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Race truck 4653

Penetrode Offroad said:
How's your LCE engine doing? Squirrels doing ok?
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Its a YotaShop engine and its been great.

Getting ready for the next race!
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Pennsylvania was a rock race! We started off the week with a tour of Big B Motorsports' shop and some pre-running. During pre-running we lost an alternator belt, swapped it out on the course and headed back to prep for qualifying the next day. We took it easy during qualifying and started the main race in the back. We got the green flag and we were off. We got help winching from other racers at the first big obstacle and continued on course winching and crawling. I jammed the truck up between some rocks on the last big obstacle coming back towards the start finish. My co driver and U4 recovery got us unstuck and moving again. Headed into lap 2 with no issues. During lap 2 I hit a stump with the front axle, broke the leafspring center pin and pushed the axle back. The next time the axle hit the bump stops it pushed the driveshaft into the t-case and boom! We had all neutrals, the rear case was bound up and we were not able to get the truck in 2wd to continue. Overall we had a great time with great people.
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richardskinner said:
damn! Any pics of the case? Cracked?
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I don't have any good pics right now. I will get some posted shortly. I do have a photo of all the gear oil leaking out lol. I also lost the fuel filler cap, this caused the fuel pump to get loud. I would switch to the other pump till it started making noise then back to the other one.
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chaplinfj60 said:
what is this fix... because this happened not too long back if i recall.
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I dug back. This thread is awesome. Thanks for posting it PBR. Lots of lessons to learn.

Provience said:
Sometimes it is easier to check your gears from the outside, not during a race normally, but whatever! :laughing:

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Pitbullcruiser said:
I think it was the new axle housing and driveshaft plus the 30 year old tcase housing. I ran the same driveshaft last year bottoming out with no shocks for a few hours with no breakage. Lesson learned, measure dummy.
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First time doesn't look like much more than measure the driveshaft well. Shearing a centering pin -- would it be craziness to drill 2 more centering pins? I see axle perches with multiple pin holes so people can move their axle, but what if you threw two extra pins through the pack?

I think ubolt eliminators would hold the axle from shifting as much even if the pin sheared. Those might help. I have them on my rear axle and it definitely stays in place better than u bolts. I hate u bolts. Only time before I go eliminators on the front.


Also, PBR, are you carrying a spare third member? Looking back for that Tcase failure I realize how many 8" R&Ps you've fried while racing. Seems like for KOH length race, that wouldn't be bad to have in the bed. You might be able to find an old axle to cut the center section out of then weld end caps onto to make a mount that will hold the third member and keep dust out of it.
 
richardskinner said:
First time doesn't look like much more than measure the driveshaft well. Shearing a centering pin -- would it be craziness to drill 2 more centering pins? I see axle perches with multiple pin holes so people can move their axle, but what if you threw two extra pins through the pack?
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ubolts probably need to be a replacement item after every race. i bet they stretched and then loosed then DNF.

any signs that the bumpstop is not striking or sliding off the pad?
 
I've found the same thing with 4 - 5/8" bolts vs ubolts. I had a center pin practically fall out and the axle never moved.

With the u bolt eliminators, you could actually torque the bolts, with u bolts they never seem to really tighten up.
 
richardskinner said:
I dug back. This thread is awesome. Thanks for posting it PBR. Lots of lessons to learn.





First time doesn't look like much more than measure the driveshaft well. Shearing a centering pin -- would it be craziness to drill 2 more centering pins? I see axle perches with multiple pin holes so people can move their axle, but what if you threw two extra pins through the pack?

I think ubolt eliminators would hold the axle from shifting as much even if the pin sheared. Those might help. I have them on my rear axle and it definitely stays in place better than u bolts. I hate u bolts. Only time before I go eliminators on the front.


Also, PBR, are you carrying a spare third member? Looking back for that Tcase failure I realize how many 8" R&Ps you've fried while racing. Seems like for KOH length race, that wouldn't be bad to have in the bed. You might be able to find an old axle to cut the center section out of then weld end caps onto to make a mount that will hold the third member and keep dust out of it.
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Good suggestions, I am going to keep the same setup for this season. Most of these problems have been caused by driver error not parts failure lol.
 
mobil1syn said:
ubolts probably need to be a replacement item after every race. i bet they stretched and then loosed then DNF.

any signs that the bumpstop is not striking or sliding off the pad?
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U-bolts are a consumable item and we swap them out often. Maybe not often enough?

Yes, the bumpstop was hitting the forward facing U-bolt nut not the center of the plate.
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It might be overkill, but you could add a second stock slip section at the case with a fuse bolt that would shear if the main slip yoke bottomed out. I think I'd rather to that vs drilling more holes in the springs. Or cables from the spring plate to the front hanger taped to the top of the main leaf to maybe catch it if one shears again.
 
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mobil1syn said:
ubolts probably need to be a replacement item after every race. i bet they stretched and then loosed then DNF.

any signs that the bumpstop is not striking or sliding off the pad?
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I've always been on the other side of the fence - new ones seem like they need to be torqued repeatedly till they hit their point of being 'broken in.' I never wanted new ones in before a race and tried to stick with my broken in old ones. If they have to come out, they get cleaned up with a tap and die, then back in they go. Can't say I've had issues with ubolts loosening up with that method
 
desertPOS said:
I've always been on the other side of the fence - new ones seem like they need to be torqued repeatedly till they hit their point of being 'broken in.' I never wanted new ones in before a race and tried to stick with my broken in old ones. If they have to come out, they get cleaned up with a tap and die, then back in they go. Can't say I've had issues with ubolts loosening up with that method
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That makes a lot of sense to me.

I always ran U bolt eliminators on my toyota axles with out issue. When I went 60s, I went with ubolts and couldn't seem to get those new ones to really tighten up like the 5/8" bolts would.

I'm sure there is a point of them stretching too much, but that ls got to be more than a few races.
 
If ubolts stretch, the thread pitch changes. How does a tap “unstretch” them? A tap should be used to cut, or recut damaged, threads. It should not be used as a die to reform stretched threads.

That’s where I’m getting lost. But I may be wrong.

Unbolt eliminators shorten the lever arm between the spring perch and the spring plate. They also tighten up the gap between the spring perch and the bottom of the leaf to more accurately represent a shear plane, rather than ubolts that have a much longer arm and rely on defeating a large bending moment placed on the much longer shank of the the u bolt. That seems like a big mechanical advantage to eliminators, but ubolts may work fine if you are a diligent driver.

I am not.
 
richardskinner said:
If ubolts stretch, the thread pitch changes. How does a tap “unstretch” them? A tap should be used to cut, or recut damaged, threads. It should not be used as a die to reform stretched threads.

That’s where I’m getting lost. But I may be wrong.

Unbolt eliminators shorten the lever arm between the spring perch and the spring plate. They also tighten up the gap between the spring perch and the bottom of the leaf to more accurately represent a shear plane, rather than ubolts that have a much longer arm and rely on defeating a large bending moment placed on the much longer shank of the the u bolt. That seems like a big mechanical advantage to eliminators, but ubolts may work fine if you are a diligent driver.

I am not.
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I don't think he means they are stretching enough to make them a different thread :laughing:

I think he's probably just cleaning up wear on the threads from rubbing leafs or plates.

I'm with you on the bolts vs u bolts, I prefer bolts.
 
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