Warren928

But seriously, the shiny stuff that makes up the hood pad is probably no different than the insulation rolls of foil you can buy at home depot that have an aluminum face, about the same thickness of aluminum foil.

I have used .010" aluminum from the roof flashing dept. of home depot and it works good on alot of projects for lightweight heat shields or light duty shields of other sorts. IT can be cut with scissors and bent over a table edge.

With some lightweight beinding equipment, you could use .025"-.050" thick 1000 or 3000 series aluminum and do alot of sheet metal fab on non structural parts of a car.
I am considering fabricating a supercharger airbox out of .040" and tack weld it together, should work out nicely.

david928

For connecting the Xpipes and cats to the rear exhaust pipes, I used Exhaust Pipe Head Shield instant repair kit. It contains an adhesive-backed aluminum strip 2"x24" that is thicker than aluminum foil. Costs about $2. This can be used to increase the outside diameter of the rear exhaust pipes when mating to the cats and X pipes.

James-man

Update.

I have since blown out my other side's fiberglass wrap and the aluminum foil patch. At 11:30pm before a dyno day event (lacking any other reasonable materials at that time of night) I guessed that an old leather belt may hold up to the heat & I cut sections out of one to patch the clamp's leak. I should have won a prize for smokiest 928 at the dyno day - smelled like someone just branded a bunch of cattle. OK. So leather doesn't make for a good temp patch.

Went looking for the right material. 4 auto parts stores later, I FINALLY find the correct fiberglass wrap but it comes in a HUGE roll - meant for wrapping a lot of exhaust lines. It is a "performance" product.

I am not sure that my repeated problem of "blowing out" the material is really blowing out. When threshold braking, the weight of the resonators and rear pipes push with ample force forward into the crossover pipe, then rebounds from the rubber suspension hangers. I am thinking that Heat + forces + some forward and back motion of the exhaust system are wiggling the wrap materials loose from what was once a pretty snug clamped connection.

Anyone have a crossover pipe at the track and NOT have the exhaust wiggle loose on you?

Ultimately, I have decided to try something a little different. I bought a 2.5" exhaust shim to make up for thickness difference and supplemented with muffler patch kit materials consisting of compressible heat resistant material & screen to secure it.

Further, I believe that if my crossover pipes were 1 - 1.5 inches shorter, I wouldn't be having any of these problems. The resonator pipes go so far into the crossover, that there is very little straight pipe sticking out to clamp on. The band clamp has to clamp on the start of the curved pipes. Someday, I may remove the X and hack a small section off so that I can get a better grip on everything.

Going to the track this weekend to see how this recent patch job holds up.

AO

James-

On my DR X-pipe, I used the Permatex Orage sensor safe stuff. It's like exhause caulk. Kinda messy, but you just lay a bead, put the tubes together, clamp and let it sit for 12 hours or so to setup. I've got one pin-hole leak, but it's not worth fixing right now. Other than that it seems to work great. When we had it up on the lift at SITM (6 mos. post install) the Permatex stuff was still pliable. Only a few bucks at your fav auto parts supplier.

the flyin' scotsman

I tried many different solutions; wrap, exhaust cement, sealer...........all only lasted a short time.

Finally went to the local muffler shop and had them tack weld the X to the resonator pipes then seal the joint with cement then the clamps. The theory of the constant problem is the clamps wont grip the outer dia of the reonator pipes tight enough which eventually allows the back and forward motion to break the seal.

James-man

Yesterday I dropped my exhaust (resonators and RMB) so I could put a 2.5" by 1" by 1-2mm shim on the smaller exhaust pipes to give something to clamp onto. I noticed that the exhaust goes into the crossover pipes by a good 4 inches. It seems like it shouldn't have to go quite so far in.

Malcolm, on your '88, is the clampable section of the smaller diameter pipe straight or beginning to curve? Not only does it begin to curve for me, it also appears to be even smaller diameter than the straight section that is inserted into the Xpipe.

What if the end of the Xpipes had 3 or 4 slits cut in them so they could compress onto the exhaust/resonator tube inside? Aside from tack welding, I think that this may be a good route to take.

AO

Question: What kind of clamps are you guys using? DR included these special band clamps that work really good. If you're using those u-bolt clamps, that could be part of the issue.

AO

BTW, they look like this except without the step.

the flyin' scotsman

Thats the same clamps I've attempted to use. The first set were 2.5" and when they didn't work Dave sent me 2.25"......if they were stepped that might be a solution.

James, my resonator pipes don't start to curve but I have GT resonators, that may be a diff. but I do have significant amount of res. pipe up inside of the X.........not sure of the measurement, it could be 4" and I did contemplate cutting them until I decided to go with the absolute solution.

If I ever do remove and reinstall I'll cut the res. pipes to align with the end of the X and weld all the way around...........no worries after that.

James-man

Yup. Just like that without the step.

928drvr86.5

I tried to get my 928SP crossover to seal up at the resonators three different times on my 86.5 using various sealing compounds and muffler repair tapes only to have it "blow through" a few weeks down the road each time. Finally i made two 18 gauge sheetmetal shims to fit over the outside circumferencer of the Resonators and it has not leaked since early April. It works great, if you do this, cut your shims a little long to allow for shrinkage when you wrap them around the resonator OD (you can always cut alittle more off if the ends overlap). I lucked out and found a pipe at work with the same OD as the resonator's and shaped my shims around that. For installing them on the car i used a sturdy hose clamp to hold them inplace/shape as i slid the Crossover tubes over them.

That 304 stainless does not collapse too well, rather it tends to go out of round, especially if the gap between it and the smaller Resonator pipe is significant as it was in my case. I had like 5-6 wraps of the muffler tape in there and it still did not fit tight. As great as the crossover is i think it needs shims included. Say maybe 18 and 20 Ga. depending on the car! ??

928drvr86.5

I used the above pictured clamps, also without the step BTW.

Bill Ball

What is the reason the x-pipe outlets cannot be made to mate up snuggly with rear exhaust? Is this just a problem due to variation in rear exhaust pipe size in certain model years?

928drvr86.5

Yes, it was made to fit the largest variation in size, of which my 86.5 apparently is not.

the flyin' scotsman

Neither is my '88.