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So, slightly off subject...wanted to ask the folks on this thread cause...well ya'll have more experience than me and I like dealing with few folks that I feel know their shit rather than just throwing this out on a general "engine" thread. Anyways, here's what I got...

V6 manual.

Just before I installed my crawler, I had some slight vibes up front. Only when rpms dropped down when switching from 1st to 2nd. (felt & sounded like a motor mount). Mostly passenger side. Wasn't too bad so I just dealt with it.

After installing crawler I noticed it made it a bit worse. I've never had to deal with motor mounts before. Is it possible that my motor mounts are going bad? And how hard is it to change them? I've read that once installing a crawler it's a good idea to firm up the motor.

True? False? Help me out guys.

Thanks
 

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So, slightly off subject...wanted to ask the folks on this thread cause...well ya'll have more experience than me and I like dealing with few folks that I feel know their shit rather than just throwing this out on a general "engine" thread. Anyways, here's what I got...

V6 manual.

Just before I installed my crawler, I had some slight vibes up front. Only when rpms dropped down when switching from 1st to 2nd. (felt & sounded like a motor mount). Mostly passenger side. Wasn't too bad so I just dealt with it.

After installing crawler I noticed it made it a bit worse. I've never had to deal with motor mounts before. Is it possible that my motor mounts are going bad? And how hard is it to change them? I've read that once installing a crawler it's a good idea to firm up the motor.

True? False? Help me out guys.

Thanks
yes, could be a busted/cracked motor or tranny mount from the extra torque you now have in the drivetrain. And yes, vibes increase with the now longer drivetrain. The main reasons I use 2 tranny/crawler mounts are to soften the vibes and put less pressure on the OE mounts themselves. Eventually I'd like to find motor mounts that will approximate the same degree of immobilization as the two OE mounts I have on the tranny/crawler. The OE motor mounts will most likely be the next thing to break :p

Most likely you are just experiencing the normal increase in vibrations associated with the crawler install. Either add a 2nd OE mount or go with the HD type like Phil has. Do NOT use the aftermarket tcase type mount (bolted to the back of the case); those greatly increase vibes and leaks. The more you immobilize the drivetrain at only one end (tcase mount) the greater the twisting of the whole thing...= leaks. Ideally you want the motor/tranny/cases to move as one...what OE mounts provide.
 

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Most likely you are just experiencing the normal increase in vibrations associated with the crawler install. Either add a 2nd OE mount or go with the HD type like Phil has. Do NOT use the aftermarket tcase type mount (bolted to the back of the case); those greatly increase vibes and leaks. The more you immobilize the drivetrain at only one end (tcase mount) the greater the twisting of the whole thing...= leaks. Ideally you want the motor/tranny/cases to move as one...what OE mounts provide.
Thanks Hytenor. I kinda figured a lil extra vibes is par for the coarse.

I currently have the stock rubber mount on the tranny. That was never removed. I purchased the HD poly mount when I bought everything and that's what my crawler is now sitting on.

So I'm running two mounts. Kinda why I'm leaning towards motor mounts. Look at my pic in post #125 of this thread.

Is this an "ok" set-up?

Suggestions?
 

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Discussion Starter #145
Hey Dudeman,

Thanks for posting up in this thread. And thanks to everyone who replied, this is good information for me.

So would you guys say that cutting out the stock trans mount and making a dual rubber mount off of the new cross member would do the best job of keeping the vibes low while handling the extra torque?
 

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Hey Chris got to disagree with you on this - as I recall you had bad vibes but ended up thinking it was a 4cyl vs. a 6cyl issue. I ran Brians tcase mount on my rig and never had a vib or a leak issues. Ran it for several years and you know I ran it hard. Never had a motor mount issue either.

yes, could be a busted/cracked motor or tranny mount from the extra torque you now have in the drivetrain. And yes, vibes increase with the now longer drivetrain. The main reasons I use 2 tranny/crawler mounts are to soften the vibes and put less pressure on the OE mounts themselves. Eventually I'd like to find motor mounts that will approximate the same degree of immobilization as the two OE mounts I have on the tranny/crawler. The OE motor mounts will most likely be the next thing to break :p

Most likely you are just experiencing the normal increase in vibrations associated with the crawler install. Either add a 2nd OE mount or go with the HD type like Phil has. Do NOT use the aftermarket tcase type mount (bolted to the back of the case); those greatly increase vibes and leaks. The more you immobilize the drivetrain at only one end (tcase mount) the greater the twisting of the whole thing...= leaks. Ideally you want the motor/tranny/cases to move as one...what OE mounts provide.
 

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Thanks Hytenor. I kinda figured a lil extra vibes is par for the coarse.

I currently have the stock rubber mount on the tranny. That was never removed. I purchased the HD poly mount when I bought everything and that's what my crawler is now sitting on.

So I'm running two mounts. Kinda why I'm leaning towards motor mounts. Look at my pic in post #125 of this thread.

Is this an "ok" set-up?

Suggestions?
what Slander said...the poly mount is a whole lot stiffer than OE...poly vs rubber. Pull the OE mount and just run the poly and the vibes will drop considerably. That said...I would not trust that welded-on platform you now have. There would simply be too much stress on the weld and it will eventually fail. What you really should do is build your own custom xmember to replace the OE one. You could utilize the OE frame mounts and replace the cross piece itself with some .187 rectangle tube and build off that but it would be better to cut off the OE mounts and start from scratch centering the new xmember directly under the case mount point.
 

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Hey Chris got to disagree with you on this - as I recall you had bad vibes but ended up thinking it was a 4cyl vs. a 6cyl issue. I ran Brians tcase mount on my rig and never had a vib or a leak issues. Ran it for several years and you know I ran it hard. Never had a motor mount issue either.
I thought that was the case as well but have talked to several with the fror style mounts who had the same vibration issues...regardless of engine. It seems to be more of a preference issue :p Some don't care about the vibrations so put up with them.

But...you are correct that the I4 has much more of a vibe issue than the v6.

That said, the physics issue still remains...the drivetrain will twist w/o having equal amounts of play at both ends of the train, vibration problems or no.
 

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what Slander said...the poly mount is a whole lot stiffer than OE...poly vs rubber. Pull the OE mount and just run the poly and the vibes will drop considerably. That said...I would not trust that welded-on platform you now have. There would simply be too much stress on the weld and it will eventually fail. What you really should do is build your own custom xmember to replace the OE one. You could utilize the OE frame mounts and replace the cross piece itself with some .187 rectangle tube and build off that but it would be better to cut off the OE mounts and start from scratch centering the new xmember directly under the case mount point.


10-4. Thanks again hytenor. I know that platform is not ideal. But it was what I had to do to get me by for the time being. The truck is my DD, so down time is something I did not have. But...I'm currently looking at a secondary vehicle to get me to work and back. So, I will now have time to focus on properly securing that.

Thanks for all the help guys.
 

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So would you guys say that cutting out the stock trans mount and making a dual rubber mount off of the new cross member would do the best job of keeping the vibes low while handling the extra torque?
why remove the OE tranny mount if you are going to do this? If you want dual rubber mounts the best option, IMO, is OE for both the Taco tranny and the early tcase (crawler box) mounts. I believe most of the aftermarket mounts use poly bushings which will be a lot stiffer.

Keeping just the OE tranny mount will work but you wind up with a lot of slop in the shifters which drove me nuts :p Swapping out to a single poly mount (not available when I did my setup) like Phil did seems to work fine. That or dual rubber will take the slop out. The fror style dam-near immobilizes the rear of the drivetrain, hence the massive vibes I experienced. I did discover, with Dr Vic's/Balistic prototype mount that using a soft rubber bushing setup in place of the usual polys did stop most of the vibration problems. I tried 4 different types of rubber that varied in stiffness.
http://www.ttora.com/~ccorley/mods/tcase xmember/

TBob is correct that the 2.7 seems to have a greater vibe issue than the 3.4. but I've talked to some 3.4 owners with the fror mounts that did have more vibrations than they would have liked.
 

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What you could do is run a stock mount at the crawl box. Jim at inchworm has used stock mounts for sale iirc

Like Chris said, one poly mount, or two oem mounts.
 

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What you could do is run a stock mount at the crawl box. Jim at inchworm has used stock mounts for sale iirc

Like Chris said, one poly mount, or two oem mounts.
the new OE tcase mounts (from Inchworm or Marlin) are pricy! I got mine used for $15 via Pirate :p
I picked up a spare some time back for about the same price.
 

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Discussion Starter #153
That said, the physics issue still remains...the drivetrain will twist w/o having equal amounts of play at both ends of the train, vibration problems or no.
Hytenor,

I'm trying to get a handle on the physics behind the case breakage you were mentioning earlier and I still don't quite have a handle on it yet.

Is it because the FROR style crossmembers put the rubber in compression and the crawlbox mount puts its rubber section in shear with rubber being more compliant in shear than compression?

Or is it simply that the rubber mounts are simply not compliant enough for the weak chain driven case, allowing vibration to weaken and crack the metal?

Or is it a combination of both? What did you see in your experience?
 

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Hytenor,

I'm trying to get a handle on the physics behind the case breakage you were mentioning earlier and I still don't quite have a handle on it yet.

Is it because the FROR style crossmembers put the rubber in compression and the crawlbox mount puts its rubber section in shear with rubber being more compliant in shear than compression?

Or is it simply that the rubber mounts are simply not compliant enough for the weak chain driven case, allowing vibration to weaken and crack the metal?

Or is it a combination of both? What did you see in your experience?
having the bushings at the frame rails vs having the bushing (rubber mount) at the center of the vehicle...way different leverages.
Two mounts at a 4' distance (one at each end of the length) makes a much bigger lever than one or two mounts at the center of that same length of whatever...in this case a x-member.

I haven't seen any reports of actual case breakage, just "breaking" seals between cases via the twisting effect. In theory, if you have everything tightened to specs there shouldn't be any movement...in theory ;)

In the case of the fror style you can compensate for the difference in leverage by using a soft bushing rather than the hard poly. The problem is finding those soft rubber bushings.
 

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Discussion Starter #155
^Ok, I finally get it. You're right, theory and actuality rarely agree.
 

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Discussion Starter #156
Got this in the mail today!

 

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A new stove? Nice.
 

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Discussion Starter #158
That's what I get for taking pictures in the kitchen instead of the garage! :missingto
 

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Haha yep. Nice kitchen though...I will give ya that. :)
 

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