strikeeagle
New Member
- Joined
- Jun 6, 2001
Everyone who’s been around a TR or any turbocharged car for that matter knows that boost hoses and clamps can be problematic.
Of the connections on a TR, in my experience, the throttle body (TB) inlet is the most difficult to clamp. The main reason is that the TB “nose” is short – about 25/32” from shoulder to tip, and only about 19/32” from shoulder to bead. By contrast, most hose clamps have bands that are nominally 24/32” wide. The problem is obvious. The clamp won’t fit behind the bead. Rather, it rides on it. This makes for very poor clamping.
There are many complicating factors:
· The TB nose is smooth and thus slippery.
· The TB bead is poorly designed. A proper bead would be significantly larger in diameter. However, since the TB nose is too short and thus a typical hose clamp rides on the bead, a larger bead would only exacerbate the problem.
· A typical boost hose is smaller in ID than the TB nose by more than is ideal. The boost hose tends to walk off the TB nose.
· The ID of the boost hose is smooth and thus slippery.
· The TB nose and boost hose may be contaminated with grease or oil. The importance of this connection above all others being scrupulously clean can’t be overstated.
· Boost pressure acts to push the connection apart. That is, it pushes the up pipe towards the front of the vehicle.
· The up pipe and TB may be misaligned.
· Inferior boost hoses. See below.
The result? At best, a hose popping off, ending your run. At worst, dents to the underside of your hood and up pipe.
The solution? Certainly a worm clamp is not suitable to the task. If you’ve been living with one consider that you’ve been dodging a bullet, and know that you’re time may be up the next time you mat the throttle. The solution of course is a very high quality t-bolt clamp.
The best clamp I’ve found for this purpose is a Breeze Spring-Loaded T-Bolt Clamp, Heavy Duty Large Spring, Series B9224. The proper size is TB263. Following is a link to Breeze:
http://www.breezeclamps.com/tbolt.htm
Regarding boost hoses, if you use short, thin, poorly constructed or old hoses, expect the worst. Quality boost hoses are silicone lined and reinforced by multiple plies of NOMEX laid in a crisscross pattern - making them reasonably, although not excessively thick. Under boost, cheap hoses grow radially and shrink axially rather dramatically, tending to pull the connection apart. Heat and pressure cycling can cause old hoses to deform, become soft or brittle, and rupture.
The abovementioned Breeze hose clamp handles a substantial amount of torque. In discussions with Breeze it was clear that they were comfortable with torques considerably in excess of their specifications. However, the clamp is of very high quality. Also, as it’s a constant torque clamp - the clamp will remain tight as the under hood area heats and cools. Therefore, it’s unnecessary and undesirable to over tighten this clamp – leave the half inch drive stuff in the tool box.
Take a look at your TB connection. Is the boost hose pulling away from or riding up on the shoulder of the TB? Are you using a worm clamp? Are you using a quality boost hose in “new” condition? Is everything clean and properly aligned? There’s no point in being on the best pass of your life if a bomb goes off at the 1000’ mark, let alone looking at an expensive hood repair.
HTH!
strike
Of the connections on a TR, in my experience, the throttle body (TB) inlet is the most difficult to clamp. The main reason is that the TB “nose” is short – about 25/32” from shoulder to tip, and only about 19/32” from shoulder to bead. By contrast, most hose clamps have bands that are nominally 24/32” wide. The problem is obvious. The clamp won’t fit behind the bead. Rather, it rides on it. This makes for very poor clamping.
There are many complicating factors:
· The TB nose is smooth and thus slippery.
· The TB bead is poorly designed. A proper bead would be significantly larger in diameter. However, since the TB nose is too short and thus a typical hose clamp rides on the bead, a larger bead would only exacerbate the problem.
· A typical boost hose is smaller in ID than the TB nose by more than is ideal. The boost hose tends to walk off the TB nose.
· The ID of the boost hose is smooth and thus slippery.
· The TB nose and boost hose may be contaminated with grease or oil. The importance of this connection above all others being scrupulously clean can’t be overstated.
· Boost pressure acts to push the connection apart. That is, it pushes the up pipe towards the front of the vehicle.
· The up pipe and TB may be misaligned.
· Inferior boost hoses. See below.
The result? At best, a hose popping off, ending your run. At worst, dents to the underside of your hood and up pipe.
The solution? Certainly a worm clamp is not suitable to the task. If you’ve been living with one consider that you’ve been dodging a bullet, and know that you’re time may be up the next time you mat the throttle. The solution of course is a very high quality t-bolt clamp.
The best clamp I’ve found for this purpose is a Breeze Spring-Loaded T-Bolt Clamp, Heavy Duty Large Spring, Series B9224. The proper size is TB263. Following is a link to Breeze:
http://www.breezeclamps.com/tbolt.htm
Regarding boost hoses, if you use short, thin, poorly constructed or old hoses, expect the worst. Quality boost hoses are silicone lined and reinforced by multiple plies of NOMEX laid in a crisscross pattern - making them reasonably, although not excessively thick. Under boost, cheap hoses grow radially and shrink axially rather dramatically, tending to pull the connection apart. Heat and pressure cycling can cause old hoses to deform, become soft or brittle, and rupture.
The abovementioned Breeze hose clamp handles a substantial amount of torque. In discussions with Breeze it was clear that they were comfortable with torques considerably in excess of their specifications. However, the clamp is of very high quality. Also, as it’s a constant torque clamp - the clamp will remain tight as the under hood area heats and cools. Therefore, it’s unnecessary and undesirable to over tighten this clamp – leave the half inch drive stuff in the tool box.
Take a look at your TB connection. Is the boost hose pulling away from or riding up on the shoulder of the TB? Are you using a worm clamp? Are you using a quality boost hose in “new” condition? Is everything clean and properly aligned? There’s no point in being on the best pass of your life if a bomb goes off at the 1000’ mark, let alone looking at an expensive hood repair.
HTH!
strike
