No Power to Rear Wheels

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Garyp

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Hi all.

I am very new to RCs and nitro so sorry if I ask a lot of daft questions.

I have a Savage 25 which has been fitted with a 4.6 engine and I think a 3 speed gearbox, bought it second hank of ebay.

The problem is that I was using yesterday and all was fine until I notice that the car was struggling for traction, the problem was that only the front wheels were providing power. The back wheels would turn when I lifted the car but any pressure on them and they stopped turning, the front wheels had all of the usual power.

With the car back at home with the engine running the rear driveshaft (think that your call it a dog bone) was not turning while the front shaft was spinning as usual.

With the engine off when I turn the front shaft in either direction the rear turns and visa versa.

I was wondering if the brake could be causing this problem as it does not appear to sit securely on the large hex part of the drive shaft, but looking at my sons XL which has a twin disc this doesn't look any better.

Sorry for my poor terminology but I will learn:\

Thanks to anyone who takes the time to answer my querry.

Regards Gary P
 

Scrogg

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I'll bet 10 bucks the pin is missing from one of the input/ output cups on the transmission or the differential.
If everything still spins freely that is the issue.
Loc-tite every metal to metal screw on a Savage. It will rattle itself apart very easily.
 

hpiracing1123

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yepp ur missing one of the pins either in ur tranny or your cup joint. it happend to me like two times.
 

Garyp

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Thanks for the quick replies.

I have just had another look at the car and if I turn the front wheels by hand, I can stop the rear shaft from rotating with my other hand. Doing the same on my sons Savage XL I cannot do this, so I guess that it is a pin inside the gearbox.

I guess that this involves removing quite a lot from the car to remove the gearbox and then opening up the gearbox to replace the pin.

Am I correct in the above asumption and is it adviseable to fit stronger pins?

Thanks
 

Scrogg

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Savage trannies rarely fail, they are the strongest on the market IMO.
Check the hub that the brakediscs are on . There is a grub screw with a pin that goes completely through the hub. It may have snapped or felll out.
If that is not it, look at the rear diff, it has a similar grubscrew in it's hub. Check it as well. If the allen grub screw is still in there, take them out to make sure it's not snapped.
They should be around 3/4" long.
Dumb question, are both rear dogbones still there? This will cause your condition as well.
If it is none of the above, bust out the manual and tear down the tranny. As long as you have the manual out the tranny is easy to work on.
 

olds97_lss

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Basically, what scrogg said, but with circles ;)
2009-0118-SavageHelpDiffTransCup.jpg
 

Garyp

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Thanks for the help, problem fixed.

The grub screw was missing from the rear cup, fortunately my car came with its old gearbox as a spare so I pinched the grub screw from that.

Thanks again for the help and thanks to those who keep forums like this running.

Regards Gary P
 

olds97_lss

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make sure you put a lot of locktite on it. For some reason, the savage cup pins like to fall out. Probably wouldn't hurt to order some up for spares.
 

Scrogg

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Pretty pictures.....god that could have saved me a ton of pecking! Anyways glad you back up and running.
 

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