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Speed sensor question and rear steer axle clarification

maveric

maveric

Squirrel Spotter
Joined
May 19, 2020
Member Number
221
Messages
162
Loc
Almost Wyoming
Couple Newb questions.
Helping a friend build a light weight buggy. So far, parts list includes small chassis (similar to a JHF), GM supercharged 3800 (L67 I believe), 700r4 with manual valve body, Behemoth 300 case, steer SD 60's F&R, 40's.

First, can anyone tell me if this combo needs a speed sensor? None of my crawlers have a VSS, so I don't actually know what it does, or if its needed in this application.

Second, for clarification, when using a front steer axle in the rear (rear steer), nothing has to be done to make it drive correctly? The output rotation on the tcase spins it correctly?
IIRC, flipping the housing was to make it run backwards for rear engine, but not needed to make a steer axle a drive axle. Am I correct?

TIA
 
Doesnt sound light...

Nothing special about running the front axle in the rear and you shouldnt need a vss.

X2 on the above 1st thought
 
YotaAtieToo said:
If you're the one helping him, and have these questions, he's probably screwed :flipoff2:

Doubt that engine needs a speed sensor, check the wiring diagram.

No, nothing magic to using a front axle in the rear.
Click to expand...
Thanks. And you are correct, he probably is.
 
2big bronco said:
Doesnt sound light...

Nothing special about running the front axle in the rear and you shouldnt need a vss.

X2 on the above 1st thought
Click to expand...
Light is relative. His old rig was probably around 4500, this one should be around 3k. Comp capable trail rig.

Reason I was asking about vss is the tcase comes with the option, and I read somewhere (can't find it now) about some engines needing the vss on tcase, others off the trans. Since I don't really know what perimeters are set by the vss (is it for shift points, or fuel settings on the engine, or engine will be set to limp mode without one?), I didn't know if he needed one. All my junk is old mechanical Toyota stuff, so have never dealt with it before.
I don't want to tell him he doesn't need the vss option, and then find that I steered him in the wrong direction.

As to the axle, I was sure nothing special was required, but I needed someone to tell me I'm not a "total" idiot, and confirm what I was thinking.
 
Assuming this is who I think it is, I'm confident the engine computer does want a speed sensor. It should run fine without but will probably throw a check engine light and will likely not run to peak performance without either a VSS or a tune to remove the VSS.
To the rear steer axle question, assuming driveshaft rotation is correct for a normal rear axle, run the steer axle right side up for what it is, and it will run the right direction. Depending on specific desires for rear axle, a VSS there might be easy, or in tcase output might be easier.
It is OK to call/text me with questions if you want too, I think you and your friend both have my number. I might even have a leftover or two.
 
From what I have seen, most guys that run non fab housings (60/14b or 60/60, 60/70) struggle to be at the 3k mark. Guys with toy 8in or 9in do much better achieving the 3k mark.
 
Not within the scope of your question, but there may also be GM VATS in the ECU (not sure when that started/stopped) and I do not believe he has the chip key/hardware to satisfy that. If it does have that, a tune or piggyback may be necessary to get it to run at all. That's a common item eliminated in tunes to make GM stuff run standalone.
 
06h3 said:
From what I have seen, most guys that run non fab housings (60/14b or 60/60, 60/70) struggle to be at the 3k mark. Guys with toy 8in or 9in do much better achieving the 3k mark.
Click to expand...
Really just shooting for as low as possible. Not set at 3k (the closer the better), just smaller/lighter/more agile than what he had before. (mostly full bodied 4runner, Supra inline 6, toy 5sp, duals and disconnect, 40's).
 
maveric said:
Couple Newb questions.
Helping a friend build a light weight buggy. So far, parts list includes small chassis (similar to a JHF), GM supercharged 3800 (L67 I believe), 700r4 with manual valve body, Behemoth 300 case, steer SD 60's F&R, 40's.

First, can anyone tell me if this combo needs a speed sensor? None of my crawlers have a VSS, so I don't actually know what it does, or if its needed in this application.

Second, for clarification, when using a front steer axle in the rear (rear steer), nothing has to be done to make it drive correctly? The output rotation on the tcase spins it correctly?
IIRC, flipping the housing was to make it run backwards for rear engine, but not needed to make a steer axle a drive axle. Am I correct?

TIA
Click to expand...
My 2002 ZR2 Blazer needs the speed sensor. Won't shift correctly without it. That is a fact.
Since I have ran a D70 for a rear steer axle since 2000, put it in and run it. I have 6* caster in mine and it tracks going down the hiway like a normal strait axle.
 
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