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Dzimm

92 Turbo, Autocross MJ

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This project can finally begin!  I sold my 2 door XJ and picked up this 92 MJ yesterday.  It's got 4.0l, AX15, and 2wd.  The truck has 177k miles on it and runs great.  PO recently replaced the clutch and master cylinder, new tires, alignment, brakes, tune up, lower ball joints, exhaust, and blower motor. 

 

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It's got rust through the rockers, the drivers cab corner, and the passenger side of the bed.  The previous owner replaced all the floors and they are in perfect shape still, which is great.  Funny thing about the PO, he owned my other MJ at one point as well, he sold it to the guy I had bought it from.  

 

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Plans for this truck so far: 

- perfect driving a standard as I'm not the best

- replace windshield

- replace blower switch and resistor

- replace drivers window regulator

- replace door locks

- headlight switch wiring and upgrade

- repair rust

- lower it by cutting the front springs and making a bastard pack for the rear

- change to bucket seats

- find or make an airdam

- build a cage/harness bar

- work on thinning out unnecessary things in the engine bay

- turbo!! 

 

This will be a very slow build and likely won't make a ton of progress until next year.  For the rest of this year I will just be fixing anything wrong with it and driving to work since it gets better mpg.  

 

It looks so tiny next to the lifted MJ. 

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These last few pictures I pulled from the ad. 

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Check with your local series sponsor as to what their safety requirements are. I find that different sponsors interpret the SCCA 'box' a little different from each other. Hate to see you build it, then have to run in a different class or not be able to run at all.

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16 hours ago, whowey said:

Check with your local series sponsor as to what their safety requirements are. I find that different sponsors interpret the SCCA 'box' a little different from each other. Hate to see you build it, then have to run in a different class or not be able to run at all.

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Thanks for the tip.  I have looked previously and what I could find seemed to just require simple stuff like a helmet.  I should probably just get ahold of them and see exactly what the requirements are, especially since eventually I won't be naturally aspirated. 

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Thanks for the tip.  I have looked previously and what I could find seemed to just require simple stuff like a helmet.  I should probably just get ahold of them and see exactly what the requirements are, especially since eventually I won't be naturally aspirated. 
I have a SCCA club and a MSCC club local to me. The SCCA affiliated club adheres to the 'box' and classes strictly. No Comanche would be allowed to run on any class stock. But the MSCC club would let a stock 2wd run in the H class if you had a current DOT approved helmet and seat belts.

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3 hours ago, whowey said:

I have a SCCA club and a MSCC club local to me. The SCCA affiliated club adheres to the 'box' and classes strictly. No Comanche would be allowed to run on any class stock. But the MSCC club would let a stock 2wd run in the H class if you had a current DOT approved helmet and seat belts.

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Yeah from the research I've done it seems that trucks and SUVs fall into a gray area in autocross classes because they really don't want top heavy vehicles out there.  Being lowered may change what classes I'd be allowed to run in but like you said, some places could be super strict.  

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Did the first repair on it today.  Removed the heater hose valve because it was leaking really bad.  Turns out that one of the connections on it was completely desintegrated.   Put some straight connectors on the hoses and plugged the vacuum line.  

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From what I remember the SCCA has a width/height ratio they abide by to determine whether or not something can run. I know my 4x4 MJ was too tall, likely a 2wd at only an inch lower would be as well. But there was a bit of a kerfuffle a couple years ago when it was discovered the Fiesta actually didn't meet the criteria, disqualifying some very competitive racers. I don't know if they've changed anything because of it though.

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From what I remember the SCCA has a width/height ratio they abide by to determine whether or not something can run. I know my 4x4 MJ was too tall, likely a 2wd at only an inch lower would be as well. But there was a bit of a kerfuffle a couple years ago when it was discovered the Fiesta actually didn't meet the criteria, disqualifying some very competitive racers. I don't know if they've changed anything because of it though.
That's the box, I was referring to. Basics of it, is that track width must be equal or larger than height. No XJ/MJ meets it by stock specifications. The lowest classes of racing don't allow suspension modifications enough to lower them into compliance either.

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18 hours ago, whowey said:

That's the box, I was referring to. Basics of it, is that track width must be equal or larger than height. No XJ/MJ meets it by stock specifications. The lowest classes of racing don't allow suspension modifications enough to lower them into compliance either.

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Hmmm interesting.  So if I run like stupid wide wheel spacers I'm good?  Lol.  What limitations are their on suspension modification? 

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The SCCA has a large .pdf on their website under the Auto X section about the classes and what is allowed. I was concentrating on the lowest classes as I wanted something fun to play with a few weekends a year, while being able to drive it the rest of the summer. The lowest class 'H' allows only factory available configurations. This includes engine and transmission changes also. Brake modifications are a little more generous in the lower classes. My local SCCA club safety officer helped me determine that a 2wd MJ/XJ would never meet the lowest two classes because drop spindles and/or coil changes aren't allowed.

 

The other side of that coin for you, is that drivetrain changes are limited at the lowest classes. Because you want a turbo, you would automatically have to move to a different class for forced induction. You can really build stuff out in some of those classes.

 

In my case, because I wanted to stay down in H or HS, it was a better decision to get something that wouldn't take a ton of work to get me racing. I ended up buying a Focus and adding the ZX4 suspension to it. Then my oldest shanghai'ed it to drive to college because it got better fuel mileage than her nice safe GM sedan.

 

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8 hours ago, whowey said:

The SCCA has a large .pdf on their website under the Auto X section about the classes and what is allowed. I was concentrating on the lowest classes as I wanted something fun to play with a few weekends a year, while being able to drive it the rest of the summer. The lowest class 'H' allows only factory available configurations. This includes engine and transmission changes also. Brake modifications are a little more generous in the lower classes. My local SCCA club safety officer helped me determine that a 2wd MJ/XJ would never meet the lowest two classes because drop spindles and/or coil changes aren't allowed.

The other side of that coin for you, is that drivers changes are limited at the lowest classes. Because you want a turbo, you would automatically have to move to a different class for forced induction. You can really build stuff out in some of those classes.

In my case, because I wanted to stay down in H or HS, it was a better decision to get something that wouldn't take a ton of work to get me racing. I ended up buying a Focus and adding the ZX4 suspension to it. Then my oldest shanghai'ed it to drive to college because it got better fuel mileage than her nice safe GM sedan.

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So I just looked at the rulebook and from my understanding, it doesn't look like adding forced induction is allowed in any of the "street" classes.  First mention of it being allowed I see is in section 17 for "Prepared."  Even suspension and seat modifications don't seem to be allowed at all in street.  For instance, there is a rule that carries through the street classes that you cannot reduce the amount of seats in the vehicle (I'm assuming to negate weight reduction) but since my truck has a bench seat, does that mean I can't put buckets in it because it reduces the number of seats?   

 

I even noticed some rules stating you have to use oem replacement parts when available and can only use aftermarket parts if you can prove that oem parts aren't available anymore, not that they would ever know something isn't oem.   I didn't realize the rules were so strict on stuff. 

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Contacting your local club and it's safety officer is really your best bet. The one I spoke to was really helpful for me understanding the differences in classes. And for a general understanding why the XJ/MJ I saw in Auto X were built the way they were and the classes they competed in.

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6 hours ago, whowey said:

Contacting your local club and it's safety officer is really your best bet. The one I spoke to was really helpful for me understanding the differences in classes. And for a general understanding why the XJ/MJ I saw in Auto X were built the way they were and the classes they competed in.

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I've been talking with the rules guy of the local group and he said that most trucks he sees just run smaller wheels/tires to fit in the street classes.  He saw no reason a Comanche couldn't be run stock with smaller wheels.  I measured my truck at 68" track width and 71.5" tall so I'd have to get different offset wheels and shorter tires to run stock since like you said, the rules require equal or greater track width compared to height. 

 

There is an event Sunday at the Iowa Events Center I am going to try to make to get to see what it's all about and ask some questions.   

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Arguably going from a bench to buckets is an increase in the number of seats, just not the max number of legal belted occupants. :grinyes:

It makes sense that suspension and power mods would automatically bump you into higher classes, because those are the two biggest ways to make your ride a ton faster, and it would get tough to draw a line between things that won't help much and things that will help a ton, because a lot of it is stuff that, depending on what you do with it, could do both. 

 

Going with 4-cyl springs would lower you a touch without violating the non-factory parts rule. The wider wheels can make a huge difference too. I just picked up a 2.5L MJ that has I believe Core racing (per the PO) wheels on it, that look like they add almost two inches to my width.

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Got some work done on the truck today.  Idk if the previous owner had He-Man  tighten everything down or what but every bolt and plug were super freakin tight.  I was really worried about snapping the oil drain plug off. 

 

Started out by installing a headlight harness.  This is the first one I've installed that I actually screwed the relays to the fender.  I usually just zip tie them to something. 

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I also changed the oil, which smelled really bad, I'm guessing it hadn't been changed in a while, and replaced oil pressure sensor because the gauge was going haywire.  When the heater hose valve was leaking, it covered the sensor and I was pretty sure that's what was causing my problems.  The new sensor however, only reads between 70-75psi no matter what the engine is doing.  I'm hoping the sensor is bad out of the box.  I really don't like how the oil filter is vertical on the older Jeeps, how is there not just a giant air pocket in it? 

 

I went through and cleaned some of the electrical connectors and grounds under the hood.  Before doing the ground on the block, my battery gauge only read 12ish volts while the engine was running.  Now it's reading 14.  

 

The truck came with a new fuel filter so I went ahead and threw that on.  I had to put a zip tie between the bracket and the fuel filter to make it tight in the bracket. 

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The last thing I did was change the fluid in the trans.  The trans was grinding while at half throttle in fifth gear.  When I pulled the fill plug out, fluid came pouring out the fill hole.  It must have been filled through the top of the trans because it had at least 4 quarts in it.   There was some metal flakes in the fluid and it was pretty dark and stank as well.  I filled it back up with Redline MT-90 and now it shifts like a dream, doesn't grind in fifth, and feels much more responsive.  

 

While doing the trans fluid change, I noticed that there was what looks like some kind of sealant around the clutch fluid line where the plastic line meets the metal fitting.  Is this normal?  I can't imagine a pressurized fluid line would depend on a connection like this.  

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