Knocking sound with manual trans

[70CHRG]

I have a 1970 Dodge charger 440 RT with a 4 speed manual trans. Driving it home yesterday I noticed a knocking noise when accelerating in second gear. The knocking got faster as I accelerated and slowed down as I did. All other gears seem fine. Any suggestions where to start looking. Anywhere I can get info schematics of these transmissions.

 

[493 Mike]

I have a 1970 Dodge charger 440 RT with a 4 speed manual trans. Driving it home yesterday I noticed a knocking noise when accelerating in second gear. The knocking got faster as I accelerated and slowed down as I did. All other gears seem fine. Any suggestions where to start looking. Anywhere I can get info schematics of these transmissions.

It sounds like you have already diagnosed your issue.
Mike

 

[70CHRG]

It sounds like you have already diagnosed your issue.
Mike

Not yet. I guess its inside the trans. Is it likely to be a bearing or gears. I've never had one apart before. I haven't had the car for long and my understanding is the first and second syncros were done not long ago. When I strip it down is it likely to be obvious. Appreciate any thoughts.

 

[493 Mike]

When you pull it out, rotate the input and feel for the issue in second gear. Then pull the side cover and look for tooth issues.
Mike

 

[AR67GTX]

Kind of hard to figure out what could make noise in 2nd gear only but a damaged drive gear tooth is about it. I would order a factory service manual for your car from one of the Mopar parts dealers. Summit has a CD version for cheap but I like the hard copy versions better.

Bishko Automotive Literature 1210 Bishko Service Manual DVDs | Summit Racing

 

[gkent]

Keep in mind that every gear is free-spinning with the cluster at all times. Only when a syncro sleeve is moved does the particular gear lock to the main shaft to drive the output. The fact that its second gear only is strange but my guess would be another syncro not fully disengaging and the teeth are still in contact.

 

[70CHRG]

Finally pulled my trans out today and took the cover off. I think I found the problem. The next thing is understanding the cause. One day it was fine the next it wasn't

 

[Sam69sat]

Check the bottom of the gear box and see what you find besides the broken teeth. Maybe a needle bearing or something was dropped on accident by the rebuilder.

 

[70CHRG]

Nothing else in there apart from the 2 teeth.

 

[70CHRG]

Now I just gotta get my head around what parts to buy and how to identify the correct ones.

 

[70CHRG]

Just starting to research the parts in my trans and would appreciate some knowledge around my main input shaft bearing. Was trying to measure up as to whether I had a 308 or 307 bearing. From what I can gather a 308 is 90mm OD and 40mm Id. 307 is 80mm OD 35mm ID. Measured my bearing and its 90mm OD and 35mm ID. So its neither. Width is 21mm which is what a 307 should be. A 308 is 23mm. There is no numbers on the bearing. Any ideas what I have.

 

[AR67GTX]

Not sure on the bearing but wondered what the counter gear unit looks like. Is it messed up too?

 

[gkent]

Go on Brewers website and look at the various parts. They will have everything. You will be able to match things there, including your bearings.

 

[Sam69sat]

Just starting to research the parts in my trans and would appreciate some knowledge around my main input shaft bearing. Was trying to measure up as to whether I had a 308 or 307 bearing. From what I can gather a 308 is 90mm OD and 40mm Id. 307 is 80mm OD 35mm ID. Measured my bearing and its 90mm OD and 35mm ID. So its neither. Width is 21mm which is what a 307 should be. A 308 is 23mm. There is no numbers on the bearing. Any ideas what I have.

There are specific 308 bearings for these transmissions. If you just look up a 308 bearing online you'll probably see 308SG which measures 90x40. The 308SG8 measures 90x35. Sounds like you have the 308 bearing.

MAIN BEARING #308 3.543" DIAMETER - Mopar A833 4-Speed Transmission & Component Specialists

MAIN BEARING #308 3.543" DIAMETER

www.brewersperformance.com