more transferring power to the tire that is still on the ground. For extreme situations where the vehicle will have one wheel in the air often a locking differential provides better power transfer to the wheel on the ground. Detroit Truetracs are designed for medium duty 2WD and 4WD applications. They work well in the front and rear, and are so smooth that there is little or no hint of resistance in the steering wheel when used in front drive steering axles. Like the Gleason Torsen®, the Detroit Truetrac does not bang or clunk, has no clutch chatter, does not wear out like clutch type positractions, does not need limited slip additive, and needs no preload or clearance adjustments. Almost sounds too good to be true doesn't it? The only drawbacks to the Truetracs are their inability to provide lockup 100% like a locking differential can. Although Gleason no longer makes the Torsen® differential, the Detroit Truetrac is a proven design that is available for many popular applications. (aftermarket) 1 yr warranty Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted November 19, 2006 Administrators Share Posted November 19, 2006 Thanks for the info, Jon. I agree with you, at least empirically, there are better diff's/LSD's. This is a bit outside the scope of the original post so I do apologize... In my opinion, if a guy was on a shoe-string, wanted improved performance, and had the time to tackle the job... the C4 rear suspension (including diff.) deserves consideration. If I recall correctly, Scottie saved upwards of 80lbs, got a fully alignable, tall geared LSD, improved brakes, and to some degree, proven geometry (at least, if it were to be installed un-altered). All things that are lacking (some more than others) in a high powered Z. And... these parts are affordable, last I checked. The one thing I would do differently, if I were to use such an animal, is to retain the Vette's overall geometry and simply fine-tune the pick-up points to better suit the Z's needs. Of course, this would dictate flares of some sort. Not a perfect solution, but I have to think that its one worthy of consideration for the budget minded guy wanting a 'little extra'. However poorly the LSD is built it can be tweeked to function within reason. There are many successful cars proving so. For the record... I did have to re-shim mine at least once per season (due to clutch wear). Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted November 20, 2006 Share Posted November 20, 2006 Why do I seem to recall that the only LSD available for the D36 was the extra crappy Trak-Lok which had an extremely weak lockup, no torque sensing ability, and tended to chew up spider gears and clutch tabs really bad? Is there another LSD for this diff, cause I would definitely not go to all the hassle to put an 8.5" ring gear in with a crappy LSD? I guess the upside is you can get those taller gear ratios some of you turbo guys are looking for... DAMN! I guess after almost 5 yrs, 1000s of miles and a couple hundred 10-sec passes I can expect this crappy diff to fail Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted November 20, 2006 Administrators Share Posted November 20, 2006 DAMN! I guess after almost 5 yrs, 1000s of miles and a couple hundred 10-sec passes I can expect this crappy diff to fail At any moment! Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 20, 2006 Share Posted November 20, 2006 Hey, you know what? If you did nothing but sell diff parts for a couple years and you sold HUNDREDS of Trak-Loks and got to the point where you could describe WHAT and HOW it was going to go wrong, you might have a different opinion. I'm just trying to save the guy who thinks that this is going to be a real upgrade from making what I think is a mistake. You guys and I can disagree, and I'll still respect your opinions in other areas. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted November 20, 2006 Administrators Share Posted November 20, 2006 You guys and I can disagree, and I'll still respect your opinions in other areas. Will you still respect me in the morning? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.