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Keeping an exhaust on a rally car

Posted by Eric Ewert 
Eric Ewert
Eric Ewert
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Location: Calgary, Ab
Join Date: 05/13/2013
Age: Party Animal
Posts: 362

Rally Car:
volvo 240


Keeping an exhaust on a rally car
November 15, 2017 09:52PM
Well been a while since I've posted, should probably throw a few updates in my volvo thread one of these days. Right now just looking for some info on what actually works for keeping an exhaust on a rally car seeing as what I have has a habit of trying to run away.thumbs down I have been using three bolt flanges that seem to enjoy not staying together. Is there something better? Maybe slip fit tubes with bolted clamps, motorcycle style exhaust retaining springs? What actually keeps the system together in a gravel rally environment? Also is a flex pipe a good or poor idea?

As far as hangers go I have seen what looks like a smaller version of a volvo motor mount pop up on a number of european built stuff, anything good or bad to be said? Link below to what I'm referring to. Fyi you can find these rubber bobbins far cheaper on amazon with m8 threads.

https://www.motorsport-tools.com/universal-exhaust-mounting-bobbin-3-8-unf-thread-stud-rubber-mount-140136.html
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Vincent Gagnon
The same thing that I just wrote
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Volvo 740



Re: Keeping an exhaust on a rally car
November 16, 2017 01:00AM
Hey man!
How's life, but more importantly, how's the 240?
Sorry, I don't have the answer to your question, but I have a few questions for you.
First, are you still looking for a 16v head? I have 3 of them now (2 without valve cover) and I will be driving through Mordor around mid-february.
Second, I have the 240 with the Toyota axle, with the m46 or m47 or whatever the fuck they called this piece of shit so called transmission.
I have a T5 layin' around and I'm about to swap it if I can find time.
What did you do regarding the drive shaft?
Do you still have a two piece one?
Do you have two slip-yokes? (wich seems weird to me?)
Do you have a single piece one and, if so, what is the OD?

Thanks, good luck and I wish you the best the hit the dirt as soon as possible.



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Robert Culbertson
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Re: Keeping an exhaust on a rally car
November 16, 2017 02:21AM
On the exhaust, the stock mounts work really well. Only 1 exhaust failure in 20+ events, and that was when the exhaust got broken off the cast iron manifold from ditch hooking over a giant rock.
We're using 2-bolt flanges without any issues at the end of the new header.

For Vincent's T5 question:
2.5in shaft diameter will just rub the tunnel on full bump with a single piece on a d30 axle. Gotta clear out all of the seat belt weld/nuts and trim off The bolts that are sticking through.
3in diameter driveline has mondo clearance problems.
If using a 2-piece, use a 740 carrier bearing or a Spicer one for a big truck. Requires a new mount, but the bearing won't push out when running two slip yokes. Two piece is way moah bettah for clearance and keeping things smooth.
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Philippe Bellefleur
same as above
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Volvo 740 imposed by vince, might be a 240... I think it will be a 240.



Re: Keeping an exhaust on a rally car
November 16, 2017 05:13PM
How about v-band? And no, don't use flex joints, they don't last too long in street use so i would expect them to be shit in rally.
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Eric Ewert
Eric Ewert
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volvo 240


Re: Keeping an exhaust on a rally car
November 16, 2017 06:47PM
Hey Vince, the 240 is back on the road but is still a ways off from being race ready. I could go on and on with this one but lets leave it at this- I got lots to do in order for me to trust it.

I got 1 piece 3 inch driveshaft. It required modifying the back end of the tunnel. I were to do it over again I would probably keep it a two piece. Shop around, I think I paid far too much to have a steel driveshaft made. Robert point on making sure bolts on the tunnel are trimmed flush is important, especially with longer travel.

I've heard good and bad things on v-band clamps. They are not cheap so its one thing if they hold up really well and are a near to 1 time purchase. However I am not so sure that is the case. Robert the stock mounts on mine left a lot to be desired, the factory exhaust had a habit of rubbing on various things so maybe it was bent or the mounts had perished. Either way I would Ideally like to ditch the bend around the gas tank and have it exit straight out so keeping the last two mounts probably wont be an option.

Since this is expanding into multiple volvo related things, any ideas as to why my car has a habit of killing MAF's? Its got bosch lh 2.4, ive checked all the wires going into the maf and everything is ok from what I can tell. Not sure what I am missing at this point.
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Philippe Bellefleur
same as above
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Volvo 740 imposed by vince, might be a 240... I think it will be a 240.



Re: Keeping an exhaust on a rally car
November 16, 2017 07:07PM
Don't see why you say they are not cheap.

https://www.summitracing.com/int/parts/sum-694930/overview/

Or you could use slip joints & springs.
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Robert Culbertson
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Re: Keeping an exhaust on a rally car
November 16, 2017 07:28PM
Quote
Eric Ewert
I've heard good and bad things on v-band clamps. They are not cheap so its one thing if they hold up really well and are a near to 1 time purchase. However I am not so sure that is the case. Robert the stock mounts on mine left a lot to be desired, the factory exhaust had a habit of rubbing on various things so maybe it was bent or the mounts had perished. Either way I would Ideally like to ditch the bend around the gas tank and have it exit straight out so keeping the last two mounts probably wont be an option.

Do you still have the sheetmetal crash structures in the rear? On a stock volvo they push into the rear axle if rear-ended hard. These absolutely must be removed if you want to keep the exhaust from banging into everything.
Fresh motor mounts and exhaust mounts are key. If using stock type motor mounts, some early 80's jaguar xj6 mounts work great. Super stiff, and $13 on Amazon.

We had the straight out the rear exhaust for a bit, but finding a muffler to get it quiet was difficult. You may have better luck. We got pulled over on transit by a sheriff who was pissed at how loud the car was.
So now we use a giant 24in "turbo" muffler in the stock location, and careful planning/routing of the exhaust makes sure it doesn't bang into anything.

Quote

Since this is expanding into multiple volvo related things, any ideas as to why my car has a habit of killing MAF's? Its got bosch lh 2.4, ive checked all the wires going into the maf and everything is ok from what I can tell. Not sure what I am missing at this point.

Are you using remans or genuine Bosch ones? I have really bad luck with remans, so I now grab a genuine bosch one when they come up locally... always have a spare one in the car.
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Eric Ewert
Eric Ewert
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volvo 240


Re: Keeping an exhaust on a rally car
November 17, 2017 08:26AM
Quote
Philippe Bellefleur
Don't see why you say they are not cheap.

https://www.summitracing.com/int/parts/sum-694930/overview/

Or you could use slip joints & springs.

Huh thats reasonable price wise. So its a question of how well they hold together. I can't help but to think they wouldn't take the abuse the underside is subject too. The slip joints and springs is one idea that crossed my mind. Im probably overthinking this as always, I just want something that will work!

With that being said I am fairly certain the second time the exhaust tried to depart was because of failing/ failed motor mounts, which are now fresh. That being said it sits too low, is dented in several spots, too loud and just needs to be redone.

Yes robert the metal crash things are long gone. Also good point on the noise. Im reducing it to a 2.5inch diameter which should shut it up a bit. I would also like a resonator in there as it makes some terrible buzzing at various rpms.

For a maf I had a new partlex one off amazon. Was lured in by the cheap cost but its probably cheap for a reason.



Oh and Vince, I will take a 16v head off your hands if your coming through!
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Robert Culbertson
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Re: Keeping an exhaust on a rally car
November 17, 2017 11:32AM
A "turbo" muffler will cut down on drone a lot compared to a chambered muffler (flowmaster type) since they have a bit of packing in them. But, if you already have a "turbo" muffler....

For reference, The 16v rally car just has a 20-24in long 2.5in turbo muffler and you don't even need intercoms on transits.

For v-bands, you want to hide them from damage. We have one on the over-axle section of the car, it helps a bit with removal and install.
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Vincent Gagnon
The same thing that I just wrote
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Volvo 740



Re: Keeping an exhaust on a rally car
November 17, 2017 01:52PM
Quote
Eric Ewert

With that being said I am fairly certain the second time the exhaust tried to depart was because of failing/ failed motor mounts, which are now fresh. That being said it sits too low, is dented in several spots, too loud and just needs to be redone.

Now, did you do this?





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Robert Culbertson
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Re: Keeping an exhaust on a rally car
November 17, 2017 02:56PM
Quote
Vincent Gagnon
Now, did you do this?


If you go this route... I like to mount them a bit lower for more exhaust clearance and it makes working on the car much easier.
Untitled by robert culbertson

Or you can keep it simple and use this, Volvo 160 motor mount:
MTC 1206612

Or this, 70s-80s Jaguar XJ6 motor mount:
Uro JLM1009 https://www.amazon.com/URO-Parts-JLM1009-Engine-Mount/dp/B0066RVFJG
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Eric Ewert
Eric Ewert
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Location: Calgary, Ab
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Rally Car:
volvo 240


Re: Keeping an exhaust on a rally car
November 17, 2017 10:50PM
No I have not done that engine mount thing... yet. The v-band in certain spots does make sense for serviceability, granted as long as they hold together. Robert I will be honest I was trying to avoid routing the exhaust like the stock system and instead having it come straight out the back for the sake of reducing two bends in the system, which is ultimately a restriction. However i'm starting to rethink that maybe this is a detail not worth chasing... the stock mounts seem to work for people.
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Vincent Gagnon
The same thing that I just wrote
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Location: Québec
Join Date: 03/12/2016
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Rally Car:
Volvo 740



Re: Keeping an exhaust on a rally car
November 18, 2017 01:54AM
Quote
Philippe Bellefleur
Don't see why you say they are not cheap.

https://www.summitracing.com/int/parts/sum-694930/overview/

Or you could use slip joints & springs.

https://www.summitracing.com/cart/estimateshipping#Estimator

46,02 USD = 58,75 CAD.



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If they don't give you work, ask for bread.
If they do not give you work or bread, then take bread.

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john vanlandingham
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Re: Keeping an exhaust on a rally car
November 18, 2017 10:02AM
Quote
Eric Ewert
No I have not done that engine mount thing... yet.
The v-band in certain spots does make sense for SPEED OF serviceability, granted as long as they hold together.

Robert I will be honest I was trying to avoid routing the exhaust like the stock system and instead having it come straight out the back for the sake of reducing two bends in the system, which is ultimately a restriction.
However i'm starting to rethink that maybe this is a detail not worth chasing... the stock mounts seem to work for people.

restriction schription...poooor baby..Yeah not worth thinking..purge the brain of those thoughts.



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Rx7Kevin
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Re: Keeping an exhaust on a rally car
November 27, 2017 03:01PM
Quote
Philippe Bellefleur
How about v-band? And no, don't use flex joints, they don't last too long in street use so i would expect them to be shit in rally.

I tried that, both of that actually. I could not keep a gasket alive on the rotary no matter what I tried. I think the V-band would have worked great had the car not been so low, one squat in the sand and a stone must have knocked it off and I drove over the exhaust.

The flex section was right behind the v-band - and it got torn to shreds on the bottom quickly causing a huge leak, I even went with a nice vibrant one and only had it 4"

I didn't even get to finish the 1st stage without it failing sad smiley

So next event the slip exhaust will be the ticket, just need to get my hangers right so I'm not relying on the block to support the weight of a huge swinging mass.



1986 Rx7 Non Turbo
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