Author Topic: Re: TEC shocks for '77 CB400F  (Read 736 times)

Offline mattsz

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Re: TEC shocks for '77 CB400F
« on: May 25, 2020, 01:11:33 PM »
I'm looking at getting new shocks - not ready to break the bank at this point, TEC seems to be a popular choice.  I can buy them directly from TEC to fit the CB400F exactly, but including shipping they're well over $100.  I searched ebay, and I found that I can buy some Honda-spec shocks from them there as well, with better pricing: $70-$80, shipped free.

But (isn't here always a "but"?), they don't list the CB400F spec on ebay - they offer shocks for three other models of similar vintage that all have the same length (319mm), but no other specs given (bushing size, spring rate, etc).  Can anyone suggest whether any of these alternatives would work?
  • CB360 CJ360 1974-77
  • CL350 1968-73
  • CL450 1968-1974
« Last Edit: July 05, 2020, 11:09:52 PM by mattsz »

Offline mattsz

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Re: TEC shocks for '77 CB400F
« Reply #1 on: May 25, 2020, 01:30:39 PM »
One of the problems I'm having is that different suppliers claim different lengths as being suitable.  TEC says 319mm is correct.  Dave Silver says the originals were 315mm.  Another site sells Emgo shocks that "fit" the CB400f (and 22 other models) but offers them at 340mm...

Offline Bryanj

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Re: TEC shocks for '77 CB400F
« Reply #2 on: May 25, 2020, 02:12:32 PM »
Girling shocks were all the same length with different springs(but only 2 from memory) accross all the fours

Offline mattsz

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Re: TEC shocks for '77 CB400F
« Reply #3 on: May 25, 2020, 02:30:53 PM »
Girling shocks were all the same length with different springs(but only 2 from memory) accross all the fours

Thanks Bryan!  The models listed above are all twins - any chance they're the same?

Any suggestions of where I might look into what the spring rates were?

Offline Bryanj

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Re: TEC shocks for '77 CB400F
« Reply #4 on: May 25, 2020, 03:02:02 PM »
If CL 450 are right length i might try those, a lot of CB 450 parts were used on 500 four and thats not much different, then again thats two suppositions in a row and they always say if you assume you make an ass out of you and me!

Offline mattsz

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Re: TEC shocks for '77 CB400F
« Reply #5 on: May 25, 2020, 03:07:29 PM »
If CL 450 are right length i might try those, a lot of CB 450 parts were used on 500 four and thats not much different, then again thats two suppositions in a row and they always say if you assume you make an ass out of you and me!

Well, I already know I'm a bit of an ass, but I'd better not drag you down into that category with me!

Offline mattsz

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Re: TEC shocks for '77 CB400F - SORTED
« Reply #6 on: May 25, 2020, 07:39:24 PM »
I contacted TEC Bike Parts through their ebay listing for the CL450 shocks ($69 with free shipping), and asked them for more info about the shocks, including some measurements.  I got a reply back quite quickly - no information, just a question: "Are you trying to fit them to something other than a Honda?"

I decided to come clean and explain why I was interested in these particular shocks, even though I don't have a CL450 - a second quick reply came back: "OK, really simple--they are the same ..."

So I ordered them on the spot.  Not sure why the listings of the same shock for different bikes come and go in their ebay "store," but there you go.  Never hurts to enquire, I guess...

Offline mattsz

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Re: TEC shocks for '77 CB400F - SORTED
« Reply #7 on: July 05, 2020, 11:07:29 PM »
Continuing on...

I just began the process of putting the new Tec shocks on the bike... in all my reading and research here, I've seen many recommendations for them, but never any mention of the mounting points being different widths than the original.  IF in fact my current ones are original, of course!

On my old shocks, the top eye is 22mm across (not including the rubber bushing which protrudes on both sides), and the gap between the lower "mounting fork" sides is about 19.2mm. On the new Tec shocks, the top eye is only 18.2mm across (again, rubber bushing not included), and the lower gap is 21mm.

Does this sound familiar to anyone?  I'm surprised at the difference with shocks that are supposedly direct replacement.  I guess I'll just pack the gaps with some washers?

Or, I wonder if I can switch out the tops of the shocks?  Hmm, probably not...

Offline MrDavo

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Re: TEC shocks for '77 CB400F
« Reply #8 on: July 07, 2020, 12:57:33 PM »
I fitted a pair to my CL450, replacing the originals which had lost their mojo. A huge improvement, but yes, there were subtle differences.



TEC shocks on the right, they came supplied with the washers, which bridged  the gap at the top as the eyes were narrower. The bottom bracket was a little wider, but as there was a locknut welded to the inside bracket, they deformed slightly when I tightened the lower bolt, just enough to be a snug fit without causing any problems.
1969 Honda CL450 'Scrambler'
1974 Kawasaki Z1A (Project)
2005 Harley XL1200R Sportster
1985 Porsche 911 3.2 Carrera Sport

Offline mattsz

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Re: TEC shocks for '77 CB400F
« Reply #9 on: July 07, 2020, 01:03:45 PM »
Thanks MrDavo, that's very helpful!  I think I'll contact TEC and see what they say - maybe they'll have some to send me, or at least let me know what size they are...

Offline mattsz

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Re: TEC shocks for '77 CB400F
« Reply #10 on: July 07, 2020, 07:26:34 PM »
I contacted TEC Bike Parts USA - they said some of the other bikes that those shocks fit use a grab handle on the shock mount, hence the narrower top.  He suggested I just get some m16 washers to fill in the gaps.  Didn't offer any, though - oh well.

To be clear: the mounting nut/washers(s) should hold the shock securely in position, but not actually clamp down on it enough to prevent it from pivoting, yes?  I don't have any original mounting hardware on either side, so I can't compare with what was there...

Offline Bryanj

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Re: TEC shocks for '77 CB400F
« Reply #11 on: July 07, 2020, 08:18:27 PM »
Well they do need to pivot as swing arm moves just not much

Offline mattsz

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Re: TEC shocks for '77 CB400F
« Reply #12 on: July 07, 2020, 09:02:24 PM »
Well they do need to pivot as swing arm moves just not much


Offline mattsz

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Re: TEC shocks for '77 CB400F
« Reply #13 on: August 28, 2020, 11:52:26 AM »
Sorry - more questions about the shocks...

You may recall the bike came to me with bodged mounting hardware securing the tops of both shocks...

http://www.sohc.co.uk/index.php/topic,17461.msg199015.html#msg199015

I'd like to mount the TEC shocks - but I'd like to get an idea of how the original hardware secured the shocks.  My parts book shows a simple acorn nut and single washer - officialy, a "WASHER, PLAIN, 10.3MM."  Can someone tell me the actual inner and outer diameters, and thickness, of this washer?  Is it bigger than the top mount opening that the rubber bushing fits into?

On the advice of the TEC guy, I looked at M16 washers to fill in the gaps left by the narrow top mount of the shock, but they seemed way too big for that purpose - both in thickness (3mm) and in OD (30mm!) - nothing like the size provided with MrDavo's shocks (see his pic above).  I wanted to find a spacer thin enough that I could use one on each side of the mount, to "center" the mount roughly where the original one would be.  The thin stainless steel shim washers I found look more like the size of MrDavo's, and they work well for centering the mount, but their OD is pretty much the same as the opening for the bushing, so while they may keep the bushing well-centered, I don't think they would really keep the shock mount from shifting sideways off the bushing if there's any proper force applied in that direction.  A larger washer against the acorn nut would keep the shock from coming off, of course, but it seems like the shock could be pushed inwards past the washer with the right encouragement.

So - can anyone check the dimensions of that 10.3mm OEM washer (P/N 90527-230-000)?

MrDavo, might you know the dimensions of the spacer washers that TEC provided with your shocks?

Offline mattsz

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Re: TEC shocks for '77 CB400F
« Reply #14 on: September 07, 2020, 01:10:40 PM »
Bump.  Would someone with original hardware be willing to measure the ID, OD and thickness of the washer on the top shock mount?

 

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