11 replies to this topic

[jamesheath]

Hi folks,

Spent the better part of today fitting my new rc40 exhaust. All well untill reattaching the brake servo bit onto the alloy inlet manifold. Did not think to take care due to the soft alloy metal and went and stripped the thread.........

Looks like I have made a mess of the thread to about 1/3 depth. With no amount of teasing or encouraging I cannot get the thread back on line with the servo screw assembly. Am I right in thinking I could recut to the the original thread size with a threading tool to the 1/3 depth and then hopefully the original thread should take over?


Any suggestions please folks.......Really dont want to get another inlet manifold due to time to getting the beast back on the road.


Ta

James

PS After removing the original pea shooter exhaust and manifold, the little air intake heating exhaust shroud clearly no longer fits. Should I simply run without one or is there some other sollution?

Edited by jamesheath, 02 September 2007 - 03:44 PM.

[Bungle]

yes do away with the hot air feed

try retaping the thread and use some PTFE tape on the dodgy bit

[Scruffs]

Am I right in thinking I could recut to the the original thread size with a threading tool to the 1/3 depth

Did you strip it or cross thread it? First thing's first is take the manifold off and clear out any swarf from the ports.

I'd have a go with a tap, it shouldn't need too much torque to seal so a half decent thread should do it. If it's stripped then there probably won't be muh material left to tap, then it's helicoil time....

[jamesheath]

Am I right in thinking I could recut to the the original thread size with a threading tool to the 1/3 depth

Did you strip it or cross thread it? First thing's first is take the manifold off and clear out any swarf from the ports.

I'd have a go with a tap, it shouldn't need too much torque to seal so a half decent thread should do it. If it's stripped then there probably won't be muh material left to tap, then it's helicoil time....

It is crossthreaded at the mo. Don't know what Helicoil is but will do some research. What does the servo link do? I understand some servos don't likt to the manifold. Is it something I can do away with?

Ta

James

[Scruffs]

The manifold vacuum acts on a diaphragm insideyour servo to assist you when you brake. End result being less pedal effort is required to get the same line pressure and hence brake torque at the wheels. Just makes it easier to brake.

Not sure if you could do away with it, you could try but pedal effort will be considerably higher...I haven't ever owned a car with a servo tho...!

A helicoil is a steel thread insert (looks a bit like a coil bound spring). You drill out the old thread, tap it the next available size up with the same thread pitch and screw the helicoil into this. You end up with the original thread that won't pull out so easily in the future!

You must have had some commitment to get it crossthreaded to a 1/3 of the way in!! I'd have a stab at retapping it, not got an awful lot to lose, just make sure it's off the engine!! and the PTFE tape is a good call too

[jamesheath]

The manifold vacuum acts on a diaphragm insideyour servo to assist you when you brake. End result being less pedal effort is required to get the same line pressure and hence brake torque at the wheels. Just makes it easier to brake.

Not sure if you could do away with it, you could try but pedal effort will be considerably higher...I haven't ever owned a car with a servo tho...!

A helicoil is a steel thread insert (looks a bit like a coil bound spring). You drill out the old thread, tap it the next available size up with the same thread pitch and screw the helicoil into this. You end up with the original thread that won't pull out so easily in the future!

You must have had some commitment to get it crossthreaded to a 1/3 of the way in!! I'd have a stab at retapping it, not got an awful lot to lose, just make sure it's off the engine!! and the PTFE tape is a good call too

It was the last job of the day and my mind wasn't 100% on the job....pants!

Will carefully remove the manifold as not to get swarf into the engine. Should not be a problem as the opening from the manifold to the engine block is on the bottom of the manifold channel (Hope that makes sense) so should all be caught in the manifold itself.

Think I may be able to borrow some tapping tools from work. If not, are they expensive and worth having in the garage?

J

[alexcrosse]

heli coil is the propper way to do it. But sometime hard to get hold of. Minisport have nocked a tenner off their inlet manifolds

[jamesheath]

Do i deffo not need the heated air intake shroud? Take it this helped to warm the incomming air? What difference will it make not having this fitted? I could probably mod the old shroud to fit with a bit of creative bening!

Ta

James

[alexcrosse]

makes no difference, you probably hav/had a headed inlet manifold anyway no?

[Scruffs]

I think it's supposed to stop the carb icing up in the first few seconds of running in cold weather. I don't have one and have many a time been out for a giggle in the snow with no probs

If anything I'd expect it to be a bit more lively as breathing cooler air means breathing denser air

[Ethel]

Are you sure the servo hose adapter and manifold use the same thread type?

I don't think a helicoil would be necessary as the thread only has to hold the adapter, might be an idea to use a fibre or nylon washer that will seal using less torque. I would be almost impossible to start a new thread and get it to line up with what's left of the original. As it's only aluminium I'd be tempted to make up a tool to drop into the manifold and wind out up the good threads.

[jamesheath]

Are you sure the servo hose adapter and manifold use the same thread type?

I don't think a helicoil would be necessary as the thread only has to hold the adapter, might be an idea to use a fibre or nylon washer that will seal using less torque. I would be almost impossible to start a new thread and get it to line up with what's left of the original. As it's only aluminium I'd be tempted to make up a tool to drop into the manifold and wind out up the good threads.

Hi Ethel,

I am pretty sure the thread of the plug which was in the manifold and the thread of the adapter is the same, whetherr they are the correct thread of the manifold is a different matter! I have ordered the correct tap for the thread of the adapter (5/8th UMF) which should rectify the situation eitherway.

Ordered from Tracy Tools Ltd In Dorset for £3! next day delivery.....recomend this lot.

I am hoping that I can cut a new thread with the tap and using PTFE and a lot of care will hopefully get away with it. The nylon washers is a great idea, will do that matey.

Will let you know how I get on.

J