Help identify: Pre 90s GT Frame & mid 90s GT Frame

[mattooooo]

Hello
unfortunately both bike are broken by now. The pink one got a broken fork. And just recently the aluminium seatpost broke on the red bike broke and its pipe is fused (or corroded) to the frame.
But while looking for a "new" 90s GT for my next couple 1000km i was wondering what i was sitting on all the years.
Can you help me identify? Type and Year?
The pink one probably is form pre 1990. One special thing, it has the rear breaks under the bottom bracket. Its a quite big and unfortunatly kinda rusty frame and i havent found a fork, thats shaft is long enought yet...
The red one i bought from a nice guy for 40€ after the pink one broke some years ago and i just swapped some parts on it. It served me quite some km...but i also have no clue what type/ how old it is...
Maybe someone of you know more

 

[kingoffootball]

I think the combination of ubrake, internal cable routing and integrated seat clamp makes the red one a 1990 Tequesta or 1991 Timberline, unless anyone can suggest another model with that combination. An 1989 Karakoram might also match those features, actually, but I think different dropouts and the cable entering the other side of the top tube.

The pink one is more difficult. I can't think of a GT I've seen with a chainstay mounted ubrake.

Do you have the frame numbers. They would be helpful for me and would also help ID them.

If the only problem with the red one is a stuck seatpost then you could go the caustic soda route.

 

[mattooooo]

Thanks for the reply
Where on the frame do i finde the SN? I could try to look them up in the afternoon.

yeah, multiple people told me to try caustiv soda...but i am hesitant to try. Firstly because its kinda dangerous to handle and i dont have a workshop, would have to do it in the patio of the apartment house i am living in, and i dont have the tools to take out the bottom bracket...but maybe i will reconsider if i dont find a GT replacement in my budget.

 

[kingoffootball]

They should be under the bottom bracket shell, on both sides. The format depends on the age, but usually it has three sections.

I can't find a photo on my laptop, but there are examples on this page of the serial thread.

 

[kingoffootball]

Caustic soda isn't too intimidating (I won't link to my own video, but it's in the thread I linked to above) but is the seatpost is sheared off you will need a tool to take out the bottom bracket.

Depending where you are based, there'll probably be a friendly Retrobiker nearby who's happy to help with the BB tool and possibly the caustic soda application.

 

[mattooooo]

Ah okay, I’ll have a look/will make pictures of the SN when I’m at home…
To be honest, it kinda looked intimidating in your video
I have both the special tools needed to take out the bottom bracket but I’m missing the 32 (or whatever it is) Hexkey to use the tool
If I can find NaOH somewhere this might become a project for the weekend…but I kind worried, that I’ll be spending money on tools and NaOH just for it to not work in the end then I better of in finding another gt bike in better shape…and probably I should rather spend the time on my bachelor thesis not on a bike atm

 

[mattooooo]

so i looked to the SN.
I couldnt find any on the red one...maybe i was repainted? Maybe ill try again when there is more light outside.
On the pink one there is one, or parts of it barely seeable. smth like I1 on the top right, then from left to right 18901? (cant read the last digit) and then 00 an maybe a 7. i marked it with paint in the picture...
can you do something with it?

 

[kingoffootball]

Ah okay, I’ll have a look/will make pictures of the SN when I’m at home…
To be honest, it kinda looked intimidating in your video
I have both the special tools needed to take out the bottom bracket but I’m missing the 32 (or whatever it is) Hexkey to use the tool
If I can find NaOH somewhere this might become a project for the weekend…but I kind worried, that I’ll be spending money on tools and NaOH just for it to not work in the end then I better of in finding another gt bike in better shape…and probably I should rather spend the time on my bachelor thesis not on a bike atm

i think I only paid about £2 for my NAOH from a small local shop Is the topic of your thesis chemistry? Or engineering? If so, this could be relevant

 

[mattooooo]

i flacked of some paint with my thumbail.
the SN is
TM
T8901 0079

so a Timberline from 89?

 

[kingoffootball]

so i looked to the SN.
I couldnt find any on the red one...maybe i was repainted? Maybe ill try again when there is more light outside.
On the pink one there is one, or parts of it barely seeable. smth like I1 on the top right, then from left to right 18901? (cant read the last digit) and then 00 an maybe a 7. i marked it with paint in the picture...
can you do something with it?

For the red one, the repaint might be a bit thick to see one size and the other side is probably also hidden by the cable guide. I'm fairly confident on '90 Tequesta or '91 Timberline though ...... until someone else comes along and corrects me.

For the pink one, the serial number format looks good. The first character should be a T, so T8901 gives us Taiwan (I think probably still Hodaka facotry, even though the stamp later became H to represent that) 89 is the year and 01 in the month. So the frame was made January 1989, making it an 1989 model. The next two digit number probably gives the model, but I don't have enough data for 1989 to say. the final number should be 4 digits, rather than 3, and is just a unique serial number for your frame.

If I deduce any more I'll let you know. all I can say about what might give the model is it is not the same as the Tequesta one I have recorded for 1989.