Craig Miller
Posts:11803
 | | 04 Oct 2011 10:31 PM |
| I'm debating front/rear True Tracs vs Detroit rear/TT front. To those of you who have had or currently have a Detroit in the rear of an AWD vehicle does it cause understeer when pushing through a long corner (E.g. freeway exit)? Craig |
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Keith
Basic Member
Posts:163
| | 05 Oct 2011 06:22 AM |
| Just don't get on the gas until you're mostly through the corner. The way I understand it is that it'll lock up when you apply power through a turn, so yeah it might push a bit |
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Ricky
New Member
Posts:4
| | 05 Oct 2011 07:06 AM |
| I've been running a automatic locker since last April in my daily driver/wheelin' and exploring rig. You do feel it in the steering but it's in no way a big deal. Like stated above I try to stay off the gas in the corners so the locker will be disengaged. The advantages of the locker for me have far out weighed any issues in driving with it to and from work etc ........... Rick |
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Mike Rupp
Veteran Member
Posts:1355
| | 05 Oct 2011 07:50 AM |
| Craig, I've had the Detroit / TT combo in my D1 for about 10 years. As your aware, it is always an interesting discussion about a Detroit in the rear of a truck. Two things complicate issues: AWD / RWD and weight distribution. Since the D1 / RRC is very rear heavy and has AWD, it behaves completely differently than in a conventional truck with part time 4WD that runs in RWD while on-road.
The Detroit has absolutely zero effect on handling when the truck doesn't have the cdl engaged. Since the truck is so rear heavy, the Detroit rarely gets any power to it. I've never had any type of understeer even in snowy conditions.
Most people are concerned with getting a Detroit in the rear of a D1 / RRC because of the horror stories from somebody that had a short wheelbase Jeep or some other truck, but if anything it is the TT that you should give thought to. Since most of the power is headed to the front diff, the action of the TT makes more of a difference in handling than the Detroit ever will.
In the early days of modifying the D1s / RRCs, the conventional wisdom was that the TT was an elegant solution to correcting the caster problems of a lifted truck. Since the TT partially engaged when there is power to it, it self centers. The big downside to this is that when power changes to the diff, the amount of self-centering / torque biasing changes as well.
Let's say you are in a long turn and have the gas pedal down to maintain speed. The diff wants to go straight even though you are in a turn. It doesn't really matter too much until you change the power going to the diff. If you suddenly let off the power, the steering wheel is going to change directions. It's not a big deal once you are used to it, but it is a definite downside to the TT. I think the ideal setup would be a Detroit rear / front ARB. The handling would be great on road and you'd obviously have wonderful traction offroad.
If you are ever down this way, shoot me an email. You can drive my truck and get a sense of how the handling would be in your RRC. |
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Benny Benson
Veteran Member
Posts:1681
| | 05 Oct 2011 07:53 AM |
| I wouldn't worry to much about the locker in the rear. While never having drove an AWD vehicle with a locker in the front I'd be more worried about binding in the front while turning slowly, say into a parking spot. or turning a corner from a stop. |
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Craig Miller
Posts:11803
| | 05 Oct 2011 08:15 AM |
| Thanks Mike. Yes, you're right about the discussion always getting interesting when people chime in with non-AWD experience.  This post was mostly targeted at you, Dan, and Todd since I know you've all run one or both of these setups in your trucks. I had dual ARBs in my DII. On this truck, I'm trying to do things as simply as possible (mechanical instead of vacuum/air). The dual ARBs *did* behave beautifully though. I really liked being able to control exactly when and how the truck locked up. I also really liked that it was completely open when driving on compact snow/ice, or twisting/turning through the trees on the trail. Anyway, your input is really good. Thinking out loud here... If I go ARBs I'd probably go dual ARBs again. I guess one advantage of going DL i the rear and ARB in the front is that both axles aren't dependent upon the air compressor working. Guess I need to mull this over a bit. Yeah, I should swing by and drive your truck sometime. That would probably tell me all I really need to know. Craig |
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Craig Miller
Posts:11803
| | 05 Oct 2011 08:17 AM |
| Posted By Benny Benson on 10/05/2011 7:53 AM I wouldn't worry to much about the locker in the rear. While never having drove an AWD vehicle with a locker in the front I'd be more worried about binding in the front while turning slowly, say into a parking spot. or turning a corner from a stop.
No worrries Benny. I'll put either a LSD or ARB in the front so it'll handle well around town and in the twisty's on the trail.
Craig |
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Craig Miller
Posts:11803
| | 05 Oct 2011 08:19 AM |
| Posted By Rick Mattick on 10/05/2011 7:06 AM I've been running a automatic locker since last April in my daily driver/wheelin' and exploring rig. You do feel it in the steering but it's in no way a big deal. Like stated above I try to stay off the gas in the corners so the locker will be disengaged. The advantages of the locker for me have far out weighed any issues in driving with it to and from work etc ........... Rick
AWD like a Land Rover or 2WD/4WD like most 4x4s?
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Mike Rupp
Veteran Member
Posts:1355
| | 05 Oct 2011 08:39 AM |
| Posted By Craig Miller on 10/05/2011 8:15 AM
I guess one advantage of going DL i the rear and ARB in the front is that both axles aren't dependent upon the air compressor working. Guess I need to mull this over a bit.
Craig
That's my thinking. Since the Detroit is going to do the most amount of work when the cdl is engaged, you'd still have good traction if the compressor / airlines / switches / etc. died out to the front ARB. You have to weigh that against the benefits of a rear ARB (better maneuverability when CDL engaged, etc).
Here's how I'd rank them: 1. Detroit / ARB 2. Dual ARB 3. Detroit / TT The one thing that I've realized, though, about the Detroit / TT setup is that while it acts oddly at times because of the TT, if the truck is a daily driver, you really get used to it and you don't even notice it. When driving, you correct your driving to compensate for the TT sub-consciously. Since my mother in law has been in town for a while, I've been driving my D1 almost daily. Now it just drives normally, if that makes sense. |
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Craig Miller
Posts:11803
| | 05 Oct 2011 08:59 AM |
| It does make sense.
My concern isn't me so much as Julie. I generally prefer to limit the modifications to keep it comfortable for her to drive if necessary. Need to mull that decision over a bit, but I have time since I'll probably do the rear axle before the front anyway. I still need to acquire HD front halfshafts, and CVs before I upgrade the diff. I may just leave the front open and put a Land Rover genuine military 4 pin diff in the front and call it good.
Craig |
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Mike Rupp
Veteran Member
Posts:1355
| | 05 Oct 2011 10:56 AM |
| Does your Rangie have the 10 spline or 24 spline drivetrain?
For what it's worth, I never upgraded to having HD CVs / inner shafts. I think most people don't run into issues with the standard front LR 24 spline stuff even with lockers on 235/85/16s. I bounced all over Moab and never popped a CV. In terms of priority, it was always lower down the list to upgrade the front end.
If you want to have a nice, easy to drive truck as well as having good performance on the trail, a rear Detroit with HD axles and front open would be a decent option. |
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Craig Miller
Posts:11803
| | 05 Oct 2011 02:57 PM |
| I converted the front to 24 spline w/ Disco hubs. I have all the parts, including HD RoverTracks axles to convert the rear, but want to pickup the locker and HD rear driveshaft before doing the work. Basically, I'm lazy and only want to do it once.
Interesting info on the front end. I was thinking about slowly putting in a HD driveshaft, stronger diff, HD CVs, HD inner shafts, and leave the easy to change outer shafts stock... then drive it and decide later if I want a TT or ARB in the front.
Craig |
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Mike Rupp
Veteran Member
Posts:1355
| | 06 Oct 2011 10:31 AM |
| Well, the nice thing about a RRC with Natos is that you can change the rear axle shafts in 5 minutes if you are going slow. FWIW, I run a LR SWB RRC ujoint driveshaft in the rear and have never had an issue with it. If I remember correctly, you have a standard OME lift, right? Are you running the stocker front driveshaft? If you don't have vibes, I would just leave the front driveshaft alone. The weak link in the front end is the factory diff and then the CVs. I'm not quite following you on "leave the easy to change outer shafts stock." The outer axle stub is part of the CV on the 24 spline setup, unlike the 10 spline. We should try to get together at a meet-and-greet so we can have a beer & driveline discussion. |
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Craig Spaeth
Basic Member
Posts:439
| | 06 Oct 2011 02:54 PM |
| I want in on that discussion. I really like the idea of some kind of rear diff lock. The front is intriguing but it is much further down on the priority list. How to build the most dependable RRC driveline without extra stuff is very high on my priority list.
the other Craig |
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Craig Miller
Posts:11803
| | 06 Oct 2011 03:24 PM |
| You're not following me because I was confusing the 10 spline and 24 spline setups.
Yep, running a 2" OME XHD lift, w/ NATOs, and 235/85-R16s. Old 1" skinny driveshafts front/rear going to an older LT230. 24spline D1 hub/axle/diff conversion on the front end. Haven't done the rear end yet, but have the hubs, HD Rovertracks axles, etc to do the conversion.
Nope, no vibes yet, but it's an ancient front driveshaft. I'd like to get out ahead of it a little, but plan to leave the front end as-is until I get the rest of the truck squared away. I'll consider running a SWB RRC driveshaft in the rear that's newer than 1987.
Beer and driveline talk is always fun! Dan and I have both been absolutely buried or we would have setup another meet and greet by now.
Craig |
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Mike Rupp
Veteran Member
Posts:1355
| | 06 Oct 2011 04:47 PM |
| I hear ya. I'm in night classes three nights per week.
Other Craig, I can't remember exactly, but I thought that the LWBs have 24 spline drivelines. If that is the case, setting up the rear is simple. All you need is a new diff carrier such as a Truetrac, ARB, or Detroit and some axle shafts. Some people would argue that you don't need the HD axles shafts, but I've seen them pop like toothpicks. |
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Craig Spaeth
Basic Member
Posts:439
| | 06 Oct 2011 09:16 PM |
| I was told that the 93 LWB usually has the 23 spline but it depended on the build date or something of that nature. I am not sure of the reliability of the source though. I will need to get in there and find out. I am just running 245/75/16 so a little less diameter than the 235/85/16, didn't think the diesel could push them very well. The rest of mine is almost identical to Craigs, OME hd 2" lift.
the other Craig |
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Craig Miller
Posts:11803
| | 08 Oct 2011 11:52 PM |
| Ashcroft and others have recently started carrying "Kaiser" lockers. They are fully mechanical like a Detroit. I'm now considering Kaiser's front/rear or Detroit rear w/ a Kaiser in the front. These are new though, so I'm going to have to ponder it a bit. Ian Gregory did a write up on them on D90 Source. |
 Attachment: Ian_Gregory_about_the_Kaisers.pdf
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Tom Lowell
Advanced Member
Posts:589
| | 24 Oct 2011 11:00 PM |
| Craig, I originally had an Eaton posi in the rear but two months after warranty was up a clip broke and the whole thing got eaten up (no pun intended). While mulling over what to do next, I finally said screw it, go with a Detroit. It's been 3 seasons now ('09. '10, '11) and only one wierd thing has happened; Northgate on ramp to northbound I-5 on wet day--that on ramp is a very tight radius 180--the van went into a slow easy powerslide. I was running my Wrangler MT's at the time. It was so slow, I decided to go with it and ended up drifting the entire corner while Jen grinned and rolled her eyes. On the one hand, it was a suprise; on the other hand it was slow and a super tight radius on-ramp. Other than that one time, I've never noticed any pushing or sliding. For the record, my van is not AWD any more, it is either 2wd or 4wd with the 4x4 only engaged in the dirt, or snow, of course. The Detroit is clunky, it's loud and proud, and it crawls up Fortune Creek like an army tank. |
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Craig Miller
Posts:11803
| | 24 Oct 2011 11:06 PM |
| Thanks Tom. I'm just not sure what I want to do. Still mulling. |
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