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Just built a 4.6L stroker for my xj, was going to put polyurathane motor mounts but heard I should just go stock, poly to tough not enough give just mess up unibody and crack etc. Any thoughts from would be helpful.:thumbup:
I put a pair of the brown dog poly mounts in my 91 when I put my 4.6 in and I hate them.
They make every little thing in the interior buzz and rattle, plus I had to take a hack saw to them right out of the box so the damn thing would fit inside the stock block bracket. :nono:
Just my experience, but I would never use the(any poly mount) for a street ride again.
X2 i had mine in for almost a year before i scrapped the rig, im reusin the mounts with poly bushings for the trail rig, great product and awsome customer suport
stay away from the stock motor mounts. they are marginal at best for stock applications. if you have a 4.6L stroker, i am assuming you take your heep beyond the limits of stock. go for a good motor mount like Brown Dog or MORE. poly wont crack the unibody but it will transmit more engine vibes into the pass compartment. rubber wont be nearly as bad but does have more play...
Is there any correlation between the flex of rubber mounts and the cracking of headers due to that flex. Would the ridgity of the poly mounts be of any benefit in that regard or is the cracking due more to expansion/contraction?
ive been running Daystar poly mounts for 3 years now without any problems. Previously i was changing my stock motor mounts every 6 months to a year. I have more vibrations than stock but nothing too much.
I just installed the brown dog rubber mounts a few weeks ago. Easy to put on. Good fit. No vibration problems. I actually kind of think I shoulda got the poly mounts so it would transmit some more beastly vibes through the chassis.
Is there any correlation between the flex of rubber mounts and the cracking of headers due to that flex. Would the ridgity of the poly mounts be of any benefit in that regard or is the cracking due more to expansion/contraction?
I put a pair of the brown dog poly mounts in my 91 when I put my 4.6 in and I hate them.
They make every little thing in the interior buzz and rattle, plus I had to take a hack saw to them right out of the box so the damn thing would fit inside the stock block bracket. :nono:
Just my experience, but I would never use the(any poly mount) for a street ride again.
I had to cut mine to fit the stock engine bracket. Not a big deal! If I had researched a bit better I would have read that they were designed to go WITH the BD engine bracket. I prefer the poly as I run a poly trans mount to. FWTW Brown Dog is the shiznit!
M.O.R.E. makes a good mount...
however, everyone seems to like brown dog, and theyve been donating to local naxja events, if i had to start over, i'd give them a call.
I had to cut mine to fit the stock engine bracket. Not a big deal! If I had researched a bit better I would have read that they were designed to go WITH the BD engine bracket. I prefer the poly as I run a poly trans mount to. FWTW Brown Dog is the shiznit!
They actually make an XJ specific mount now that doesn't require any trimming or other modifications when keeping your stock engine brackets. Brown Dog will even swap it out for one of their regular mounts should you decide to upgrade to the BD Super Brackets down the road. Here's a pic of both for comparison:
I run their rubber mounts and Super Brackets and really like them. There are some noticeable vibes when you're stopped, at idle, with the transmission in drive, but the rest of the time I really enjoy the sportier feel (and peace of mind) that they provide. Two thumbs up! :thumbup: :thumbup:
Has anyone actually broken an engine mount before upgrading them or just upgrading as a precaution? I'm not talking about wearing the rubber out in the stock mount, but actually braking part of the metal mount.
