I have been reading the 3rd gen archives regarding reliability mods, and I have a question: Replacing vacuum hoses is high on the list, but what hose material is the best? I have read of silicone, and Viton, but what about Neoprene (polychloroprene)? Comments or advice anyone?

FYI, our bone-stock '94 PEP has 70 K miles, and I have just ordered a Bonez downpipe/cat converter kit, and Thermotec header wrap. Motivation was a recent emissions test failure (CO just missed spec at 25 mph dyno test condition). I also convinced my wife that her car would last longer if the pre-cat went away. Promised her lower passenger compartment temperature too; hope I didn't lie too much!

---- Bill

 

http://www.hosetechniques.com/

 

Viton would probably be the best, but its expensive, and I'm not sure that it comes in any color besides black. Most people use silicon without any problems (including me). I bought mine from Hose Techniques.

 

Thanks for the tips, folks. Does anyone have any experience with Neoprene in this application? I used to use it for high-temp hose applications years ago, and it was very flexible and long-lasting. Is it out of date? Not as good as silicone?

---- Bill

 

i'd say stick with what works, that would be silicon.

neoprene would be more expensive wouldn't it? I figure silicon to be more flexible as well, and most likely less expensive.

danny

 

Danny,

OK, I'll give silicone a try. Thanks for your response.

---- Bill

 

If you go with silicone definitely go with hose techniques. You do not necessarily need the whole kit. The hose techniques is definitely good stuff.

 

Rated R1,

I planned to do that. However, although I have visited the Hose Techniques website, three times in a row I have tried to access their "Car-specific SVH Kits" page, and all three times, loading that page has crashed my browser (Mozilla 1.1b). So I guess I'll have to call them. Thanks for your input.

---- Bill

 

Viton isn't THAT much more expensive than silicone. It also is much more kink resistant, easier to work with, and is resistant to oil and gas. It is only available in black. A good source is McMasters.

 

I would go with viton. Check out the writeup on this site:
http://www.geocities.com/sdrx7_club/technical.html

7. Neoprene, Silicon, and Viton tubing test Report

 

http://128bitencrypted.com/hosetechn...75493241680832


That is the link for the FD page.

I am having no problems with Mozilla 1.0 RC3

I don't want to think about how much labor it would be to replace all those hoses

 

Thanks again, folks! Now that I've read the pdf files I think I will go with Viton. We keep our cars a long time. Bought my Miata new in '89; not planning on letting it go in the forseeable future. Bought the wife's RX-7 in '94, ditto.

---- Bill

 

I'm thinking of doing the same thing. Is there a Viton "kit" available for the Rx7? So far all I've seen on the McMaster site is hose priced by the foot. Still looking though ...

 

So is there a Viton kit available ?

Thanks,
:-) neil

 

I think the stock hoses may be Neoprene, and we know what happens to those. I remember doing some reading about Neoprene when I was shopping for hose (4-5 years ago), and it seemed to have a lower temp rating than what I thought the temps might be in the "rat's nest" (200+F, maybe even as high as 250F).

Tons of people have used Silicone successfully. It isn't as good as Viton, but it seems to be good enough. That's what I used and it had held up reasonably well, though I do take my car apart a lot and replace hoses sometimes. I've never had one fail, but I just prefer to use new hoses on reassebly. However, I do think Viton is better. Make sure you get thick-walled Viton to avoid kinks, or get samples first to test it out (for kind resistance and sizing) before placing a large order. I tried some thin-walled Viton hose once (because it was cheaper than the thick-walled stuff) and found that it kinked too easily.

Also, zip-ties are pointless for the small hoses. They can be useful when you are installing a hose on a barbed nipple, but they are actually a liability (might slice the hose) for the no-barb, tube nipples. I used them when I first did my hose job. What I found later was that they tended to get very hard and crack, and some had even damaged (cut) the hose they were on. Since that time, I haven't used any zip-ties on the little hoses (unless there was a barb on the nipple) and never had any pop off. I never used any adhesive, either.

-Max

 

Just to reiterate what max said, the viton is best. I have it, and it's a whole lot better than the tired silicone some past owner had installed. But it only comes in the stock-looking black. (Personally, I prefer it that way, and it looks clean)

Neoprene has the worst temp/gas/oil resistance of the lot. If you want to do neoprene, you may, but it will only last a few years before it brittles again. Mazdaformance.com had the whole stock kit for $169 including check valves. That's actually a good deal.

If you buy viton from McMaster.com, make sure you get the right durometer and wall thickness - I picked up a few samples (guessed wrong) and got some really thin stuff that's useless. Hightempsilicone.com has made runs of viton specifically for this task - if you go with 60-75% of the 'kit' size (same runs as Hosetechniques.com) you'll still have plenty and save a load of money. But while you're at it, do get some 1/4" - 1/8" hose connectors because there are a few places on the car where that helps a bunch.

One thing about viton - I always use a touch of saliva to get them installed, but they grip REALLY good and usually require a deft touch with pliers. Zip-ties are totally unnecessary, which is good though. It's also where you're most susceptible to tearing the hose. So I would recommend taking a set of cheap bent- needle-nose pliers and grinding grippy surfaces smooth and rounding all the edges that will touch the hose. I got a set from HarborFreight that I'll be doing it to.

Dave

 

Paging HighTempSilicone or anyone with a Viton hose kit for sale . . .

:-) neil

 

Really, I think going with Viton tubing is just overengineering the problem. If you use good quality silicone vacuum lines, and do a good job with the installation, you WILL NOT have any problems, now or down the road.

In all the years I've been around RX-7's, and with all the MANY feet of silicone vacuum hose I've used and friends have used, I have NEVER seen a hose failure that wasn't attributed to something dumb, like a hose resting on a hot turbine housing or rubbing against a sharp surface. I've never seen one fail from oil vapors, which is the argument for using Viton.

Again, you do need to use HIGH QUALITY hose. The previous owner of my FD replaced all the vacuum lines with cheap, thin-wall silver silicone vacuum hose. It tears VERY easily if you try to remove a line, kinks very easily, etc.

http://www.hightempsilicone.com is a great source for silicone hose - fair price, well-made, and he's active on the forum. It's thick wall and fits great, won't kink, won't tear or burst, etc.

And, yes, I am planning on replacing all the vacuum line on my car - that crappy hose pains me bigtime.

Dale

 

Dale: are the "Hose Techniques" silicone hoses good quality ?

:-) neil

 

I've been using them for ages. I have heard, though, that the newer runs aren't as good as they used to be. HTS's stuff is of top quality, he's available on the forum to answer questions, and his stuff is fairly priced.

But, if I had a pile of Hose Techniques sitting around, or had a deal on it, I'd go for it.

Dale

 

I am going to start another run of Viton after Christmas. I have ordered the compound already but wont arrive until after the holidays. On this run I am going to stock up on 3.5MM for future runs.

"But, if I had a pile of Hose Techniques sitting around, or had a deal on it, I'd go for it."
Need SuperBlue? LOL I have about 30,000 feet left of HT Superblue in 8MM, 10MM, 3.5MM and 4MM. It needs a home. I would blow the 8MM out at $.50/ft if I could find a buyer.

Jim

 

" Need SuperBlue? LOL I have about 30,000 feet left of HT Superblue in 8MM, 10MM, 3.5MM and 4MM. It needs a home. I would blow the 8MM out at $.50/ft if I could find a buyer. " -Jim

how many feet (of each size) is needed?
and how much ($) for everything?

 

This is the kit that we have been selling. Come to find out it may be a little overkill.

40Ft 3.5MM
16Ft 4.0MM
15Ft 6.0MM
4Ft 8.0MM

If you want to pick this stuff up cheap you can find it here:

http://stores.ebay.com/High-Temp-Sil...isplayZ2QQtZkm

The 6MM is a shade darker than superblue though.

As soon as it is gone it will never be made again. Too many complained about it being too purple so we changed our blue color to match our couplers.

Jim

 

Another since new owner. We need to hang on the the special cars... go with Viton, it is made for this apllication and just a nominal amount more.

-Julian

 

Try Samco silicone hose, used on Ferrari and cars along that line.