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Transmission Hitting firewall

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BigRand

15+ Year Contributor
2,181
32
Nov 17, 2004
Toronto, Ontario_Canada
Okay so here is the deal.

about a month or 2 ago I took my car to a transmission shop to have them put my Southbend clutch in on a warranty job from before since they did the transmission work etc.

Well after it went in and everything, the car experienced a vibration, almost like it was hitting the firewall.

After extensive diagnostics ect. I decided to change my stock rear mount, back to the polyurathene mount. It helped for a day or 2, until I decided to test it in track like conditions at a stop light by practicing my launch. I slipped the clutch around 3500-3700, and it took off like a rocket nothing hitting (just the usualy vibrations from the mounts)

The next day I started driving around again and noticed that this vibration was happening again, I had my friend over at good year throw the car up on a lift and confirmed where exactly the transmission was hitting (pictures to come).

So my questions are

a)What else could be the problem? (I have all stock mounts in other then the rear firewall poly mount)

b)Is there anyway my transmission could have been mounted incorrectly to be close enough to hit the bottom of the firewall.

c) Would a front motor mount (prothane or afx solid mount) fix my problem

d) how close should the transmission be to the firewall
 
Okay so here is the deal.

about a month or 2 ago I took my car to a transmission shop to have them put my Southbend clutch in on a warranty job from before since they did the transmission work etc.

Well after it went in and everything, the car experienced a vibration, almost like it was hitting the firewall.

After extensive diagnostics ect. I decided to change my stock rear mount, back to the polyurathene mount. It helped for a day or 2, until I decided to test it in track like conditions at a stop light by practicing my launch. I slipped the clutch around 3500-3700, and it took off like a rocket nothing hitting (just the usualy vibrations from the mounts)

The next day I started driving around again and noticed that this vibration was happening again, I had my friend over at good year throw the car up on a lift and confirmed where exactly the transmission was hitting (pictures to come).

So my questions are

a)What else could be the problem? (I have all stock mounts in other then the rear firewall poly mount)

b)Is there anyway my transmission could have been mounted incorrectly to be close enough to hit the bottom of the firewall.

c) Would a front motor mount (prothane or afx solid mount) fix my problem

d) how close should the transmission be to the firewall


Did you know for a FACT it's the tranny hitting something? I hear a vibration alot on my car especially on left turns around 3k but it's just the heat shield (OEM under car) bouncing around. Hopefully it's the same case for you.

Ever consider it to be your TOB?
 
From the looks of it... since half my motor is ripped out and the tranny is still there... the transmission isn't anywhere near the firewall... I mean not close enough that any sort of torque would make it hit.. unless mounts were royaly trashed.
 
From the looks of it... since half my motor is ripped out and the tranny is still there... the transmission isn't anywhere near the firewall... I mean not close enough that any sort of torque would make it hit.. unless mounts were royaly trashed.

X2 :confused:

Are you sure Rand? Crossmember OK?

MB
 
Yeah Only think I can think of is they put it (cross member) in the wrong place or something...
I got pics (cell phone)
 

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Still kinda far away for that amount of movement...

But Maybe I can jack up the car and take the same pics you took...

The pictures don't really show it... but from your point of view, do you see any rubbing or any areas that look slightly damaged, sctrached or whatever?
 
Its not my Throttle body, becaue I've had that completely take a shit on me before, I can see where the transmission bell housing is hitting, at first I just thougt it was because I was putting down a lot of torque that the stock mounts couldn't handle it, but even after the poly one went in the back firewall position, it was stiffer for a while, until I really put some stresss on it, and now its back.....

I watched when my good year buddy was torquing down the front mount, and there seeemed to be a lot of movement in the front, however I still don't think my transmission should be that close, but hey, ya'll tell me what you think
 
There shouldn't be alot of movement. But... is it rubbing all the time? or only on heavy acceleration? Cause if its just on heavy acceleration, I say drive her like a baby and protect from any damage.... I'd hate to see your tranny get a hole punched in it.
 
I highly doubt its it... but did you check the mount under the battery, to see how its holding up? Maybe the engine is dropped a little bit ?

***EDIT*** Randy if you need or want any more pictures, Lemme know what to take since my head is off... its easy to maneuver throughout my engine bay with a camera.
 

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I think the movement you're talking about is coming from your front mount. If you have ever looked at the bolt that goes into the mount, it is way too thin. I'm going to bore the holes on the frame that goes around the mount to be flushed and stick the thickest bolt I can find. I pretty sure theres a thread on this on 2gnt.

Edit: Ok, I found it, here you go:

http://www.2gnt.com/index.php?d=Front Motor Mount Bolt

Hope this helps.
 
Ever consider it to be your TOB?

Were he is talking about your TOB he means your throw out bearing. It couls ba making alot of noises. Mostly they make a whine or a ticking but ive heard them make alot of different noises. And when the shop put your clutch in did they change it. Because ive always been told any time you remove your tranny its always safer to replace it so it dont go out.
 
I think the movement you're talking about is coming from your front mount. If you have ever looked at the bolt that goes into the mount, it is way too thin. I'm going to bore the holes on the frame that goes around the mount to be flushed and stick the thickest bolt I can find. I pretty sure theres a thread on this on 2gnt.

Edit: Ok, I found it, here you go:

http://www.2gnt.com/index.php?d=Front Motor Mount Bolt

Hope this helps.
I agree with this 10 fold! Thanks for the link Abe... I'm going to do that now since I'm bored! :D

Were he is talking about your TOB he means your throw out bearing. It couls ba making alot of noises. Mostly they make a whine or a ticking but ive heard them make alot of different noises. And when the shop put your clutch in did they change it. Because ive always been told any time you remove your tranny its always safer to replace it so it dont go out.
I didn't catch on at first... but now noticed that Randy did say Throttle Body... In response to the TOB... But I know he meant Throw Out Bearing instead of Throttle Body...
 
I would check out your trans and engine mounts. I doubt thats its your bushings, but than again it could be. For your trans to actually be hitting the firewall or something there would have to be quite a bit of play. Before you go tearing everything apart, try putting a floor jack under the trans and gently lift up a bit to see if the trans has room to spare. I find it hard to believe that they reinstalled your crossmember incorrectly, it just wouldnt fit. while your there check the mounts for loose bolts, bent mounts, or anything else that looks out of place.

I wouldnt drive it until you figured this out, worse case scenarie, but your driving only to have your trans drop down and fragment under your car taking half your engine and some of the underbody with it.
 
I don't think a broken mount will give that much damage... But very much possible to crack the trans and then you'd need a new trans or bell housing... depending on what gets damaged...

I agree with you tho... A bent mount or lose bolt. Look at the pic I provided... that mount, if those bolts got lose... I think it would cause that effect.
 
Hey is that picture from the top to the bottom (standing over the hood of your car?)

Man this really sucks, my car is is ready to be driven hard, except for this one problem.

Yeah sorry about the Throw out bearing vs throttle body incident, I was tired.

I'll give that bigger bolt theory a read.
 
Hey is that picture from the top to the bottom (standing over the hood of your car?)

Yeah, Josh took that picture from the top, looking down.

I'll give that bigger bolt theory a read.

There is slop there from the factory, which may cause noise. I have not performed that mod yet, and can hear a clunk between shifts. Scared me at first, but while investigating, the stethoscope confirmed noise from the front mount while letting the motor gently torque against the brakes. Though, I don't see how this would allow for your issues.

I have no useful thoughts for you, other than what has already been mentioned. Sorry. I hope you figure it out.
 
Umm, well if you could check the distance between the firewall wall, and the transmission on the bottom side (IF you want too) that would be great. (from underneath, You don't even have to take a picture, just a genral one fiinger or 2fingers of disntance.

If not, I think I'm gonna go with a front mount insert kit, and do that bolt mod, this week and see if it corrects the issue.
 
Blitz, yeah... but when Randy responded he accidentally said Throttle Body... even tho he meant Throw Out Bearing.


Randy, Since the car is on the ground, measuring from the top just by looking at it... at least a 1.5-2 finger distance... and I don't have a big hand. I mean if you had some major play... I'd believe that it was hitting... but play like that, would be visible in a damage perspective.
 
Having not played around with that mount in awhile (got a solid front so no problems), I seem to remember that mount actually being offset toward the top (as opposed to centered. Or maybe vice-versa). I'm positive that I got one of those mounts from a company (that filled them. This was early on in my endevours) that was offset incorrectly. Had a bi*** of a time trying to get the engine/tranny to mount and I pulled off the mount and matched it to the stocker to find that the offset was different. Now I can't remember if it was that it was supposed to be centered or supposed to be offset, but I definitely got one where the hole was incorrectly placed.

Possibly your situation Rand? Guys, help me out with the offset idea here if you can.

MB
 
Well here is the thing, When they had my transmission the first time they had their luk performance clutch (stage 1 or none, LOL, but it held for a while) in and there was no problem.

Throw my SBC Stage 3 in there and then it sounds like a new mount.

I think I"m gonna see if fixing the front mount (stiffing it up with inserts and a bigger bolt) will do the trick. Because when I checked it for tightness on the lift I saw a lot of movement when I torqued on it with two wrenchs.

I'm expecting the inserts tomorrow thanks to sean at CI putting a rush on it, a quick trip to home depot or tacoma screw, and I'm in business...MAN I HOPE THIS WORKS
 
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