True-Trac 1031 3.31:1 ratio fitment

[Matt Dupuis]

Public service announcement for all of you wanting to put a Tractech True-Trac in your 3.54 or 3.31:1 ratio'd 1031 rear end: Don't buy the #374 part that's supposed to fit the 3.54 and 3.31 gears!

I did, and after having a quick measure, I found it to be about 0.120" off. Apparently, and I think I actually knew this by doing a VADIS search a couple years ago :-( , the same diff carrier was used for all ratios of 1031 rear end. I can't speak for the 1030 or the 1041 rears, but it appears that the 1031 made up the thickness difference in the ring gear. I'm fairly certain that the 1030 is the same way, in that the same diff carrier is used for all axle ratios.

Luckily, Dale loaned me his #411 part, in hopes that I can rectify the situation and get him one sooner than he needs it.

James (945Ti) bolted a 1031 3.31:1 ring gear to his 1041 3.73:1 differential, and though they bolted up properly, that combination put the ring too close to centerline. That's opposite of "conventional" wisdom, which states that the larger pinion of the 3.31 gear needs to push the ring outboard to maintain adequate thickness. However, he's currently running that same 1031 3.31:1 ring on a 1041 3.31:1 differential, in his 1031 housing, and it's all working tickety-boo.

Anyone have anything to add?

[240Psycho]

Public service announcement for all of you wanting to put a Tractech True-Trac in your 3.54 or 3.31:1 ratio'd 1031 rear end: Don't buy the #374 part that's supposed to fit the 3.54 and 3.31 gears!

I did, and after having a quick measure, I found it to be about 0.120" off. Apparently, and I think I actually knew this by doing a VADIS search a couple years ago :-( , the same diff carrier was used for all ratios of 1031 rear end. I can't speak for the 1030 or the 1041 rears, but it appears that the 1031 made up the thickness difference in the ring gear. I'm fairly certain that the 1030 is the same way, in that the same diff carrier is used for all axle ratios.

Luckily, Dale loaned me his #411 part, in hopes that I can rectify the situation and get him one sooner than he needs it.

James (945Ti) bolted a 1031 3.31:1 ring gear to his 1041 3.73:1 differential, and though they bolted up properly, that combination put the ring too close to centerline. That's opposite of "conventional" wisdom, which states that the larger pinion of the 3.31 gear needs to push the ring outboard to maintain adequate thickness. However, he's currently running that same 1031 3.31:1 ring on a 1041 3.31:1 differential, in his 1031 housing, and it's all working tickety-boo.

Anyone have anything to add?

Is this part a typo?

dont you mean in his 1041 3.73:1

I have the same rear in my 244 and i was wondering how this is working?

[945ti]

When we (Matt and I) were looking at the true-tracs, the difference in the thickness of the ring gear flange was quite obvious between the "Jeep? 3.54-" and "volvo 3.73+" true-trac diffy. Matt might or might not have a measurement handy, but it was definately visible.
When I had my two 1041 carriers stacked on a flat bench sitting in their bearings, I observed no significant difference in flange thickness or overall profile of the diffies that I could see with my eye. Unfortunately, I definately don't have any recorded measure of the flange thickness of each (3.54- or 3.73+) 1041/G80 carrrier or a precise measurement from the flange to the centerline of the case, I wish I did.
When I test fit that (3.73+ 1041 carrier) diffy like Matt describes, I was about 5 thou from it fitting.
I don't know what to make of all this exactly. However, it seems more or less that volvo made up basically all of the potential difference in the ring gears and uses a universal carrier like Matt suggests.
edit :My 3.73 ring gear is most definately a little fatter than the 3.31.

[Matt Dupuis]

Is this part a typo?

dont you mean in his 1041 3.73:1

I have the same rear in my 244 and i was wondering how this is working?

I typed it correctly, according to what I've been told. 1031 gear and housing, 1041 carrier and axles.

When I test fit that (3.73+ 1041 carrier) diffy like Matt describes, I was about 5 thou from it fitting.

That's really strange, because the difference between the two Dana carriers is visible from about 20 feet, when they're sitting side-by-side. The 3.54 carrier has the flange almost 1/8" more offset than the 3.73 carrier or the Volvo carrier. Where the .005" you're estimating came from, I don't know. A difference in bearing shims, maybe?

[945ti]

I typed it correctly, according to what I've been told. 1031 gear and housing, 1041 carrier and axles.

This is quite correct. :-D


That's really strange, because the difference between the two Dana carriers is visible from about 20 feet, when they're sitting side-by-side. The 3.54 carrier has the flange almost 1/8" more offset than the 3.73 carrier or the Volvo carrier. Where the .005" you're estimating came from, I don't know. A difference in bearing shims, maybe?
My bad, all this diff talk got me reversed, the 3.73 was definately fatter....wow, sorry.
The ~ .005" difference seems likely to be a small shim difference now that I think about it. I didn't investigate further at the time as when it didn't fit it sort of made sense. I just wanted the car to actually work and tossed the open diff that came in the 3.31:1 1031 housing/axle right back in as it was.

[285wagon]

Luckily, Dale loaned me his #411 part, in hopes that I can rectify the situation and get him one sooner than he needs it.


Correct me if I'm wrong, isn't #411 for the 3.73 and up? I've got the 1031 rear with a 3.54 ratio and was just looking at the Truetrac. It would be nice to know exactly what combination of components it takes to make the Truetrac install work in a rearend like mine.

[Matt Dupuis]

This is my point.

I've got a 3.31:1 1031 diff in my V8 car, and I bought a #374 True Trac because it's supposed to work with the 3.54 and down gears. When I pulled the gears and bearings off my carrier, I measured the distance from the shoulder of each bearing surface to the face of the ring gear mounting surface, and the #374 is about .120" too far offset (away from the centerline, towards the drivers side of the car, whatever) compared to the carrier that was in the diff. I measured a #411 part, and it's within .002" of my old one in all dimensions. I've also got a #314 to measure at another buddy's house, but since I wanted the high preload version anyway, knowing that the #411 fits is just fine with me.

Now I'm not sure about the 1030 differential, but based on all my VADIS searches, there's only one carrier part number for all ratios, unless you get the anti-spin which is another part number, again useable with all ratios. I'm guessing that Volvo thinned the ring gear on the taller ratios, rather than move the flange and have two separate carriers.

It seems that the 1041 might be an exception, in that there are two different carriers depending on the range of ratios. It's hard to tell, because in my half hour of looking last night I could only find part numbers for the carrier halves, not the entire differential, and the documentation wasn't all that clear.

Granted, I've seen shims that let you mount a short gear on your long gear differential - they shim the ring gear away from the face of the diff carrier, so if you've got a factory LSD for a 3.27 gear you can mount a set of 4.11s on it by using the shim. I haven't specifically seen them for Dana 30s, but this might be a possible fix for the #374 part. I think getting the #411 or #314 part is the right way to go anyway, but there's the chance that it might be wrong for a 1030 axle... All I can say is that the 1031 APPEARS to require the #411/#314 for all gear ratios.

[towerymt]

Correct me if I'm wrong, isn't #411 for the 3.73 and up? I've got the 1031 rear with a 3.54 ratio and was just looking at the Truetrac. It would be nice to know exactly what combination of components it takes to make the Truetrac install work in a rearend like mine.
411 is rear axle. Supposed to be a better version for RWD applications.

I have the 912A314, dana 30 front, 3.73+, in a 1031 3.73 axle. Of the 5 we got at one time, all went into 3.73+. Two in 1030, the rest in 1031.

912A374 is dana 30 front, 3.54-

912A411 is dana 30 rear, 3.73+

No listing for dana 30 rear, 3.54-

[245gti]

411 is rear axle. Supposed to be a better version for RWD applications.

I have the 912A314, dana 30 front, 3.73+, in a 1031 3.73 axle.-

Interesting...the info I had when ordering was the 411 was the high preload and the 314 was the low preload. Makes sense though...

[dl242gt]

Dana 30 front 912A314 for 3.73-> Works in RWD but not as well as the 411 version with the high preload.

[gsellstr]

Correct, the 411 is the higher preload than the 314.

[Matt Dupuis]

912A314, dana 30 front, 3.73+

912A374 is dana 30 front, 3.54-

912A411 is dana 30 rear, 3.73+

No listing for dana 30 rear, 3.54-

Right, that's what got me confused and lead me to buy the #374 for my 3.31:1 axle. It really doesn't work, but the #411 measures up just right.

The catalogue I have lists the #411 as a Volvo-specific part, but also specifies 3.73+. Once upon a time there was a 912A404, dana 30 rear 3.54-, but it's been discontinued.

[Morley]

So the morale of the story is.....912A411 works in all 1031 axles?

[Matt Dupuis]

I don't want to say yes and cause someone to make a $350 mistake, but I believe that's the truth.

Hard to believe nobody else has tried fitting a TT to a 3.54 or 3.31 axle before.

[Morley]

I don't want to say yes and cause someone to make a $350 mistake, but I believe that's the truth.

Hard to believe nobody else has tried fitting a TT to a 3.54 or 3.31 axle before.

Well on the 'wegian boards word is that you should always get the 411....:e-shrug:

[Tha VZA]

I've also got a #314 to measure at another buddy's house...

i hope you don't mean me...i've got the 912A411, dana 30, 3.37 and up rear end

which should work...:party:

ciao

[stylngle2003]

matt, i would have tried it, since i want to stick with 3.31s and want a nice diff, but i always just ASSumed that when they said it was only for 3.73+ they meant it. it would be hella cool if the 912a411 worked in my 3.31 diff, cuz i actually enjoy being able to sorta use 1st gear :rofl:

but the m46 still sucks :)


wonder how hard it would be to get em to make the 912a404 again?

[245gti]

i hope you don't mean me...i've got the 912A411, dana 30, 3.37 and up rear end

which should work...:party:

ciao

Nope...not you. Athal has the other one; which leads to an interesting question. Do we have 2 diffs that don't fit?

[Matt Dupuis]

404 should just be the guts from the 411, and the only difference there might just be the shims. The gears might have tighter helixes for more grip, but maybe not. Even so, it doesn't look like it's useable in our axles so why bother wondering?

Morley, I don't speak Norweigan, so I wouldn't know. If it's common knowledge to only get the 411 part, I certainly never heard it here.

Dale, the 314 should aughta fit. It'll have the same dimensions as the 411, and Towery already said he's got the 314 in his car, working just fine.

[945ti]

Makes sense. The 1041 might or might not be an exception indeed. I am tempted to try the 1031 3.31 open carrier in the spare 1041 housing and see how far out it is. If it is an exception, it seems like a minor one. Is it possible that volvo just used a slightly different cover/shim combo to make up a minor spec difference? I suppose it would be best if I had two 1041 housing/casings around to be more sure, one 3.54- and one 3.73+.
Anyway, I'll try and root through my parts pile from making my bastard hybrid diffy work and see if I can find a logical combination of parts that might tell me a little more about any possible 1041/1031 differences/exceptions.

[Morley]

Morley, I don't speak Norweigan, so I wouldn't know. If it's common knowledge to only get the 411 part, I certainly never heard it here.

Well I wasn't pointing a finger at you...just added in a "fact". Just because it's said on a Norwegian board doesn't necessarily mean it's true.

[towerymt]

Interesting...the info I had when ordering was the 411 was the high preload and the 314 was the low preload. Makes sense though...
That's why I said... ;-)

NO ONE should buy the 314 if you can afford and find the 411. Mine works, but it's hardly the best diff out there because of the weak preload or whatever it is that makes it spin the inside tire on tight corners. I'd go with the dana pow-r-loc or whatever it's called, clutch diff, rather than the 314 if price is similar. Rob and Dana have both had problems drifting a 314 truetrac with turbo power. Call it a street performance diff that won't bite you like a welded or locker might. Smooth operation and easy maint.

[Matt Dupuis]

Well I wasn't pointing a finger at you...just added in a "fact". Just because it's said on a Norwegian board doesn't necessarily mean it's true.

And I wasn't bitching. I was just saying that I'd never heard it before. It's good to hear that it's being backed up on another board, though.

[turbobrick211]

Arrgh. I went round and round with Reider Racing about which unit to put in my 3.31 rear end, and they weren't quite sure. They thought that they could use the 411, but would have to machine a little off the ring gear side of the housing, or something like that, to make it fit. So, now I wonder what to put in my 1030 3.31.

[dl242gt]

I've been using my 314 version rwd in my 82 turbo for over 65k miles. I bought it and had it installed when there wasn't a 411 version to buy. Later when the 411 came out I asked Reider Racing or Randy's Ring and Pinion(I forget which) what the difference is and they told me it's the same unit with the preload added for better rwd operation.

Even without the preload the 314 unit has added a lot of traction. With the better 411 type it must be a lot more fun.

[gsellstr]

I've got a 411 in my 140 and it's AWESOME. Never broken just one wheel loose (with my whopping 105 ft.lbs at the rear wheels).

One comment about the possible difference in the old 404 unit. The 314 and 411 units, as with most of the current TT diff's is they have 3 helical gearsets instead of 2 like the earlier units (too many of the early ones snapped in 4wd app's). Dunno if that's at all related, but there's a little trivia for ya.

[Matt Dupuis]

I've got a 411 in my 140 and it's AWESOME. Never broken just one wheel loose (with my whopping 105 ft.lbs at the rear wheels).

One comment about the possible difference in the old 404 unit. The 314 and 411 units, as with most of the current TT diff's is they have 3 helical gearsets instead of 2 like the earlier units (too many of the early ones snapped in 4wd app's). Dunno if that's at all related, but there's a little trivia for ya.

All the TT's designed for C-clips have two gearsets too. I don't believe the 404 would be any different from my 374 in that case.

[Poik]

Later when the 411 came out I asked Reider Racing or Randy's Ring and Pinion(I forget which) what the difference is and they told me it's the same unit with the preload added for better rwd operation.
Ok is "Randy's Ring and Pinion" like a chain or is the local shop here just like nationally known? I got my exhaust done at Randy's Custom Exhaust nextdoor to it, and I swear the guy's name was Randy..

[Matt Dupuis]

Randy's Ring & Pinion
10411 Airport Road SE
Everett, WA 98204
Tel 425-347-1199
Fax 425-347-1440

http://www.ringpinion.com/content/aboutRandys/default.asp

[Poik]

Ah so..

[mikep]

Randy's has an installation shop.

[dl242gt]

Ok is "Randy's Ring and Pinion" like a chain or is the local shop here just like nationally known? I got my exhaust done at Randy's Custom Exhaust nextdoor to it, and I swear the guy's name was Randy..

My installation shop had heard of them so for the winning answer it's B. A local business nationally known.

My installation shop was 'Camper Bob's 4x4 Truck and RV Parts, in Mt. Holly, NJ for those Tb'ers in NJ that want traction.

[Matt Dupuis]

Ah so..

Yeah, you've gotta read more Hot Rod type car magazines... they're all over the place.

[towerymt]

The 314 front axle true trac will paint 2 stripes all day long. It's just certain times in certain situations where one wheel drive may occur. Generally when I understeer, load the outside front wheel, unload the inside rear wheel (with 25mm rear bar pulling it up), and it may spin a tire. A hairpin type sweeper can do it sometimes, too. I remember one where I was trying to drift the exit and could only spin one tire. I wanted the car to turn (throttle steer).

[Matt Dupuis]

As a small-ish follow up, I installed the 3.31 ring gear on Dale's #411 diffy, and bolted it into the car. Smack on .005" backlash first try.

Now I've gotta get Dale another True Trac...

[Roguls]

Hey Matt, hows about a write up? What to buy, where to buy it kinda thing...that would alleviate me from doing any work when it comes time for me to do this mod (ha!).

Tell us how you like the thing too.

[stylngle2003]

Matt, you're a god for trying that for me....was that a 1031 or 1030 axle?

sounds like i've found the solution for my traction problems :badboy:

[Matt Dupuis]

Matt, you're a god for trying that for me....was that a 1031 or 1030 axle?

Um, says something about that right in the title, Billy...

It's an easier install than a Powertrax locker. Seriously! The bearings cost me $30, and I could have got 'em cheaper, and I got some new shims 'cause I wrecked the old ones. Measure up the old shims, keeping track of what thickness was used on which side of the old diff, install the same thickness on the proper sides of the True Trac, coat the inside of the bearings with grease, heat with a propane torch until the grease melts, press (hammer) the bearings on with a bearing race installation tool (or the proper tool of choice), and install. Best to check the backlash after you're done, but adjustment means pulling the bearings again so if you're really serious about setting it up perfectly, you'll need some checking bearings, which are basically brand new bearings that you ruin by honing out the inner race with a brake lathe hone so they slip on and off the diff.

There's your write-up! Sorry, no pictures.

I'm sure I'll love it, since so many others on the board have done it before me.

[mikep]

I use a dial indicator and two plates to compare the face to face width of the case at the bearing mounts, and the bearing race to ring gear face distance. That way I can change the shims in one shot. The new one is usually a little different from the old one.

[Matt Dupuis]

I messed with that when I was measuring the offset of the ring gear flange, but couldn't get an accurate reading. If I were setting up a number of them (and it looks like I will be) I would (should) make a rig to do the measurements.

[Tha VZA]

Dupuis when we do my diff we'll take pics and stuff complete with hands holding parts etc, measurements included on the picture

ciao

[Canuckvolvo]

The ugly duck, holding hands with the peacock. Oh my, you both had me at hello.

Can't wait for "diff" day, that means my car will be running!

[Tha VZA]

The ugly duck, holding hands with the peacock. Oh my, you both had me at hello.

:rofl:

ciao

[DaButcher]

I run the High preload TrueTrack in a 1031 axle, from a 92' 240.
The axle had 3.73 already.

I always thought (untill recently) that the diff would only work in a 3.73 -> without swapping the R & P.

However, I would have swapped for a 1031 anyways, as it's a bit more beefy and when buying a new differential, I dont see a reason to save some $$ on mounting it in a rear axle which may or may not handle the extra stress.

As always, LSD, wider tires, etc. will give you more strain on your driveline. (Transmission, Engine, indirectly tires and brakes).

Yesterday (Sunday); I drove my car on track.

My setup:
B6304FS engine, with AW30-43 transmission.
225/45-ZR17W tires on Eiker Polaris 17x7.5
24mm 264 swaybar in front, original in rear
Polyurethane bushings in front, original rear
GT-bars
Lower tie bars
OMP strut tower bar
Yellow konis (on full rebound setting)
Lesjöfors / K & N 45mm springs
2 x 20mm spacers (volvo original, as in my tutorial)

The car is great, accellerates great and is easy to control.
However, I have too much grip on the rear tires, vs. the front ones, which I think I have to adjust by adding a stiffer rear swaybar.

Especially on wet tarmac, I would like to have the rear a bit stiffer.

Or maybe I should just add spacers in front too? :P 2 x 10mm would work, I guess.

ps. 1" ~ 25mm


After some rounds with too little grip on front tires, vs. rear., I added some more tire pressure in the rear tires.. However, I dont think it's a good sollution for longterm, as my car is a street-car.

[mikep]

I wonder if the different ratio carriers are made for those numbers in an aftermarket gear?

[Matt Dupuis]

I think that's a bit of a stretch, Mike. Dana definitely uses different carriers for different gear spreads. To me it seems more logical that Volvo is the oddball, since we're only using a D30-based diff.

Hey, we're lucky enough to have options, am I right?

[OttoB]

From GPC web-catalogue (scans of volvo orginals) of 164 -75 which have 1031 rear-axle Volvo uses diff number 384727.
R-Sport catalogue offers same diff number for 120 and 140 series. (120 needs different spider-gears due different splines, not included)
164 (1031 and M31) has ratios from 3.31 to 3.73, and 120 and 140 uses M30, ratios 4,1, 4,56 and 5,38. So 384727 suits from 1031 with 3.31 to M30 with 5.38, why situation should be differnt with TT?

[740ATL]

you know... I know how a rear end works... I know what the gears do, I know what the shims accomplish, I know how lsd's work.... but it is readily apparent (to me) from this thread that I don't know my ass from a hole in a ground when it really comes to rear ends. I read this thread, and I see all sorts of numbers and ratios and my head hurts... whereas you guys converse fluently with total ease...

I rest easy knowing that one day, when I need to know exact numbers/details, threads like this will be in the archives.

my hat's off to y'all !

Mike

[Matt Dupuis]

I rest easy knowing that one day, when I need to know exact numbers/details, threads like this will be in the archives.
Maybe, but who'll ever look to find 'em?

[turbobrick211]

Speaking of 164 rear axles, I am trying to find out what the gear ratio is of the parts car I have, because I would like to swap it into my 240T and put a posi into it. It is a '75 with the M410 manual tranny. I would assume it is the 3:73, but I'd be stoked it it was a 3.31. Anybody know how to tell what I've got? I looked in the Volvo green book, and it just says that it either has a 3.31, 3.54, or 3.73.

[Matt Dupuis]

Support one wheel in the air and leave one wheel on the ground. Turn the wheel that's in the air so that the valve stem is pointing straight down, and note the position of the bolts on the differential pinion. Turn the wheel slowly two complete revolutions, and count how many pinion bolts go by. 3.31 will be 13, 3.54 will be 14, 3.73 will be 15, 3.91 will be almost 16, 4.10 will be 16.

[945ti]

Speaking of 164 rear axles, I am trying to find out what the gear ratio is of the parts car I have, because I would like to swap it into my 240T and put a posi into it. It is a '75 with the M410 manual tranny. I would assume it is the 3:73, but I'd be stoked it it was a 3.31. Anybody know how to tell what I've got? I looked in the Volvo green book, and it just says that it either has a 3.31, 3.54, or 3.73.
Look on ye olde axle tag like always?

[towerymt]

...but I'd be stoked it it was a 3.31.
3.31 are common. '83+ n/a 4cyl manual trans should be 3.31. Grab an '86+ for a 1031 w/speedo pickup.

[qwkswede]

Great post guys. I may be considering buying a True Trac this week considering my recent differential explosion. I'll probably put 3.31 gears on it and try to make my wagon get 25+ mpg. The pricey gas is and 100 miles a day commuting really make a person reconsider practical performance. Besides, it would be fun to see 130mph in the Volvo wagon.

[qwkswede]

Matt,
when you did the true trac install, did you buy any other parts to go along with the differential? I'm thinking about making an order from Randy's today, just wanted to get everything I'll need.

[qwkswede]

Right, that's what got me confused and lead me to buy the #374 for my 3.31:1 axle. It really doesn't work, but the #411 measures up just right.

The catalogue I have lists the #411 as a Volvo-specific part, but also specifies 3.73+. Once upon a time there was a 912A404, dana 30 rear 3.54-, but it's been discontinued.

They do list this 404 part at Randy's ring and pinion website. But I'm sticking to the #411 story.

[PRVersion]

Well on the 'wegian boards word is that you should always get the 411....:e-shrug:

that's because that's the truth :-P

[Matt Dupuis]

Matt,
when you did the true trac install, did you buy any other parts to go along with the differential? I'm thinking about making an order from Randy's today, just wanted to get everything I'll need.

We just bought differentials when we ordered them. You'll also need new carrier bearings and some shims if you nick/damage your old ones. I got those from a driveline shop locally. Also an inspection cover gasket if you don't keep 2 or 3 spares around like I do.

[qwkswede]

Are the carrier bearings a standard Dana 30 part that Randy's can supply? I asked them and they had them. Or is it a Volvo Carrier bearing? I'll probably get a set of ring gear bolts too.

[Matt Dupuis]

I'm really not sure. Since the carrier is a Dana 30, at least the inner race diameter must be the same, but I'm not sure about the outer and all the rest. I'm pretty sure they're the same as Dana 30 pieces... The pinion bearings are different on the 1031, that much I know.

[mikep]

Matt,
when you did the true trac install, did you buy any other parts to go along with the differential? I'm thinking about making an order from Randy's today, just wanted to get everything I'll need.
Just ask for the kit. It's worth it.

[hockey930]

Ben, Billy, Chris, is the 411 the new truetrack we were talking about at breakfast at SE?
Eamonn

[blkaplan]

no the 411 is not the new one....
iirc 568 is the new one?

[some guy]

close...
it's the 588 that's the new one:
http://store.summitracing.com/partdetail.asp?autofilter=1&part=DTL%2D912A588&N=700+4294925134+4294839047+4294918887+400949+4294 907702+115&autoview=sku

[hockey930]

wow, it's $460. How much were the old ones? Anyone know any cheaper places to get them?
Eamonn

[Matt Dupuis]

What's s'posed to be the difference?

[245gti]

What's s'posed to be the difference?

I think it's a good excuse to bump the price a bit for the same unit. Remember when I sent that one back and ordered the 411? I had to pay another $60 because the prices had just gone up...

[Tuff240]

The 314 front axle true trac will paint 2 stripes all day long. It's just certain times in certain situations where one wheel drive may occur. Generally when I understeer, load the outside front wheel, unload the inside rear wheel (with 25mm rear bar pulling it up), and it may spin a tire. A hairpin type sweeper can do it sometimes, too. I remember one where I was trying to drift the exit and could only spin one tire. I wanted the car to turn (throttle steer).
The 411 will do this also.
Experienced by both me and Lee Cordner on the same day at the same track in similar but different 242's.

[dl242gt]

The 411 will do this also.
Experienced by both me and Lee Cordner on the same day at the same track in similar but different 242's.

When I was crewing for my brother at Lime Rock and discussing traction with the Volvo ITB folks and Volvo Historic Series Volvo racers they all told me that the tru trac is good for the street but they all still spin the inside tire on tight turns. They told me that for racing they still like the clutch type units better because they can dial in the locking percentage to remove the spinning inner rear tire. No, they wouldn't tell me the locking percentage they use to dial out the spinning inner rear tire.

I'm very happy with my tru trac 314 and it is the worst one being the standard Jeep unit. I'd like to try another version with it's increased preload someday.

[hockey930]

Would the 388 still spin the inside wheel in tight turns? what is the advantage to haveing the 388?
Eamonn

[blkaplan]

Torsen diffs do not work if one wheel is off the ground and one is on the ground, so if your car gets light on the inside corner (almost off the ground) it will spin the inside...... Because of the torque "sensing" nature of the diff....

[hockey930]

diffrences between the 411 and the 588
- now works on a 3 pinion system
- steel case instead of cast iron- eaton says between the steel and the extra pinion it should be about %50 stronger then the 411
- Same preload as 411 from what I understand (100lbs)
- I am getting a phone call tomorrow to see if anything has been done about the speedo
Eamonn

[mikep]

Where did you get the 100# preload from?

From what I understood, the difference is in the angles in the gear teeth. No springs to preload, and not your typical clutch rotational preload to measure.

[Matt Dupuis]

I think it means 100 lbs-ft to slip without any torque input. They're preloaded with shims between the gears and case. The shims DO wear out, eventually, which is why drifting with a TT tends to loosen them up.

Good to know about the stronger version.

[hockey930]

Where did you get the 100# preload from?

From what I understood, the difference is in the angles in the gear teeth. No springs to preload, and not your typical clutch rotational preload to measure.


I know nothing about diffs, so I have no idea what I mean.
Eamonn

[mikep]

I know nothing about diffs, so I have no idea what I mean.
Eamonn
No, I was just wondering if you had a link for me to read.

[hockey930]

I called somewhere down here in the dirty south and found someone who said they would install the diff for 300-350 plus bearings and fluid. Is that reasonable? Do I have to change out the ring and pinion also?
Eamonn

[mikep]

That's a little high, and no, you re-use the gears.
What do they charge per hour?

[hockey930]

I have no idea what they charge, I think he said it was going to take them 5 or 6 hours. just how far away is Perry racing shop??

[Canuckvolvo]

Hopefully matt will chime in, but I'm pretty sure the last 2 diffs he's done (he's "doing" all the guys in Calgary) took him less than 3 hours each. He hasn't had to mess around with any shims afaik, so that will add time if required.

[hockey930]

The 588 does not have a custom tone ring. They just called me again.
Eamonn

[Matt Dupuis]

If all you're doing is slapping in the diffs like I am, yeah, it only takes a couple hours. If you're doing it properly, rebuilding the differential and replacing all the bearings in the pinion at the same time, 5-6 is probably not out of the question. Just doing the diff properly, with checking bearings and adjusting shims to get the perfect backlash, I'd say 2-3 hours tops.

[stylngle2003]

any info on this guy http://store.summitracing.com/partdetail.asp?autofilter=1&part=DTL%2D912A585&N=700+1006+400949+115&autoview=sku

912A585...reccomended for 3.73+ ratios. lots cheaper than the 588. maybe its a low preload version?

[mikep]

That's a front.
I filtered the search for : Front : Dana 30 :
http://store.summitracing.com/egnsearch.asp?N=700+400949+314530+4294902532+115+4 294902533&autoview=sku



I have no idea what they charge, I think he said it was going to take them 5 or 6 hours. just how far away is Perry racing shop??

From central NC? 8 hours or so. But Drew might be able to recommend some redneck stock car guys in the Mooresville area.

[hockey930]

Drew, do you know the proper redneck for the job?
Eamonn

[SteveMD]

Anyway, what I was trying to say/display is my new sig.

[mikep]

Funny, but Drew isn't here. Maybe on the SAE or NASCAR forums.
I have to call him.

[some guy]

That's a front.
I filtered the search for : Front : Dana 30 :
http://store.summitracing.com/egnsearch.asp?N=700+400949+314530+4294902532+115+4 294902533&autoview=sku


It's also a rear. Here's a search filtered for : Rear : Dana 30 :

http://store.summitracing.com/egnsearch.asp?N=700+400949+314530+4294902533+115+4 294902613&autoview=sku

:e-shrug:

[hockey930]

Mike that would be great if you would be willing to give him a call. I don't have any connections down here. p.s., that's a great sig!
Eamonn