Th350/400 guys in here please....
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TECH Enthusiast
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Joined: Mar 2005
Posts: 503
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From: West suburbs of Chicago
Th350/400 guys in here please.... I am having an issue with my new set up and the trans mount/ umi conversion crossmember. I called umi today and spoke with their support put I still have no answer.
I am using umi's chassis mount conversion crossmember without torque ARM relocation. I am using my energy suspension poly trans mount from when I had my t56. Believe it is part number 31108. I use a spohn race chassis mount torque arm with a d.s.l. and a 3.5" drive shaft loop. Motor mounts are poly energy suspension pieces.
My problem is the tailshaft (9") pitches upwards and the driveshaft isn't inline with the rear end. When on all 4 wheels the driveshaft hits and rubs the d.s.l. I have plenty of room at the bottom of it. I confirmed with umi that the correct crossmember was sent. This was the first time he has heard of an issue with one. The trans mount worked fine in my t56 set up and also when I had the 4l60e. I have not seen or heard of anyone having to use a different mount for this all to work. I need the tailshaft to come down maybe an inch, would have to measure to be sure. I don't have a stock mount to compare heights between both mounts but I know there is no way I could even think about running a stocker launching off a trans brake. I can't run a solid mount either in fear of cracking the case. Looking at the trans pan, the drain in the back is up high and would never drain down.
I am at a loss on what I can use to bring the tailshaft down to where it needs to go. Has anyone run into this problem before? If so what did you do to fix it?
Thanks in advance.
I am using umi's chassis mount conversion crossmember without torque ARM relocation. I am using my energy suspension poly trans mount from when I had my t56. Believe it is part number 31108. I use a spohn race chassis mount torque arm with a d.s.l. and a 3.5" drive shaft loop. Motor mounts are poly energy suspension pieces.
My problem is the tailshaft (9") pitches upwards and the driveshaft isn't inline with the rear end. When on all 4 wheels the driveshaft hits and rubs the d.s.l. I have plenty of room at the bottom of it. I confirmed with umi that the correct crossmember was sent. This was the first time he has heard of an issue with one. The trans mount worked fine in my t56 set up and also when I had the 4l60e. I have not seen or heard of anyone having to use a different mount for this all to work. I need the tailshaft to come down maybe an inch, would have to measure to be sure. I don't have a stock mount to compare heights between both mounts but I know there is no way I could even think about running a stocker launching off a trans brake. I can't run a solid mount either in fear of cracking the case. Looking at the trans pan, the drain in the back is up high and would never drain down.
I am at a loss on what I can use to bring the tailshaft down to where it needs to go. Has anyone run into this problem before? If so what did you do to fix it?
Thanks in advance.
A shorter trans mount, or you could use spacers on the transmission cross member to pull it down some.. An Inch would be an awful lot though. Is the trans mount universal for our cars?
Thread Starter
TECH Enthusiast
iTrader: (12)
Joined: Mar 2005
Posts: 503
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From: West suburbs of Chicago
I compared 4 different mounts at the parts place. A stock replacement, a 90's truck, a 76 nova, and the energy suspension 3.1108g. Stockers were 1.820" and poly one was 1.937" with plate compressed. I brought home the new poly mount to try it. It was worse than my other poly one. Driveshaft was pushed into the d.s.l. pulled the bolts on the new crossmember and dropped it 5/8 of an inch, reset Pinion angle and the driveshaft is centered in the loop and trans pan is now level. When talking with UMI they told me mock up was done with a stock mount. Regardless, the difference in height between the stock and poly mount is not 5/8". The trans tail shaft is 9" long on my th350. Should be the same length as a 4l60e since guys still do the swap and still use the stock driveshaft with a stock rear. Even though my driveshaft is shortened for the s60 rear, it doesn't complicate the install. I will say though UMI has been exceptional as always as we try to figure this out. I just don't want to space this thing down 5/8" to make it work with the power level I am at. It could get ugly fast.
