Broke another RP axle....

749 Views 16 Replies 8 Participants Last post by powermaxx, May 12, 2005

powermaxx

Discussion Starter · May 8, 2005

This time it was the passenger side (see my other thread on this) What is going on here. I'm not making that much power up here at 5800ft altitude. I recentered the engine very carefully this time when I installed the replacement RP drivers side axle last week. I got 8 runs on the replacement and 15 on the pass side. It broke in the same place: inboard CV right before the tripod.

I do rev it pretty high (about 5k) and drop the clutch. But this one broke well after the clutch was engaged (hard to remember the details). I can't launch much lower as my custom cal has a very, very bad bog/stall/dead spot between 3000-4000rpm (working the cal to solve but that is another story). If I do get into that rpm range I lose a full second off my ET!

What am I doing wrong here folks? I need to solve this or I'm going to make it a north/south engine (87 GLHS) and put a 904 auto and an 8 3/4 rear in it!!!!!

1 - 17 of 17 Posts

beefalobilly

· #2 · May 9, 2005

You mean you broke that nice brand new axle I sent you?

powermaxx

Discussion Starter · #3 · May 9, 2005

beefalobilly said:
You mean you broke that nice brand new axle I sent you?

Nope, the other side. I'm going to step up to the "driveshaft shop" program ($600 a pair!). I'm going to sell the one I just got from you (less than 2 weeks ago ), already listed.

I think I rev too high and drop the hammer. I'm used to drive trains that don't go "boom" like in my old V8 setups. And if I can't get this FWD stuff to live I'll be changing the GLHS to a "North/South" setup (yeah, I know it's numbered and all) but I'm like our namesake Shelby "I race to win and I don't baby the cars" (you shouldn't have to!).

glhsken

· #4 · May 9, 2005

Steve.

That's the way we launch too. My guess is you really don't have it centered. No way you should have had to re-slot the mount.

Honestly, with as many engines as I've put in, I've never had to re-center one. If an axle won't go in, it's the wrong size. One of my "beefy" axles arrived wrong. I'll just use it in the daytona.

powermaxx

Discussion Starter · #5 · May 9, 2005

glhsken said:
Steve.

That's the way we launch too. My guess is you really don't have it centered. No way you should have had to re-slot the mount.

Honestly, with as many engines as I've put in, I've never had to re-center one. If an axle won't go in, it's the wrong size. One of my "beefy" axles arrived wrong. I'll just use it in the daytona.

Nice to hear I'm not "abusing" the launch RPM!

As far as centering goes I had 5/8" "push in" on either axle end. When I lengthened the slots it was only off by 1/8" (car was never wrecked to my knowledge, etc...) I thought this was strange to have to do this.
Maybe the stub axle isn't seating all the way in? It looks okay to me. The trans (555/520 hybrid) has a "True-Trac" (?) LSD which never has given me any kind of LSD from day one. Trans guy had a devil of the time to install it (I don't know, grasping at straws here).

Anything else to look for?

BLUEBALL

· #6 · May 9, 2005

Does the rad support have any bracing? Mine got cracks around the welds so a little angle angle iron was used to stiffen it up. May help you out some controlling engine movement.

powermaxx

Discussion Starter · #7 · May 9, 2005

BLUEBALL said:
Does the rad support have any bracing? Mine got cracks around the welds so a little angle angle iron was used to stiffen it up. May help you out some controlling engine movement.

Rock solid! All poly stuff from Johnny :thumb:

csxt665

· #8 · May 9, 2005

I agree with Ken. Something in the centering/engine alignment department is funky. I have a set of Alabama Man/RP HD Axles in the T, and with rev-limit launches, I've never had a problem. Heck, even Autozone ones have held up (except with one wheel hop incident on Drag Radials).

glhsken said:
Steve.

That's the way we launch too. My guess is you really don't have it centered. No way you should have had to re-slot the mount.

Honestly, with as many engines as I've put in, I've never had to re-center one. If an axle won't go in, it's the wrong size. One of my "beefy" axles arrived wrong. I'll just use it in the daytona.

derek502

· #9 · May 9, 2005

I had a set of those AL Man/HP axles that were not the right size for my 87 GLHS, he sent me 1 L-body and 1-p-body axle, I could install them but they were tight. I ended up with the correct length axles but later I took them out and went with the 90 Onmi setup. The AL Man axles made too much noise and vibration for a daily driver.

powermaxx

Discussion Starter · #10 · May 9, 2005

csxt665 said:
I agree with Ken. Something in the centering/engine alignment department is funky. I have a set of Alabama Man/RP HD Axles in the T, and with rev-limit launches, I've never had a problem. Heck, even Autozone ones have held up (except with one wheel hop incident on Drag Radials).

I agree, has to be something wrong in the setup or the axle is a little long. But I thought the RP axles were only for the L bodies? I think the G-bodies are an inch longer(?) which should mean some trouble getting them in place on an L body if it's all possible? These went in pretty easy so I'm pretty sure they are the right length. Anyway to measure one (compressed I imagine) so I can check?

THX

Ordered my new axles from the Driveshaft Shop ($$$$)this morning, so it may not matter anymore....

The Pope

· #11 · May 11, 2005

powermaxx said:
I agree, has to be something wrong in the setup or the axle is a little long. But I thought the RP axles were only for the L bodies? I think the G-bodies are an inch longer(?) which should mean some trouble getting them in place on an L body if it's all possible? These went in pretty easy so I'm pretty sure they are the right length. Anyway to measure one (compressed I imagine) so I can check?

THX

Ordered my new axles from the Driveshaft Shop ($$$$)this morning, so it may not matter anymore....

Sounds like the back of the engine is dropping hitting the CV to the K member. I have had this trouble with other cars. Clark, a friend of mine had this and it shot the axle out onto a side walk. Just a 84 Z, not that much power needed to break them when they hit the K frame. Put duct tape on the K under the axle and drop the clutch, if it hits you need to rock the engine more or get more rear mount preload

powermaxx

Discussion Starter · #12 · May 11, 2005

The Pope said:
Sounds like the back of the engine is dropping hitting the CV to the K member.
"snip"
you need to rock the engine more or get more rear mount preload

Engine is in solid, absolutely no movement! (Dyno vid confirms it too!) The back of the engine had to be jacked up a little to just get the rear bobble strut (Spiva's/Quickor's mount) by about a 1/4". I did look at the top of the K member and there are no signs of rubbing/hitting.

Looks like I'll put a stock axle back in for this weekends racing (all MOPAR day this Sunday).

Are P-body axles the same length as G bodies?

BLUEBALL

· #13 · May 11, 2005

powermaxx said:
Rock solid! All poly stuff from Johnny :thumb:

I meant try bracing the lower radiator support where the mount bracket bolts to. You would be surprised how much flex goes on here. If you can lessen the flex a 1/2 inch,that may be enough to help keep tripod inside the cup .

glhsken

· #14 · May 11, 2005

Look on the drivers side of the rad support where it meets the frame. You might be surpriced what you see... Look for buckling.

powermaxx

Discussion Starter · #15 · May 12, 2005

glhsken said:
Look on the drivers side of the rad support where it meets the frame. You might be surpriced what you see... Look for buckling.

Looks perfect to me, no sign of buckling or bending.

BLUEBALL said:
You would be surprised how much flex goes on here.

I've watched the engine during a dyno pulls and there is absoulutly no movement. I mean none.

mopar2ya

· #16 · May 12, 2005

A dyno cant really simulate what happens under a 5K launch. You can always stitch weld the front end together to be double sure everything is tight.

powermaxx

Discussion Starter · #17 · May 12, 2005

mopar2ya said:
A dyno cant really simulate what happens under a 5K launch. You can always stitch weld the front end together to be double sure everything is tight.

Agreed... I guess it may be time to build my traction bars that I've designed. Designed for wheel hop mainly but it has a chromoly cross bar that the front motor mount would tie into.

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