skid plate material...... Tcase/tranny

[jeff krause]

93' YJ looking to make a flat skid.. (it'll hang down maybe 2" from the rails but be FLAT and stout) ..I'd go total belly up but don really want to go looking for a HP rear axle.. or do a W.B. stretch...... I figure the 2" drop and flat ness is better than the 3plus " drop with a shovel.

QUESTION: 1/4 plate or 3/8" plate for the skid

I will make it like the stock skid..( tranny bolts to the skid directly)

QUESTION: COST for a 4 ft by 3 ft plate ??????

Jeff....

Got some pictures of your homebrew skid.. post um up

[westy]

3/8" will be thick enough -

[Craig]

I think 1/4 is overkill and 3/8 is just crazy. With the correct design and cross bracing, you don't need any more than a 3/16th thick skid. Hunter built the flat skid for my CJ, which I have beaten the living crap out of for the past 4+ years. It is 3/16 and is still almost flat. I do have the tranny mounted to a seperate removable cross member that gives extra support to the skid on big hits. If you do it right you can save the extra weight and still have all the strength you need. You'll also save a few $.

[Offroader5]

I think 1/4 is overkill and 3/8 is just crazy. With the correct design and cross bracing, you don't need any more than a 3/16th thick skid. Hunter built the flat skid for my CJ, which I have beaten the living crap out of for the past 4+ years. It is 3/16 and is still almost flat. I do have the tranny mounted to a seperate removable cross member that gives extra support to the skid on big hits. If you do it right you can save the extra weight and still have all the strength you need. You'll also save a few $.

Agreed....1/4" is more than enough with some strategicaly placed ribbing. I would say 1/4" or 3/8" if your using aluminum...but using steel, I would say more than 1/4" and your just adding weight without an added benefit of strength.

[xFallen]

93' YJ looking to make a flat skid.. (it'll hang down maybe 2" from the rails but be FLAT and stout) ..I'd go total belly up but don really want to go looking for a HP rear axle.. or do a W.B. stretch...... I figure the 2" drop and flat ness is better than the 3plus " drop with a shovel.

QUESTION: 1/4 plate or 3/8" plate for the skid

I will make it like the stock skid..( tranny bolts to the skid directly)

QUESTION: COST for a 4 ft by 3 ft plate ??????

Jeff....

Got some pictures of your homebrew skid.. post um up

Stock has a transmission mount that isolates the transmisison from the skid. I think you will want or even need this to avoid possible cracking of the housing.

I like Craig's (Hunter's?) approach of the separate cross member. This allows dropping the skid without having to support the drivetrain. Anything more than 3/16" is going to weigh a lot. My current one is 1/4" and while I can manage it myself it is tricky to Re & Re solo.

BTW, mine is bowed in the middle even though it was ribbed and had bent edges. My next one will likely be 3/16" but with appropriate reinforcement and a separate cross member for the drivetrain.


Barry

[YGOHOME]

...and a separate cross member for the drivetrain.

Barry

are you describing the single crossmember bar going from the inside of the frame rail to the other inside frame rail... with bushings at the frame end (not at the drivetrain)? Having the bushings at the frame instead of at the tcase would free up valuable space and allow a slightly lower driveline angle while maintaining a perfectly flat skid.

do you have a link or photo of the one youve seen (hunter's or craigs)?

Thanks,

Ben

PS. Then I just need to get with a shop to do the work for me :)

[OlneyJeeps]

we have a 4x4 slab of tempered 1" (ok it's in AK):eek:
took three of us to get up on saw horses
its an old commercial griddle!!
made a great auto trans building bench (complete with grease/oil drain):D

seriously I would think 1/4 properly braced would be more than enough. I'm making one for project commando and it will have high dollar super tough super slippery plastic skid stuff you see on lots of the high dollar rigs (I've spent almost $3 and have almost enough to cover skid:D

[xFallen]

are you describing the single crossmember bar going from the inside of the frame rail to the other inside frame rail... with bushings at the frame end (not at the drivetrain)? Having the bushings at the frame instead of at the tcase would free up valuable space and allow a slightly lower driveline angle while maintaining a perfectly flat skid.

do you have a link or photo of the one youve seen (hunter's or craigs)?

Thanks,

Ben

PS. Then I just need to get with a shop to do the work for me :)

I do not have pictures to post at least not without permission but maybe Craig can post if he has some, or John, or one of the other people who have built these.

I would think bushings at the frame end would be sufficient, which means hard mounting the cross member to the transmisison. However, the ones I have seen that are flush and flat are using both. The bushings on the cross member to frame interface are stiff polyurethane bushings and therefore quite rigid. The stock rubber bushings is modified to fit to the cross member.

You can do this and still get it 100% flat and flush between the frame rails with a 1+" BL and 1" MML, and maybe a bit of clearancing. Stock wheelbase without a good short SYE may cause less than ideal driveline angles. Nobody I know who has built these has had that trouble due to a proper short SYE or extended wheelbase.

I think you could get away without the cross member to transmission bushings if the frame bushings flexed about as much as the motor mounts. But, why not incorporate the stock mount if possible since it works nicely. I am sure ride quality will suffer without the stock mount due to additional vibrations being transmitted to the driver if that is a concern.

I would be concerned about cracking the transmission housing without the factory style lower bushing or something similar. Wrangler bodies and drivetrain twist a lot. The body flexes a rather serious amount in relation to the drivetrain, and the drivetrain moves around a lot too, enough for fans to take out fan shrouds, and for transfer case linkages to pop out of the tub side mount. Have a look and grock just how much twisting that entails. Hard mounting, well, all that energy has to go somewhere.


Barry

[Craig]

The tranny crossmember is a must have. The ability to drop the pan is really nice for servicing everything without having to worry about supporting the whole drive train.

Here are a couple of pics;

http://www.virtualjeepclub.com/attachment.php?attachmentid=8899&stc=1&d=1167462444

The first one shows a partial pic of the crossmember. It is two bushings mounted to each side of the frame. There are two pieces of tube with a plate in the middle which bolts to the tranny. At first I had the tranny bolted directed to the steel plate, thinking the bushings at the frame would provide enough give. That didn't happen and I kept working the bolts loose, so I cut down some old spring bushings and ran some longer bolts through to the tranny to allow just a little more give. This is a V8/auto and the motor is mounted with bushings like the crossmember. If you are running stock motor mounts make sure you build a little more give into the tranny mount.

http://www.virtualjeepclub.com/attachment.php?attachmentid=8901&stc=1&d=1167462444

This next one shows a top view of the skid. It is actually three pieces of 3/16 steel on the bottom. It is not perfectly flat, as the center section overlaps the two sides, but the seams run front to back and don't hang on anything. The overlap adds some extra support as well. Notice the stiffeners at the rear. They come up right behind the D300 which is clocked flat. My ladder bar is mounted to the skid as well. The crossmember hits right in the center of the skid plate for that extra support.

http://www.virtualjeepclub.com/attachment.php?attachmentid=8902&stc=1&d=1167462444

This shows the mount for my two piece front drive shaft, a skid for the tranny, the frame rail mounts and the small drop bent into the skid needed to clear everything as I do not have a body lift on the rig. A one inch lift would have allowed for a completely flat skid.

http://www.virtualjeepclub.com/attachment.php?attachmentid=8900&stc=1&d=1167462444

This just shows how the drive shaft mounts and some of the skid plate mounts.

[Craig]

Here is a crappy one of the crossmember.

http://www.virtualjeepclub.com/attachment.php?attachmentid=8903&stc=1&d=1167464887

Some others

http://www.virtualjeepclub.com/attachment.php?attachmentid=8904&stc=1&d=1167465216

http://www.virtualjeepclub.com/attachment.php?attachmentid=8905&stc=1&d=1167465216


That should give you some ideas.

[YGOHOME]

excellent. thank you