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Rear diferential getting pretty hot from exhaust

61K views 123 replies 25 participants last post by  Hunterworks 
#1 ·
I just wanna hear what some of you think about this. I read on the Viking forums where a guy is making heat shields for the rear diffs due to the heat of the exhaust heating them up. I have noticed mine get really hot after I ride a while.. just trying to get some input on the situation... and maybe see if anyone is building anything for the wolverine to deflect some of the heat. Or to see if any of you think it even matters. IMO I would think it would affect the integrity of the rear diff and the oil in it a bit quicker than if it weren't getting hot. I mean they got shields to protect the bottom of the bed looks like they'd stick something above the rear diffs to keep them from getting so dang hot... but that's why I'm out here in the gas field working and not in an office building drawing up schematics for new utv's, atv's, motorcycles etc etc...
 
#5 · (Edited)
Hard to say, seemed too hot to me. I just stuck a temp gun in my truck for the next ride. Weather permitting I will be able to put a good ride in this Saturday and instead of me speculating any more than I already have I'll just shoot it with a temp gun after I put some miles on it. If my memory serves me right the differential that day was to hot for my liking. Hey I hope I'm totally wrong about this! I had the bike stopped some that day at idle for a few minutes at a time and ambient temp down here in LA is pretty warm. Maybe that was it I dunno. I scoped the Viking forum out cause I remembered reading some stuff over there about this and they got a guy over there making heat shields and selling them to what seems to be quite a few of the folks riding the Vikings to fix a similar problem.
 
#12 ·
shoot I dunno it just seems to hot for my taste if its from the exhaust I think it can be fixed if its from the rear diff I dunno what you'd do. The exhaust is near 600 degrees in some places. It started out at 96 degrees and gradually went up I checked it ever 10-15 minutes those pics are the last ones I took then I parked it.
 
#14 ·
Shoot its got me wanting to take it to the dealer tomorrow but I mean what are they gonna do about it haha theres a guy making heat shields for the Viking for the same problem and he took the heat shields up to Yamaha today and told me they'd fit the wolverine I may be getting me some of those.
 
#16 ·
Should I take this thing to the dealer????????? What would yall do haha Im thinking yesssss. We got a Polaris Ranger 800 out here at the plant and you can ride it for ever the exhaust sits right on top of the diff also but you can hold your hand on the diff after a long ride.. it don't get hot like this Yamaha does. If you read the Viking forum they have two diff forums about this same heat issue the whole set up on the Viking is very similar to the wolverine, no surprise. I like this bike a lot but im really not wanting to cook my rear end with just 10 hours on the dang thing.. I ordered some heat shields from this dude they call blue wolf on the Viking forum he said his shields will fit and many with the Vikings have found heat relief on the diff by using this product... you could make them but I aint got time for that... Just anxious to see what the dealership is gonna tell me when I show them those pics. Probably gonna say that it aint a big deal. We shall see.
 
#17 ·
Could it have anything to do with the wet brake parking brake? I know rear diff's that have that get hotter than normal diff's aka Grizzly 450, Brute Force. That does seem hot, but if it was an issue you would think it would be melting seals or making them leak.
 
#18 ·
Talked to one of the guys at the yamaha dealer today a service guy he said that its not uncommon to see 200-400 degrees in there and that the exhaust will be glowing red and the engine can get up to 1200 degrees and that the rear diffs can handle it. So i may slap some heat shields in there when i get em and just forget about it
 
#19 ·
Well, I just ran the shit out of mine for about 20 mins, testing the new JBS sheave setup before I go riding this weekend. My diff was at 159F about 1 minute after stopping(ran to grab gun out of truck). My exhaust was about 210 at the head pipe, and 305 at the can. This is after adding some fuel to the WOT position with my fuel controller last week, as it was very lean. Now, I did the same test before adding fuel, and the exhaust was so hot it was glowing BRIGHT CHERRY RED from the head almost halfway to the can. For a point of reference, here is a table on color temperatures to judge how hot metal is. This is ball park, but gets you close be it stainless, cast iron, etc.
*C----*F---
400 -- 752 -- Red heat, visible in the dark
474 -- 885 -- Red heat, visible in the twilight
525 -- 975 -- Red heat, visible in the daylight
581 -- 1077 - Red heat, visible in the sunlight
700 -- 1292 - Dark red
800 -- 1472 - Dull cherry-red
900 -- 1652 - Cherry-red
1000 - 1832 - Bright cherry-red
1100 - 2012 - Orange-red

As you can see, the exhaust had to be at least 1600-1800F. That is too f*cking hot! That is a LEAN condition for sure. Now, I use to work in engine testing, and we had a ford ecoboost that would hum on an engine stand at 75% load for days. Literally. It would have cherry red head pipes as well, but that is because of the heat soak, nothing else. Under the conditions we see in a real driving environment, there is no reason you should see you head pipe glow, I don't care how thin the stainless is. Unless you are sitting in a mudhole spinning tires for 15 mins with no airflow or something like that, you shouldn't see exhaust temps above bout 1000F. But hey, that's just my opinion...
 
#20 ·
Just curious, has anybody that is taking the readings with the heat gun changed their differential fluid? If you did, what viscosity did you use? Also were you running fast or slow as you noted the rising temperature?

I'd like to share this with my dealer but I'd like additional info to take with me.

Thanks!
 
#25 ·
I'm not far from you chief, so I know it's hot..lol

So far everyone is running a fuel programmer as well. Cvt suck hp, they are seeing 4hp to the wheels 6 more tq So I'm thinking that are likely making about 8 more hp at the crank. That's a sizable gain for the cash, if the temps are lower as well I'd call the exhaust a win. That's my thoughts
 
#27 ·
Well I got the wrap on last night, still waiting on the aluminum plate for the heat guard. I rode it 2 nights ago and seen where the head pipe gets red hot and its not red past where I stopped with the wrap. I didnt want to wrap to much or the whole thing seeing as I dont know if it will last a long time here, I really think the heat shield will help the most. But the wrap where I did should help keep most of the diff cooler and the passenger side shock a lot cooler. I could put my hand 3 inches away from the header after I wrapped it! I may do more or take it off in the future, test ride coming this weekend with it and hopefully have my shield done tonight! I'll keep ya'll informed
 

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