brokebolt

Thanks for the Tire sizing, been looking for that for some days now.

Thanks for spending time on this subject and dealing with my problem. This discussion is getting real close to the one on VLSD "rear end ID". Also thanks for pointing out that the 39:11 stamp is ring tooth count and pinion tooth count, I wounder how long it would have taken me to realize that, Duh!!! I see what your saying about the spider gears and clips, I was hoping this too would be true. The distance from the clip ring groove and the end of the shaft is the same left to right on the ZXT and the SXT. The difference is in the 'groove' area inside the carrier (I have no idea what it is really called). This part of the shaft exists with small spiral grooves cut in it. If the CV is installed in it's original fashion, looking from left to right it is cut Anti-clockwise and both are cut exactly the same, length of groove and number of grooves. Here is the difference, one CV has a length of 10mm between the grooved area and the next section where the other does not have this gap. There are three diameters on the input and all three have special functions. the spline area, the groove area, and the seal area. The splines run up the shaft to an area wider than the splines. There the grooves are cut (both are the same up to this point). Here one has the 10mm 'dead' area where the grooves stop, but still have the same diameter. The other has grooves cut all the way to the next larger diameter of shaft. The shaft continues on, here you enter the area for the outer case seal. At this point you exit the case and enter the first CV, than more shaft, the second CV and finally the flange area where it is bolted to the hub companion flange. I don't see that the spider gears are any different left to right nor does it look like they are shimed any differently, but they do appear to have a space. The 10mm on the shaft would need to be on the same side as the carrier side that has the 10mm spacer (shim) with the small 2.1mm shim. I did talk to a guy at work about this issue (he races sprint cars) and he said (very long story short ) that you do "ususally" shim only the carrier to remove ring and pinion backlash, "but" in your case, have a shim for the ring made. I agree that this would be the 'easiest' solution to this problem, with some risks associated. This certainly has been a project from the word GO!!! Mike thanks again for your insite into this issue.

Hey all, Just looked and the stamp is 37:9 on both ring and pinion shaft NOT 37:90 which means that the math is correct. The decimal moves right and 37/9=4.11...now it's true. The ring tooth count is 37 and the pinion tooth count is 9! This weekend is looking up! Not that you would care much but I always add place holders and so I did in my notes to the "ring and pinion stamp 37:90 = 4.11... rear end differential" It's nice to find your own errors before someone else does.

Mike, DAW, Thanks for all your help and info. The information I have on the ring stamp does fallow the 39:11=3.54, etc. except the 37:90=4.11, I read that you divide the first number by the second you get the ratio. 39/11=3.5454...this is true until 37/90=0.411...almost true. Unsure what Datsun was thinking breaking form like that. The real issue is the CV's, and unfortunity I don't know anyone else that is a Z'er, let alone a car nut, well exept for my machinist who is a Chevy guy. I wounder if the CV's from a SXT would drop in with the R-200? I know that the bolt pattern is the same but are the companion flanges splined the same? The SXT CV's look a bit longer but the companion flanges are definetly shorter, or so it would appear. Looks like for me a weekend full of... well full of something

Mike thanks for responding, As for using the ZXT carrier vs. the SXT I can see no difference, and both use the 10mm bolt. No damage, I was originally thinking the carrier was different but on closer inspection, I see none. I understand what your saying about the ring needing to be closer to the pinion. The SXT accomplished this by moving the carrier and shiming the unit exactly opposite of the 3.545 (I think more luck than mathamatical planning) and thus needing longer inputs on the CV's on the right and a shorter one on the left. The ZXT is just the opposite with short CV's on the left and longer on the right. I would need to shim the carrier as to move it left to accomidate the ZXT CV's and the ring would need to be shimed right to accomidate the ring. That would mean I would need shims for the ring itself. Do they (any aftermarket parts supplier) make shims for the ring gears? Is that wise to do something like that? I am looking in the neighborhood of 10mm on the ring shim...that is half the length of the bolt (about).

Thanks for responding... The shims micrometer out about the same: R-200 280ZXT left (drivers side) one shim at 2.8mm and right two shims, outer shim is 2.1mm and inner shim is 10mm. R-200 200SXT left two shims, outer shim is 2.8mm and inner shim is 10mm and right one shim at 2.8mm. Ring gear is difficult to get exact measurement but both look equal on the calipers or even a micrometer, too many angles for accurate numbers. From your post it sounds like you don't shim the ring gear but the carrier itself. So does that mean when you swap ratio's around that you use 'only' the ring gear and not the pinion gear. Both 4.11 pinion and gear is stamped 37:90, I have a second 4.11 and it too is stamped the same. I though they were a matched set, the tooth count on the pinion is like 11 on the 4.11 vs. 17 (unsure of the exact numbers) on the 3.545. I can put the 280 carrier in the 200 housing with either shims set no biggy but that means the CV's have the wrong spacing. The left doen't contact the clip and the right bottoms out before it is all the way inserted.

That little orange sticker intrigues me, does the two output shafts spin as if it were an open differential? Is the carrier (VLSD) the same as a 'regular' R-200, or have you even opened it up yet? Nice find anyway.

Another R-200 question, I did do a search with no specific results. I am doing some parts swapping using a 1986 R-200 200SXT 4.111 ring and pinion and a 1983 R-200 280ZXT carrier. Basically trying to put the R-200 280ZXT carrier with carrier shims into a stock R-200 200SXT differential, with all other items staying put (bearings, housing, and such). My question is this, do I need to shim the 4.111 ring gear 'only' out away from the 280ZXT carrier? If so how much would be needed? And finally is there any significant difference in the housings of the R-200 280ZXT vs. the R-200 200SXT? The entire 280ZXT carrier with 3.545 ring and pinion in it's original housing is shimed on the passenger side between the outer carrier bearing and the housing. The 200SXT with 4.111 ring and pinion is shimed on the drivers side in the same manner. The half shafts reflect this shimming in penitration length. I need the 280ZXT haft shaft penitration length not the 200SXT set up as it is going into the 280ZXT car. Currently on mock-up there is WAY too much backlash. My goal was to keep the 200SXT ring and pinion gear and drop the 280ZXT carrier into the 200SXT housing. Any help would be appriciated. Mike

The 240sx has a shorter "snout" than the R-200 from a Z. Also there are no holes to bolt the front differential mount. I could be off on this but I recall this being true when I looked into the 240sx being a donor car. Mike

I read a lot of post for tons of good into but never reply. Here goes! I ran the black lawn edging material (mine was brown) for a summer. Excellent for making the car 'stick' at speed. Fuel economy went from 17 MPG to a gas gusseling 12 mpg when used as a conservatively driven daily driver on the freeway at 65 MPH. Unsure how much HP was sucked up, but I was unable to achieve the 120 mark on the cars speedo. Mike

Thanks for the tongue lashing, the information was exceptional! If only more post were as informative. So... stacking up the corners with disks is the best upgrade but the debate of cheap upgrade is still the issue. I've heard of available bone yard parts being used for that up grade, anyone care to share. Seriously, thanks again for the info. Mike

First time here, very concerned on the brake upgrade issue. Are the front 70-78 Z rotors not actually a problem of not disapatting heat but that the pads don't preform at temperature. I've seen road race cars rotors glow red at dust and evening. For the daily driver the pads would not get hot enough to perform normally but for the track they would be fine. Are their any aftermarket pads that would be an 'upgrade' over the standard 'Napa' replacements? Pads at $50.00 has to be cheaper than new parts.